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
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Differentiated priority actions determined by risk level
 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
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yellowing progresses from the older to younger leaves, which distinguishes Fusarium wilt from
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 bananaproducing 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 diseasefree 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
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planting 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 wiltlike symptoms.
Disease/Pest
Fusarium wilt
Bacterial wilts*
Armilaria
External symptoms
Internal symptoms
Yellowing and browning of leaves,
Yellow-brown discolouration of inner
starting from oldest to youngest
rhizome and pseudostem
Yellowing of leaves, starting from
Oozing
youngest to oldest
pseudostem, stark and fruit
Yellowing of older banana leaves
White growth at root collar and inside
of
yellow
bacteria
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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from
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
Pre-border activities
Assess national biosecurity legislation and regulations
Assess country abilities to prevent and respond to Foc TR4
Gather knowledge on Foc TR4 and means to deal with it
Raise awareness among policy makers, producers and other stakeholders
Standardise training manuals, identification and surveillance protocols
Develop national capacity and infrastructure to deal with intrusions
Train scientists, plant health officials, extension officers and producers
Distribute posters, brochures and information materials on Foc TR4
Prepare technical materials on prevention, detection, containment and eradication
Introduce an emergency fund to rapidly respond to intrusions
Develop an entrance risk analysis and identify high-risk entry points
On-border activities
Evaluate quarantine measures and strengthen border control
Include Foc TR4 as quarantine pest on national lists
Develop national legislation and phytosanitary regulation for bananas and/or parts
Control importation of banana and plant parts from Foc TR4-affected countries
Request in vitro plants to be accompanies with certificates for disease indexing
Identify and strengthen high risk entry points for Foc TR4-infected banana plants
Training 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 countries
Gather epidemiological data to establish means of introduction and spread
Assess, train and introduce surveillance systems and teams in-country
Introduce national legislation to regulate the movement of banana plants
Introduce quarantine zones to prevent the movement of planting materials
Collaborate nationally and regionally to prevent and manage Foc TR4
Organise training workshops and expert consultations
1
Farm border activities
Obtain clean planting and propagation material from reputable sources
Put up highly visible and clearly understandable signs at farm entrances
Properly clean vehicles visiting farms and take off clay and plant parts
Manage 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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2
3
High risk
4
1
2
3
At risk
4
1
2
3
4
 Use only farm vehicles and boots provided to visitors in plantations
Enquire about employment history, nationality and movement of farm workers
Avoid sharing farm machinery, equipment and field tools with other growers
Strictly control access of contractors and service providers to farm
On-farm activities
Early detection
Management
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 burning
Prevent the movement of soil and water outside affected areas
Restrict and control movement of farm workers and farm equipment
Use disinfectants to clean shoes and plantation tools
Limit vehicle movement to designated roads and regulate routes
Abandon production in newly affected sites and plant ground covers
Enable farmers to distinguish between Fusarium wilt and closely related diseases
Introduce protocols to identify, isolate and monitor Fusarium wilt outbreaks
Prevent flow of irrigation or rain water out of affected areas
Regularly test irrigation water and planting materials to prevent further spread
Use of biological control products in infested fields
Use of fungicides for planting material treatment and stem injections
Use surface sterilants to disinfect shoes and field equipment
Apply soil fumigants to reduce the inoculum in soils
Use of plant activators to strengthen plant response to infection
Use of clean planting material: tissue culture and clean suckers
Sanitary and phytosanitary actions
Crop rotation and fallow periods
Soil amendments and fertilizers: pH, nitrogen, calcium, silicon, iron, organics
Flood fallowing and bio-fumigants: leek, brassicas, anaerobic fumigation
Grow ground covers that stimulate microbial activity and prevent soil movement
Introduce proper irrigation schedules and drainage
Fence-in infested fields to prevent unnecessary pedestrian and animal movement
Determine natural resistance in local banana varieties to Foc TR4
Employ Foc TR4-resistant plants in affected areas
Planting 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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