Policy and Technical Guide for

Prevention and Management of

Fusarium Wilt Disease of Banana (Fusarium oxysporum f. sp. cubense )

in Particular Tropical Race 4 (Foc TR4)

(Draft working paper)

Rome 2014

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Table of Contents

Executive summary

Background Background on banana Fusarium wilt

Brief history of the disease

Importance of the disease and current global status

The threat by TR4

Why it needs to be addressed

Biology and epidemiology of Foc Biology of the pathogen

Race concept

Global distribution of Foc

Means of spread

Considerations needed for prevention

Develop and introduce policies for sustainable banana production and prevention of Foc TR4 Holistic and integrated approach for prevention

Ensuring multi sectorial / institutional consultation and coordination mechanisms

Enhancing awareness at all levels

Legislation and regulation for movement of planting materials

Strengthening seed production and certification system

Diversifying production system and varieties

Monitoring, risk analysis and reporting (using IPPC standards)

Inspection capacities at borders

Preparedness and contingency planning

Strengthening capacities for management

Technical procedures for surveillance and on farm management Diagnosis and surveillance,

Implementation of sanitary and phytosanitary measures

Use of clean certified planting materials

Good agronomic practices

Eradication of initial infestation points

Disinfection of tools, vehicles and clothing

Training public officers and farm workers

Differentiated priority actions determined by risk level

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By countries already affected by Foc TR4

By countries at high risk

By countries potentially at risk

Differentiated priority actions according to production system Production systems based on large-scale commercial Cavendish banana plantations

Production systems based on small-scale commercial Cavendish banana fields

Production systems based on mixed banana varieties

Production systems based on mixed cropping systems

Appendix 1: Six easy steps to protect farms against Foc TR4

Appendix 2: Differences between banana Fusarium wilt and other biotic constraints causing wilt-like

symptoms.

Appendix 3: Activities that can be used to prevent and manage Foc TR4 in different risk areas and

under different banana production systems.

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EXECUTIVE SUMMARY

1. Fusarium wilt disease caused by Fusarium oxysporum f. sp. cubense (Foc) has been a major

constraint to banana production for more than 100 years. The disease first gained prominence when it

caused significant losses to Gros Michel bananas grown for export to the USA and Europe during the

first half of the 20th century. To prevent the international export industry from complete collapse, Gros

Michel was replaced with Cavendish bananas. However, in the last two decades Cavendish varieties

recently succumbed to the disease, first in the subtropics and eventually also in the tropics. The

reason for these outbreaks was the discovery of a new variant of the Fusarium wilt fungus, called Foc

TR4, in Asia. Until recently Foc TR4 has been restricted to five Asian Cavendish-producing countries

and Australia, but was recently discovered in the Middle East and Mozambique. This led to

international concerns that the fungus is threatening bananas worldwide, and could severely

endanger food security and also damage the international banana trade.

2. Banana Fusarium wilt is particularly difficult to control. The responsible fungus is soil-borne and can

survive for decades in the absence of bananas, making it difficult to target with fungicides. Once

susceptible bananas are planted in infested fields, the fungus infects it through the roots to cause a

lethal wilt. Suckers taken from diseased areas spread the Fusarium wilt fungus over large distances,

while it can be disseminated within and between fields with soil attached to shoes and plantation

tools, vehicles and in irrigation water. The only means to protect bananas is to prevent the fungus

from being introduced into disease-free fields through preventive measures, or by planting resistant

varieties. Because of the wide host-range of Foc TR4, bananas grown as food crop and for local

markets, as well as that grown for international trade, are all potential targets. Proper awareness and

appropriate legislation is thus needed to secure the future of bananas worldwide

3. The objective of this document is to provide technical guidelines to assist policy makers, regulators,

scientists and producers to respond to the threat of Fusarium wilt, in particular to Foc TR4, for banana

production in countries affected and those at risk. It is built around four components: policy

development, guidelines for prevention and management of Foc TR4, priority actions according to risk

and priority action according to production system.

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BACKGROUND

4. Background on banana Fusarium wilt

Bananas are considered the eighth most important food crop in the world, and the fourth most

important staple food in developing countries. The crop is grown throughout tropical Asia, Africa and

Latin America, mostly to supply local markets. Smaller quantities of bananas are also produced in

subtropical areas in China, Pakistan, the Mediterranean, Canary Islands, Australia, South Africa and

Brazil. Approximately 13% of bananas produced worldwide enter the export market, and these consist

primarily of Cavendish bananas. Cavendish bananas are also planted widely for local markets, and

constitute more than half of India’s 700 00 ha, and almost 90% of China’s 350 000 ha of bananas.

The remaining 60% of bananas grown globally consist of other sweet dessert varieties and cooking

bananas. In Africa, cooking bananas and plantains comprise more than 70% of all bananas grown on

the continent, whereas cooking varieties are found in smaller quantities in Asia and the Americas.

Banana produces vegetatively, which makes them highly vulnerable to biotic and abiotic stresses.

5. Banana Fusarium wilt, or Panama disease as it is frequently called, is considered the most

important disease of bananas in the world and one of the most significant diseases in modern

agricultural history. The disease is caused by a soil-borne fungus (Fusarium oxysporum f. sp.

Cubense) that survives in plantation soils as resilient chlamydospores. Once susceptible banana

varieties are planted in infested fields, the fungus infects them through their roots and colonizes the

vascular tissue in their rhizomes and pseudostems to cause a lethal wilt disease. When the disease

spreads in-field or in banana-producing regions, significant damage can occur and production can be

reduced by up to 100%. The soil-borne nature and ability of the fungus to survive for extended periods

makes is extremely difficult to control. The only effective means to prevent significant losses are to

prevent the fungus from being introduced into banana fields and by planting resistant varieties.

Brief history of the disease

6. Fusarium wilt of banana was first discovered in Australia in 1876, but gained prominence in Central

America during the early 1900s. The causal organism, called Fusarium oxysporum f. sp. cubense

(Foc), was most likely brought to the Caribbean much earlier with Silk bananas collected in Asia, but

was only discovered when it caused damage to larger monoculture plantings of Gros Michel bananas

in Panama and Costa Rica. Because of the disease’s early association with Panama and its unknown

cause, it was named Panama disease, a name that is still used. From Central America the fungus

was spread with diseased planting materials throughout the region, into South America and West

Africa. The outbreak of Fusarium wilt caused significant damage to Gros Michel production in the

areas where it was introduced. Eventually multinational banana companies were forced to replace

their Gros Michel bananas with resistant Cavendish cultivars. Cooking bananas such as the East

African Highland bananas and plantain also proved to be resistant. Consequently, Fusarium wilt was

not more considered a major threat to bananas until the discovery of a new, highly virulent strain

named Tropical Race 4 in Malaysia and Indonesia in 1990. The host range of this new strain is wider

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than that of the Central American strain, and its movement out of Asia raised concerns that the fungus

can spread globally and once again threaten world banana production.

Importance of the disease and current global status

7. Banana Fusarium wilt has been described one of the most destructive plant diseases of the 20 th

century after it decimated commercial Gros Michel banana export plantations throughout Central

America, with losses of prime agricultural land surpassing 100 000 acres. These losses disrupted not

only the banana export industry, driving it to near bankruptcy and forcing it to continuously change

production areas, but also severely disrupted social community structures, political systems and

sensitive ecological environments in Latin America for decades. The ultimate replacement of Gros

Michel with resistant Cavendish bananas brought temporary relief, as a new race of Foc is now

severely affecting Cavendish bananas, mainly in Asia, but recently also in the Middle East and Africa.

More concerning is that this new Foc race has the ability to threaten some of the banana varieties

planted as staple food by subsistence farmers in Southeast Asia and Africa.

8. Banana Fusarium wilt of banana has been reported from all banana-producing countries except the

South-Pacific islands, parts of Melanesia, countries around the Mediterranean Sea and Somalia.

Strains of the pathogen are grouped based on their vegetative compatibility. Foc races 1 and 2 are

widely distributed in Asia, Africa and the Americas. Foc subtropical race 4 occurs mainly in subtropical

banana-producing countries such as Australia, South Africa, southern Brazil, Canary Islands and

China. In Australasia, Foc TR4 can be found in most islands of Indonesia, in Malaysia and in Taiwan

province of China, and is present in the Northern Territory of Australia, Mindanao in Philippines and in

five banana-producing provinces in mainland China. It has, however, not been found in countries

bordering affected ones, such as Thailand, Cambodia and Vietnam. In the Middle East Foc TR4 has

been reported from Jordan and the Sultanate of Oman, and in Africa from Mozambique. Foc TR4 is

more virulent than Foc subtropical race 4 and does not require predisposing factors to infect

Cavendish bananas. With its wider host range and severity to Cavendish bananas, Foc TR4 poses a

significant threat to global banana production.

The threat by TR4

9. Currently Foc TR4 is primarily a Cavendish monoculture problem. Once introduced into plantations,

the fungus can cause significant damage. There are no examples where the disease has ever been

eradicated or brought under control. In Malaysia and Indonesia Foc TR4 is now widely spread, and

also affects varieties other than Cavendish bananas in small-scale farmer fields. Foc TR4 has

destroyed almost 5 000 ha of Cavendish and Latundan bananas grown by small growers in the

Philippines, and in northern Australia commercial banana land was reduced by 80%. China has been

most severely affected, with almost 40 000 ha of farmer land now being infested with Foc TR4. The

disease has spread rapidly in in infested areas in Jordan, Oman and Mozambique, and there are

significant concerns that it could spread to small grower fields in the Africa. The threat of Foc TR4 to

the two largest banana producers of bananas in the world, India and Brazil, is immense, as both

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countries produce significant amounts of Cavendish bananas. The large monoculture Cavendish

plantations in Central America can also be severely affected by Foc TR4 if the fungus is introduced

into the area.

Why it needs to be addressed

10. Foc TR4 was discovered more than two decades ago. It was limited to five Asian countries and

northern Australia for a long time where it caused severe damage to Cavendish bananas and some

local varieties grown by small-scale and subsistence farmers. The discovery of the fungus, for the first

time in the Middle East and now in Africa, has raised concerns that Foc TR4 might decimate

Cavendish bananas on a global scale and also affect bananas grown for local markets and

consumption threatening the food security of smallholder farmers as well. It is not clear when and how

Foc TR4 arrived in the Middle East and Africa nor if it has been spread also to other countries already.

Thus, considering the significant international movement of people and service providers working for

the banana industry, the pathogen can severely affect the international banana trade which is worth

US$ 9 billion, local banana production, food security and income generation of millions of people.

BIOLOGY AND EPIDEMIOLOGY OF Foc

Biology of the pathogen

11. The causal agent of Fusarium wilt of bananas belongs to the section Elegans in the genus

Fusarium. The fungus is characterized by micro- and macroconidia that are produced on branched

and unbranched monophialides. Microconidia are one or two-celled, oval- to kidney-shaped and are

produced in false heads. Macroconidia are four to eight-celled and sickle-shaped with foot-shaped

basal cells. Chlamydospores are usually globose and are formed singly or in pairs in hyphae or

conidia. They are resistant to desiccation and unfavourable environmental conditions, and enable the

fungus to survive for more than 30 years in the soil even after their hosts have been removed. In the

presence of banana root exudates, Foc chlamydospores, conidia and hyphae will germinate to

penetrate susceptible plants.

12. Foc infects bananas by penetrating the root tips of the small lateral or feeder roots of the plant.

Penetration takes place through wounds or injuries that expose the xylem vessels to the pathogen.

The fungus then invades the water conducting tissue (xylem) where it produces microconidia that are

carried up the plant, plugging the vascular tissue and reducing the movement of water. When blocked

by sieve cells, the spores germinate and continue to spread until the entire water conducting system

is blocked. Internal symptoms of Fusarium wilt of banana usually become visible as yellow, red or

brownish dots and streaks localized in the vascular strands of the rhizome and pseudostem. In

advanced stages of infection, rhizome discoloration is more prolific and the stains are more intense.

Externally, infected plants show premature yellowing of the leaves which start on older leaves along

the leaf margins and continue to the midrib until the leaves are completely brown and die. The

yellowing progresses from the older to younger leaves, which distinguishes Fusarium wilt from

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bacterial wilt symptoms (which start with the youngest leaves). Eventually dead leaves will be hanging

down the pseudostem. In some banana cultivars, leaves of Foc-infected plants will not turn brightly

yellow, and green leaves will instead buckle and hang down the pseudostem. Splitting of the

pseudostem just above the soil level may also occur. The heart leaf of affected plants eventually dies

and the pseudostem will remain standing until it is removed or collapses.

Race concept

13. Based on pathogenicity to different banana cultivars, three

- races have been recognized in Foc. Foc race 1 causes disease in the Gros Michel (AAA) and

Silk (AAB) cultivars. Foc races 2 attacks Bluggoe (ABB), and race 4 infects Cavendish (AAA) cultivars

and most cultivars susceptible to Foc races 1 and 2. Foc race 3 has been omitted as a pathogen of

banana, as it only attacks Heliconia spp. Strains affecting Cavendish bananas have been divided in

subtropical (Foc STR4) and tropical (Foc TR4) strains, depending on the climatic conditions required

to cause disease to Cavendish bananas. Substantial variation exists within Foc as measured by

vegetative compatibility, volatile production, electrophoretic karyotyping and various molecular

techniques. Twenty-four vegetative compatibility groups (VCGs) have been identified from a

worldwide collection of Foc isolates.

Global distribution of Foc

14. The center of diversity of Foc is believed to be Southeast Asia, where most VCGs of the banana

Fusarium wilt pathogen can be found. The first outbreak of the disease, however, was reported from

Australia in 1876. Fusarium wilt became notorious when it destroyed banana plantations in Central

America around the turn of the century. During the early 1900’s the disease was also recorded in

Hawaii, South America, Asia and West Africa, and by 1950 it had spread to most of the banana-

producing regions of the world. The disease was recently reported from New Guinea and Yap in the

Federated States of Micronesia, which indicates that Foc spread has crossed Wallace’s line, originally

demarcating the eastern border of the disease in the Indo-Malayan region. These outbreaks were

mostly caused by Foc races 1 and 2. Foc STR4 was first reported from the Canary Islands, Australia,

South Africa and Taiwan province of China. Foc TR4 was discovered in Malaysia and Indonesia in

1990, and thereafter reported from China (1996), Australia (1997) and the Philippines (2006). Another

significant occurrence was the discovery of Foc TR4 outside Southeast Asia. It was also reported

from Jordan in the Middle East and more recently from Mozambique in Africa. This raised significant

concerns that the fungus affecting Cavendish can spread globally and result in immense damage to

world banana production.

Means of spread

15. Banana Fusarium wilt was discovered in the New World approximately 150 years after the crop

was first introduced into the Caribbean. It is believed that Foc was introduced into Central America

with contaminated Silk (AAB) bananas planted for shade in the West Indies. The disease was most

likely not immediately apparent, as suckers with visible disease symptoms would probably not have

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been removed. Even if symptoms were present, it would not have been associated with the much

later decline of the plant. The early outbreaks of Fusarium wilt, therefore, could have been sporadic,

which might explain why the disease was not detected at the time of introduction. Additional factors,

such as naturally suppressive soils and the pathogen’s nature, being limited to the soil, could also

have slowed the development of the disease.

16. Foc is disseminated locally, nationally and internationally with infected planting material which

may or may not exhibit external disease symptoms. Once the pathogen is introduced into a disease-

free plantation, it can spread from mat-to-mat through root contact and from an infected mother plant

into the suckers. Foc also spreads with contaminated irrigation water and in soil attached to

implements, shoes, vehicles and plantation tools. Heavy rainfall and floods can lead to increased

spread of the pathogen from plant to plant and from the surface down to the roots. The run-off water

may contaminate the irrigation reservoirs and increase the spread of the fungus through the plantation

and between plantations.

Considerations needed for prevention

17. Banana Fusarium wilt is exceptionally difficult to control, and the only means to protect the crop is

to prevent the pathogen from entering production areas, or to replace susceptible varieties with

resistant ones. For instance, after Foc race 1 was introduced into Central America the continued

production of Gros Michel became impossible, and the variety was replaced with Cavendish which

was resistant to that race as the new export banana. With the global spread of Foc TR4, continued

reliance on Cavendish as the primary export banana has come under immense threat. Prevention of

infection through awareness and appropriate legislation is thus needed to secure the future of

bananas worldwide.

DEVELOPMENT AND INTRODUCTIONOF POLICIES FOR SUSTAINABLE BANANA PRODUCTION AND PREVENTION OF Foc TR4

Holistic and integrated approach for prevention

18. Intensive farming systems are more susceptible to economically important pathogens such as Foc

TR4, and therefore require stricter biosecurity protocols. Agricultural best management approaches,

including good sanitary and phytosanitary practices along with the use of resistant varieties can play a

major role in preventing and controlling Foc TR4. Practices to prevent the introduction of Foc into

clean banana production areas include the use of disease-free tissue culture plants and proper

sanitation methods. The treatment of vehicles, machinery, tools and footwear with an effective surface

disinfectant is important. Once the disease is introduced into banana fields, the planting of resistant

cultivars becomes essential, if such cultivars are acceptable to the local markets.

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Ensuring multi sectorial/institutional consultation and coordination mechanisms

19. Stakeholders share the responsibility to enhance national and regional capacities to identify,

monitor and manage plant health risks. Above all, national policy makers should facilitate an effective

coordination among the relevant stakeholders and institutions to establish national strategies and

plans for prevention and management of the disease. In this process, engagement of all institutions

and participatory and inclusive approaches would ensure integrity and synergy. Furthermore roles and

responsibilities of the participating institutions would need to be established clearly in context of

contingency plans. Quarantine measures, based on scientific risk assessments are considered and

taken by national plant protection organizations to keep non indigenous pathogens or their races from

countries and areas where they are present and cause damage. They are then implemented by plant

protection institutions, quarantine bureaus, extension offices, producer organizations and industry to

keep farms disease-free. Information on disease occurrence and research progress should be shared

as rapidly as possible utilizing advanced communication tools and appropriate platforms such as

symposia, workshops, and regular stakeholder meetings. .

Enhancing awareness at all levels

20. Raising awareness is an easy and affordable means to prevent incursions of Foc TR4 into

countries at risk. Awareness should be raised at all levels. The producers need to informed of the

disease and its potential impacts as well as about means to prevent its introduction. Policy makers

and governments should be made aware of the impact of intrusions to national food security, and

what damage to crops and losses of income can be incurred. Particularly the public should be

sensitized about the dangers associated with the movement of infected planting materials.

Legislation and regulation for movement of planting materials

21. Pests and diseases are regularly moved from affected to non-affected production areas through

seeds and planting materials. An important means of spread of Foc is through infected planting

materials. It is thus important to prevent movement of infested planting materials both into and within

countries. Banana materials most at risk are suckers and bits, whereas tissue culture bananas are

considered to be disease-free. The movement of banana planting materials into countries, thus,

needs to be legislated and controlled. Within countries, the movement of bits and suckers should also

be discouraged, and producers are encouraged to use only tissue-culture plants.

Strengthening seed production and certification system

22. As Foc free plants form a key component of preventing the disease spread, national seed systems

should facilitate production and distribution of only clean banana planting materials to ensure a

healthy agricultural and food sector. This is not always possible in developing countries and in rural

areas where tissue culture plants cannot be afforded by banana producers. Under these

circumstances, extension services should encourage use of planting materials coming from disease

free areas. Producers should be trained on the role and importance of using clean planting materials

through demonstrations and workshops.

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Diversifying production systems and varieties

23. Circumstantial evidence show that mixed banana and other cropping systems are more resilient to

banana Fusarium wilt than monoculture production. For instance, Gros Michel has been proven

sustainable when planted in combination with cacao and timber trees in Foc race1infested fields in

Latin America. However, Gros Michel becomes highly vulnerable when planted in such fields in

monoculture production systems. Banana production in Foc TR4affected countries, such as

Indonesia, can be continued when a number of banana varieties of different levels of resistance are

planted in infested fields, but not when susceptible varieties are grown in monoculture.

Monitoring, risk analysis and reporting

24. Monitoring of the disease in and around the national boundaries and that of possible entry

channels is essential for prevention of the disease. The risk posed by Foc TR4 to national banana

industries requires assessment, monitoring and management to benefit all stakeholders. Surveillance

and risk assessments should be carried out according to the standards provided by the International

Plant Protection Convention (IPPC) and supported by expert scientists. This should be performed by

using all available resources, analysing possible entry points, by setting priorities and communication

mechanisms. Risk assessment and monitoring consist of four important steps, including risk

identification (sources, communities and production systems), analysis (likelihood and

consequences), evaluation (prioritization) and treatment (response to the risk). These steps should be

continuously monitored and reviewed, and regularly communicated to all stakeholders.

Inspection capacities at borders

25. All countries have inspection services at their national borders to protect and promote a healthy

agricultural industry. These services are needed to protect farmers from invasive pests in the interest

of local production and international trade. The efficiency of plant health inspection services, however,

also depends on the training and ability of the officers to target and intercept risky materials brought

into countries. Therefore, strengthening of capacities of plant inspection services is essential to deliver

inspection and control services effectively. Despite the availability of plant health inspection services

at border posts, illegal biological materials can still be introduced over national borders by not

declaring such materials or by illegal emigration/trade over porous border lines. It is thus also the

responsibility of all stakeholders in the national, regional and international banana community to

respect and report any unlawful movement of risky materials between countries and over country

borders.

Preparedness and contingency planning

26. Banana-producing countries need to be prepared for any emergency actions assuming that Foc

TR4 might circumvent border inspection or enter the country incidentally. This should involve gaining

and disseminating information to detect banana Fusarium wilt early in affected fields, reporting

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outbreaks to the required authorities, and to respond to such outbreaks appropriately without delay.

Effective preparedness and contingency plans are available for many pests and diseases which can

be taken as examples. These should be established with participation of all stakeholders focusing on

institutional coordination, prevention and immediate response in case of disease outbreaks. Such

plans should be prepared ahead of any likely incursion of especially for Foc TR4 and should include

resources and financial plans, and proper legislative backing and step by step actions that would be

needed.

Strengthening capacities for management

27. Capacity development involves the strengthening of a country and region’s ability to prevent and

respond to incursions of pathogens and pests that could harm production and food security in affected

areas. It involves the training of government officers, scientists,industry personell, farmers and farm

workers in various aspects related to disease prevention and management, such as diagnostics,

surveillance and integrated pest management. It also includes the availability of equipment and

infrastructure to execute research. Capacity building is not only the responsibility of affected countries,

but also those at risk.

TECHNICAL PROCEDURES FOR SURVEILLANCE AND ON-FARM MANAGEMENT

28. Since the discovery of Fusarium wilt of banana, various methods have been attempted to curb the

damage caused by the disease. Soil fumigation, fungicides, crop rotation, flood-fallowing and organic

amendments are all disease management strategies that can reduce fungal inoculum and slow down

disease development. Yet, no long-term measures are available to control the disease other than the

planting of resistant cultivars. To employ resistant genotypes in areas where the crop is grown for

food security and income generation a proper knowledge of diversity within the Fusarium wilt fungus,

and its presence in different geographical areas, is required.

Diagnosis and surveillance

29. When introduced into banana-growing countries, accurate diagnosis of Foc TR4 is required to

confirm the presence of the pathogen, to determine its boundaries of distribution and to monitor its

spread. To identify the pathogen and monitor its movement, scientists require training, technical

facilities and equipment. Courses on diagnostics of banana Fusarium wilt to assist national and

regional plant health programmes in developing capacities to prevent or rapidly respond to Foc TR4

incursions are available in Australasia, Africa and Latin America. Diagnostic laboratories require

standard operating procedures to ensure consistency among diagnostic facilities regionally and

globally. These need to include field guides with symptom description and sampling procedures, and

laboratory guidelines for pathogen isolation, DNA-based and other forms of diagnostics, pathogen

storage, and data recording and sharing.

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Implementation of sanitary and phytosanitary measures

30. National phytosanitary legislation on Foc TR4 should be introduced to regulate the movement of

planting materials and plant parts coming from countries affected by Foc TR4 at country borders and

entry points. In countries already affected by Foc TR4, quarantine officials need to establish

quarantine zones to prevent its spread from infested to clean areas. If Foc TR4 is present in a country

or region, good sanitary and phytosanitary practices should also be introduced at farm gates and

inside farm borders. These include the fencing in of farms to control the movement of people and

vehicles, the introduction of notice boards and control points at farm entrances, and the use of

pressure sprays and disinfectants to clean the vehicles and shoes of visitors. While national

preventative actions are the responsibility of government officials, on-farm activities is primarily the

responsibility of farm owners and workers.

Use of clean certified planting materials

31. New banana fields are established either with suckers and bits taken from existing plantations, or

with micro-propagated banana plants obtained from banana tissue culture laboratories. Extreme care

should be taken to always use planting material free of important pathogens and pests. The risk of

planting material being infected with Foc TR4 is greater when using suckers collected in the field,

even if they appear to be disease-free, than when planting tissue culture plants. It is thus important to

only use banana suckers collected from fields known to be without Foc TR4. Banana tissue culture

plants are considered clean of fungal diseases when multiplied under laboratory conditions. However,

these can also become contaminated when planted in potting soil infested by Foc TR4 or irrigated by

water contaminated with the Fusarium wilt fungus. Both potting soil and irrigation water, therefore,

should be clean of Foc TR4 when banana plants are hardened-off in nurseries before field-planting.

Good agronomic practices

32. Once banana Fusarium wilt is present in plantations, the responsible fungus cannot be eradicated.

However, the development of the disease can be slowed down by agronomic practices that reduce

inoculum pressure in the soil and/or improve plant vigour. Practices that reduce inoculum pressure

include treatment of soils with plant extracts or biological control agents, the growing of cover crops

that stimulate biological activity in the soil and prevent soil movement, and leaving infested sites fallow

for periods of 2-3 years. Those that improve plant vigour include proper irrigation schedules, fertilizer

applications and soil management. It is also important to control the movement of people, vehicles

and run-off water not to contaminate disease free areas.

Eradication of initial infestation points

33. When outbreaks of Fusarium wilt are discovered in farmer fields affected plants should be isolated

and destroyed. The site where the disease was discovered needs to be isolated by fencing-off of the

diseased and healthy neighboring plants within a radius of at least 5 m in all directions. The diseased

plant should be slashed and immediately burned to reduce fungal inoculum, and neighboring plants

killed by injection with herbidices and burned later. The plants should never be moved off-site. A

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trench of at least 50 cm deep has to be dug inside the fence to prevent root-to-root contact of plants

and the escape of run-off of irrigation water. Only designated laborers should be allowed inside

isolated areas, and clothes and equipment properly cleaned and disinfected afterwards.

Disinfection of tools, vehicles and clothing

34. Proper cleaning and disinfection of vehicles, shoes and plantation tools is a key component of

both disease prevention and management. This activity is entirely the responsibility of banana farmers

and managers. It involves control points at farm and plantation entrances where the movement of field

workers and visitors is controlled. Cleaning of vehicles and shoes should not only take place upon

entrance onto farms and into plantations, but is even more important when leaving these sites. The

use of when and foot baths are common in many commercial farms, but similar practices should also

be introduced onto small-grower farms. In plantations, de-leafing, de-suckering and de-weeding tools

need to be regularly cleaned and disinfected particularly before they are used in new areas. Special

care should be taken to ensure that the disinfectants are used effectively and replaced regularly.

Training public officers and farm workers

35. Public officers need to have sufficient knowledge about the biology, epidemiology and

management of banana Fusarium wilt to support farmers and farming communities. If this knowledge

is not available locally, for the short term external experts should be utilized but for the long term

internal expertise should be developed through training in their own countries. Farm workers also

need to be trained to identify plants with Fusarium wilt symptoms in the field, to distinguish these

symptoms from those caused by other diseases and abnormalities, and the means to report these.

Early detection is important to isolate new outbreaks, so highly skilled farm workers are needed to

spot new outbreaks as soon as possible.

DIFFERENTIATED PRIORITY ACTIONS DETERMINED BY RISK LEVELS

By countries already affected by Foc TR4

36. Countries already affected by Foc TR4 include Indonesia (1990), Malaysia (1990), mainland

China (1998), Australia (1997), Taiwan Province of China (after 2000), Philippines (2005), Oman

(2012), Jordan (2013) and Mozambique (2013). These countries all produce Cavendish bananas in

monoculture, but also have small-scale growers producing local varieties. It is this group that is most

vulnerable to Foc TR4, as they cannot move to other areas or countries like multi-national companies

when their land becomes unproductive.

37. Activities in affected countries depend on the distribution of the disease (widespread or newly

introduced), the intensity of production (continuous plantations or long distances between plantations),

the production system (commercial vs subsistence farmers), the varieties grown (Cavendish vs non-

Cavendish) and the abilities of governments to introduce and enforce legislation. Designation of

quarantine areas should be considered in all affected countries, and the movement of planting

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materials legislated. Stringent sanitary activities should be introduced on farms affected by Foc TR4

for visitors and farm workers moving on and off the farm. In this respect, it is important to consider

whether the disease has become endemic to a region, as this would affect the introduction of

quarantine measures. It is important to upscale surveillance, research and extension activities in Foc

TR4-affected countries, and to train farmers and scientists in disease diagnosis and pathogen

diagnostics, as well as in the prevention and management of banana Fusarium wilt. Awareness

campaigns should be launched, and agronomic practices improved to reduce the spread of the

disease through irrigation, drainage, run off water and soils attached to shoes,farm tools and vehicles.

In areas where a great diversity of bananas is present, farmers can be advised about the resistance

status of local varieties, while resistant somaclones can be introduced into areas where Cavendish or

susceptible bananas are grown.

By countries at high risk

38. Countries that are at high risk include those bordering affected countries, trade with infected

countries, and have international movement of staff from infected countries. In these areas, policies

need to be introduced to legislate the movement of planting materials and to raise awareness of

producers about the threat of Foc TR4. Preparedness strategies should also include the training of

plant health officials, especially at borders and other possible entry points, and development of

contingency plans. These areas include large-scale Cavendish monoculture farms and small-scale

producers moving planting materials cross-border. Regional collaboration and institutional

coordination is especially needed for development and implementation of successful contingency

plans, including awareness campaigns, capacity development, effective border control, surveillance

and proper regulation.

By countries potentially at risk

39. Countries potentially at risk include those that produce for local markets and that are far away

from Foc TR4-affected countries. It also includes those bordering or near Foc TR4-affected countries,

but that grow mainly non-Cavendish or cooking banana varieties. Yet, it is important for the

authorities, scientists and growers in such countries to be aware of the dangers of Foc TR4, how it is

introduced and spread in new countries, and to thus introduce legislation and quarantine measures to

prevent uncertified planting materials entering from affected countries. Contingency plans should also

be developed in case Foc TR4 is introduced into such countries despite all preventive measures.

DIFFERENTIATE PRIORITY ACTIONS ACCORDING TO PRODUCTION SYSTEM

Production systems based on large-scale commercial Cavendish banana plantations

40. Large-scale commercial Cavendish banana production systems are most vulnerable, as they

consist of many hectares of genetic clones that are all highly susceptible to Foc TR4. Production on

such farms are intensive meaning that workers are moved between plantations, farms and countries;

service providers are often visiting; fields are irrigated from a single water source; that drainage

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canals move water around; and that farm workers move continuously through plantations. Such farms

might also have highly trained staff with the ability to recognize and report suspicious symptoms early.

Production systems based on small-scale commercial Cavendish banana fields

41. These smaller farms are highly vulnerable to Foc TR4. Chances of contamination because of

human movement and through irrigation water are higher. Financial constraints result in suckers being

used for planting instead of tissue culture, plantation tools and transport being shared, and sanitation

practices being neglected. Farms become affected only after large-scale Cavendish farms are

affected. As small-scale growers supply local markers, they are more flexible to plant resistant

somaclones.

Production systems based on mixed banana varieties

42. Some small-scale growers plant several different banana varieties to supply local markets. These

growers are therefore flexible to change the bananas that they grow when affected by diseases.

However, such changes depend on the availability of resistant varieties and market demands.

Production systems based on mixed cropping

43. This production system involves production of more than one type of crop in a given farm and is

the most resilient system to banana Fusarium wilt. Several examples exist where mixed cropping

systems had been affected by both Foc race 1 and also Foc TR4, yet production of susceptible

bananas continues. If banana production becomes impossible, the crop will be replaced with other

crops not affected by Foc TR4.

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44. Appendix 1. Six easy steps to protect farms against Foc TR4 (adopted from: Farm Biosecurity

Manual – Australia).

1. Be aware of the threat of Foc TR4: Make sure that farm management and farm workers are

familiar with important plant diseases

2. Always use clean planting material: Ensure that all planting material and other farm inputs are pest

free. Tissue culture plants are recommended

3. Introduce good agricultural practices and proper farm hygiene: Take care to prevent the entry and

movement of pests on your farm by proper farm hygiene practices. Ensure that workers, visitors,

vehicles and equipment are decontaminated before they enter and leave your farm.

4. Inspect your plantations: Check your crops frequently for anything new or unusual

5. Report any suspicious symptoms: If you suspect a new pest – report it immediately

6. Abide by the law: Be aware of legislative regulations established to protect the banana industry

from biosecurity threats

45. Appendix 2. Differences between banana Fusarium wilt and other biotic constraints causing wilt-

like symptoms.

Disease/Pest External symptoms Internal symptoms

Fusarium wilt Yellowing and browning of leaves,

starting from oldest to youngest

Yellow-brown discolouration of inner

rhizome and pseudostem

Bacterial wilts* Yellowing of leaves, starting from

youngest to oldest

Oozing of yellow bacteria from

pseudostem, stark and fruit

Armilaria Yellowing of older banana leaves White growth at root collar and inside

the rhizome

Banana weevil Yellowing of older banana leaves Tunnels of larvae in rhizome

*Includes Moko disease, Blood disease and Xanthomonas wilt

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46. Appendix 3. Activities to prevent and manage Foc TR4 in different risk areas and under different banana production systems.

Level of actions Activity Affected High risk At riskPre-border activities Assess national biosecurity legislation and regulations

Assess country abilities to prevent and respond to Foc TR4Gather knowledge on Foc TR4 and means to deal with itRaise awareness among policy makers, producers and other stakeholdersStandardise training manuals, identification and surveillance protocolsDevelop national capacity and infrastructure to deal with intrusionsTrain scientists, plant health officials, extension officers and producersDistribute posters, brochures and information materials on Foc TR4Prepare technical materials on prevention, detection, containment and eradicationIntroduce an emergency fund to rapidly respond to intrusionsDevelop an entrance risk analysis and identify high-risk entry points

On-border activities Evaluate quarantine measures and strengthen border controlInclude Foc TR4 as quarantine pest on national listsDevelop national legislation and phytosanitary regulation for bananas and/or partsControl importation of banana and plant parts from Foc TR4-affected countriesRequest in vitro plants to be accompanies with certificates for disease indexingIdentify and strengthen high risk entry points for Foc TR4-infected banana plantsTraining in the use of reliable diagnostics for Foc TR4 identification

Post-border activities Map the distribution of Foc TR4 and other Foc races in banana-growing countriesGather epidemiological data to establish means of introduction and spreadAssess, train and introduce surveillance systems and teams in-countryIntroduce national legislation to regulate the movement of banana plantsIntroduce quarantine zones to prevent the movement of planting materialsCollaborate nationally and regionally to prevent and manage Foc TR4Organise training workshops and expert consultations

1 2 3 4 1 2 3 4 1 2 3 4Farm border activities Obtain clean planting and propagation material from reputable sources

Put up highly visible and clearly understandable signs at farm entrancesProperly clean vehicles visiting farms and take off clay and plant partsManage the movement of farm visitors and vehicles by: Allowing visitors onto the farm by appointment only Disinfecting the shoes and vehicles of visitors

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Use only farm vehicles and boots provided to visitors in plantationsEnquire about employment history, nationality and movement of farm workersAvoid sharing farm machinery, equipment and field tools with other growersStrictly control access of contractors and service providers to farm

On-farm activities Early detection Train and employ scouts to identify and immediately report any suspect plants

Isolate and eradicate any new outbreaks of banana Fusarium wilt by fencing-in of diseased and neighbouring plants, killing of such plants and burningPrevent the movement of soil and water outside affected areasRestrict and control movement of farm workers and farm equipmentUse disinfectants to clean shoes and plantation toolsLimit vehicle movement to designated roads and regulate routesAbandon production in newly affected sites and plant ground coversEnable farmers to distinguish between Fusarium wilt and closely related diseasesIntroduce protocols to identify, isolate and monitor Fusarium wilt outbreaksPrevent flow of irrigation or rain water out of affected areasRegularly test irrigation water and planting materials to prevent further spread

Management Use of biological control products in infested fieldsUse of fungicides for planting material treatment and stem injectionsUse surface sterilants to disinfect shoes and field equipmentApply soil fumigants to reduce the inoculum in soilsUse of plant activators to strengthen plant response to infectionUse of clean planting material: tissue culture and clean suckersSanitary and phytosanitary actionsCrop rotation and fallow periodsSoil amendments and fertilizers: pH, nitrogen, calcium, silicon, iron, organicsFlood fallowing and bio-fumigants: leek, brassicas, anaerobic fumigationGrow ground covers that stimulate microbial activity and prevent soil movementIntroduce proper irrigation schedules and drainageFence-in infested fields to prevent unnecessary pedestrian and animal movementDetermine natural resistance in local banana varieties to Foc TR4Employ Foc TR4-resistant plants in affected areasPlanting of mixed cropping systems

1 = Large-scale Cavendish monoculture; 2 = small-scale Cavendish monoculture; 3 = small scale mixed banana; 4 = small-scale mixed crops

Required Optional Not necessary

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