agriculture,forestry & fisheriesDepartment: Agriculture, Forestry and FisheriesREPUBLIC OF SOUTH AFRICA

OlivesOlives— Production guideline —

OlivesOlives

— Production guideline —

March 2010

Department of Agriculture, Forestry and Fisheries

2010

Printed and published by

Department of Agriculture, Forestry and Fisheries

Compiled by

Directorate Plant Production in collaboration with the ARC

Design and layout by

Directorate Agricultural Information Services

Obtainable from

Resource Centre Directorate Agricultural Information Services Private Bag X144 PRETORIA 0001

CONTENTCONTENT

General ................................................................................................. 1

Cultivation practices ............................................................................. 8

Post-havest handling ............................................................................ 18

Production schedule ............................................................................. 18

Utilisation .............................................................................................. 19

References ........................................................................................... 22

Personal communication ...................................................................... 23

Notes .................................................................................................... 24

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GENERAL GENERAL

Scientific name: Scientific name: Olea europeae L.

Common names: Olive (English), Olyf (Afrikaans), Umnquma (isiXhosa)

The type of olive tree which produces edible olives and olive oil, belong sto the family Oleaceae and is classified as Olea europeae L. The genus Olea includes approximately 30 other species of which only the species Europeae bears edible fruit from which oil can be extracted. Some of these olivewood (Olea europeae subspecies africana), ironwood (Olea capen-sis), dune olive (Olea exasperata) and forest olive (Olea woodiana).

Origin and distribution

Olives were sacred to Athena, the ancient Greek goddess of peace and wis dom (Anon, 2006a). According to folklore, Athena and Poseidon (ancient Greek god of the sea) had a dispute on whose name should be given to a new city in Greece. In order to resolve the matter, they agreed to name the city after the person who offered the most precious gift to the citizens. Poseidon then struck a rock with his sceptre and produced salt water, hence the sea. Athena on the other hand, drove her spear into the soil and it turned into an olive tree. Athena’s gift was regarded as being more beneficial to the citizens and the city was therefore named Athens in honour of Athena (Anon, 2006b).

According to Anon (2006a) the olive is also an emblem of:

Virtue—Greek newly-married brides wore an olive-garland in stead of the usual orange-blossom one;

Productivity—Olive trees bear large numbers of fruit and are therefore regarded as valuable to their owners;

Merit—A crown of olive twigs was the highest honour which could be be-stowed on a citizen of ancient Greece;

Peace—An olive branch was a symbol of peace in ancient times. If a person presents an olive twig, it can be regarded as a gesture of peace;

Prosperity—King David states in Psalm 52:8 ‘But I am like an olive tree in the house of God’ (Anon, 2006a);

Victory—A wreath made of olive leaves was used to crown the athletes in the ancient Olympic Games. The Greeks continued this tradition during the 2004 Summer Olympics (Anon, 2006c).

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Homer, an ancient Greek poet, singer and composer of the legendary Odyssey and who lived between 800 and 700 BC, called olive oil ‘liquid gold’ (Anon, 2006b). According to him the olive tree has been thriving in Greece for more than 10 000 years. Plinius Secundus (79 BC to 23 BC), an ancient Roman author, cited a sacred Greek olive tree that was 1 600 years old. However, in Genesis 8:11 it states that ‘When the dove returned to him in the evening, there in its beak was a freshly plucked olive leaf. Then Noah knew that the water has receded from the earth’ (Anon, 2006a). Olive trees were also mentioned in the Bible as to have grown in the Garden of Gethsemane during the times of Jesus (Anon, 2006d).

According to Anon (2006d and references within), olive trees are native to the Mediterranean and wild olives were harvested by Neolithic peoples as early as 8 000 BC and processed into oil by 4 500 BC in the country that is currently known as Israel. Olive stones were found in archaeological sites dating as far back as 9 000 BC, however, there is clear evidence of do-mestication of olive trees in the Mediterranean region from approximately 3 500 BC (Anon, 2006e).

Modern olive cultivars descend from multiple wild ancestors, however, the detailed history of domestication is not known yet (Anon, 2006d and refer-ences within).

Olives were introduced to South Africa by Jan van Riebeeck, the first Governor of what was then known as a Dutch settlement. The first refer-ence to olives was on 6 August 1659 when he recorded in his diary: ’The season is also approaching for planting and grafting the olive and all kinds of home and Indian fruit trees…’ (Karsten, 1955).

The current olive industry was established by an innovative Italian nursery-man, Ferdinando Costa, who arrived in South Africa in 1903. The vigorous growth of the indigenous wild olives (Olea europeae subspecies africana) on the slopes of Table Mountain made him realise the potential of growing the European olive in South Africa. He therefore imported known cultivars from Italy and started propagating trees by using the indigenous wild olive seedlings as rootstocks. Ferdinando bought a farm at Paarl in the Western Cape Province and erected an oil-processing plant. He also encouraged other farmers in the region to cultivate olives. The greater part of the olive industry is still based within the Paarl Valley in the Western Cape Province. However, olives are also grown in certain summer rainfall regions of the country.

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Production levels and areasSouth Africa

According to Mr Andries Rabie (2007), Chairperson of the South African Olive Growers’ Association, the total estimated olive production within the Republic of South Africa for 2006 is as follows:

Olive production in South Africa

Type Quantity

Table olives (fruit) Olives for processing into oilOlive oil

2 000 to 2 500 metric ton3 000 to 3 500 metric ton600 000 to 650 000 kg

Internationally

South Africa‘s contribution is insignificantly small in comparison to the top three producers, namely Italy, Spain, and Greece.

The major international olive producers (FAO, 2006) for 2005 were as follows:

Major international olive producers (FAO, 2006) for 2005

Rank CountryProduction(Metric ton)

Income(international $ 1 000)

123456789

1011121314151617181920

ItalySpainGreeceTurkeyTunisiaSyrian Arab RepublicMoroccoEgyptPortugalLebanonLibyan Arab JamahiriyaAlgeriaPalestineUnited States of AmericaArgentina JordanIsraelPeruIslamic Republic of IranCroatia

4 114 2933 712 7002 200 000

850 000700 000620 000450 000310 000270 000180 000180 000170 000140 000113 400103 000

73 99050 00043 00041 00033 000

2 058 2571 857 3521 100 594

425 230350 189310 167225 122155 084135 073

90 04990 04985 04670 03856 73151 52837 01525 01421 51220 51116 509

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Major production areas in South Africa

Although olives are established throughout the Republic of South Africa, the olive industry is centred around Paarl and Wellington in the Western Cape Province. This area recently expanded to include the Riebeek-Kasteel, McGregor and Hermanus farming districts. A number of orchards have successfully been established in other regions of the country, viz. Western Cape Province (Prince Albert, Oudtshoorn, Beaufort West and Laingsburg), Northern Cape Province (Vaalharts, Prieska and Upington), Eastern Cape Province (Alicedale), North West Province (Brits) and Limpopo Province (Modimolle).

Both the production and local consumption are currently growing. How-ever, table olives and olive oil are still imported into the Republic of South Africa as the current demand exceeds the local production. The current state of affairs can change as the South African producers are known for producing crops of the highest quality and can compete with larger produc-ers in foreign countries. The olive industry has the potential to grow and export to foreign markets.

Graaf ReinettEast London

Port ElizabethStellenboschCape Town

Beaufort West

GeorgePaarl

Durban

Pretoria

Prieska

KimberleyUpington

Sout Africa

Lesotho

BotswanaNamibia

Swaziland

Zimbabwe

Mo

zam

biq

ue

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Description of the plant

Roots

The root system is generally shallow and widespread. Approximately 80 % of the roots occur within the top 60 cm of soil. The soil characteristics will determine the depth of the root system.

Stem

The different cultivars vary in their growth habitat. Young shoots are soft and flexible yet strong, while the older stems as well as the trunk of the tree are very hard. The tree has numerous branches which bend down as they mature, giving the tree a bushy appearance. Shoot growth mainly occurs in two flushes, i.e. the primary flush during spring, followed by a second-ary flush during autumn. Olive trees have two kinds of shoots. Shoots are either vegetative (woody) or reproductive (bearers with little or no terminal elongation). No fruit will be borne on the vegetative shoots while all the fruit will be borne on the reproductive shoots.

Leaves

The leaves are lance shaped and are arranged alternatively on opposite sides of the shoots. The upper leaf surfaces usually have a dark green colour while the undersides are silvery-grey. The silvery-grey colour can be ascribed to the presence of tiny, umbrella-shaped hairs also called trichomes. These trichomes cover the stomata of the leaf. The presence of these trichomes as well as a thick cuticle protects the plant from water losses. Leaves have a lifespan of 2 to 3 years, after which they turn yellow and drop from the tree. Their photosynthetic activities and storage func-tions are taken over by the younger leaves.

Flower

Daylength is not important in stimulating the development of flowers. However, olives need optimum chilling temperatures for flower develop-ment. The initiation of flower buds already starts during the summer. Flower development is stimulated by lower temperatures during the early winter months, slightly higher temperatures during the middle of winter (average minimum of 13 °C) and higher temperatures towards the end of winter. Flower differentiation takes place in the lateral buds. These buds

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eventually develop into flower clusters. Each flower cluster has between 10 to 12 individual flowers. In the Western Cape Province the flowers bloom during the last part of October. The petals of the flowers will be shed within 1 day after blossoming. The flowers will then be either ‘perfect’ or ‘imperfect’ flowers. The perfect flowers have two stamens (male reproduc-tive organs) and a pistil (female reproductive organ) while the imperfect flowers have two stamens and an undeveloped pistil. Imperfect flowers can therefore bear pollen but would not be able to bear fruit. A heavy crop load will be achieved if only 1 % of the all the fruit sets. Olive trees are wind pollinated. Cross-pollination was found to be beneficial to fruit set.

Fruit

Olive fruit mature normally between 4 to 6 months after blossoming. However, fruit maturation will also be influenced by the kind of cultivar, weather conditions and specific cultural practices. The first 42 days after full bloom is a critical period during which active vegetal growth takes place. Flowers which were not fertilised, will also abort during this period and the remaining fruit will start to develop. Fruit is usually harvested at 4 to 6 months after flowering. The fruit changes colour as it ripens, i.e. from green to straw-yellow and eventually to dark red or black. Olives should not be harvested too late in the season as this will have a negative effect on the following year’s production. Olive trees tend to bear heavy crops

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followed by light crops in alternate years. This phenomenon is called alter-nate bearing.

CultivarsThe following aspects should be taken into account in determining which cultivar to establish:

• Market demand (table olives vs oil production)

• Adaptability of cultivar to the specific farming area

• Pollination requirements

• Availability of planting material

• Scheduling harvesting of olives with harvesting times of other crops on the farm.

Recommended cultivars

Mission—black table olive and olive oil

Kalamata—black table olive

Manzanilla—green table olive

Barouni—green queen table olive

Frantoio—high-quality olive oil and cross-pollinator

Climatic requirementsTemperature

The production of olives under harsh, unfavourable conditions will not be economically viable, although olives are known to survive under these con-ditions. Olives are traditionally grown in regions which have relatively cool, frost-free winters followed by hot, dry summers. Olive trees are less sensi-tive to wind damage than other types of fruit. However, wind-damaged fruit will not be suitable as table olives and would only be suitable for the production of oil. It is, therefore, important to select the specific cultivar in accordance with the prevailing weather conditions of an area.

Rainfall

An annual rainfall of between 650 and 900 mm would be required for dry-land production.

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Soil requirementsOlives can be grown on marginal soils. However, the growth and produc-tion will not be optimal. Olives therefore require well-drained and well-aerated soil. The soil should be prepared to a depth of at least 80 cm. It is important to have the soil analysed before planting in order to obtain guidelines for soil preparation.

Poor production of olives will be obtained on shallow soils. Trees cultivated on wet or waterlogged soils are susceptible to plant diseases. Water up-take will be restricted in wet soil owing to low oxygen levels in the soil. Very sandy soils have poor water-holding capacities and will therefore require careful management in terms of irrigation and nutrition. Soils with a clay content of above 30 % are unsuitable for olive production while soils with a high gravel content are ideal. The pH (KCl) level of the soil should be above 5,0, preferably close to 6,0. However, a moderate harvest could still be obtained with lower or higher soil pH levels. Olives are more resistant to saline conditions in comparison to stone fruit but far less tolerant than dates. Nitrogen (N), potassium (K) and boron (B) are the most important nutrients for olive trees. A soil analysis will determine how much fertiliser should be applied to ensure optimum production.

CULTIVATION PRACTICESCULTIVATION PRACTICES

PropagationOlive trees can be propagated by using several methods such as grafting of young wood on seedlings of cloned rootstocks or by the rooting of hard-wood, semihardwood or softwood cuttings. The method used, will depend on the cultivar, facilities that are available as well as the expertise of the grafter.

The propagation of hardwood cuttings is a traditional method used in the Mediterranean countries and it requires low capital input and minimal infra-structure. However, it is not advisable to use hardwood cuttings as the risk of infections by pests and diseases is increased by the utilisation of older wood. Semihardwood cuttings, which are dipped in synthetic plant growth regulants, are most often used. The only disadvantage of this method is that the cuttings should be kept under controlled environmental conditions such as a high humidity glasshouse. However, such a facility is very ex-pensive to erect.

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It is, therefore, advisable to order trees from a reputable nursery that is registered with the South African Olive Growers’ Association (SAOGA). It is also important to ensure that the following criteria are met before olive trees are purchased. The trees should:

• be true to type

• be free of pests and diseases

• not have any signs of nutrient deficiency

• have a well-developed root system

• have one main straight stem with some secondary lateral branches sprouting from approximately 20 to 30 cm above the soil surface

• be 18 months old

• have a height of approximately 0,5 m.

Soil preparation

An olive tree has a lifespan of at least 30 years. It is, therefore, important to select the correct locality and to prepare the soil properly. It is beneficial to seek expert advice with regard to site selection and soil preparation. Soil samples should be taken prior to soil preparation in order to determine the water-holding capacity as well as the nutrient content of the soil.

At least five soil sample holes should be made in a plot of 1 ha (100 m x 100 m). A spade should be used to make a hole of 1 m wide, 1 m in length and 1 m deep. A vertical sod on the side of the hole to a depth of 30 cm must be taken and transferred into a marked plastic bag. The second sam-ple should be taken on the side of the hole in the bottom part of the profile (30 to 60 cm deep). The blade length of a new spade is approximately 30 cm.

Any layers in the soil, such as a stone or clay layer as well as the depth at which it occurs should be recorded. All stones larger than 10 cm in diam-eter may be removed from the sample. However, the number and sizes of stones not included in the sample should be recorded. The samples can be sent to a reputable institution where the soils will be analysed. The sampling hole should be filled again. The bottom layer soil, in other words the layer that was removed last, should be replaced first into the hole. This step is important as the bottom layer usually consists of more clay. If the bottom layer of soil is replaced into the top part of the hole, it can lead to

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soil compaction. The samples taken at the different holes should not be mixed or added together. This is important as the soils, within one plot can differ in texture. The positions within the plot where the samples were taken, should be marked.

The results of the soil analysis will indicate whether the soil is suitable for olive cultivation and, if so, which kind of fertilisers as well as the quantity of fertiliser has to be applied. Perennial weeds should be removed before soil preparation. Soils should be assessed for the presence of harmful nematodes or soil pathogens, especially if the soils have previously been planted with other types of crops such as vines. The soil should be fumi-gated if necessary. However, it is important to seek expert advice with regard to soil fumigation. Aspects such as the availability of water and drainage should also be considered. Soil preparation is usually done on a large scale by professional contractors. Planting holes, 1 m wide, 1 m in length and 80 cm deep (1 x 1 x 80 cm), should be made on plots which are too steep to be prepared by implements or on plots which are too small for the movement of large implements. Specific quantities of lime, phospho-rus, potassium and microelements, based on the soil analysis, should be applied to the soil during soil preparation. The edges of the planting holes should be roughenedto allow the plant roots to penetrate the soil adjoining the planting hole. The hole should be filled again as described previously and marked clearly. Soil preparation should be done during the month of May.

Planting

There are certain aspects that should be taken into account, such as slope of the plot, planting density, planting date and planting depth.

Slope

The steeper the terrain, the more expensive orchard management be -comes for the producer.

PLANTING DENSITY/SPACING

Planting distances will depend on cultivar, soil fertility, level of orchard management, availability of water and the size of the orchard. Trees are traditionally spaced 7 m apart within the planting row while the rows are

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spaced 7 m apart, resulting in a planting density of 200 trees per hectare. Modern orchards are planted at a higher density with the rows spaced 6 to 7 m apart while the plants are spaced 3 to 5 m apart within the planting row. Cultivars such as Manzanilla should be spaced more closely, while strong growers, such as Mission, would be spaced further apart.

Planting date

The trees should be planted during late winter or early spring.

Planting depth

Trees which are obtained from a nursery would usually be supplied in plastic bags. A square-shaped planting hole should be made in the mid-dle of the previously prepared hole (see soil preparation). This planting hole should not be deeper than the original length of the plastic bag. The roots should not be disturbed during planting. The plastic bags should be removed carefully before planting, taking care not to damage the roots or allow the roots to dry out. The roots should not come in contact with any fertiliser or manure which was applied into the planting hole as it could result in scorching. The soil should then be packed firmly around the roots and irrigated directly after planting. The trees should be supported with sturdy bamboo of wooden stakes and tied with decomposable twine in order to ensure upright growth and to prevent wind damage. The stems of the trees can be protected for the first couple of years by painting it with whitewash or white PVA paint.

Fertilisation

Olives, similar to other fruit trees, require macronutrients such as nitrogen (N), potassium (K), phosphorus (P), calcium (Ca) and magnesium (Mg). Trace elements such as boron (B), zinc (Zn), iron (Fe), copper (Cu), manganese (Mn) and molybdenum (Mo), are only required in small quan-tities. Application rates of fertilisers should be done in according to the results of proper leaf and soil analyses. Nitrogen applications should be managed carefully as it is critical to maintain a balance between vegetal growth and yield. Small quantities of nitrogen should be applied regularly to prevent excessive vegetal growth caused by single large applications. Foliar applications (sprays) could be beneficial under very dry conditions, or in the case of nutrient deficiencies, but are generally not recommended.

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Potassium is usually applied directly after planting followed by applications during every spring and autumn. It is critical to restore the K levels in the shoots before the start of flower initiation as it will reduce the tendency of alternate bearing. Phosphorus does not leach from the soil. The phospho-rus that was applied during soil preparation would therefore be sufficient for several years. The pH levels have to be rectified only when necessary and in accordance with a soil analysis.

Method(s) and time of application

NITROGEN

This element is utilised by the trees throughout the growing season and should be applied three times per year, i.e. at the beginning of August when the trees start growing, just before bloom (early October) and in autumn (mid March). Two types of fertilisers can be used, viz. ammonium sulphate [(NH4)2SO4] or limestone ammonium nitrate (LAN). The quantity of nitrogen that should be applied, will depend on the production potential, for instance if a production of 2 t/ha is envisaged, the nitrogen fertiliser ap-plication rate would be 15 kg/ha. However, young trees should be fertilised differently. During the first year, 20 g of LAN or 30 g of (NH4)2SO4 (for more alkaline soils with a pH (KCl) of above 7) should be applied per tree per month throughout the growing season. The quantity of fertiliser should be increased during years 2 and 3 with 40 g LAN or 60 g of (NH4)2SO4 per tree per month throughout the growing season. From the fourth year after establishment, 60 g of LAN or 90 g of (NH4)2SO4 should be applied per tree per month throughout the growing season.

POTASSIUM

Potassium in the form of potassium chloride (KCl) should be applied during late winter or early spring (70 % of the recommended quantity) and during autumn (30 % of the recommended quantity). The quantity of potassium which should be applied should be based on the production and leaf as well as soil analyses. It is therefore important to seek expert advice.

BORON

This is the only trace element which appears to have a marked influence on olive production. Boron is necessary for the growth of pollen-tubes, which is important to ensure successful pollination and subsequent fruit develop-

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ment. Boron, in the form of Borax (sodium borate, Na2B4O7.10H2O), which contains 11,3 % boron, can be applied to the soil at a rate of 200 g per tree. It could also be applied as a foliar spray using Solubor, which contains 20,8 % boron. The foliar sprays should be applied during the spring, at an application rate of 1,5 l/ha. Boron should only be applied if the boron levels of the soil decrease to less than 2 mg/kg. Foliar application of boron is highly effective when it is applied during spring, just before flowering. Other trace elements can be applied according to leaf and soil analyses. The fertiliser programme should be amended when fungicides are used which contain copper, manganese or zinc.

Irrigation

Irrigation is a prerequisite for a regular production of high-quality fruit. Dryland olive production under South African conditions is generally not recommended. The irrigation requirements of a tree, i.e. the volume of wa-ter applied at a specific time and the frequency of irrigation are influenced by the following factors, viz. the age and size of the trees, the season and growth stage, the crop size, rainfall, temperature, relative humidity, wind, soil texture, soil structure, soil depth as well as the type of irrigation system that is used. A physical analysis of the soil to determine the water-holding capacity of the soil will assist in ensuring efficient water usage. A good general rule to use is to wet the soil to the full rooting depth. A young olive tree requires 15 to 20 litres of water per week during the first growing season. The volume and frequency of irrigation from the second year after planting and for mature olive trees will depend on the climate, season as well as tree size and age. It is therefore important to seek expert advice on irrigation scheduling.

Weed controlWeed control should start before planting. Repeated ploughing or disk-ing of the infested area during the summer months prior to planting, will eradicate the weeds. Weeds growing in the root zone of the olive tree compete with the tree for available moisture, nutrients and oxygen in the soil. Weed control should therefore be done on a regular basis by either removing the weeds mechanically or by applying herbicides. A strip of 1 m wide on both sides of the olive trees, within the planting row, should be cleared of weeds. The weeds in the working row should remain, however, these should be kept short. The presence of the weeds and other natural

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vegetation in the working row has certain advantages. It will prevent soil compaction, reduce soil erosion, will enhance water infiltration and it harbours beneficial insects and other biological control agents which are necessary in the orchards.

Care should be taken when using herbicides. It is necessary to ensure that the specific herbicide is registered for use in olive orchards in the Republic of South Africa. Fluasifop is the only herbicide which will not cause any damage to the olive tree. Glyphosate (e.g. Roundup) and thiazopyr (Visor) can only be used if the herbicide does not come into contact with the leaves, suckers or the trunk of the tree.

In an organic farming system a relatively thick layer of mulch could be placed within the tree row to control weeds. This mulch will assist in sup-pressing weed growth. and it will also stimulate the olive tree to develop tiny, secondary roots, which is beneficial for nutrient uptake.

Pest controlOlive pests can be controlled primarily by their natural enemies. The use of pesticides would consequently be unnecessary and provides the op-portunity to farmers to grow olives organically. Farmers should be careful not to disturb the delicate balance between predator and prey by the unnecessary use of pesticides. Other orchard practices, such as pruning correctly and minimising the dust raised by orchard traffic, can reduce pest infestation.

The main pests which occur on olives grown in tSouth Africa are yellow and black-striped olive beetles, olive lacebugs and olive flies.

Olive beetle Olive lace bug Olive fly

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• Yellow and black-striped olive beetles—the larvae of this beetle feed and tunnel into leaves of especially young trees, thereby inhibiting plant growth.

• Olive lacebugs—these bugs suck the sap from the leaves, especially in the case of trees which have a dense canopy. The damage to the leaves is usually visible as tiny yellow spots on the leaves. These leaves will turn chlorotic (lose the normal green colouration) and will die eventually

• The olive fly—The adult female insect stings the fruit on the outside and lays her eggs inside. The eggs later hatch and develop into larvae. The latter destroy the fruit from the inside as they tunnel into the flesh.

Minor pests which occur on olives in South Africa include:

• Scale insects—such as Ross scale, black scale and oleander scale. Infestations can occur under dusty conditions.

• Olive psylla—this is a small sucking insect which is related to aphids. It becomes a serious pest when the ecological balance is disturbed.

• Olive mites—this insect causes leaf deformation, floral damage and bud drop.

• Mediterranean fruitflies—they leave unsightly marks on fruit, making the fruit unsuitable for processing

• Seed wasps—these wasps occur only occasionally on domesticated olive trees. They damage the fruit by burrowing from within the fruit, leav-ing a small exit hole on the skin of the fruit. The fruit will consequently only be suitable for oil production.

• Leaf-rollers—the larvae of these insects feed on young leaves and the shoot tips.

• Stem borers—the damage caused by these insects will be visible as the individual shoots die back suddenly.

• Termites—these insects chew the leaves and twigs on newly planted trees.

Nematodes

The olive trees are attacked by the same nematodes which parasitise on grapevines. Olive trees should therefore not be planted directly in soils which have previously been planted to grapevines. It is advisable to seek

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professional advice in order to determine whether fumigation of the soils would be necessary.

Disease controlThere are two main fungal diseases which occur in olive orchards:

• Anthracnose—this disease causes major production losses as the fruit is mainly attacked. The first infections will be visible as small, reddish-brown spots which will appear on the flower clusters. The infected flowers will die before they are able to open. Small, circular, depressed, brown-coloured spots will appear on ripe and partially ripe fruit. The damaged fruit will not be suitable for processing.

• Olive leafspot—this disease will occur in orchards with restricted air movement because of densely spaced trees. The first symptom of this disease is the appearance of faint, dirty spots on the upper and lower leaf surfaces. The leaves will eventually turn yellow, resulting in leaf- drop and death of shoots.

Olive trees are also susceptible to soil-borne root diseases. The trees are usually infected as a result of poor irrigation scheduling. Continual rainfall for several consecutive weeks will promote the rapid spread of a fungal disease. It would be very difficult to control fungal infections under these adverse conditions. Appropriate orchard management practices and the application of suitable fungicides can control the diseases mentioned. However, it is important to follow the instructions carefully, which usually accompany the fungicide.

Other cultivation practices

Pruning and training

The lifespan of an olive orchard will be determined by the pruning strategy that is followed. Pruning should be kept to a minimum during the first few years. Only those branches which are obstructing the growth of other branches or which grow near the soil surface should be removed.

There are different approaches to the pruning and training of mature olive trees. In a more extensive type of pruning and training system, three to six main scaffold branches are selected, which will eventually be shaped into a semiopen vase. All the upright growth in the centre of the tree should be

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removed to improve light penetration throughout the tree. However, care should be taken not to expose the scaffold branches to too much sunlight as the risk of sunburn will be increased.

The more intensive pruning and training system is quite different, as a single leader shoot is selected. This shoot is then supported by a stake and trained upright. Lateral branching is encouraged over the entire length of the leader from a height of about 40 cm above the soil surface, upwards. The bottom branches of the tree should be allowed to thrive in order to obtain a conically shaped tree. Lateral branches should have a diameter of less than a third of that of the main leader. These lateral branches should be kept at a somewhat flat angle. Vertically growing smaller branches, which sprout from the lateral branches, should be removed regularly.

Mulching

It would be beneficial to apply organic mulches such as kraal manure or decomposed wood sawdust, as it would:

• reduce water loss from the soil• protect the soil from compaction• protect the soil against extreme temperature changes• provide a habitat for earthworms

• suppress weed growth.

Harvesting

This is the most expensive operation in commercial olive production and can represent about 40 % of the total cost involved in producing olives.

Table olives should be picked by hand. Fruit should be picked individually and placed carefully into picking bags or buckets which have been lined with foam rubber. Care should be taken not to damage the fruit during pick-ing. Olives which will be used to produce oil are usually removed (stripped) from the trees onto nets that are positioned underneath the trees. Olives are usually harvested from February to July. However, the harvesting date will depend on the specific cultivar and intended processing method. Fruit which is intended to be processed green, should be harvested when the colour has changed from a bright green to yellowish-green or when the first fruit on the tree shows a light pink or purple blush. Only fruit with the specific size, which are required by the processor, should be harvested. The rest of the fruit should be harvested at a later stage.

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Fruit which is intended for processing as ripe black olives should be picked when having a completely black colour, but before softening or becoming overripe.

Olives harvested for oil production should be harvested when most of the fruit on the trees is ripe. The oil content within the fruit increases as the fruit colours and ripens and then remains relatively constant. Delaying the harvest until all of the fruit on the tree is ripe will only result in oil of a lower quality.

It is always a good idea to familiarise oneself well in advance with the fruit quality requirements of the company which will process the fruit.

POST-HARVEST HANDLINGPOST-HARVEST HANDLING

Olives should be transported to the packing-shed as soon as possible after harvesting. The containers and crates used for transporting table olives should be smaller than those used for deciduous fruit and be lined with foam rubber to minimise fruit damage. The fruit should then be graded according to size. Any stalks, leaves, malformed, bruised, infested and overripe fruit should be removed. Olives are extremely delicate fruit and decay rapidly when bruised, which would make them unacceptable for processing. Damaged fruit should therefore be processed within 24 hours after harvesting to ensure good-quality oil. Undamaged fruit could be cool- stored for a limited period at a temperature of 10 °C.

The harvested fruit can either be delivered to a commercial processor for processing or it could be processed at home, but on a smaller scale. Many olive producers prefer to deliver the harvested fruit to processors as a large amount of capital is needed to erect a processing plant.

PRODUCTION SCHEDULESPRODUCTION SCHEDULES

Activities

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Feb

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ob

er

No

vem

ber

Dec

emb

er

Soil sampling

Soil preparation

Planting

19

Activities

Jan

uar

y

Feb

ruar

y

Mar

ch

Ap

ril

May

Jun

e

July

Au

gu

st

Sep

tem

ber

Oct

ob

er

No

vem

ber

Dec

emb

er

Fertilisation

Nitrogen

Potassium

Boron

Lime

Irrigation

Pest control

Disease control

Weed control

Pruning

Leaf sampling

Harvesting

Marketing

UTILUTILISATIISATIONON

Olive oil is unique compared to other culinary oils in that neither refining nor the addition of any kind of chemical is necessary to obtain the oil. The oil can also be consumed immediately after extraction. The oil is an excellent salad dressing and is ideal for frying and baking. Table olives are usually served as a snack or in salads and pizzas.

Many of the health benefits attributed to olive oil are supported by various research findings. The South African consumer has to be educated on the health benefits of olives and olive oil. They should also be knowledgeable about olives in order to distinguish between good-quality, locally produced table olives and olive oil and those inexpensive, third-rate products which are usually imported. According to the standards of the International Olive Oil Council (Anon, 2007g), the labels on the olive oil containers should clearly indicate the grade of the oil:

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• Extra-virgin olive oil—this oil is obtained from the first pressing of the olives through the cold pressing process and acidity is less than 0,8 %. This oil has a superior taste. There can be no refined oil in extra-virgin olive oil.

• Virgin olive oil—It is made from olives that are slightly riper than those used for extra-virgin oil and is produced in exactly the same manner. This oil is judged to have a good taste and acidity is less than 2 %. There can be no refined oil in virgin olive oil. Virgin olive oil is essentially defective extra-virgin oil.

• Olive-pomace oil is a blend of refined pomace olive oil and possibly some virgin oil. Pomace is the pulpy mass that remains after the olives have been crushed and pressed to extract oil. Although olive-pomice oil is fit for consumption it may not be called olive oil.

• Lampante oil is olive oil that is not used for consumption; lampante comes from olive oil’s ancient use as fuel in oil-burning lamps. Lampante oil is mostly used in the industrial market.

Processing of table olives

Olives cannot be consumed fresh and have to be processed. The strong, bitter taste of olives can be ascribed to the glucoside compound called oleuropein. Although this substance is harmless, it should be removed from the fruit in order to improve the taste of the olives.

There are several methods that can be used to process the olives, such as the Spanish Green Pickling process, the Greek Natural Black process, the Kalamata process, the American Canning process and the Greek Dry-Salted Olives (Costa, 1998).

According to Anon (2007h), a long, slow, natural fermentation process in brine would ensure a better quality olive as it would retain its taste. Green olives should be washed in a strong solution of water and sodium hydrox-ide or potassium hydroxide, before being placed in the brine solution. Black olives, on the other hand, should only be rinsed in clean water before being placed in the brine solution. This process of fermentation could take up to 9 months and should therefore be monitored regularly. There are other, easier and quicker methods that could be used at home. However, the taste of the olives might be affected and flavourings such as vinegar, garlic and herbs could be added to enhance the flavour of the olives.

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According to Anon (2007h), there are certain aspects that should be kept in mind before the actual processing can commence:

• Some olive cultivars should be processed when still green, such as Manzanilla, while other cultivars such as Kalamata and Mission are best processed when black.

• Only healthy, newly picked fruit must be used. If the fruit has to be stored, it is important to ensure that it is stored in clean, cool, dry, well-ventilated crates after harvesting. The fruit must be still be firm and not shrivelled.

• The fruit should be handled carefully in order to prevent bruising.

• The work area should be hygienic. All the equipment (buckets, spoons etc.) should be clean. High-quality, chlorine-free water should be used.

Black olives

• Wash the olives to remove dust and dirt.

• Place the olives in an airtight container (stainless steel, glass or high- grade plastic containers) and cover completely with fresh water.

• Change the water twice a day (once in the morning and once at night-time) for a minimum period of 4 to 6 weeks.

• Prepare a brine solution:

– 750 g to 1 kg salt – 10 l of water– Wine vinegar to taste (± 1 liter)

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• Cover the olives with the brine in an airtight container and allow to cure for at least 4 months.

• Bottling: Place olives into glass jars and cover with hot brine:

– 20 g salt mixed into 1 l boiling water. – Add a film of good-quality extra-virgin olive oil on top of the brine. – Cover immediately with the lid and leave to cool. – Store in a cool place and refrigerate after opening.

• Sprigs of fresh herbs such as rosemary or thyme; or a few cloves or garlic; or lemon slices could be added before closing the lid.

REFERENCESREFERENCES

ANON, 2006a. Olive. Http://www.websters-on-line-dictionary.org/ defini-tions/olive, 04/01/2007, 09:15.

ANON, 2006b. Olive oil history. http://www.olympia-oliveoil/oliveoil_history/, 30/10/2006, 10:00.

ANON, 2006c. Ola’s olives—Olive trivia. http://www.olasolives.com/trivia.html, 30/10/2006,11:00.

ANON, 2006d. History of olives. http://en.wikipedia.org/wiki/Olive_oil History 08/01/2007, 08:15.

ANON, 2006e. Olea europaea (Olive). Iziko museums of Cape Town. http://www.museums.org.za/bio/plnats/oleaceae/olea_europaea.htm, 31/10/2006, 10:45

ANON, 2007f. Online Bible. http://bibleresources.com, 10/01/2007, 07:45.

ANON, 2007g. Olive oil. http://en.wikipedia.org/wiki/Olive_oil, 23/03/2007, 14:15.

ANON, 2007. Processing table olives. Olives South Africa. http://www.olivessouthafrica.com/site_files/index.asp, 23/03/2007, 15:30.

BEUKES, O. 1999. Irrigation training manual for deciduous fruit. ARC Infruitec-Nietvoorbij, Stellenbosh.

COSTA, C. 1998, Olive production in South Africa. A handbook for olive growers. ARC Infruitec-Nietvoorbij, Stellenbosch.

FOOD AND AGRICULTURAL ORGANIZATION, 2006. Major food and agricultural com-modities and producers. http://www.fao.org/es/ess/top/commodity.html, 21/11/2006, 3:00.

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KARSTEN, M.C. 1955. The old Company’s Garden at the Cape and its Superintendents. Maskew Miller Limited, Cape Town.

PERSONAL COMMUNICATIONPERSONAL COMMUNICATION

RABIE, A. 2007. Chairperson of the South African Olive Growers’ Asso ciation.

Further information can be obtained from

Directorate Plant Production Private Bag X250 PRETORIA 0001

Tel: +27 12 319 6072 Fax: +27 12 319 6353 E-mail: DPP@daff.gov.za

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