tomato post-harvest spoilage, causes and use of …
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TOMATO POST-HARVEST SPOILAGE, CAUSES AND USE OF SELECTED
BOTANICAL EXTRACTS IN THEIR MANAGEMENT IN
MWEA, KIRINYAGA COUNTY
MUGAO G. LYDIA (BSC. AGED)
I56/CE/22256/2010
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENT
FOR AWARD OF THE DEGREE OF MASTER OF SCIENCE (PLANT PATHOLOGY)
IN THE SCHOOL OF PURE AND APPLIED SCIENCES KENYATTA UNIVERSITY
(APRIL, 2015)
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DECLARATION
I declare that the work presented in this thesis is my original work and has not been
presented for award of a degree in any other university or for any other award.
Mugao Lydia Gakunyi
Department of Plant Sciences
Signature…………………………………………..Date……………………………….
Declaration by supervisors
We confirm that the work reported in this thesis was carried out by the candidate
under our supervision as university supervisors.
Dr. Jonah Birgen
Department of Plant Sciences
Kenyatta University
Signature…………………………………………..Date……………………………….
Dr. George Kariuki
Department of Agricultural Science and Technology
Kenyatta University
Signature…………………………………………..Date……………………………….
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DEDICATION
To my family who have been my strong pillar of support and inspiration. For you I will
undertake all that is desirable within my reach.
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ACKNOWLEDGEMENTS
I wish to register my sincere and heartfelt gratitude to my supervisors, Dr. Jonah Birgen
from the Department of Plant Sciences, Kenyatta University and Dr. George Kariuki from
the Department of Agricultural Science and Technology, Kenyatta University for their
inspiring guidance, encouragement, keen interest, scholarly comments, and constructive
suggestions throughout the course of the study. Special thanks to Dr. George Kariuki for
facilitating the survey and laboratory work. I also wish to appreciate the Department of
Agricultural Science and Technology, Kenyatta University for providing the laboratory
space for this study.
I am also indebted to Andrew Thuo, Patrick Mbucho and John Gachoki for their tireless
assistance during the survey. I acknowledge farmers in Mwea, Kirinyaga County for
allowing me to interview them and collect samples from their farms. The technical
assistance of Madam Karen Kaaria and Mr. Bonface Nzau is also appreciated. I am also
grateful to Dr. Alex Machocho from Chemistry Department for his assistance in the
analysis of the chemical composition of the plant extracts that were used during the study.
Thanks to Dr. Silas Thuranira from KARLO (NARL) for guiding in data analysis. I’m
grateful to my fellow students; Joyce, Pauline, Simon and Lilian for their constructive
criticism and encouragement. Special thanks to my family for support and patience
during the study period. Above all, I thank Almighty God for giving me knowledge,
patience and strength to accomplish this work.
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TABLE OF CONTENTS
DECLARATION ................................................................................................. ii
DEDICATION ................................................................................................... iii
ACKNOWLEDGEMENTS ................................................................................ iv
TABLE OF CONTENTS ..................................................................................... v
LIST OF TABLES ............................................................................................. ix
LIST OF FIGURES ............................................................................................. x
LIST OF PLATES .............................................................................................. xi
ABBREVIATIONS AND ACRONYMS .......................................................... xiii
ABSTRACT ..................................................................................................... xiv
CHAPTER ONE.................................................................................................. 1
INTRODUCTION ............................................................................................... 1
1.1 Background information of the study ............................................................. 1
1.2 Problem statement and justification ................................................................ 4
1.3 Research questions......................................................................................... 5
1.4 Hypotheses .................................................................................................... 5
1.5 Objectives ...................................................................................................... 6
1.5.1 General objective ........................................................................................ 6
1.5.2 Specific objectives ...................................................................................... 6
1.6 Significance of the study ................................................................................ 6
CHAPTER TWO ................................................................................................. 7
LITERATURE REVIEW .................................................................................... 7
2.1 Tomato .......................................................................................................... 7
2.2 Medicinal plants .......................................................................................... 16
2.2.1 Garlic ........................................................................................................ 16
2.2.2 Ginger ....................................................................................................... 20
2.2.3 Neem ........................................................................................................ 23
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CHAPTER THREE ........................................................................................... 30
MATERIALS AND METHODS ....................................................................... 30
3.1 Description of the study area ........................................................................ 30
3.2 Survey of post-harvest losses in Mwea ......................................................... 31
3.3 Collection of infected fruit samples and isolation of pathogens .................... 31
3.3.1 Collection of infected fruit samples ........................................................... 31
3.3.2 Isolation of pathogenic fungi and bacteria from rotting fruits .................... 32
3.4 Identification of pathogens ........................................................................... 33
3.4.1 Fungal identification ................................................................................. 33
3.4.2 Bacterial identification .............................................................................. 34
3.5 Pathogenicity test ......................................................................................... 34
3.6 Susceptibility of the cultivars to post-harvest diseases .................................. 36
3.7 Plant materials ............................................................................................. 37
3.7.1 Preparation of plant crude extracts ............................................................ 37
3.7.2 Chemical analysis of crude plant extracts .................................................. 38
3.7.3 Effects of crude plant extracts on growth of fungal mycelia and bacterial
colonies ............................................................................................................. 39
3.7.4 Effects of plant extracts on post-harvest tomato disease development ........ 40
3.8 Data analyses ............................................................................................... 41
CHAPTER FOUR ............................................................................................. 42
RESULTS ......................................................................................................... 42
4.1 Tomato post-harvest losses survey in Mwea, Kirinyaga County ................... 42
4.1.1 Tomato cultivars grown in Mwea, Kirinyaga County ................................ 42
4.1.2 The maturity state of tomatoes at harvesting time ...................................... 43
4.1.3 Harvesting time of tomatoes ...................................................................... 43
4.1.4 Treatment of tomato fruits after harvesting ................................................ 43
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4.1.5 The source of labor used for picking tomatoes........................................... 44
4.1.6 Grading ..................................................................................................... 44
4.1.7 Packing ..................................................................................................... 45
4.1.8 Duration between harvesting and collection of fruits by the buyers ........... 46
4.1.9 Means of transporting tomato to the markets ............................................. 46
4.1.10 Marketing of the produce ........................................................................ 47
4.1.11 Number of days taken to sell the tomato at the market ............................. 47
4.1.12 Losses due to different handling methods after harvesting ....................... 48
4.1.13 Common pests damaging tomatoes in Mwea ........................................... 50
4.1.14 Common tomato post-harvest diseases in Mwea ...................................... 50
4.1.15 Estimation of post-harvest losses due to different post-harvest factors ..... 51
4.2 Isolation and identification of pathogens associated with post-harvest
losses ................................................................................................................. 52
4.2.1 Geotrichum spp. ........................................................................................ 52
4.2.2 Curvularia spp. ......................................................................................... 53
4.2.3 Bipolaris spp. ............................................................................................ 54
4.2.4 Fusarium spp. ........................................................................................... 56
4.2.5 Botrytis spp. .............................................................................................. 57
4.2.6 Rhizopus spp. ............................................................................................ 58
4.2.7 Erwinia (Pectobacterium) ......................................................................... 59
4.3 Pathogenicity test ......................................................................................... 60
4.4 Determination of tomato fruit damage by the isolated pathogens .................. 61
4.5 Susceptibility of tomato cultivars to selected post-harvest pathogens ........... 63
4.6 Anti-microbial compounds from selected plant crude extracts ...................... 63
4.6.1 Ginger crude extract .................................................................................. 63
4.6.2 Garlic crude extract ................................................................................... 64
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4.6.3 Neem crude extract ................................................................................... 65
4.7 Efficacy of crude plant extracts on selected tomato post-harvest pathogens .. 66
4.7.1 Fusarium spp. ........................................................................................... 66
4.7.2 Geotrichum spp. ........................................................................................ 68
4.7.3 Rhizopus spp. ............................................................................................ 71
4.7.4 Comparison of efficacy of different extracts on the test fungal pathogens.. 74
4.7.5 Efficacy of crude plant extracts on Erwinia (Pectobacterium) ................... 75
4.7.6. Comparison of efficacy of different extracts on Erwinia spp. ................... 77
4.8. Efficacy of crude extracts in controlling tomato rots ................................... 77
CHAPTER FIVE ............................................................................................... 79
DISCUSSION ................................................................................................... 79
5.1 Tomato post-harvest losses survey in Mwea................................................. 79
5.2 Pathogen isolation, identification and pathogenicity test............................... 83
5.3 Determination of fruit damage by the isolated pathogens on the cultivars ..... 84
5.4 Plant extracts compounds ............................................................................. 84
5.5 Effects of the extracts on the test pathogens ................................................. 85
CHAPTER SIX ................................................................................................. 90
CONCLUSIONS AND RECOMMENDATIONS .............................................. 90
6.1 Conclusions ................................................................................................. 90
6.2. Recommendations....................................................................................... 91
REFERENCES .................................................................................................. 92
APPENDICES ................................................................................................. 110
Appendix I: Questionnaire ............................................................................... 110
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LIST OF TABLES
Table 2.1 Production of tomato in selected counties in Kenya .............................. 9
Table 4.1 Tomato cultivar grown in Mwea ........................................................ 42
Table 4.2 Maturity state of tomatoes at harvesting time ..................................... 43
Table 4.3 Duration between harvesting and collection of fruits by the buyers .... 46
Table 4.4 Time taken to sell the tomato at the market in Mwea .......................... 48
Table 4.5 Tomato losses due to decay in Mwea ................................................. 49
Table 4.6 Loss due to poor grading .................................................................... 50
Table 4.7 Common pests damaging tomatoes in Mwea ...................................... 50
Table 4.8 Estimation of post-harvest losses ........................................................ 51
Table 4.9 Pathogens isolated from infected tomato in Mwea .............................. 52
Table 4.10 Comparison of rot diameter caused by different pathogens on tomato
Cultivars (Kilele and Roma) ............................................................. 62
Table 4.11 Cultivar susceptibility to rots ............................................................ 63
Table 4.12 Anti-microbial compounds from ginger crude extracts .................... 64
Table 4.13 Anti-microbial compounds from garlic crude extracts ...................... 65
Table 4.14 Anti-microbial compounds from neem leaf crude extract .................. 66
Table 4.15 Efficacy of crude extracts on radial growth of Fusarium spp ............ 67
Table 4.16 Efficacy of crude extracts on radial growth of Geotrichum spp ......... 69
Table 4.17 Efficacy of crude extracts on radial growth growth of Rhizopus spp. 72
Table 4.18 Efficacy of crude extracts on the test fungi ....................................... 75
Table 4.19 Efficacy of crude extracts on the C.F.U of Erwinia spp .................... 76
Table 4.20 Efficacy of different extracts on the C.F.U of Erwinia spp................ 77
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LIST OF FIGURES
Figure 3.1 A map of Mwea showing the study site…………………………….….….....30
Figure 4.1 Tomato packing materials ……………………………………………………45
Figure 4.2 Means of transporting tomato to the markets………………………………...47
Figure 4.3 Common tomato diseases Mwea…..…………………………………………51
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LIST OF PLATES
Plate 2.1 Tomato production in Mwea ............................................................... 10
Plate 2.2 Garlic bulbs that were used in the study............................................... 17
Plate 2.3 Ginger rhizomes that were used in the study. ....................................... 21
Plate 2.4 Neem leaves and Neem tree where leaves were harvested from ........ 24
Plate 3.1Infected tomato fruits collected from farms and markets in Mwea ........ 32
Plate 3.2 Direct plating of infected tomato tissues in sterile PDA plates ............. 33
Plate 4.1. Ungraded tomato fruits in a farmer’s farm in Mwea. .......................... 44
Plate 4.2 Tomato fruits in plastic crate lined with a paper carton ........................ 45
Plate 4.3 Geotrichum spp. colony growing on PDA and arthroconidia ............... 53
Plate 4.4 Colonies of Curvularia spp. growing on PDA and mycelia ................. 54
Plate 4.5 Bipolaris spp. colony growing on PDA and the conidia ....................... 55
Plate 4.6. a Fusarium spp. growing on PDA ...................................................... 56
Plate 4.6.b Macroconidia, microconidia and mycelia of Fusarium spp ............... 57
Plate 4.7 Botrytis spp. growing on PDA and mycelia and conidia. ..................... 58
Plate 4.8 Rhizopus spp. growing in PDA ............................................................ 59
Plate 4.9 Micrograph of Erwinia cells and Bacterial colonies reverse. ................ 59
Plate 4.10 Tomato fruits inoculated with Pathogens ........................................... 61
Plate 4.11 Growth of Fusarium spp. on PDA amended with varying
concentration of garlic crude extract ............................................... 67
Plate 4.12 Growth of Fusarium spp. on PDA amended with varying
concentration of ginger crude extract ............................................ 68
Plate 4.13 Growth of Fusarium spp. on PDA amended with varying
concentration of neem leaf crude extract ....................................... 68
Plate 4.14 Growth of Geotrichum spp. on PDA amended with varying
concentration of garlic crude extract .................................................. 70
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Plate 4.15 Growth of Geotrichum spp. on PDA amended with varying
concentation of neem leaf crude extract ............................................ 70
Plate 4.16 Growth of Geotrichum spp. on PDA amended with varying
concentrationof ginger crude extract ................................................. 71
Plate 4.17 Growth of Rhizopus spp. on PDA amended with varying
concentration of ginger crude extract ................................................ 73
Plate 4.18 Growth of Rhizopus spp. on PDA amended with varying
concentration of neem leaf crude extract ........................................... 73
Plate 4.19 Growth of Rhizopus spp. on PDA amended with varying
concentration of garlic crude extract .................................................. 74
Plate 4.20 Efficacy of Garlic crude extract on the tomato fruits .......................... 77
Plate 4.21 Efficacy of Ginger crude extract on the tomato fruits ......................... 78
Plate 4.22 Efficacy of Neem crude extract on the tomato fruits .......................... 78
xiii
ABBREVIATIONS AND ACRONYMS
ANOVA Analysis of variance
AVRDC Asian Vegetable Research Development Centre (World
Vegetable Centre)
CD Colony diameter
CFU Colony forming units
DMC Dichloromethane
FAO Food and Agricultural Organization
GC Gas chromagtography
GC-MS Gas chromatography – mass spectrometer
HPLC High Performance Liquid Chromatography
HCDA Horticultural Crop Development Authority
KALRO Kenya Agricultural and Livestock Research Organisation
PDA Potato dextrose agar
pH Potential of hydrogen ion concentration
NA Nutrient agar
SNKT Students – Newman – Kuels Test
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ABSTRACT
Tomato is an important vegetable crop in Kenya. It is widely grown for home
consumption and for sale. The demand for fresh tomato is high both for domestic use and
markets. However, tomato post-harvest losses are a threat to the harvested tomatoes.
There is no well documented current knowledge on the nature and status of post harvest
losses on tomato in Kenya particularly with regard to pests and diseases. In areas where
post-harvest losses have been documented the figures vary considerably such that their
usefulness is short lived. Periodic surveys are therefore necessary to help understand the
severity of losses in a specific place at a specific time. The aim of this study was to carry
out a survey on the post-harvest losses of tomato in Mwea, Kirinyaga county and
document pests and diseases contributing to the same. The study also aimed at evaluating
the efficacy of some selected plant crude extracts against four major post-harvest tomato
damaging pathogens. The target tomato cultivars were those commonly grown by the
farmers in the target areas. A survey was carried out to access the current status and
causes of post-harvest losses. Factors such as cultivar disposition to diseases, means of
transport to the market, distance to the market, source of labour for harvesting, packing
containers, time lag in the market, pest and disease attacks were investigated. Disease
causing micro-organisms that were suspected to cause the post-harvest damage were
isolated, identified and re-inoculated to wounded surface sterilized fresh harvested ripe
tomato to establish pathogenicity. Crude plant extracts from neem leaves, garlic bulbs and
ginger rhizomes were tested for the control of the most potent fungal and bacterial
pathogens. An in vivo experiment was carried out where healthy ripe tomato fruits were
dipped into the selected crude plant extracts and disease development on them monitored
and compared with the untreated tomato samples. Data was analysed using SPSS and
SAS One way ANOVA and means separated using Students – Newman – Kuels Test. The
survey revealed that factors such as means of transport to the market, packing containers,
decay of fruits and time lag in the market differed significantly (p<0.001) and contributed
to post-harvest losses that averaged 30.63%. Seven pathogens were isolated from infected
tomato samples and they varied significantly (p<0.001) with Furasium spp. being the
most prevalent (30%). Damage caused by the pathogens on tomato fruits also varied
significantly (p<0.001) with Rhizopus spp. causing (100%) rot. Plant extracts were tested
for their efficacy in controlling four most damaging pathogens where their efficacy
differed significantly (p<0.001) with garlic extracts being the most effective. The in vivo
study demonstrated that the extracts could be applied to control the rots on the tomato
fruits. Results of this study showed that plant extracts had antimicrobial compounds such
as linalool, geraniol, nimonal, diallyl disulphide, azadrachtin that acted against the test
pathogens and can be an important step in developing plant based bio-pesticides for the
management of fruit rots because the plants are readily available, affordable and
environmental friendly. The study recommends that farmers shorten the distance between
harvesting and collection time to reduce chances of fruit exposure to the pathogens.
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CHAPTER ONE
INTRODUCTION
1.1 Background information of the study
Tomato (Solanum lycopersicum L.) belongs to the family solanaceae and it is an annual
sub-tropical fruit vegetable crop. The crop originated from South America and was
introduced to Europe in the 16th Century and later to East Africa by colonial settlers in
early 1900 (Wamache, 2005). In Kenya, tomato plays a vital role in meeting domestic and
nutritional food requirements, generation of income, foreign exchange earnings and
creation of employment (Sigei et al., 2014). The crop is grown for both fresh domestic
and export market but there is increasing demand for processed tomato products (Mungai
et al., 2000).
Tomato production in Kenya accounts for 14 % of the total vegetable produce and 6.72 %
of the total horticultural crops (Gok, 2012). The crop is grown either on open field or
under greenhouse technology. Open field production account for 95 % while greenhouse
technology accounts for 5 % of the total tomato production (Seminis, 2007). Kenya is
among the Africa’s leading producer of tomato and is ranked 6th
in Africa with a total
production of 397,007 tones (FAO, 2012). HCDA 2013 stated that the major tomato
production area in Kenya is Kirinyaga County producing 14 % of the total produce.
Other major tomato producing Counties in Kenya Kajiado (9 %), Taita Taveta (7 %),
Meru (6 %), Bungoma and Kiambu (5 %), Migori and Makueni (4 %), Homa bay and
Nakuru (3 %) and Machakos (2 %).
2
Tomato crop does well in warm climate with an altitude range of 0 – 2100 m above sea
level. It requires rainfall ranging between 760 mm to 1300 mm and deep fertile loam soil
that is well drained, with high content of organic matter and a pH ranging between 5-7
(Rice et al., 1994). Fruits are used in salads or cooked as a vegetable, processed into
tomato paste, sauce and puree. The nutritional value of tomato makes it a widely accepted
vegetable by consumers. Fruits are rich in calcium, phosphorus, magnesium, copper,
niacin, iron, folate, Vitamin A, B6, Vitamin E, Vitamin B2, Vitamin C, iron and
carbohydrates (Wamache, 2005). Furthermore, the fruit has medicinal value as a gentle
stimulant for kidneys, and washing off toxins that contaminate the body systems. It
improves the status of dietary anti-oxidants (lycopene, ascorbic acid and phenols) in diet
(George et al., 2004). Tomato juice is known to be effective for intestinal and liver
disorders (Wamache, 2005).
Tomato production is constrained by factors such as poor pre-harvest practices, adoption
of poor production techniques, rough handling and moisture condensation causing
pathogen infestation (Kader, 1992). Packaging in bulk without sorting and grading of
produce, damage during transport and storage due to mechanical injuries are other factors
contributing to post-harvest losses (Kader, 1992). Inadequate storage, distance and time
consuming market distribution, poor access to the market, post-harvest spoilage micro-
organisms and cultivars disposition to diseases causes high post-harvest losses of
tomatoes (Kader, 1992).
3
According to FAO (2002), records of post-harvest losses do not exist and if available they
do not cover enough period of time and the figures are only estimates made by observers.
It has been estimated that 20-50 % of tomato fruits harvested for human consumption are
lost through microbial spoilage while other losses result from damage by dynamic
stresses during transit, and through rough handling during loading and unloading (Kader,
1992; Okezie, 1998). Thirupathi et al. (2006) estimated the magnitude of post-harvest
losses in fresh fruits to be 25-80 %. Post-harvest decay remains a major challenge in
tomato production. The magnitude of post-harvest losses vary from one country to
another, one season to another and even one day to another (Mujib et al., 2007). There are
numerous micro-organisms that cause post-harvest decay of tomatoes. Among these,
fungi and bacteria are the most destructive.
Most of the tomato fruits are also damaged after harvesting because of inadequate
handling and preservation methods (Wills et al., 1981). Fruits, due to their low pH, high
moisture content and nutrient composition are very susceptible to attack by pathogenic
fungi, which in addition to causing rots, may also make them unfit for consumption by
producing mycotoxins (Stinson et al., 1981; Moss, 2002). Mycotoxins are potential
health hazards to man and animals and in most cases they are unnoticed. Control of fruit
rot also remains a major challenge in tomato production.
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1.2 Problem statement and justification
Tomatoes are an attractive cash crop for small scale farmers and provide potential source
of employment to many rural and urban Kenyans. The tomato fruits have been marketed
freshly picked from the field and is the best selling fresh market vegetable crop (AVRDC,
2006). Despite the human need of tomato, damage as a result of post-harvest spoilage
micro-organisms has been of serious concern. Microbial decay is one of the main factors
that determine losses and compromises the quality of the produce. The extent of the
losses especially through microbial decay has not been quantified in most areas and
where this has been quantified the results are short lived. Periodic surveys may help in
understanding the severity of losses in a specific place and at a specific time. Estimates of
post-harvest losses in Mwea have not been established. Therefore the study aims at
establishing estimates of post-harvest losses in Mwea, Kirinyaga County, identify
pathogens involved in post-harvest decay of tomato fruits and evaluate ways of managing
them using crude plant extracts.
Several kinds of synthetic fungicides have been successfully used to control the post-
harvest decay of fruits and vegetables (Adaskaveg et al., 2004, Kanetis et al., 2007).
However, there are three major concerns: (a) the increasing consumer concern over
pesticide residues on foods which are toxic and carcinogenic, (b) predominance of
fungicide resistant strains of fungi due to excessive use of fungicides, (c) environmental
pollution. Therefore there is need for new effective means of post-harvest disease control
that poses less risk to human health and the environment.
5
Natural plant products and their analogues have been found as important sources of
agricultural bio-pesticides which serve as ant-imicrobial properties of the plant extracts
(Cardelina, 1995; Okigbo, 2009). Arokiyaraj et al. (2008), Shanmugavalli et al. (2009),
Swarnalatha and Reddy (2009), reported that plants are sources of natural pesticides that
lead in new pesticide development. Anti-fungal and anti-bacterial compounds of neem
plant leaf, ginger rhizome, and garlic bulb crude extracts on rot pathogens of post-harvest
tomato fruits were also targeted in this study.
1.3 Research questions
(i) What is the current status and causes of post-harvest losses of tomato in Mwea,
Kirinyaga County?
(ii) Does tomato cultivars grown by farmers influence post-harvest losses?
(iii) What are the effects of the selected plant crude extracts on the major pathogens
causing rots on harvested tomato?
1.4 Hypotheses
(i) Post-harvest decay of harvested tomatoes is not associated with fungi/bacteria.
(ii) Common tomato cultivars planted by farmers have no influence on post-harvest
losses of tomatoes.
(iii) Plant extracts have no effect on the pathogens that cause post-harvest diseases in
tomatoes.
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1.5 Objectives
1.5.1 General objective
To assess and document the causes of post-harvest losses of tomato in Mwea, Kirinyaga
County and evaluate a management strategy using crude plant extracts.
1.5.2 Specific objectives
(i) To determine the status of post-harvest losses in Mwea, Kirinyaga County.
(ii) To determine the biotic causes and the extent of post-harvest losses of tomatoes in
Mwea, Kirinyaga County.
(iii) To determine whether tomato cultivars grown by farmers and post-harvest
handling process influences post-harvest losses.
(iv) To evaluate the effect of the selected crude plant extracts on major micro-organisms
causing post-harvest spoilage.
1.6 Significance of the study
This study provides important information on the current status, causes of post-harvest
losses of tomatoes in Mwea and their management using crude plant extracts. The outputs
of this study will be important in reducing tomato post-harvest losses by improving the
efficiency of post-harvest handling due to better post-harvest management strategies.
7
CHAPTER TWO
LITERATURE REVIEW
2.1 Tomato
Tomato is a climbing, annual fruit vegetable crop. It originated from South America and
was introduced to Europe in the 16th Century and later to East Africa by colonial settlers
in the early 1900 (Wamache, 2005). In Kenya tomato production accounts for 14 % of
the total vegetable produce and 6.72 % of the total horticultural crops (Gok, 2012). The
crop is grown either on open field or under greenhouse technology. Open field production
account for 95 % while greenhouse technology accounts for 5 % of the total tomato
production (Seminis, 2007). Kenya is among the Africa’s leading producer of tomato and
is ranked 6th in Africa with a total production of 397,007 tones (FAO, 2012).
The edible part of the plant is the ripe juicy berry fruit. Its fruits are used in salads or
cooked as a vegetable, processed into tomato paste, puree and sauce. It is rich in calcium,
iron, phosphorus, Vitamin A, Vitamin C and carbohydrates. Red tomato fruits are said to
contain up to 1000 IU (International Units) of vitamin A per 100g of the ripe fruit
(McGraw-Hill, 1987). Tomato fruits are also a good source of proteins but most of it is
found in the seeds. The fruit has medicinal value as a gentle stimulant for kidneys,
washing off toxins that contaminate the body system. The tomato juice is known to be
effective for intestinal and liver disorders (Wamache, 2005). Campbell (1985) stated that
tomato fruit is one of the most perishable vegetables. The crop is grown both for fresh
domestic and export market but there is increasing demand for processed products
8
(Mungai et al., 2000). In Kenya, tomato plays a vital role in meeting domestic and
nutritional food requirements, generation of income, foreign exchange earnings and
creation of employment (Sigei et al., 2014).
The crop is fairly adaptable and grows well in warm conditions. Optimum diurnal
temperatures of 20-27°C day time and 15-17°C at night are required. Day temperatures
above 28°C during flowering are known to cause pollen sterility (Rice et al., 1994). In
the semi arid regions of Kenya, high temperature and reduced humidity leads to both high
fruit set and yields. The most widely used index of tomato fruit maturity is skin color.
The fruit skin color remains green during the fruit development on the plant but as the
fruit becomes mature the blossom end changes to light green or white in color. White
streaks form on the blossom end in the shape of a star. At this stage the fruit is referred to
as being mature green. The color once again changes to pink-yellow and is referred to as
breaker stage. After that the entire fruit color turns to pink, then light red and finally deep
red (Kader, 1992).
The deep red fruits have shorter market life and are more susceptible to bruising during
harvest and post-harvest handling. High humidity and low temperature delay color
formation and ripening as well as increased disease and pest infestation. However,
excessive rainfall can harm a tomato crop, particularly if it is not staked, due to the spread
of leaf diseases. Fruit rarely ripen fully during wet periods and production is generally
higher during the dry season with irrigation. Erratic irrigation may cause cracking and
splitting of the fruit skin. Un-even levels of water application combined with inadequate
9
calcium and potassium in the soil may lead to physiological disorders like blossom end
rot (Rice et al., 1994). Tomato establishes well in soils that are well drained, light loam
with a high content of organic matter and pH of 5 to 7 (Rice et al., 1994). Most of the
regions in Kenya produce tomatoes which are marketed locally. The major tomato
producing Counties in Kenya are Kirinyaga (Mwea area – Plate 2.1) producing (14 %),
Kajiado (9 %) and Taita Taveta (7 %) as shown in table 2.1.
Table 2.1 Production of tomato in selected counties in Kenya
Source: HCDA (2013)
Counties Areas (Ha) Quantity
(Tonnes)
Value
(kshs)Millions
Share by quantity
Kirinyanga
1,978
54,524
1,070
13.7 %
Kajiado 1,551 36,460 990 9.1 %
TaitaTaveta 548 27,400 959 6.9 %
Meru 420 22,214 468 5.6 %
Bungoma 1,022 21,720 887 5.5 %
Kiambu 930 20,972 884 5.2 %
Migori 1,068 18,429 910 4.6 %
Makueni 408 17,552 682 4.4 %
Homabay 803 13,120 638 3.3 %
Nakuru 580 10,990 257 2.7 %
Machakos 314 10,240 357 2.6 %
All counties Total 18,613 397,007 12,840 100%
10
Plate 2.1 Tomato production in Mwea: A - tomato seedlings in the nursery, B - tomato
seedlings in the farm, C - tomato plants with fruits and D - harvested tomato
fruits in the farm.
The produce from these areas are marketed in bigger cities like Nairobi, Mombasa,
Nakuru, Kisumu, Eldoret and other major towns. The rest of the produce is sold by
retailers in the local market centres. The crop is grown for both fresh domestic and export
market but there is increasing demand for processed tomato products (Mungai et al.,
A B
C D
11
2000). The fruit is a highly perishable crop and it has been shown that as high as 50 % of
the produce is lost between rural production and town consumption in the tropical areas
(Oyeniran, 1988). Tomato fruit has a short shelf life as well as high vulnerability to post-
harvest spoilage micro-organisms. Oyekanmi (2007) showed that more fresh fruits are
needed to supply the growing population in developing countries. However as more
produce is transported to non producing areas and as more commodities are stored longer
to obtain a year round supply, post-harvest loss prevention and technology measures
become paramount.
Major factors responsible for post-harvest losses include; poor pre-harvest measures,
poor production techniques (cultivars with low shelf life, imbalanced use of nutrients,
insect pest and disease infestation and abiotic stress), harvesting at improper stage,
improper care at harvesting time, rough handling, moisture condensation causing
pathogen infestation, packaging in bulk without sorting and grading of the produce,
improper transportation and storage. The losses result in low return to growers,
processors and traders (Kader, 1992). During extended storage, tomato fruits are prone to
post-harvest spoilage by various pathogens. The growth and subsequent disease
development of the different micro-organisms on fruits is of varying degree and rate
resulting in deterioration.
One of the most common, and obvious causes of deterioration is fungal activity (Kader,
1992). Jones et al. (1993) reported that in developing countries, commercialization of
tomato fruits is limited by rotting which is caused by Alternaria alternata or Botrytis
12
cinerea. Aworth (1985) also stated that the primary causative agents of microbial post-
harvest spoilage of tomatoes are moulds, bacteria and yeasts. According to Ogawa et al.
(1995), the most important fungi causing post-harvest diseases include; Penicillium spp.,
Aspergillus spp., Alternaria spp., Botrytis cinerea, Monilinia lax, and Rhizopus stolonifer.
Attack by most organisms follows physical injury or physiological breakdown of the
commodity. In a few cases, pathogens can infect apparently healthy tissues and become
the primary cause of deterioration (Kader, 1992). Due to the physiological form of fruits
they deteriorate easily in transit and storage, especially under conditions of high
temperature and humidity and as a result, heavy losses occur (Idah et al., 2007).
Mukaminega (2008) further suggested that post-harvest losses of tomato fruits also occur
on transit due to long distance to markets, poor and inadequate infrastructures and the
method of transportation. The longer the distance from the farm to the market, the longer
the time it will take for the produce to get to the market and so the losses will increase
because of congestion of the tomato fruits and build up of heat. Food supply can be
improved either by an increase in production or reduction in losses. Since many
researchers show that great effort is being made in the area of food production especially
in developing countries, the decline in food production can be traced to food losses. Thus,
reduction in post-harvest losses increases food availability, hence alleviation of food
problems. The effect of post-harvest losses reduces the effect of the efforts put into
production and lowers marketing efficiency (Bautista, 1990; Okunmadewa, 1999).
13
Post-harvest losses range between 4-8 % in developed countries where refrigeration
facilities are well developed to 50 % where these facilities are minimal in developing
countries (Eckert and Ogawa, 1985). According to Agrios (2005), post-harvest diseases
account for about 50 % of losses in fruits stored in poor conditions especially under high
humidity. Evidence shows that such losses tend to be highest in countries where the need
for food is greater. Some authorities put post-harvest losses of sweet potatoes, tomatoes,
bananas and citrus fruits sometimes as high as 50 % (FAO, 2002). Zaldivar (1991)
showed several reports, with losses of figures of 28-42 % worldwide, and 15-60 % in less
industrialized countries.
In developing countries, losses of fruits and vegetables after post-harvest fluctuate
between 20 and 50 % (Kader, 1992; Okezie, 1998). These losses result from damage by
dynamic stresses during transit, and through rough handling during loading and
unloading (Aworth, 1985). This means that half of what is produced never reaches the
consumer. Fruits have high moisture content which makes them very susceptible to
attacks by pathogenic fungi that cause rots, making the fruits unfit for human
consumption due to mycotoxins produced (Stinson et al., 1981; Philips, 1984; Moss,
2002).
Majumder et al. (1997) reported that a sizeable portion of the world population in
developing and under-developed countries of Africa are poor and suffer from health
problems associated with consuming mycotoxin from contaminated grains, cereals, fruits,
and vegetables. Stinson et al. (1981) reported toxigenic fungi isolated from spoiling
14
fruits. During refrigeration some fungi may produce mycotoxins (Tournas and Stack,
2001). Mechanical injuries that occur during harvesting and handling are good sites for
entry of pathogens that cause decay in fruits (Jerry et al., 2005).
Control of tomato fruit rot has been by application of synthetic chemicals. Several types
of synthetic chemicals have been used successfully to control the post-harvest decay of
fruits and vegetables (Adaskaveg et al., 2004; Kanetis et al., 2007). However there are
three major concerns: (a) the increasing consumer concern over pesticide residues on
foods (Wisniewski and Wilson, 1992); (b) the predominance of fungicide resistant strains
due to excessive use of fungicides (Naseby et al., 2000; Rosslenbroich and Stubler,
2000); (c) environmental pollution. Onuegbu (2002), and Ramazani et al. (2002),
concluded that there is increased crop production by use of synthetic chemicals for
management of plant pathogens, pests and weeds but with deterioration of environmental
quality and human health. However, consumers demand less use of chemicals and still
want food devoid of microbial growth, toxins as well as other quality deteriorating factors
(Lingk, 1991).
According to Bull et al. (1997), Paster and Bullerman (1988), synthetic fungicides such
as thiabendazole, imazalil and sodium ortho-phenyl phonate have been used to control
the post-harvest diseases, but their excessive use complemented with high costs, residues
in plants, and development of resistance, has left a negative effect on human health and
the environment. Efficient and effective control of seed borne fungi can be achieved by
use of synthetic fungicides, but the same cannot be applied to fruits and vegetables
15
because of fungitoxic effects (Dukic et al., 2004). Reports by Eckert (1990) showed that
use of chemicals such as thiabendazole (TBZ) and imazalil to control fungi causing fruit
rots has led to low number of natural enemies thus increasing the number of the
pathogens in the environment.
According to Nicholson (2007), the use of synthetic chemicals for controlling mold fungi
in fruit has been counter-productive; causing damage to the environment.There has been
increased demands to reduce the use of the chemicals that accumulate in fruits and
vegetables. Therefore there is need for new and effective means of post-harvest disease
control that poses less risk to human health and the environment. Obi (1999) found out
that many researchers are carrying out research on the use of pesticides and fungicides of
botanical origin as an option to synthetic fungicides. Cardellina (1988) and Gulter (1998)
suggested that natural plant products are important sources of new agricultural chemicals
used in control of insect pests, plant diseases and bird repellants.
Chemicals extracted from plants are known as botanical pesticides. The botanicals
degrade more rapidly than most chemical pesticides, and therefore are less likely to affect
beneficial organisms (Samson, 1984). Bio-control agents with extracts from plants such
as lemon, citronella, clove, mint, thyme, and oregano oils have been used as alternatives
to synthetic pesticides (Samson, 1984). Adaskaveg et al. (2000) and Serrano et al. (2005)
reported the use of garlic as a natural alternative to control Penicillium digitatum. Bashar
and Baharat (1992) reported that lime fruit peel has essential oil to inhibit linear growth
during spore germination of P. italicum, P. digitatum and Geotrichum cadidum. Dushyent
16
and Bohra (1997) studied the effects of eleven different plant extracts on mycelial growth
of Alternaria solani and found that leaf exracts of Tamarix aphylla and Salsola baryosma
totally inhibited the growth of the pathogen in vivo. Reports by Stoll (1988) and
Oparaeke (2007) showed that neem, garlic and ginger extracts contained insecticidal
properties that control a wide range of insect pests such as Maruca vitrata and
Clavigralla tomentosicollis.
Garlic extract also reduced early blight disease on tomato (Wszelaki and Miller, 2005).
According to Karapynar (1989) garlic clove completely inhibited the mycelial growth of
Aspergillus flavus and aflatoxin production. Currently, several promising biological
approaches that include microbial antagonists (Schena et al., 1999; Xi and Tian, 2005)
have been advanced as potential alternatives to synthetic chemicals to control post-
harvest decay of tomato fruits.
2.2 Medicinal plants
2.2.1 Garlic
Allium sativum plant is classified under the family Alliaceae. The plant is hardy and not
easily attacked by pests and diseases. The crop does well in loose, well drained fertile
soils. They can grow closely together leaving enough space for the bulbs to expand and
mature (Bowers and Locke, 2004). There are different kinds of garlic and they occur in
different sizes, color, shape and number of cloves per bulb. Local garlic is usually white
in color (Plate 2.2).
17
Plate 2.2 Garlic bulbs that were used in the study.
Garlic plant has been used as medicine for millennia because of its properties to inhibit
microbial pathogen infections by its organo-sulfur compounds (Lawson, 1998; Ankri and
Mirelman, 1999; Obagwu and Korsten, 2003). Its sharp odour, appetizer property and
bitter taste make it to be used in food. It is also consumed fresh, as pills, capsules and
extracts. Ayaz and Alpsoy (2007) reported that garlic is safe when taken in correct dosage
as it can ulcerate the stomach when consumed in excess amounts. It kills bacteria, fungi,
parasites and lowers glycemia and cholesterol levels in the blood. It has anti-tumor agents
acting against cancerous cells.
Garlic has liver protector properties therefore known to protect the human body against
many illnesses. A. sativum contains a compound known as allicin which is effective
against a wide range of bacterial and fungal species (Stoll, 1998). Cavallito et al. (1944)
reported that the anti-bacterial principle of garlic is diallyl-thio-sulphinate compound
known as allicin. Reports by Stoll and Seebeck (1951) showed that allicin is produced
during the crushing of garlic cloves by the interaction between the amino acid alliin and
18
the enzyme alliinase. Allicin is a precursor of a number of secondary products formed in
crushed garlic and possesses various biological activities.
Cellini et al. (1996) and Lernar et al. (2000) reported that garlic has an anti-bacterial
agent, being effective against many gram negative and positive bacteria like Helicobacter
pylori, E. coli, Lactobacillus casei and this effect is sourced from allicin in it.
Components like bio-flavonoids and sulphur have value in preventing infections. Active
substances of garlic such as allistatin I and allistatin II are powerful against
Staphylococcus and E. coli (Baytop, 1999; Ayaz and Alpsoy, 2007). Imai et al. (1994),
Ayaz and Alpsoy, (2007) pointed out that garlic water had been used in typhoid and
meningitis treatment. Fumes from garlic have been used in treating whooping cough.
Garlic wicks are used to treat yeast infections and garlic soup used to treat pneumonia. It
also controls Candida albicans, Histoplasma capsulatum, Aspergillus, Trichophytum and
Penicillium species (Imai et al., 1994).
It has been demonstrated that garlic extracts can be used in the prevention of gastritis and
stomach cancer which are caused by H. pylori (Limurca et al., 2002). Chopped garlic
added to raw meatball, which is a traditional food product in Turkey had a slowing-down
effect on microbial growth in ground meat depending on garlic concentration (Aydin et
al., 2007). Josling (2001), Hanafy et al. (1994), and Weber et al. (1992) demonstrated
that garlic was effective both against influenza B and herpes simplex viruses. It was also
used successfully against pertinacious virus in horses. They also reported that garlic
19
mobilizes immune system and empowers the defence ability of the body against
infectious organisms.
Garlic has been used against Candida spp., Aspergillus spp. and Cryptococci as an
effective anti-fungal substance (Ayaz and Alpsoy, 2007). It was also observed that a
combination of Amphotericin B which is an anti-fungal treatment for mycoses, with
allicin was a promising strategy for the therapy of candidiasis (Ogita et al., 2009).
Ledezme et al. (1996) carried out a clinical and mycological study made on Tinea pedis
showed that an organo-sulphur component from garlic, a 0.4% cream form was used for
seven days. Caporaso et al. (1983) reported that anti-fungal activity in fresh garlic taken
orally, the antibody forming against Candida and Cryptococcus species are limited.
According to Kurucheve and Padmavathi (1997), garlic extract was used on seeds to
depress the growth of Pythium aphanidermatum by inhibiting hydrolytic enzymes
production by the pathogen. Reports by Upadhyaya and Gupta (1990) showed that
ethanol extracts of garlic had inhibitory effect against Curvularia lunata. According to
Tansey and Appleton (1975), garlic extracts have shown inhibitory effect on the growth
of a number of fungi. Shalaby and Atia (1996), reported garlic to be effective against
Fusarium solani, Rhizoctonia solani, and Sclerotinia sclerotium that causes damping off
in water melon and cantaloupe. According to Portz et al. (2008), allicin component in
garlic is active against a wide range of pathogens both in vitro and in vivo. Curtis et al.
(2004), reported that garlic is effective against Phytophthora infestans on tomato
seedlings. Reports by Bowers and Locke (2000), and Bianchi et al. (1997), showed that
20
garlic extracts inhibit mycelial growth of F. solani and R. solani. According to
Qvarnstrom (1992) only 2-10 % of the leaf areas were infected by Erysiphe
cichoracearum in cucumber plants that were treated with 5 % garlic extract compared to
83-85 % in the control treatment. According to Singh et al. (1995), active compound of
garlic extracts had complete inhibition on conidial germination of E. pisi when applied at
the rate of 25mg/liter and when applied at 100mg/liter the extracts controlled powdery
mildew in growth chamber.
Research by Locke (2006) showed that red garlic contained flavonoids and saponins that
exhibited anti-bacterial properties against Bacillus subtilis. Ayazpour et al. (2010)
revealed that high concentrations of A. sativum leaf extracts increased mortality of
Tylenchulus semipenetrans in laboratory conditions. Fadzirayi et al. (2010) reported that
garlic extract has indirect effect on nematode populations as it disrupts their mobility,
food absorption and reproduction. According to Block (2010), garlic oil offers significant
protection to crops against free-living soil inhabiting nematodes.
2.2.2 Ginger
Zingiber officinale plant is classified under the family Zingiberaceae. It is a creeping
perennial plant with a slender stem. Ginger does well in hot and moist climate with some
shading and loam soils that are well tilled to allow rhizome expansion (Herbs, 2000). It is
usually planted in rows at spacing of 60 cm between the rows and 30 cm between the
plants. It has an underground stem (branched rhizome) which is thickened to form
structure like a swollen hand (Abdel-Azz et al., 2006). The outer skin is brown and is
21
usually removed before use (Plate 2.3). The inner part is yellow in color. Shoots
(pseudostems) arise from buds on the rhizome. The rhizome is consumed as a delicacy,
medicine or spice. It is used extensively for domestic and commercial purposes.
Plate 2.3 Ginger rhizomes that were used in the study.
The demand for ginger rhizomes in the world markets is increasing year by year. The
ginger rhizome has been used in herbal medicine for treatment of catarrh, rheumatism,
nervous diseases, gingivitis, toothache, asthma, stroke, constipation, and diabetes
(Awang, 1992). The rhizomes are used in various industries such as medicine, ready-
made foods and cosmetics. Ginger rhizomes contain volatile oils, phenols, alkaloids, and
mucilage that have some therapeutic benefits (Awang, 1992; Wang and Wang, 2005;
Tapsell et al., 2006). It has been used as traditional medicine for treatment of human
diseases such as inflammation, morning sickness in pregnancy among many others.
Ginger contains anti-viral compounds that give relief against common cold virus
(rhinoviruses). Gingerols, shogaols, gingerdione, and gingerdiol relieve cold symptoms
by reducing pain and fever, suppressing coughing and have sedative effects that
22
encourage rest (Kalra et al., 2011). Ginger can treat migraine headache without any side
effects (Mustafa and Srivastava, 1990). It has anti-oxidants and anticarcinogenic
properties that inhibit production of free radicals thus helping prevent diseases and slow
aging process (Abdel-Aziz et al., 2006). Studies have revealed that ginger can relieve
chemotherapy related nausea. Patients receiving chemotherapy for breast and lung
cancers were given different concentrations of ginger and it was revealed that all ginger
doses relieved nausea (Manju et al., 2005).
Many laboratory experiments have provided scientific support for the belief that ginger
constituents are anti-inflammatory. It contains products that share pharmacological
properties with non steroidal anti-inflammatory drugs (Grzanna et al., 2005). Ginger
components are known to reduce platelet aggregation which leads to coronary artery
disease with no effect on blood lipids or blood sugar (Bordla et al., 1997). It is known to
manage prostate cancer and ovarian cancer (Jeong et al., 2009). Fricker et al. (2003)
reported that ginger extract containing gingerol inhibits the growth of many bacteria and
fungi in vitro.
The extracts have inhibitory effect against Candida albicans that causes candidiasis
(Gugnani and Ezenwanze, 1985; Mascolo et al., 1998; Deboer et al., 2005). Foster and
Yue (1992) reported ginger to have a broad range of biological activities such as anti-
bacterial, anti-convulsant, analgesic, anti-ulcer, gastric anti-secretory, anti-tumor, anti-
fungal, anti-spasmodic and anti-allergenic. Cammarata (1996) reported ginger to have
23
vasodilating property and widely used to increase blood circulation. Ginger rhizome is
also effective against many diseases and pests of cultivated crops (Stoilova et al., 2007).
Krishnapillai (2007) evaluated fungicidal properties of ginger against Fusarium spp,
Colletotrichum spp. and Curvularia spp. and it was effective. Hot water extracts of ginger
were fungitoxic and suppressed the growth of F. oxysporum, A. niger and A. flavus in
culture and reduced rotting of yam tubers (Okigbo and Nmeka, 2005). Reports by
Wszelaki and Miller (2005) showed that garlic extracts reduced early blight of tomato
significantly.
2.2.3 Neem
Azadirachtin indica is classified under the family Meliaceae. It is a drought resistance
plant and requires annual rainfall ranging between 400-1,200 millimetres. It grows in a
wide range of soils but does best in well drained loam soils. Neem is propagated by use
of seeds in the nursery bed and then transplanted to the main field and planted at a
spacing of 8m by 8m (Khann and Wassilew, 1987). It is a fast growing tree that can reach
a height of 15-20 metres. Branches are wide spread forming a broad round crown (Plate
2.4). The tree is usually evergreen but can be deciduous in dry areas. It has an extensive
deep root system which is responsible for their survival in arid and semi-arid areas.
Leaves are pinnate with medium to dark green leaflets (Biswas et al., 2002).
24
Plate 2.4 Neem leaves (A) and Neem tree (B) where leaves were harvested from.
Petioles are usually short, flowers are arranged axillary in more or less drooping panicles
and they are bisexual where male and female parts exist in one flower. The fruit is small
with a thin exocarp while the mesocarp is fibrous and bitter. The endocarp has seeds that
have a brown seed coat. All parts of the plant have a bitter taste and are medicinal. Every
part of the tree has been used as traditional medicine against various human ailments.
Neem leaves, bark and fruits have been known to have a wide range of pharmacological
properties such as anti-bacterial, anti-fungal, anti-ulcer, repellant, pesticidal, ecdysone
inhibitor, anti-feedant, sterilant and molluscicidal properties (Biswas et al., 2002; Das et
al., 2002).
Water soluble crude extract of neem leaves posses hypoglycemic, hypolipidemic, hepato-
protective, hypotensive and anti-fertility properties. Udeinya (1994) reported that neem
extracts reduce the adhesion of cancer cells to other body cells thus preventing the spread
of cancer. The immune system of the body is able to destroy the few cancer cells,
therefore reducing cancer spread. Among the plants analysed as having blood purifying
A B
25
properties, neem was found to have a wide range of beneficial effects (Vohora, 1986).
Chattopadhyay et al. (1992) showed that neem leaf extracts remove toxins from the blood
and gives healthy circulation of blood. The extracts also protect the liver from damage
when toxic agents are used to induce hepato-cellular necrosis. Moreover, studies have
shown that neem extracts can be used to control hepatitis (Unander, 1992).
According to Khan and Wassilew (1987), neem leaves contain compounds such as
gedunin and nimbidol that control fungal attacks in humans such as those that cause
athlete’s foot, ringworms and candida. Azadirachtin compound from neem plant has been
found to have anti-viral, anti-bacterial and anti-fungal properties (Isman et al., 1990;
Harikrishnan et al., 2003). Research activities carried out by Khan et al. (1991) showed
that extracts from neem leaves and seeds have the ability to destroy disease causing
fungi, viruses and parasites. Neem leaves are known to contain compounds such as
triterpenoids (nimbin, Azadirachtin, nimbidine), nimbandial, vepinin, nimbolide,
quercentin, nimbinene, nimbin, nimbicidine, desacetylnimbinase, nimbidol, gedunin,
sodium nimbinate and liminoids (salannin and melintrol) which are anti-hormonal,
repellant, anti-fungal, anti-bacterial and nematicidal.
Aqueous extract of neem leaves have been used in fish farms as an alternative control of
fish parasites and fish fry predators like dragon-fly larvae (Martinez, 2002). Neem acts as
a broad spectrum repellant, insect growth regulator in that it causes deformity in insect
offsprings and it is poisonous to insects. It acts as an anti-feedant to insects by
suppressing their appetite or by making the plants unpalatable to them. The compound
26
azadirachtin has been used as an alternative to chemical pesticides. The compound acts as
anti-feedant, repellant, and inhibitor of ecdysis and growth. Experiments have revealed
that over 250 insect species are susceptible to neem extracts (Kovel et al., 2000). Morgan
and Thornton (1973) extracted azadirachtin from neem fruits which served as anti-feedant
to insects that infested stored grains.
Extracts from crushed neem kernel was said to be effective as a repellant on Sitophilus
oryzae (Jotwani and Sircar, 1965). Pereira (1983) stated that neem oil is effective against
insects of stored grain on cowpea, groundnuts and red gram. According to Mulla et al.
(1999), Nimbin and azadirachtin are the most active insecticidal ingredients in neem and
are present predominantly in leaves and seeds. Gianotti et al. (2008) stated that neem
seed extracts applied on the breeding sites of mosquitoes eradicate the larvae stages thus
reducing their population. Gedunin component is effective in treating malaria.
According to Udeinya et al. (2006), the anti-malarial activity of neem is superior to
chloroquin on faliciparium malaria parasite. The compounds from the tree also have
nematicidal properties. Soil treatment with neem seed effectively controlled Meloidogyne
incognita on tomato (Kovel et al., 2000). Extracts from seeds and leaves caused 100 %
juvenile mortality of the root-knot nematodes and some free living nematodes on the
tomato (Upadhyay et al., 2003). Neem leaf extracts contain flavonoids that are said to be
anti-mycotics (Khan et al., 1988). Neem products also controlled Uncinula necator that
causes powdery mildew in grapevine (Rhe and Schlosser, 1994). Anti-fungal effects of A.
indica were used against yam rot pathogen (R. stolonifer), (Hycenth, 2008).
27
Siva et al. (2008) reported on the use of A. indica in inhibition of F. oxysporum (wilt
pathogen) on egg plant. Control of rice blast in vitro and in vivo was reported by
Amadioha (2000). Paul and Sharma (2002) reported the use of A. indica to control soil
borne pathogenic fungal growth. According to Ehteshamul et al. (1998), soil amendment
with neem seed cake had inhibitory effect against F. solani, Macrophomina phaseolina
and R. solani. Neem oil was reported to inhibit growth of Alternaria alternata. Neem
was also used as a biological control of Fusarium root rot in cucumber (Nahed, 2007).
Hoque et al. (2001) showed that A. indica contains a compound known as mahmoodin
which has an anti-bacterial activity against gram-positive and gram-negative bacteria.
Treatment of banana fruit with aqueous leaf extract of A. indica controlled rot
development with minimum percentage loss in fruit weight (Singh et al., 1993). Leaf
exracts of A. indica inhibited mycelial growth and spore germination of
Helminthosporium oryzae and Pycularia oryzae that causes blast and brown spot of rice
plant (Ganguly, 1994). Patil et al. (2001) reported that neem leaf extract was effective in
controlling early blight and increased yield in tomatoes infected by A. solani. Ethanol
neem leaf extract has inhibitory effect to Phaeoisariopsis personate fungi that cause late
leaf spot of ground nut (Kishore et al., 2001). Aboellil (2007) showed that trilogy, a
natural component from neem was used to reduce growth of Podosphaera xanthii causing
powdery mildew disease on cucumber and increases plant resistance.
28
Srivastava et al. (1997) reported the effectiveness of fungicidal properties of aqueous leaf
extracts of A. indica against A. altanata infecting pear fruits with 85% control of fruit rot
in vivo. Neem ethanol extracts also showed fungitoxic properties against A. brassicola
and F. oxysporum (Chivpuri et al., 1997). Bankole and Adebanjo (1995) reported that
neem leaf extract inhibited the growth of four pathogenic fungi (M. phaseolina, F.
moniliforme, F. Solani, and Botryodiplodia theobromae) in vitro. Meena and Marappan
(1993) also showed the inhibitory effect of neem leaf extract on growth and spore
germination of seed mycoflora such as A. tenuis, A. flavus, C. lunata, F. moniliforme and
R. stolonifer.
Research carried by Pasini et al. (1997) showed that water extracts from neem leaves and
seeds were effective against the fungus Spherotheca pannosa which causes powdery
mildew. Reports by Locke (1995) and Tewari (1991) showed that neem leaf extracts were
effective against many disease causing fungi through addition of the extracts into the soil
or by direct application. According to Sinha and Saxena (1987) neem leaf extract was
effective against tomato rotting caused by the fungus A. flavus and A. niger. Reports by
Ghewande (1989) showed that neem leaf water extract was effective against the fungal
leaf rust of ground nuts caused by P. arachidis.
According to Bhowmick and Vardhan (1981), neem leaf extracts reduced the growth of
C. lunata and also resisting fruit rotting in cucurbitaceae caused by F. equisitifolium.
Alabi and Lorunju (2004) showed that neem seed extract inhibited development of
groundnut late spotting disease. According to Suresh et al. (1994), nimbidin component
29
found in neem seeds was effective against F. oxysporum, A. tennis, R. nodulosum and C.
tuberculata. Dwivedi and Shukla (2000) stated that the mycelial growth inhibition rate
increased with increase in plant extract concentration.
30
CHAPTER THREE
MATERIALS AND METHODS
3.1 Description of the study area
The study was carried out in Mwea, Kirinyaga County (Fig. 3.1). Mwea is a semi arid
region at an altitude of 1100 metres above sea level. Rainfall ranges from 800-2200 mm
annually and is received in two seasons. The annual temperature ranges between 9.7-
21.6°C. The type of vegetation in the area is savanna grassland and woodland. Farmers
in Mwea specialize in production of food and horticultural crops. For horticultural crops,
tomato cultivation is widely practiced for both domestic and commercial purposes.
Figure 3.1 A map of Mwea showing the study site. (Source: Google maps)
31
3.2 Survey of post-harvest losses in Mwea
A survey was carried out in Mwea area of Kirinyaga County in December 2012 to collect
tomato fruit samples and to determine the causes of the post-harvest losses in the area.
Structured questionnaires were used to gather information on the factors that contribute to
post-harvest losses (Appendix I). Random sampling was used to determine the sample
size of the farmers that were interviewed by use of the questionnaires. A sample size of
sixty eight (68) farmers was selected and interviewed. The sample size was determined
using the formula n= N
1+ N(e)2.
Information collected sought to understand the extent of losses, packing materials, means
of transport, grading, time the crop takes in the farm before collection, pests, spoilage
micro-organisms and source of labor for harvesting. Post-harvest losses were estimated
by adding the average losses from the post-harvest handling processes. The post-harvest
handling processes that caused losses were; poor grading, transportation and packing.
3.3 Collection of infected fruit samples and isolation of pathogens
3.3.1 Collection of infected fruit samples
Farms and market centres in Mwea area were targeted for the survey. Infected tomato
fruit samples were identified by physical examination and then collected randomly from
the local markets like Red soil, Kimbimbi, Mutithi, Rurii, Mbui Njeru, and Ngurubani
and from the individual farms (Plate 3.1). One hundred and fifty (150) fruits with various
rot symptoms were collected, placed in polythene bags and brought to the Agricultural
32
Science and Technology Departmental Laboratory, Kenyatta University for processing
and further analysis.
Plate 3.1 Infected tomato fruits collected from farms and markets in Mwea
3.3.2 Isolation of pathogenic fungi and bacteria from rotting fruits
Potato dextrose agar (PDA) and Nutrient agar (NA) were the standard media used to
isolate the fungal and bacterial pathogens respectively from the fruits. The infected
tomato samples were first washed under a running tap, then dipped into 1 % Sodium
Hypochlorite to surface sterilize for three minutes and rinsed in three changes of sterile
distilled water. They were then blotted dry by using sterile blotting paper.
For fungal isolation, direct plating method was used. A sterile scalpel was used to cut 3
mm x 3 mm sections of tissue from the tomato moving from the healthy portions to the
decayed portion where the pathogens are likely to be more active. The pieces were dried
using sterile filter paper to dry the juice. The dried infected tissues were directly plated on
33
sterile PDA and then incubated in the laboratory at room temperature (25°C) for 5 days
(Plate 3.2). For bacteria isolation, a sterile loop was used to get some cells of the fruit
tissue and streaked on the NA in petridishes. Colony formation was observed after the
second day.
Plate 3.2 Direct plating of infected tomato tissues in sterile PDA plates.
After incubation fungal and bacterial colonies of different shapes and colors were
observed on the plates and were re-isolated and sub-cultured on separate sterile media.
3.4 Identification of pathogens
3.4.1 Fungal identification
Fungal identification was done using morphological characteristics and comparing with
established keys (Barnnet and Hunter, 1999). Each isolate was subjected to colony and
microscopic examinations during which their morphological features were observed and
recorded. Identification of the fungi was based on growth patterns, color of mycelia and
microscopic examinations of vegetative and reproductive structures.
34
3.4.2 Bacterial identification
The bacteria were first identified using colony color and morphology on nutrient agar
(NA) according to Schaad (1980). Gram staining (De Boer and Kelman, 1975) was done.
Incubation test on potato tuber slices was also carried out. Single colonies of the bacteria
were transferred from NA to 10 ml sterile distilled water and serial dilution was done to
obtain a cell density of 108 CFU ml
-1. Sterile filter paper disks (5 mm in diameter) were
immersed in the bacterial isolate suspension for five minutes. Potato tuber of uniform size
was washed in running tap water; surface sterilized in 1 % NaoCl solution for three
minutes and then rinsed with three changes of sterile water. It was blotted dry using
sterile blotting paper and cut longitudinally into slices of about 5 mm. Slices were placed
in a sterile petridish with 5 mls of sterile water and the 5 mm filter paper disc with the
bacterial suspension placed at the centre of each of the potato tuber slices. A control was
set with the sterile filter discs dipped in sterile distilled water. Soft rot development was
observed after five days where the filter paper discs were removed and the rotting zone
diameter was observed to confirm the pathogenicity.
3.5 Pathogenicity test
Pathogenicity test was carried out using the techniques described by Okigbo et al. (2009).
Healthy tomato samples were obtained from the farmers in Mwea, and brought to
Agricultural Science and Technology Laboratory at Kenyatta University in polythene
bags. The tomatoes were then washed under running tap to eliminate dirt from their
surfaces. They were surface sterilized in 1 % NaoCl for three minutes. Thereafter, they
35
were rinsed in three changes of sterile distilled water and wiped dry using a sterile
blotting paper.
A sterile five (5) mm cork borer was used to punch the tomatoes and the discs removed.
The same size of the cork borer was used to cut sections of each of the cultures of the
previously isolated fungal pathogens and the discs were used to inoculate the healthy
wounded tomatoes (Elmougy et al., 2004). The wound on the inoculated tomatoes was
sealed using sterile transparent adhesive tape. The negative control was also set in the
same manner but sterile PDA was used without fungal cultures. Three tomatoes were
placed in each sterile polythene bag as a treatment, replicated four times and stored at
room temperature (25°C) in the laboratory. Disease development was checked after two
days. The pathogens were re-isolated and identified as described earlier.
For bacterial isolates a sterile loop that had been dipped into the culture isolate was used
to introduce the bacteria into wounded healthy tomatoes. The negative control was also
set in the same manner but sterile NA was used without bacterial cultures. Three tomatoes
were placed in each sterile polythene bag, replicated four times and stored at room
temperature in the laboratory. Disease development was checked after two days. The
pathogens were isolated and identified as described earlier.
36
3.6 Susceptibility of the cultivars to post-harvest diseases
Two tomato cultivars (Kilele F1 and Roma VF) were the most common cultivars planted
by farmers in Mwea during the period of this study and hence they were the ones selected
for further experiments. The fruits of the two different cultivars were obtained from the
farmers’ farms in Mwea, carried in polythene bags and brought to the Agricultural
Science and Technology laboratory at Kenyatta University. The samples were washed
under running tap water and surface sterilized in 1 % NaoCl for three minutes. They were
then rinsed in three changes of sterile distilled water and dried using sterile blotting
paper. A cork borer of 5 mm diameter was used to make holes on the fruits. Five (5) mm
fungal discs and bacteria colonies respectively were inoculated as described above.
Three tomato fruits were inoculated with the same pathogen to constitute a treatment and
each treatment replicated four times. Sterile transparent adhesive tape was used to cover
the holes made on the fruits. The three fruits were placed in sterile polythene papers tied
with rubber bands and incubated in the laboratory at room temperature. Susceptibility of
the cultivars to disease development was determined by the second day by measuring the
diameter of the infected tissue (rot) from each of the samples inoculated with different
disease pathogens in different cultivars.
37
3.7 Plant materials
3.7.1 Preparation of plant crude extracts
Crude plant extracts were obtained from neem leaves, garlic cloves and ginger rhizomes.
The extraction process followed the procedure described by Handa et al. (2008). Neem
leaves were collected from Kenya Agricultural and Livestock Research Organisation
(KALRO) station in Embu and brought to Kenyatta University Plant Sciences Laboratory
for drying. The leaves were washed under tap water, rinsed in three changes of sterile
distilled water and dried using sterile blotting paper. They were then placed in the oven
and dried at a temperature of 40°C for three days. Ten ginger rhizomes and ten garlic
bulbs were bought from Mwea market and brought to the same laboratory. Garlic cloves
were peeled, washed in sterile distilled water and dried using sterile blotting papers. They
were then cut into smaller pieces and placed in the oven to dry at a temperature of 40°C
for three days.
Ginger rhizomes were also washed under tap water and rinsed in three changes of sterile
distilled water. They were blotted dry using sterile blotting papers, peeled, cut into
smaller pieces and placed in the oven at the same temperature for three days. The neem
leaves were then ground to powder by use of a sterile mortar and pestle so as to rapture
leaf tissues and cell structures to release the active cell contents. The extracts were placed
in sterile specimen bottles. The ginger and garlic were also ground into powder by use of
a sterile motor and pestle and placed in the sterile specimen bottles. This was done to
maximize the surface area which in turn enables the mass transfer of active ingredients
from the plant material to the solvent.
38
Fifty (50 gms) of each of the powder were put into separate sterile conical flasks and 150
ml of methanol added to each of the plant powder ensuring that the powder was
completely immersed into the solvent, then shaken vigorously and allowed to stand on
the bench at room temperature but shaken at different intervals for two days. A sterile
funnel was placed into a 500 mls conical flask and then a Whitman’s (No.2) filter paper
was folded and placed into the funnel. The extract was poured gradually into the filter
paper and allowed to trickle into the conical flask. The filtrate was then poured into
sterile universal bottles.
The crude extracts in the universal bottles were placed in a vacuum evaporator for 60
minutes at 50°C to concentrate the extracts by evaporating the solvent. The concentrated
crude extracts were dried in an oven at 40°C for two days until a powder like substance
remained at the bottom of the universal bottles. The labeled universal bottles containing
the powder were stored in the refrigerator at 4°C.
3.7.2 Chemical analysis of crude plant extracts
The HP 5890 series II Gas Chromatograph interfaced to a 5973 Mass Selective Detector
(MSD) and controlled by HP Chemstation software (version b.02.05, 1989-1997) was
used. The chromatographic separation was achieved using a HP5-MS capillary column
(30.0 m x 250 m x 0.25 m). The column stationary phase comprised of 5:95% diphenyl:
dimethylpolysiloxane blend. The operating GC condition was an initial oven temperature
of 35 °C for 3 min, then programmed to temperature of 280 °C at the rate of 10°C/min,
39
and then kept constant at 280°C for 23 min. The injector and detector temperatures were
set at 270 °C and the carrier gas was nitrogen flowing at a rate of 1.2 ml/min. The mass
spectrometer was operated in the electron impact mode at 70 eV. Ion source and transfer
line temperature was kept at 280 °C.
The mass spectra were obtained by centroid scan of the mass range from 40 to 800 amu.
Samples of 3.0 g garlic bulb powder, ginger rhizome powder, and powdered neem leaves
were dissolved separately in 5 ml of Dichloromethane (DCM). They were shaken and
mixed using the ultra sound path for 3 min, then filtered using glass wool. The sample
was drawn into small vials and then 1 µl was injected into the GC-MS for analysis.
Identification of the constituents was done on the basis of retention index, library mass
search database (NIST & WILEY) and by comparing with the mass spectral data.
3.7.3 Effects of crude plant extracts on growth of fungal mycelia and bacterial
colonies
The effectiveness of the crude extracts in controlling rots was evaluated with the four
most damaging pathogens as determined during the pathogenicity tests. These were:
Fusarium spp., Rhizopus spp., Geotrichum spp. and Erwinia spp. The experimental
design was a completely randomized design, replicated four times. The method of
Amadioha and Obi (1999) was used to determine the effects of the crude extracts on the
fungi. Different concentrations of the crude extracts were prepared by weighing
separately 1 mg, 2 mg and 3 mg of ginger, garlic and neem powder respectively. Each
powder was dissolved in 1ml sterile distilled water to form solutions of different
concentrations. A hundred ml of PDA and NA were amended with 3 ml of each of the
40
different extract concentrations and dispensed into four petri dishes replicated four times.
Three (3) ml of water was mixed with the media for the negative controls. The media was
allowed to cool and solidify. The bacteria were streaked on each of the amended media.
The colony forming units (CFU) were counted after 48 hr. For the fungal treatment 5 mm
fungal culture discs from one week old cultures of Geotrichum spp., Fusarium spp. and
Rhizopus spp. were cultured at the centre of each petridish per replicate and incubated at
room temperature. Radial growth from each of the treatment was measured after the
second day and repeated at an interval of 24 hr up to the seventh day. The mean growth of
the fungi on the amended media was compared to the control. For the bacteria, colony
forming units in different extract concentrations were counted.
3.7.4 Effects of plant extracts on post-harvest tomato disease development
Healthy tomato samples were obtained from farmers’ farms in Mwea and brought to the
Agricultural Science and Technology Laboratory, Kenyatta University. A sample of fruits
were washed in running tap water but were not surface sterilized so as not to interfere
with surface pathogens. The fruits were then dipped into the treatments prepared by
dissolving 3 mg of each of the crude extract into 1 ml of sterile distilled water for five
minutes and then air-dried.
For each extract three treated tomatoes were placed into a bowl and replicated four times.
The experimental design was a completely randomized design replicated four times. The
control treatment was immersed in tap water in a basin, dried and placed into the plastic
41
bowls without being dipped into the crude extracts. The fruits were left uncovered in the
laboratory at room temperature and disease development observed. The number of rotting
fruits was counted after twelve days.
3.8 Data analyses
Different techniques were used to analyse the data obtained. For descriptive statistics;
SPSS frequency, percent and chi-square test statistics especially when analysing field
survey data and the fungal isolates were used. The biocidal activity of the plant extracts
and susceptibility of the tomato varieties to the pathogens was analysed using SAS one
way ANOVA and Students-Newman-Keuls Test (SNKT p<0.05) was used for means
separation. The GC-MS chromatograms obtained from each active sample were
subjected to HP Chemstation software; each peak was analyzed for the most abundant
compound that contains active constituents -OH, -COOH, - Cl, -S, N, -F and –NH2. The
compounds were identified by direct comparison of their mass spectra to the Wiley NBS
and MIST database library of mass spectra.
42
CHAPTER FOUR
RESULTS
4.1 Tomato post-harvest losses survey in Mwea, Kirinyaga County
Sixty eight (68) farmers were interviewed using structured questionnaire but eight were
dropped from the sample size because of outliers reducing the sample size to sixty.
4.1.1 Tomato cultivars grown in Mwea, Kirinyaga County
From the survey, the most commonly grown cultivars of tomato in Mwea are: Kilele F1
Hybrid, Roma V. F. locally known as safari, Rio grande and Carl J. The largest
percentage (80 %) of the farmers grew Kilele F1 while 10 % of the farmers grew Roma
V. F and 3 % grew Rio grande and Carl J as shown in table 4.1. There was significant
difference (p< 0.001) between cultivars grown by farmers in Mwea. Only 1.7 % of the
farmers grew Danish and Royal Sluice.
Table 4.1 Tomato cultivar grown in Mwea
Percent values varied significantly (Chi-square test α=0.05)
Cultivar Frequency Percent
Kilele F1 48 80
Roma V.F 6 10.0
Rio grade 2 3.3
Carl J 2 3.3
Danish, Griffaton 1 1.7
Royal sluice 1 1.7
Total 60 100.0
p-value <0.001
43
4.1.2 The maturity state of tomatoes at harvesting time
The survey revealed that some farmers (17 %) harvested their tomatoes when they were
unripe. Others (82 %) harvested their tomatoes when they were ripe while the rest (2 %)
harvested their fruits when they were over ripe (Table 4.2).
Table 4.2 Maturity state of tomatoes at harvesting time
Percent values varied significantly (Chi-square test α=0.05)
4.1.3 Harvesting time of tomatoes
Most farmers (78 %) picked tomato fruits early in the morning while (22 %) picked their
produce in the afternoon in order to make the produce ready for collection and
transportation and be available for sale in the wholesale markets in the following
morning. Harvesting time differed significantly (p<0.001).
4.1.4 Treatment of tomato fruits after harvesting
The study revealed that 92 % of the respondents did not treat their tomato fruits after
harvesting. However a small percentage (8 %) treated their fruits using sodium
State Frequency Percent
Ripe 49 81.7
Unripe 10 16.7
Over ripe 1 1.7
Total 60 100.0
p-value <0.001
44
hypochlorite after harvesting. Results indicated significant difference (p<0.001) between
farmers who treated their tomato fruits after harvesting and those who never treated them.
4.1.5 The source of labor used for picking tomatoes
Harvesting was done using two major sources of labour that differed significantly
(p<0.001). Majority (88 %) of the respondents used hired labour while a smaller
percentage (13 %) used family labour.
4.1.6 Grading
The survey showed that all the respondents graded their tomatoes before packing in the
crates for transportation. Grading involved only separating the diseased and healthy
fruits. Grading was done in the presence of buyers several hours after harvesting (Plate
4.1). Farmers did not grade tomato fruits in terms of size, color, and firmness. Soft and
overripe fruits were also mixed together.
Plate 4.1 Ungraded tomato fruits in a farmer’s farm in Mwea.
45
4.1.7 Packing
The packing materials used by the farmers varied significantly (p<0.001). Most of the
respondents (79 %) packed their tomatoes in wooden crates and a few in plastic crates
(18 %) as shown in plate 4.2. The rest of the respondents (3 %) used paper cartons for
transportation of tomatoes (Fig.4.1).
Plate 4.2 Tomato fruits in plastic crate lined with a paper carton in Mwea market
Figure. 4.1 Tomato packing materials
0
10
20
30
40
50
60
70
80
90
100
Wooden crates Plastic crates Cartons
Per
cen
t
Packing material
46
4.1.8 Duration between harvesting and collection of fruits by the buyers
The respondents who sold their produce in wholesale to buyers from far distances like
Nairobi took more than four hours before they collected them from the farm (37 %).
Furthermore, 24 % of the respondents allowed the products to stay for four hours before
they were graded and packed while 21 % took three hours, 10 % took two hours, and 8 %
took one hour (Table 4.3). There was a significant difference (p=0.038) between the
length of time fruits were kept in the farm before transportation.
Table 4.3 Duration between harvesting and collection of fruits by the buyers
Percent values differed significantly (Chi-square test α=0.05)
4.1.9 Means of transporting tomato to the markets
Tomatoes sold to brokers were transported to the market by use of pickups (57 %) and
lorries (29 %). Those who sold in the neighbouring markets transported their products by
motorbikes, (7 %) carts (4 %) and bicycles (1 %) (Fig. 4.2). Some respondents used more
than one means of transport depending on availability. The means of transport varied
significantly (p<0.001).
Time (hr) Frequency Percent
1 3 7.9
2 4 10.5
3 8 21.1
4 9 23.7
>4 14 36.8
Total 38 100.0
p-value 0.038
47
Figure 4.2 Means of transporting tomato to the markets
4.1.10 Marketing of the produce
The study showed that 87 % of the farmers sold their produce in wholesale to brokers
who came to buy from the farms and took them to towns like Nairobi, Embu and Nyeri.
The rest (12 %) of the farmers sold in retail to the local markets like Kimbimbi and
Wang’uru. The marketing of the produce varied significantly (p<0.001).
4.1.11 Number of days taken to sell the tomato at the market
The study revealed that most of the wholesalers (63 %) took less than a day to sell their
produce in the market while 17 % took two days. Some farmers sold their products in
wholesale in the farms. The rest (10 %) of the respondents who were also retailers took
0
10
20
30
40
50
60
70
80
90
100
Pickup Lorry Motor bike Cart Human transport
Bicycles
Pe
rce
nt
Means of transport
48
one day and three days to sell their produce (Table 4.4). There was a significant
difference (p<0.001) on the time taken to sell the produce at the market.
Table 4.4 Time taken to sell the tomato at the market in Mwea.
Percent values differed significantly (Chi-square test α=0.05)
4.1.12 Losses due to different handling methods after harvesting
(a) Loss due to transportation
The study revealed that 52 % of the respondents experienced 10 % loss during
transportation while 2 % experienced 30 % loss. Other respondents did not experience
losses during transportation. The loss varied signicantly (p<0.001) depending on the
mode of transport.
(b) Loss due to packing
The study revealed that 5 % of the respondents experienced 10 % loss due to packing
while 37 % experienced less than 10 % loss. The other respondents did not experience
losses due to packing.
Time (days) Frequency Percent
<1 19 63.3
1 3 10.0
2 5 16.7
3 3 10.0
Total 30 100.0
p-value <0.001
49
(c) Loss due to decay
The study showed that 11 % of the respondents experienced 10 % loss due to decay,
while 2 % experienced 20 % and forty 40 % losses, respectively. Seven (7) % of the
respondents experienced less than 10 % loss as indicated in table 4.5. Other respondents
did not experience losses because they sold in wholesale at their farms.
Table 4.5 Tomato losses due to decay in Mwea
Percent values did not differ significantly (Chi-square test α=0.05)
(d) Loss due to poor grading
Poor grading resulted to fruits being rejected by the buyers and resulted to increased rot
development. The study revealed that 58 % of the respondents experienced 10 % loss due
to grading. Furthermore, 20 % of the respondents experienced 20 % loss during grading
while 8 % of the respondents experienced 30 % loss as shown in table 4.6. Moreover, 7
% of the respondents experienced less than 10 % loss while 2 % experienced more than
40 % loss during grading. The loss was significant (p<0.001).
Loss Frequency Percent
10% 7 11.7
20% 1 1.7
< 40% 1 1.7
< 10% 4 6.7
Total 13 21.7
p-value 0.232
50
Table 4.6 Loss due to poor grading
Loss Frequency Percent
10% 35 58.3
20% 12 20.0
8.3 30% 5
< 10% 4 6.7
> 40% 1 1.7
Total 57 95.0
p-value <0.001
Percent values differed significantly (Chi-square test α=0.05)
4.1.13 Common pests damaging tomatoes in Mwea
About 69 % of the respondents mentioned fruit worms as the most damaging pests while 1
% birds, 20 % spider mites, 8 % thrips and 2 % whitefly as damaging pests (Table 4.7).
Table 4.7 Common pests damaging tomatoes in Mwea
Pests
Responses
N Percent
American bollworm 52 68.5
19.8
8.1
Spider mites 17
Thrips 7
Whitefly 2 2.3
1.2
100
Birds 1
Total 79
p-value <0.001
Percent values varied significantly (Chi-square test α=0.05)
4.1.14 Common tomato post-harvest diseases in Mwea
Diseases affecting tomato fruits in the farms varied significantly (p<0.001).The
respondents (45 %) identified Fusarium rot and bacterial soft rot (50 %) as the most
51
damaging diseases. However 5 % of the respondents indicated phoma rot as another
disease that affected their tomatoes (Fig. 4.3).
Figure 4.3 Common tomato diseases in Mwea
4.1.15 Estimation of post-harvest losses due to different post-harvest factors
According to the study losses due to poor grading and packing averaged 10 % each, while
losses due to transportation 10.63 % (Table 4.8). Total post-harvest losses experienced
averaged 30.63 %.
Table 4.8 Estimation of post-harvest losses
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
Fusarium rot Phoma rot Bacterial soft rot
Percent
S.No Handling process Average % loss
1 Grading 10.0
2 Packing 10.0
3 Transportation 10.63
Total 30.63
52
4.2 Isolation and identification of pathogens associated with post-harvest
losses
The pathogens that were isolated and identified were Fusarium spp., Botrytis spp.,
Curvularia spp., Geotrichum spp., Bipolaris spp., Rhizopus spp. and Erwinia
(Pectobacterium) spp. Among the fungi Fusarium spp. was the most prevalent with three
species constituting 30 %. Rhizopus spp. constituted 21 %, Curvularia spp., 8 % while
Geotrichum spp. formed 18 % of the total population. Bipolaris spp. constituted 5 %,
Botrytis spp., formed 15 % while the remaining 4 % was made up of Erwinia
(pectobaterium) bacteria. There was a significant difference (p<0.001) between the
pathogens isolated from the infected tomato samples (Table 4.9).
Table 4.9 Pathogens isolated from infected tomato in Mwea.
4.2.1 Geotrichum spp.
The fungus colony grew in PDA being low, flat, white and leathery with no reverse
pigmentation (Plate 4.3). Hyphae were hyaline septate, branched and broke up into chains
Pathogens Frequency Percent
Bipolaris (fungi) 4 5.0
Botrytis (fungi) 12 15.0
Curvularia (fungi) 6 7.5
Erwinia (bacteria) 3 3.8
Fusarium (fungi) 24 30.0
Geotrichum (fungi) 14 17.5
Rhizopus (fungi) 17 21.3
Total 80 100.0
p-value <0.001
53
of hyaline, smooth, one-celled, subglobose to cylindrical, slimy arthroconidia
(ameroconidia) by the holoarthric fragmentation of undifferentiated hyphae. The
arthroconidia, were quite variable in size, aerial, erect or recumbent, cylindrical, hyaline,
unicellular and barrel shaped.
Plate 4.3 Geotrichum spp. colony growing on PDA and arthroconidia
4.2.2 Curvularia spp.
Colonies of the fungus on PDA were fast growing; brownish and cottony (Plate 4.4). The
reverse was dark brown (Plate 4.4). Conidiophores were straight to flexious, multi-
septate, usually simple but sometimes branched, brown and bearing spores apically.
Front
Reverse
Microscopic arthroconidia
54
Conidia (porospores) were dark, septate, end cells lighter, 3 to 5 celled, more or less
fusiform, typically bent, with one of the central cells enlarged and darker (Plate 4.4).
Plate 4.4 Colonies of Curvularia spp. growing on PDA and mycelia and porospores
4.2.3 Bipolaris spp.
The fungal colonies were moderately fast growing; effuse, grey to blackish brown, suede
like to floccose with a blackish brown reverse on PDA (Plate 4.5). Hyphae were septate
and branched. Conidiophores were brown, simple, producing conidia through apical pore,
resuming growth sympodially and forming conidia on successive new tips. Conidia
(porospores) were brown; several celled (phragmosporous), fusoid, and straight or
Front Reverse
Microscopic porospores
55
curved, germinating by one germ tube at each end. The spores were unique in that they
were not made up of normal cells separated by septae instead the cells of spores were
compartmentalized by distosepta, meaning they were contained in sacs that had a wall
distinct from the outer wall of the conidium.
Plate 4.5 Bipolaris spp. colony growing on PDA and the conidia
Front Reverse
Microscopic conidia
Conidia
56
4.2.4 Fusarium spp.
Three species of Fusarium were identified. Colonies were fast growing, mycelia
extensive, cottony in culture, and pink, yellow and white in color (Plate 4.6.a).
Conidiophores were variable, slender and simple, or stout, short, branched irregularly or
bearing a whorl of phialides, single or grouped into sporodochia; conidia (phialospores)
were hyaline, variable, often held in small heads. Macroconidia hyaline, several celled
slightly curved or bent at the pointed ends, typically canoe-shaped. Microconidia were
also hyaline, pyriform, fusiform to ovoid, straight or curved, 1-celled, borne singly or in
chains; some conidia intermediate, 2 or 3 celled, oblong or slightly curved (Plate 4.6.b).
Plate 4.6.a Fusarium spp. growing on PDA
Front Reverse Front
Reverse
Front Reverse
57
Plate 4.6.b Macroconidia, microconidia and mycelia of Fusarium spp
4.2.5 Botrytis spp.
Fungal colonies growing in PDA were woolly, dark grey with a black reverse (Plate 4.7).
The colonies were also fast growing but the growth was patchy or irregular.
Conidiophores were long, slender, hyaline or pigmented, branched, sometimes near the
apex, the apical cells enlarged or rounded, bearing clusters of conidia on short sterigmata;
conidia (botryoblastospores) hyaline or ash-colored, gray in mass, 1-celled and ovoid.
58
Plate 4.7 Botrytis spp. growing on PDA and microscopic mycelia and conidia
4.2.6 Rhizopus spp.
It grew rampantly filling the petridish with sparse white mycelia within four days. Colony
whitish becoming grayish-brown due to yellowish brownish sporangiophores and brown
black sporangia, with extensive mycelia growth in culture as it ages (Plate 4.8). The
texture was typically cotton candy like. The mycelia was non septate. Sporangiophores
were large with striate walls and irregular in shape. Their color ranged from almost
colorless to dark brown with slightly rough-walled stolons opposite the branched
Front Reverse
59
rhizoids. Sporangia were globose to subglobose and blackish-brown at maturity.
Columella projected into the sporangium. Sporangiospores (asexual spores) were
irregular in shape and were formed within pinhead like sporangium, which break to
release the spores when mature (Plate 4.8).
Plate 4.8 Rhizopus spp. growing in PDA, compact sporangium and an open
sporangium that has released spores
4.2.7 Erwinia (Pectobacterium)
It was a flagellated rod, gram-negative bacteria. Colonies growing in NA were circular,
convex and creamy white in color (Plate 4.9). Potato tuber slice incubation test showed
that the potato slices, developed a soft, watery, decaying mass after fourty eight hours and
a foul smell was noted after five days.
Plate 4.9 Micrograph of; A - Erwinia cells, and B - Bacterial colonies reverse.
A B
Front Reverse
60
4.3 Pathogenicity test
The study revealed that the micro-organisms isolated from the infected tomato fruits were
pathogenic but with varied pathogenicity. When inoculated into healthy tomato fruit,
Rhizopus spp. caused the most rapid (100 %) infection where the inoculated fruits were
completely rotten by the end of the second day after inoculation. The fruits were
completely disintegrated with extensive mycelial growth forming a dark color covering
the fruit skin (Plate 4.10.a ). The fruits looked water soaked in appearance and wrinkled
with depression. Fruits inoculated with Fusarium spp. had water soaked lesions with
some white to pink mycelia (Plate 4.10.a) while fruits inoculated with Geotrichum spp.
had whitish cheesy like lesions (Plate 4.10.b).
Samples inoculated with Curvularia spp. had small water soaked lesion with slightly
brownish appearance on the inoculated areas while tomato fruits inoculated with
Bipolaris spp. had small hard dark lesion around the inoculated area. Moreover, fruits
inoculated with Erwinia spp. also had water soaked lesions around the inoculated areas
while fruits inoculated with Botrytis spp. had water soaked lesions with a dark
appearance on the inoculated areas. The pathogens were isolated and identified as
described earlier to confirm pathogenicity.
61
Plate 4.10.a Tomato fruits inoculated with A – Rhizopus spp., B – Fusarium spp., C -
Botrytis spp., and a negative control on the right for each pathogen
Plate 4.10.b Tomato fruits inoculated with; A – Geotrichum spp., B – Curvularia spp.,
C –Bipolaris spp., D – Erwinia spp. (Pectobacterium) and a negative control on the
right for each pathogen
4.4 Determination of tomato fruit damage by the isolated pathogens
This study revealed that the most damaging pathogen was Rhizopus spp. causing 100 %
rot in both cv. Kilele F1 and cv. Roma V.F. It disintegrated the entire fruit by the fourth
day. Geotrichum spp. with a mean rot diameter of 28.08 mm in cv. Kilele F1 and 21.25
mm in cv. Roma V.F was the second most damaging pathogen (Table 4.10). The rot
damage differed significantly in the two cultivars (p<0.001). Fusarium spp. and Erwinia
spp. were the third most damaging pathogens with a mean rot diameter of 19.33 mm and
18.25 mm in cv. Kilele. The mean of the two differed significantly within cv. Kilele.
A B C D
A B C
62
Erwinia spp. caused the same damage in cv. Roma while damage caused by Fusarium spp,
on the two varieties differed significantly (p=0.002). Bipolaris spp. had the least damage,
followed by Curvularia spp. in cv. Kilele. The damage caused by Erwinia spp. in both
cultivars did not differ significantly (p=0.855). Rot caused by Curvularia spp. also did not
differ significantly in the two cultivars (p=0.102). Bipolaris spp. caused more damage on
cv. Roma than on Kilele (p=0.004). However the rot caused by Curvularia spp. and
Botrytis spp. on cv. Roma did not differ signicantly. All the pathogens caused more damage
on cv. Kilele than on cv. Roma. The pathogens caused significant damage on the two
cultivars (p<0.001). There was no rot development observed on the uninoculated fruits
(control).
Table 4.10 Comparison of rot diameter caused by different pathogens on tomato
Cultivars (Kilele and Roma)
Pathogens
Kilele (n=12)
MeanRD±SD
RomaV.F
(n=12)
MeanRD±SD
p-
value
Botrytis 16.25±3.62d 13.42±0.79
d 0.001
Geotrichum 28.08±2.61f 21.25±2.14
f <0.001
Bipolaris 6.33±1.44b 5.08±0.50
b 0.004
Fusarium 19.33±2.84e 15.83±1.53
e 0.002
Curvularia 10.58±1.44c 9.42±1.88
c 0.102
Erwinia 18.25±2.63e 18.50±3.87
e 0.855
Control 5.00±0.00a 5.00±0.0
a -
p-value <0.001 <0.001
Mean values followed by the same lower case within the same column are not
significantly different (One way ANOVA, Students-Newman-Keuls test, α=0.05)
RD refers to rot diameter and SD (standard deviation)
63
4.5 Susceptibility of tomato cultivars to selected post-harvest pathogens
The study revealed that susceptibility of the two cultivars to the study pathogens
differed significantly (p=0.045) (Table 4.11).
Table 4.11 Cultivar susceptibility to rots
Independent t-test showed that the susceptibility of cv. Kilele and cv.
Roma V.F differed statistically (p=0.045)
4.6 Anti-microbial compounds from selected plant crude extracts
The anti-microbial compounds in ginger, neem and garlic crude extracts determined
using gas chromatography varied in identity and amounts depending on the source of the
extracts.
4.6.1 Ginger crude extract
The study revealed that ginger rhizomes had compounds that were antimicrobial and
were in varying amounts. The compounds were: α-Zingiberene which was the most
abundant (25.08 %), with retention time of 18.8 minutes (Table 4.12); 2-Butanone, 4-(-
hydroxy-3-methoxyphenyl) constituted 14.14 % with retention time of 20.63 and
Geraniol with 1.05 %. The least compound was Beta-tocopherol (0.032 %) followed by
Cultivar N MeanRD±SE
Kilele 84 15.69±1.24
Roma V.F 84 13.79±1.39
p-value
0.045
64
Benzo[h] quinoline, 2,4-dimethyl (0.042 %). The compounds were mainly terpenoids,
some of which have strong inhibitory activity against pathogenic miro-organisms.
Table 4.12 Anti-microbial compounds from ginger crude extracts
Relative percent abudance of anti-microbial compounds in ginger
4.6.2 Garlic crude extract
The study revealed that garlic bulbs had fourteen anti-microbial compounds that probably
acted against the test pathogens (Table 4.13). These were: 3-Vinyl-1,2-dithiacyclohex-4-
ene which had 21.43 % of the total chemical compounds found in it. Diallyl disulphide
was the second most abundant which constituted 10.84%, while the third compound 1,4-
Diathiane formed 3.176 % of the total chemical compounds. The compound with the
lowest composition was 1,3-Dioxolane-2-[dichloromethyl]- which had 0.36 % and
Compound Retention
time (min
Relative%
abudance
α –Terpineol 14.562 0.61
Linalool 13.066 0.50
2-Heptanol 9.222 0.24
Borneol 14.49 0.81
Citronellol 15.067 0.50
Geraniol 15.458 1.05
Geranic acid 16.825 0.15
Elemol 19.447 0.73
E –Nerolidol 19.537 0.43
2-Butanone,4-(-hydroxy-3-methoxyphenyl) 20.628 14.14
Ketone,1-cyclohexen-1-yl methyl,semicarbazone 28.736 0.51
α-Zingiberene 18.769 25.08
Gingerol 25.059 0.067
Gingerol 28.597 0.424
Beta-tocopherol 33.973 0.032
Benzo[h] quinoline,2,4-dimethyl 37.750 0.042
Gingerol 27.838 0.147
65
Cyclohexen-1-ol, 3-methyl constituted 0.62 %. All anti-microbial compounds from
garlic were sulpur containing compounds except Acetamide,n-tetrahydrofurfuryl-2-
methoxy, which might be responsible for anti-microbial activity of garlic extracts.
Table 4.13 Anti-microbial compounds from garlic crude extracts
Relative percent abudance of antimicrobial compounds in garlic
4.6.3 Neem crude extract
The study revealed that neem leaf extract had ten antimicrobial compounds that inhibited
the growth of the test pathogens. They were: Nimonal (25 %), Azadirachtin A (14 % and
12 %), Azadirachtin C (9 %), Azadirachtin B (4 %), Azadirachtin D (3 %), Azadiradione
(1.2 %), 6de-acetylnimbin (0.45 %), Expoxyazdirodione (0.06 %) and
Expoxyazdirodione (0.045 %) as shown in table 4.14.
Compound
Retention time (m) Relative
%
abudance
Acetamide,n-tetrahydrofurfuryl-2-methoxy 14.250 1.35
Octadecanoic acid,3-hydroxy, methyl ester 20.178 0.66
1,4-Diathiane 9.527 3.176
Amidinothiourea 12.341 0.671
1-propene-3, 3-thiobis 8.170 2.90
Thiourea,N-N’-dimethyl 9.869 0.84
Diallyl disulphide 12.734 10.84
3-Chlorothiophene 13.069 6.49
3-Vinyl-1,2-dithiacyclohex-4-ene 14.541 21.43
3-Vinyl-1,2-dithiacyclohex-5-ene 14.723 3.09
Cyclohexen-1-ol, 3-methyl 15.500 0.62
Ethyl trifluoromethyl trisulphide 17.163 1.67
1,3-Dioxolane-2-[dichloromethyl]- 17.584 0.36
Acetic acid, chloro-2-butoxyethyl ester 17.852 2.73
66
Table 4.14 Anti-microbial compounds from neem leaf crude extract
Relative percent abudance of antimicrobial compounds in neem
4.7 Efficacy of crude plant extracts on selected tomato post-harvest pathogens
4.7.1 Fusarium spp.
The study revealed that the plant extracts inhibited radial growth of Fusarium spp. as
compared to control but the efficacy varied with concentration (< 0.001). At 1 mg/ml
neem, Fusarium spp. was completely inhibited (Plate 4.13). There was slight growth in
garlic (5.40 mm) and a mean diameter of 6.4 mm was noted on treatment with ginger
(Table 4.15). At 2 mg/ml concentration growth of Fusarium spp. on the PDA amended
with garlic and neem was completely inhibited (Plate 4.11 and plate 4.13) but there was
slight growth in the PDA amended with ginger (Plate 4.12). At 3gm/ml concentration
there was no growth in all the extracts. There was a significance difference in the effect
of different concentrations of ginger (p<0.001). The effects of different concentrations of
garlic also differed significantly (p=0.012) (Table 4.15).
Compound Retention
time (m)
Relative %
abudance
Azadirachtin A 8 14
Azadirachtin B
Azadirachtin C
Azadirachtin D
Nimonol
8
8
8
52
4
9
3
25
Expoxyazdirodione 61 0.06
Expoxyazdirodione 70 0.045
6de-acetylnimbin 24 0.075
Azadiradione 54 1.2
Azadirachtin A 23 12
67
Table 4.15 Efficacy of crude extracts on radial growth of Fusarium spp.
Concentration
(mg/ml)
Neem
meanRG±SD
Ginger
meanRG±SD
Garlic
meanRG±SD p-value
1 5.00±0.00A 6.40±0.50
Cb 5.40±0.82
Bb <0.001
2 5.00±0.00A 5.20±0.41
Ba 5.00±0.00
Aa 0.012
3 5.00±0.00A 5.00±0.00
Aa 5.00±0.00
Aa -
<0.001 0.012
Mean values followed by the same lower case within the same column are not
significantly different while mean values followed by the same upper case within the
same row are not significantly different (One way ANOVA, Students-Newman-Keuls
test, α=0.05)
RG refers to radial growth and it includes inoculum disc which was 5mm.
Plate 4.11 Growth of Fusarium spp. on PDA amended with varying concentration of
garlic crude extract; A – unamended control, B – 1 mg/ml, C – 2 mg/ml,
D - 3 mg/ml
B
C D
A
68
Plate 4.12 Growth of Fusarium spp. on PDA amended with varying concentration of
ginger crude extract; A – unamended control, B – 1 mg/ml, C – 2 mg/ml,
D – 3 mg/ml
Plate 4.13 Growth of Fusarium spp. on PDA amended with varying concentration
of neem leaf crude extract; A – unamended control, B – 1 mg/ml, C – 2
mg/ml, D – 3 mg/ml
4.7.2 Geotrichum spp.
The results indicated that the three plant extracts can inhibit radial growth on Geotrichum
spp. as compared to the control but the rate of inhibition varied with concentrations (p <
0.001) (Table 4.16). One mg/ml concentration of the three plant extracts differed
B
C D
A
B
C
D
A
69
significantly in their effects on Geotrichum spp. (p<0.001) as indicated in table 4.16.
Garlic was most effective followed by ginger (Table 4.16). At the concentration of 2
mg/ml the effects on Geotrichum spp. also differed significantly (p<0.001). At
concentration of 3 mg/ml all the extracts were found to be effective. The effectiveness of
neem differed significantly (p<0.001) at different concentrations (Plate 4.15). The most
effective concentration was 3 mg/ml. The effect of ginger also differed significantly
(p<0.001) at different concentrations and 3 mg/ml concentration was the most effective
(Plate 4.16). Garlic was effective in all the concentrations and therefore was the best for
controlling Geotrichum spp. (Plate 4.14).
Table 4.16 Efficacy of crude extracts on radial growth of Geotrichum spp.
Concentration
(mg/ml)
Neem
meanRG±SD
Ginger
meanRG±SD
Garlic
meanRG±SD p-value
1 7.70±2.08Cc
6.10±1.07Bb
5.00±0.00A <0.001
2 6.20±1.20Cb
5.60±0.50Ba
5.00±0.00A <0.001
3 5.00±0.00a 5.00±0.00
a 5.00±0.00 -
p-value <0.001 <0.001 -
Mean values followed by the same lower case within the same column are not
significantly different while mean values followed by the same upper case within the
same row are not significantly different (One way ANOVA, Students-Newman-
Keuls test, α=0.05)
RG refers to radial growth and it includes inoculum disc which was 5mm.
70
Plate 4.14 Growth of Geotrichum spp. on PDA amended with varying concentration of
garlic crude extract; A– unamended control, B – 1 mg/ml, C – 2 mg/ml,
D – 3 mg/ml
Plate 4.15 Growth of Geotrichum spp. on PDA amended with varying concentration of
neem leaf crude extract; A – unamended control, B – 2 mg/ml, C – 1 mg/ml,
D – 3 mg/ml
B
C D
A
C
B
D
A
71
Plate 4.16 Growth of Geotrichum spp. on PDA amended with varying concentration
of ginger crude extract; A – unamended control, B – 2 mg/ml, C – 1mg/ml,
D – 3 mg/ml
4.7.3 Rhizopus spp.
The study revealed that the three plants extracts inhibited radial growth on Rhizopus spp.
as compared to the control although the rate of inhibition varied with extracts and
concentrations. One mg/ml concentration of the three extracts differed significantly
(p=0.010) on their effectiveness and the most effective extract at 1 mg/ml concentration
was garlic (Table 4.17). There was no growth of the Rhizopus spp. even at the lowest
concentration. The effectiveness of ginger and neem did not differ significantly. At 2
mg/ml concentration the extracts differed significantly (p=0.007) on their effectiveness
and garlic was the most effective. The effectiveness of ginger and neem did not differ
significantly (Table 4.17). At 3 mg/ml concentration there was no growth in all the
extracts.
C
B
D
A
72
The effectiveness of different neem concentrations differed significantly (p<0.001) with
3 mg/ml being the most effective where there was no growth (Plate 4.18). There was little
growth in 2 mg/ml concentration and more growth in 1 mg/ml concentration. The
effectiveness of ginger on Rhizopus spp. at different concentrations differed significantly
(p=0.028) with the 3 mg/ml being the most effective. The 1 mg/ml and 2 mg/ml
concentration did not differ significantly in their effectiveness on Rhizopus spp. All the
concentrations of garlic effectively inhibited Rhizopus spp. growth (Plate 4.19).
Table 4.17 Efficacy of crude extracts on radial growth of Rhizopus spp.
Concentration
(mg/ml)
Neem
meanRG±SD
Ginger
meanRG±SD
Garlic
meanRG±SD p-value
1 7.20±1.77Bc
6.70±3.57Bb
5.00±0.00Aa
0.010
2 5.85±0.88Bb
5.55±1.15Bb
5.00±0.00Aa
0.007
3 5.00±0.00 A a
5.10±0.11Aa
5.00±0.00 Aa
0.012
p-value <0.001 0.028 -
Mean values followed by the same lower case within the same column are not
significantly different while mean values followed by the same upper case within
the same row are not significantly different (One way ANOVA, Students-Newman-
Keuls test, α=0.05)
RG refers to radial growth and t includes inoculum disc which was 5mm.
73
Plate 4.17 Growth of Rhizopus spp. on PDA amended with varying concentration
of ginger crude extract; A – unamended control, B – 1 mg/ml, C – 2 mg/ml,
D – 3 mg/ml
Plate 4.18 Growth of Rhizopus spp. on PDA amended with varying concentration
of neem leaf crude extract; A – unamended Control, B – 2 mg/ml, C – 1 mg/ml,
D – 3 mg/ml
A
D C
B
A
D
B
A
C
74
Plate 4.19 Growth of Rhizopus spp. on PDA amended with varying
concentration of garlic crude extract; A – unamended control, B – 1
mg/ml, C – 2 mg/ml, D – 3 mg/ml
4.7.4 Comparison of efficacy of different extracts on the test fungal pathogens
The results obtained revealed that plant extracts inhibited growth of test fungi, although
the rate of inhibition varied with different extracts and concentrations. However growth
inhibition in all the test pathogens took similar trend in all plant crude extracts. All the
concentrations of the tested plant extracts were found to be inhibitory to all the test fungi
and the rate of inhibition increased with increase in the concentration. The highest
concentration had the highest inhibition on the pathogens. On Goetrichum spp., the
effectiveness of the extracts differed significantly (p<0.001) comparing with the control
(Table 4.18). The same was observed on Fusarium spp. and Rhizopus spp. The
effectiveness of ginger and garlic crude extracts did not differ significantly (Table 4.18).
A
D
B
C
75
Neem crude plant extract was the most effective on Fusarium spp. as indicated by no
growth (Plate 4.13). However, it was less effective on Geotrichum spp. and Rhizopus spp.
The effectiveness of ginger and garlic did not differ significantly on the three pathogens.
However garlic was the most effective extract on all the pathogens compared to ginger
and neem (Table 4.18). Ginger was the second most effective on the pathogens.
Comparing the three fungi, Fusarium spp. was the pathogen whose growth was mostly
affected by all the extracts. The Susceptibility of Geotrichum spp. and Rhizopus spp. did
not differ significantly. The unamended control differed from all other treatments.
Table 4.18 Efficacy of crude extracts on the test fungi
Geotrichum Fusarium Rhizopus
Treatment
Mean
RG±SE
Mean
RG±SE MeanRG±SE
Control 34.80±2.42d 42.85±2.68
d 80.15±0.89
c
Neem 6.30±0.23c 5.00±0.00
a 6.02±0.19
b
Ginger 5.57±0.10b 5.60±0.09
c 5.75±0.29
b
Garlic 5.00±0.00a 5.13±0.06
b 5.00±0.00
a
p-value <0.001 <0.001 <0.001
Mean values followed by the same lower case within the same column are not
significantly different (One way ANOVA, Students-Newman-Keuls test, α=0.05)
RG refers to colony radial growth and it includes inoculum disc which was 5mm.
4.7.5 Efficacy of crude plant extracts on Erwinia (Pectobacterium)
The study revealed that in different concentrations of the extracts, the number of colony
forming units of Erwinia spp. on the amended NA varied significantly as compared to the
control. At 1 mg/ml of all the extracts, garlic was the most effective with the least colony
forming units (Table 4.19). Neem extract was the second most effective while ginger was
76
the least effective (Table 4.19). At 2 mg/ml garlic extract was the most effective where
there were no colony on amended NA. Ginger was the second most effective while neem
was the least effective. However, at 3 mg/ml the three extracts were effective. The
effectiveness of neem extract at different concentrations differed significantly (p<0.001)
with the 3 mg/ml being the most effective as indicated by no growth on the amended
Nutrient agar. At 2 mg/ml the colony forming units were less than at 1 mg/ml.
The efficacy of ginger crude extract on growth of Erwinia spp. differed significantly
(p<0.001) at different concentration and also comparing to the control. Three mg/ml was
the most effective while the 1 mg/ml was the least effective. The effectiveness of garlic
also differed significantly (p<0.001) when compared to the control. Three mg/ml and 2
mg/ml concentrations had the same effect such that no growth occured on the amended
NA. A few colony forming units were on the NA amended with 1 mg/ml. On evaluation
of the three extracts, garlic was the most effective but ginger and neem crude extracts did
not differ significantly.
Table 4.19 Efficacy of crude extracts on the C.F.U of Erwinia spp.
Concentration
(mg/ml)
Neem
Mean±SE
Ginger
Mean±SE
Garlic
Mean±SE
0 276.25±6.88d 276.25±6.88
d 276.25±6.88
c
1 89.50±8.77c 52.00±6.45
c 28.25±1.65
b
2 37.50±4.79b 10.25±1.49
b 0.00±0.00
a
3 0.00±0.00a 0.00±0.00
a 0.00±0.00
a
p-value <0.001 <0.001 <0.001
Mean values followed by the same lower case within the same column are not
significantly different (One way ANOVA, Students-Newman-Keuls test, α=0.05)
77
4.7.6. Comparison of efficacy of different extracts on Erwinia spp.
The study revealed that the effectiveness of the extracts at 1 mg/ml differed significantly
(p<0.001) with the garlic extract being the most effective (Table 4.20). At 2 mg/ml the
effectiveness also differed significantly (p<0.001) with garlic extract being the most
effective. At 3 mg/ml there was no growth in all the treatments.
Table 4.20 Efficacy of different extracts on the C.F.U of Erwinia spp.
Mean values followed by the same lower case within the same column are not
Significantly different (One way ANOVA, Students-Newman-Keuls test,α=0.05)
4.8. Efficacy of crude extracts in controlling tomato rots
All the extracts from the three plants were effective in controlling the rot pathogens on
tomato fruits as compared to the control (Plate 4.20-22).
Plate 4.20 Efficacy of Garlic crude extract on the tomato fruits
Concentration
(mg/ml)
Neem
Mean±SE
Ginger
Mean±SE
Garlic
Mean±SE
p-
value
1 89.50±8.77c 105.00±6.45
c 28.25±1.65
b <0.001
2 37.50±4.79b 11.25±1.49
b 0.00±0.00
a <0.001
3 0.00±0.00a
0.00±0.00a
0.00±0.00a -
78
Plate 4.21 Efficacy of Ginger crude extract on the tomato fruits
Plate 4.22 Efficacy of Neem crude extract on the tomato fruits
79
CHAPTER FIVE
DISCUSSION
5.1 Tomato post-harvest losses survey in Mwea
The survey carried out revealed that factors such as poor grading, packing containers,
means of transport, duration between harvest and transport to the market, pests and
diseases have significant impact on post-harvest losses. Tomato fruits were usually
spread on the ground waiting for grading after harvest. Mixing of healthy and infected
tomato fruits during harvesting possibly increased chances of the spread of disease
causing micro-organisms to healthy fruits. Harvested fruits were usually thrown on the
ground or dropped into the harvesting containers and the impact could cause bruises on
the fruits that may act as routes for secondary infections. Heaping of fruits in the farm
results to squeezed fruits causing injuries that allow entry of micro- organisms that
cause decay.
It is possible that spreading of the harvested fruits on the ground during the harvesting
makes the harvested fruits carry heavy spore load from the farm. Some harvested fruits
were left lying in the farm for an average of over four hours before grading and packing.
The results agree with those of Kader (1978), that showed that most of pathological
disorders found during post-harvest handling of tomato fruits originate from the field and
are increased by physical damage that makes the fruits more susceptible to decay. Some
fruits were harvested in the morning and packed in the evening. Most of the farmers did
not treat their tomatoes after harvesting. This increases the chances of fruits having heavy
load of disease causing micro-organisms. During grading the infected tomato fruits that
80
could not be taken to the market were left in the farm. They continue to rot in the farm
and may create a favourable environment for multiplication of disease causing micro-
organisms.
From the survey it was also noted that the type of labor plays a vital role in the post
harvest losses. Majority of the respondents used hired labour for harvesting of tomatoes
while a few used family labour. Hired labour aimed at harvesting as much fruits as
possible to get a higher pay but there is poor handling of fruits resulting to bruises that
increases chances of infection by pathogens that cause decay. Sometimes the fruits are
harvested with fruit stalks which sometimes are not removed and during packing, the
stalks cause injuries on other fruits.
In the research area, picking time was determined by the commitments of farmers with
the buyers, for long distance transportation. It was observed that most of the farmers, who
brought their produce to the local and nearby markets, picked tomato crop early in the
morning while a few of the farmers who transported their produce to distant markets
picked their produce in late afternoon in order to make the produce ready for
transportation overnight and be available for sale in the wholesale markets in the
morning. Tomatoes picked very early in the morning are sometimes wet due to dew or
rains and when packed, the wetness encourages the spread of decay causing micro-
organisms. According to the survey carried out it was revealed that all the respondents
graded their tomatoes before packing into the crates for transportation.
81
Grading was done in the presence of the buyers meaning that the ungraded harvested
tomatoes remained spread on the farm (Plate 4.1.1) for many hours making them collect
very high spore load from the farm. Long contact hours of healthy and infected fruits
probably increases the rate of spread of disease causing pathogens. Grading also
involved only separating the diseased from healthy fruits. Farmers did not grade in terms
of size, color, and firmness. Mixing of small fruits with large fruits cause more bruises on
the small fruits. Soft and overripe fruits were also mixed together with firm fruits making
the soft ones to be compressed resulting to losses. Sometimes tomatoes were harvested
early in the morning with the morning dew. This increases moisture content that makes
them more prone to fungal spoilage (Efiuvwevwere, 2000).
From the survey it was noted that majority of the respondents packed their tomatoes in
wooden crates that were poorly ventilated and a few in plastic crates. A few also used
paper cartons. Tomatoes are likely to suffer compression injury when piled into the
transport containers. Some lined the crates with paper cartons (Plate 4.1.2) to prevent
damage of the fruits. The crates were also covered with paper cartons on the top part
especially during transportation. This increases temperature in the boxes creating a
conducive environment for multiplication of pathogens. Time lag in transportation, bulky
packing in the traditional wooden crates wrapped with papers may cause high humidity
making the micro-climate favorable for mycoflora. Erile (1983) reported that reduction in
losses and enhancement of shelf life of tomato fruits can be achieved through careful
method of harvesting, handling, packaging and mostly preservation and storage.
82
The survey also revealed that respondents who sold their fruits in wholesale to brokers
had their products transported to the market by use of lorries and pickups from the
buyers. Respondents who sold their produce to the neighbouring markets transported
their products by bicycles, carts and motorbikes. Such means of transport may cause
bruises on the harvested tomatoes which allow entry of pathogens that cause decay. Some
fruits are also transported for longer distances to reach the market. In such cases it is
possible that losses increase because of heat build- up in the packing crates and physical
damage due to impact on the roads. Kader and Kasmire (1978) reported that physical
damage can occur during harvesting and post-handling processes which include
punctures, internal bruising due to impact and compression. The magnitudes of losses
vary depending on distribution systems, and duration between harvest and consumption.
This study estimated the post-harvest losses to be 30.63 %. This was done by averaging
losses that were reported by the respondents during the interview and offloading areas in
the market. The losses were attributed to poor means of transport, packaging and poor
grading. These findings agree with those of Raja and Khokhar (1993), and Iqbal (1996),
that showed that post-harvest losses of fruits and vegetables range from 25-40 % or even
greater in developing countires. FAO (2002) reported that post-harvest losses are great
but there may be no figures to support the view because in most cases records do not
exist and if they do exist the figures are only estimates.
83
5.2 Pathogen isolation, identification and pathogenicity test.
Aworth et al. (1985) reported that the major causative agents of post-harvest spoilage of
tomatoes are bacteria and fungi. The isolated pathogens were Rhizopus spp., Fusarium
spp., Geotrichum spp., Botrytis spp., Curvularia spp., Bipolaris spp., and Erwinia spp.
The results of pathogenicity test from this study (Plates 4.3.1-4) revealed that all tomato
fruits showed symptoms of rot while the uninoculated control fruits showed no symptoms
of rot. However the rate of rot varied significantly between the pathogens with Rhizopus
spp. being the most virulent pathogen causing the most damage (100 % rot) within two
days. Bipolaris spp. caused the least damage meaning that it was not one of the most
damaging pathogen. Bipolaris spp. and Curvularia spp. are mostly cereal pathogens and
since rice is grown in Mwea, they were found to contaminate tomato fruits.
These results agrees with those of Chuku et al. (2008), that showed that Fusarium spp.,
R. stolonifer and Aspergillus spp. were responsible for soft rot of tomato. Ijato et al.
(2011) isolated A. niger, F. oxysporum, R. stolonifer and G. candidium from rotten tomato
fruits. F. moniliforme, A. niger and R. stolonifer were isolated from rotten tomato fruits
(Onyia et al., 2000). The decay of fruits during storage is due to the micro-organisms
which could have gained entry through cracks, surface injuries due to rough handling,
poor road and transport facilities (Wills et al., 1981; Liu and Ma, 1983). According to
Kader (2002), the pathogens infect fruits during prolonged periods of rainfall and high
humidity, especially when fruits are poorly packed. According to Villareal (1980), a
84
damaged tomato fruit may harbor pathogens that may spread and spoil all tomatoes in a
lot.
5.3 Determination of fruit damage by the isolated pathogens on the cultivars
From the study it was noted that Rhizopus spp. caused the most rapid rot (100 %
infection) within the first two days. This observation agrees with the report of Okoli and
Erinle (1990), which recorded that R. stolonifer caused the most rapid rot on stored
tomatoes in Nigeria. According to Chuku (2005), Rhizopus recorded the highest rot (80
%) on Avocado and pears in Nigeria. Geotrichum spp. was the second most damaging
pathogen, followed by Fusarium spp. and Erwinia spp. Bipolaris spp. and Curvularia
spp. had the least rot on the tomato fruits meaning that they are not major post-harvest
pathogens of tomato fruits.
5.4 Plant extracts compounds
The compounds which were present in all the samples contain the following functional
groups: -COOH, -OH, -N, -Cl, -F, -NH2 and –S groups which may be associated with
microbial inhibition and are found in conventional antibiotics. Studies have shown that
sulphur containing compounds have strong inhibitory anti-microbial activities (Julia and
Ann 1947; Kyung and Fleming, 1996; Yanyali et al., 2001). Nitrite has toxic properties
while nitrous acid is bactericidal, chlorine releasing compounds such as chlorine dioxide
(ClO2), acidic and alcoholic compounds act as anti-bacterial agents (Gerald and Russell,
1999).
85
5.5 Effects of the extracts on the test pathogens
The study revealed that all the concentrations were effective on the test pathogen but the
efficacy varied with the concentration used. According to the results garlic, ginger and
neem extracts contained anti-fungal and anti-bacterial properties which completely
inhibited mycelial growth of the test fungi and bacteria cells (0.00± 0.00) at 3 mg/ml
concentration. Fusarium spp. was the most sensitive pathogen in all the plant extracts
tested. The findings show that garlic was the most effective crude extract in inhibiting
the growth of all the test pathogens in low concentration as compared to ginger and neem.
The differences in the inhibitory potentials between the three crude plant extracts may be
due to sensitivity of each of the test pathogen to the different doses of the extracts. Garlic
seemed to have the highest anti-microbial activity and could be useful in controlling post-
harvest pathogens.
Garlic extracts in almost all the concentrations had significant reduction on both mycelial
growth of fungi and the colony forming units of Erwinia. The findings are in agreement
with those of other scientists such as Dutta et al. (2004), who reported that 10 %
concentration of crude garlic showed total inhibition of sclerotial production and 20 %
concentration showed excellent mycelial inhibition of R. solani causing sheath blight of
rice. Reports of Anjorin et al. (2008) showed that garlic effectively inhibited Fusarium
spp.
86
Bhuiyan et al. (2008), found garlic extracts to be effective in controlling growth of
Colletotrichum dematium at 20 % concentration. Sowjanya and Manohara (2000) also
reported that amongst five plant extracts tested, garlic was the most effective completely
checking the mycelial growth at 10 % concentration. Among other plants that garlic was
evaluated with were neem and ocimum. This shows that higher plants are untapped
reservoirs of various valuable chemicals that are anti-pathogenic. However the results
from this study did not agree with those of Chuku et al. (2010) who reported that garlic
was not effective in controlling fruit rot pathogens. Reports by Paradza et al. (2011)
showed that when garlic and neem extracts were used to control bacterial soft rot, garlic
was the most effective in reducing bacterial maceration of the potato tissue.
According to Amadi and Olusanmi (2009), extracts from garlic and neem have anti-
microbial properties against a wide range of pathogens but garlic was the most effective.
Garlic contains a compound known as allicin which is readily membrane-permeable and
undergoes thiol-disulphide exchange reactions with free thiol groups in proteins and the
compound is anti-bacterial, anti-fungal and anti-viral (Miron et al., 2000 and Daniela et
al., 2008). When garlic bulbs are damaged a substrate alliin mixes with the enzyme alliin-
lyase and forms a volatile compound which is fungicidal and disrupts fungal cell
metabolism due to oxidation of proteins (Slusarenko et al., 2008). Such properties may
be the basis for anti-microbial action. According to Alan et al. (2008) reduction in disease
was due to direct action against the pathogen since no accumulation of salicylic acid was
observed after treatment with garlic crude extract to control downy mildew of
87
Arabidopsis. Reports by Udo et al. (2001) showed inhibition of growth and sporulation of
fungal pathogens in Ipomea batatas by garlic extracts.
Stangarlin et al. (2011) revealed that aqueous extract of ginger at different concentrations
had effect on the mycelial growth and sclerotial production of Sclerotina sclerotium in
vitro. The anti-microbial property of ginger in reducing the mycelial growth of fungal
pathogens agrees with the results of this study. The inhibitive effect was proportional to
the concentration of the crude extract: the higher the concentration the higher the
inhibitory effect. According to Ijato (2011), extracts of Z. officinale and Ocimum
gratissimum were mycotoxic to F. oxysporum, A. flavus and A. niger that causes post-
harvest rot of yam tubers and that the effectiveness of the extracts increased with increase
in concentration as was observed in this study.
Chiejina and Ukeh (2012) reported that the efficiency of ginger extracts may be due to
high contents of alkaloids contained in it. Reports of Okwu (2004) ranked alkaloids as
the most significant, efficient and therapeutic plant substances. Results of Chuku et al.
(2010) showed that ginger extract at a concentration of 3 gm/20ml of extract completely
inhibited fungal growth. According to Ilondu et al. (2001) some plants contain phenolic
compounds and essential oils, which have inhibitory effects on micro-organisms. Ahmed
and Stoll (1996) reported that extracts of ginger rhizomes are specially valued for their
effectiveness against fungi.
88
Neem leaf extract was found to be the most effective extract on Fusarium spp. These
results agree with the report of Hassanein et al. (2008), where four concentrations of
neem extracts were evaluated and the lowest concentration (20 %) effectively suppressed
mycelial growth of F. oxysporum (100 %). This reveals that Fusarium spp. is more
sensitive to neem extracts than other pathogens. Singh et al. (1980) also found that the
growth of F. oxysporum, R. solani, S. rolfsii and S. sclerotiorum were inhibited with
extracts of leaves from neem tree. Bankole and Adebanjo (1995) reported that neem leaf
extracts inhibited the growth of M. phaseolina, F. moniliforme, F. solani, and B.
theobromae in vitro.
According to Meena and Mariappan (1993), neem leaf extracts inhibited the growth and
spore germination of seed microflora including A. tenuis, A. flavus, C. lunata, F.
moniliforme and R. stolonifer. Sharma and Jandaik (1994) reported that different extracts
from neem leaves have inhibitory effect on R. solani. Reports from Nahed (2007) showed
that cold extracts of A. indica inhibited growth of F. oxysporum, which causes rot of
cucumber. Cassava anthracnose caused by C. gloesporides was controlled using neem
extracts (Fokunang et al., 2000). Hoque et al. (2007) reported that neem contains a
compound known as mahmoodin which is active against gram-positive and gram-
negative bacteria. This supports the results of this study with respect to Erwinia spp.
which indicates that the extracts significicantly slowed growth in petri dishes treated with
neem extracts. According to Amadioha (1999), neem seeds and leaf extracts reduced the
growth of fungi P. oryzae of rice.
89
The results from this study suggest that there were anti-bacterial and anti-fungal
compounds present in the ginger, neem and garlic crude extracts which were able to
control the growth of fungal and bacterial pathogens tested.
90
CHAPTER SIX
CONCLUSIONS AND RECOMMENDATIONS
6.1 Conclusions
From this study, it can be concluded that most of the farmers pick their tomatoes early in
the morning. Tomato fruits are packed in wooden or plastic crates before being
transported to the market by use of pickups, lorries, motor bikes, carts and bicycles. It can
also be concluded that losses occur as a result of poor picking methods, poor handling,
poor packing methods, poor transportation and decay. The estimates of post-harvest
losses averaged 30.63 %. It was also noted that there are micro-organisms (fungi and
bacteria) that caused post-harvest losses on tomato fruits irrespective of the cultivar. In
this study Rhizopus spp., Geotrichum spp., Erwinia spp., Fusarium spp., Botrytis spp.,
Biplolaris spp. and Curvularia spp. were identified. Among the pathogens identified
Rhizopus spp. was the most destructive pathogen. Bipolaris spp. caused the least rot
demonstrating that it is not one of the most damaging pathogens. The study indicated that
cultivars evaluated (Kilele F1 and Roma V.F) had influence on the post-harvest losses.
Ginger, garlic and neem crude plant extracts were found to have potential anti-microbial
compounds that inhibit tomato fruit rots at various concentrations. The evaluated
concentrations were effective against the test pathogens but efficacy varied with the
concentration. This can provide an alternative means for the control of tomato fruit rot by
farmers. Results of this study can be an important step in developing plant based bio-
pesticides for the management of fruit rots because the plants are readilavailable, affordab
91
6.2. Recommendations
This study recommends that:
1. The duration between tomato harvest and transport to the market be shortened to
reduce post-harvest rots.
2. Farmers grade their produce thoroughly by separating the infected from healthy ones,
separate in terms of size and ripening level.
3. Farmers disinfect the tomato fruits after harvesting to reduce chances of infection. This
can be done by use of sodium hypochlorite.
4. Farmers should avoid lining their crates with papers to increase aeration in the crates.
5. Further research be carried out to determine residual levels of the plant extracts on
fruits and their implication on the health of the consumers.
92
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APPENDICES
Appendix I: Questionnaire
A structured questionnaire was used to collect information or data on post-harvest losses
from the farmers in Mwea, Kirinyaga County. Farmers growing tomato were interviewed.
The questions were translated into the local language by some members of the research
team.
The questionnaire used in the study.
Date------------------- Questionnaire No. ------------------ Village --------------------
Name of farmer --------------------------- Contact ---------------------
INSTRUCTIONS
PLEASE TICK THE CORRECT ANSWER IN THE BOXES PROVIDED.
1. What tomato varieties do you grow?
Primabel Carl J Kenya Beauty 10X Hybrid
Any other (specify)………………………………………………………..
2. At what stage do you harvest the tomatoes?
Unripe ripe very ripe
3. At what time do you pick your tomatoes?
In the morning Afternoon
4. What kind of labour do you use for harvesting the tomatoes?
Family labour Hired labour
5. Do you treat your tomatoes after harvesting?
Yes No
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6. Do you grade tomatoes before packing?
Yes No
7. What packing materials do you use?
Sacks Cartons Wooden Crates Plastic Crates
Any other (specify) ………………………………………………………
8. Do you create layers in the packing containers?
Yes No
9. If yes, what materials do you use?
Grass News papers
Any other (Specify)……………………………………………………….
10. How many days does the fruit spend on the farm before reaching the market?
One Two Three four
Any other (specify) …………………………………………………….
11. What means of transport do you use to take your produce to the market?
Cart Human transport Pickup Lorry
Any other (specify)………………………………………………………….
12. How long does the produce take to reach the market?
One hour Two hours Three hours Four hours
Any other (specify)…………………………………..
13. How do you sell your produce?
Wholesale Retail
14. How many days do you take to sell the produce in the market?
Less than a day One day Two days Three days
Any other (specify)……………………………………………………….
15. What percentage of tomato yield is damaged ------?
(a) During transportation?
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10% 20% 30% 40%
Any other (specify) ……………………………………………………….
(b) Due to packing?
10% 20% 30% 40%
Any other (specify) ……………………………………………………….
(c) Due to decay?
10% 20% 30% 40%
Any other (specify) …………………………………………………………..
(d) Due to time lag from the farm to the market?
10% 20% 30% 40%
Any other (specify) ……………………………………………….
(e) During grading?
10% 20% 30% 40%
Any other (specify) ……………………………………………….
16. Which tomato post harvest pests affect tomatoes?
Fruit worms Spider mites Thrips Moths
Any other (specify)………………………………………………..
17. Which tomato postharvest diseases affect tomatoes?
Fusarium rot Phoma rot Bacterial soft rot Gray mold
Any other (specify) …………………………………………………….