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Tropical race 4


Distribution of TR4
Factsheet on TR4 in Africa
Tropical race 4 in Africa
Protocols
Source: FAO
Grower kit on TR4
Produced by Biosecurity Queensland
Produced by Biosecurity Queensland
On-farm biosecurity
Managing footwear

Tropical race 4 (TR4) is the name given to the fungal strains of Fusarium oxysporum f. sp. cubense (Foc), the fungus that causes Fusarium wilt (aka Panama disease) in Cavendish cultivars. The term TR4 was coined to distinguish these strains from the ones that also affect Cavendish cultivars, but only in the presence of predisposing factors, such as low temperatures, and have since become known as subtropical race 4 (STR4). The term TR4 usually refers to isolates belonging to a particular vegetative compatibility group called VCG 01213/16, although other VCGs have also been shown to cause Fusarium wilt in Cavendish cultivars. It should be noted that TR4 has a wider host range than just Cavendish bananas. In addition to hitherto unaffected cultivars, such as 'Lakatan' and 'Pisang mas',  it also causes disease in groups of cultivars susceptible to races 1 and 2, such as Gros Michel, Silk, Pome and Bluggoe.

The strain associated with TR4 was identified in 1990 in samples from Taiwan1. For the next 20 years or so, the distribution of TR4 was limited to parts of Asia and Australia's Northern Territory. In 2013, TR4 was reported to be Jordan2, the first record of TR4 outside the Asia-Pacific region. Later that year it was also reported to be in Africa3. Like all other soil-dwelling Foc strains, TR4 cannot be controlled using fungicides and cannot be eradicated from soil using fumigants.

The capacity of TR4 to survive decades in the soil, along with its lethal impact and wide host range, are among the main reasons it was ranked as the greatest threat to banana production4. The severity of the damage depends on interactions between the strain, its host and environmental conditions. To avoid further losses to the pathogen, the United Nations' Food and Agriculture Organization (FAO) has called on banana-producing countries to step up monitoring and reporting, and to contain suspected incursions to prevent the fungus from getting established5.

Contents

Distribution

By the turn of the 20th century TR4 had been observed in Taiwan, Malaysia6 (including Sarawak on the island of Borneo), Indonesia (Java, Sumatra, Sulawesi, Halmahera, Kalimantan7 on the island of Borneo, and Papua Province8 on the island of New Guinea), mainland China (Guangdong9, Hainan10, Guangxi, Fujian and Yunnan), the Philippines' island of Mindanao11 and Australia (Northern Territory12).

In 2013, TR4 was reported in Jordan13 (a 2014 survey revealed another infected area north of the original outbreak14) and Mozambique15 (where it has since been observed in a second plantation 16). In 2015, it was reported in Lebanon and Pakistan1718, as well as Queensland in Australia19. It has also been in Oman since at least 2012202122.

See Race 4 for more details.

Host range

In addition to Cavendish cultivars, TR4 affects cultivars susceptible to races 1 and 2 as well as hitherto unaffected cultivars such as, 'Barangan' (Lakatan subgroup, AAA genome group)7 and 'Pisang Mas'. The often cited figure that TR4 affects cultivars that account for more than 80% of the world's banana production23 assumed that Plantains were also susceptible. At the time, however, the only Plantain-like material that had been evaluated against TR4 were hybrids produced by breeders24. The reaction of the Plantains domesticated in Africa, along with another group of locally domesticated bananas, the East African highland bananas (EAHB), was not known. The first field screening of these two subgroups was conducted in 2011-2012 in the Philippines using accessions from the ITC genebank. Most of the accessions tested were slightly to moderately susceptible25. Except for the 'Obubit Ntanga' Plantain accession that was still symptom-free after 10 months (a relatively short time given the perennial nature of most banana production), the disease incidence was below 5%. with the exception of 'Ibwi', for which the disease incidence was 29%. However, the ploidy of the ITC accession called Ibwi (2x/3x26) suggests that the material tested might not be the EAHB cultivar  'Ibwi'.

The FHIA improvement programme has produced hybrids that are resistant to races 1 and 4, while the Taiwan Banana Research Institute (TBRI) has released Giant Cavendish tissue-culture variants (GCTCV) that are partially resistant to TR427. In field trials conducted in China, FHIA-01, FHIA-02, FHIA-18, FHIA-25, Pisang Jari Buaya, Rose (AA), and to a lesser extent GCTCV-119 and FHIA-03, have shown resistance to TR428. In a field trial conducted in the Philippines, only 1% of the GCTCV-219 plants exhibited symptoms of Fusarium wilt in the second crop cycle, whereas none of plants of the Cardava cultivar (Saba subgroup) did29.

Symptoms and diagnosis

The symptoms of a TR4 infection are the same as those caused by any other Foc strains (see symptoms of Fusarium wilt). However, the wide host range of TR4 makes it difficult to diagnose TR4 on non-Cavendish bananas that are susceptible to other strains. For example, a Gros Michel infected with TR4 would not raise alarm because the assumption would be that it is infected with a race 1 strain. The quickest way to confirm a TR4 infection is by analysing tissue samples using a TR4-specific PCR test30. Fungal isolates can also be analysed to determine their vegetative compatibility group (VCG). The majority of TR4 isolates belong to the VCG 01213/16 complex.

Modes of transmission

TR4 can be spread through infected planting material, infested soil and water. For more information, see the section on the modes of transmission of Fusarium wilt.

Management

Like all the other Foc strains, TR4 cannot be controlled using fungicides and cannot be eradicated from soil using fumigants. The use of tissue-culture plantlets prevents the spread of the disease through planting material, but once the fungus is established, the solution best adapted to the continued production of bananas in infested soils is replacing susceptible cultivars by resistant ones (see Host range above). However, given TR4's wide host range, virulence and persistence in the soil31, experts stress the importance of preventing the spread of the fungus232. Following the detection of TR4 in Queensland, Australia, Biosecurity Queensland published a document on best practices to minimize the risk of spreading TR433.

For more information, see the section on control options of Fusarium wilt.

Impact

TR4 has devastated commercial plantations of Cavendish bananas in Taiwan, Indonesia, Malaysia and Australia’s Northern Territory34. In mainland China, the strategy of establishing Cavendish plantations in TR4-free areas to stay ahead of the disease has led to the spread of the fungus to all the main banana-growing provinces35. In the Philippines, the extent of the damage in Cavendish plantations has not been documented. The Mindanao Banana Farmers and Exporters Association, which represents small-scale farmers growing Cavendish cultivars for the export market, has reported that about 5,900 hectares of their members’ aggregate plantation area had been infected, including 3,000 hectares that have been abandoned36. Some growers say their farm was infected by run-off from a nearby large commercial farm37. In the few instances in which losses to TR4 have been estimated, they amounted to 121 million USD in Indonesia, 253.3 million USD in Taiwan  and 14.1 million USD Malaysia38.

In Africa, where TR4 was reported for the first time in 2013 in an export plantation of northern Mozambique, the number of symptomatic plants had risen to more than 570,000 (out of a total of more than 2.5 m plants) by September 201539. TR4 has also been detected in another plantation40.

For more information, see the section on the impact of Fusarium wilt.

Efforts to address the threat of TR4

Africa

Following the announcement that TR4 had been detected in Mozambique3, the African Consortium for TR4 (AC4TR4) was launched at a workshop held at the University of Stellenbosch in April 201441.

Asia

The Banana Asia-Pacific Network (BAPNET) is coordinating a number of TR4-related projects and activities in various Asian countries42.

Australia

Following the first confirmed case of TR4 in Queensland43, Biosecurity Queensland, in partnership with the Australian Banana Growers' Council, set up a programme of surveillance and containment4445.

Latin America and the Carribean

OIRSA, a regional organzation for plant and animal health, has produced a contingency plan specific to TR4 for its nine member countries (Belize, Costa Rica, Dominican Republic, El Salvador, Guatemala, Honduras, Mexico, Nicaragua and Panama), the plan is available in Spanish only46.

The banana research network for Latin America and the Caribbean, MUSALAC, has been organizing training on quarantine pests, with a special emphasis on TR447.

In 2014, the Caribbean Agricultural Research and Development Institute (CARDI) organized a seminar and a training workshop to raise awareness of the potential threat of TR4 as a key step to prevent its introduction to the Caribbean48.

Global

In December 2013, a task force on TR4 was set up within the framework of the World Banana Forum49. In December 2014, the FAO held a consultation with a group of international experts to agree on the framework for a global programme32. The plan would work on three main fronts: preventing future outbreaks, managing existing cases, and strengthening international collaboration and coordination among institutions, researchers, governments and producers.

The Wageningen university & research centre in the Netherlands is leading three projects on TR4: INREF, KNAW-SPIN and PromoBanana50.

References


2. TR4's transcontinental leap published in InfoMus@'s News and analysis section on 21 November 2013.
3. The year of TR4 published on 19 December 2013 in the ProMusa blog.
4. Ploetz, R.C. 2009. Assessing threats posed by destructive banana pathogens. Proceedings of the International ISHS-ProMusa Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods held in White River, South Africa, 10-14 September 2007. Jones, D.R. and Van den Bergh, I. (eds). Acta Horticulturae 828:245-252.
6. Ong Kim Pin. 1996. Fusarium wilt of Cavendish banana in a commercial farm in Malaysia. p.211-217. In: Frison, E.A., Horry, J. and De Waele, D. (eds.). Proceedings of New Frontiers in Resistance Breeding for Nematode, Fusarium and Sigatoka, Kuala Lumpur (MYS), 1995/10/2-5. New frontiers in resistance breeding for nematode, Fusarium and Sigatoka. INIBAP, Montpellier (FRA).
7. Hermanto, C., Sutanto, A., HS, E., Daniells, J.W., O'Neill, W.T., Sinohin, V.G.O., Molina, A.B. and Taylor, P.. 2011. Incidence and Distribution of Fusarium Wilt Disease of Banana in Indonesia. Proceedings of the International ISHS-ProMusa Symposium on Global Perspectives on Asian Challenges held in Guangzhou, China, 14-18 September 2009. Van den Bergh, I., Smith, M. and Swennen, R. (eds). Acta Horticulturae 897:313-322.
8. Davis, R.I., Moore, N.Y., Bentley, S., Gunua, T.G. and Rahamma, S. 2000. Further records of Fusarium oxysporum f. sp. cubense from New Guinea. Australasian Plant Pathology 29(3):224.
9. Qi, P. 2001. Status report of banana Fusarium wilt disease in china. p.119-120. In: Molina, A.B., Nik Masdek, N.H. and Liew, K.W. (eds.). Proceedings of International Workshop on the Banana Fusarium Wilt Disease, Genting Highlands Resort, 1999/10/18-20. Banana Fusarium wilt management: Towards sustainable cultivation. INIBAP, Los Banos, Philippines.
10. Qi, Y.X., Zhang, X., Pu, J.J., Xie, Y.X., Zhang, H.Q. and Huang, S.L. 2008. Race 4 identification of Fusarium oxysporum f. sp. cubense from Cavendish cultivars in Hainan province, China. Australasian Plant Disease Notes 3(1):46-47
11. Molina, A., Fabregar, E., Sinohin, V.G., Herradura, L., Fourie, G. and Viljoen, A. 2008. Confirmation of tropical race 4 of Fusarium oxysporum f. sp. cubense, infecting Cavendish bananas in the Philippines. Abstract of presentation to the 2008 Centennial Meeting of the American Phytopathological Society
12. Moore, N. 1998. Bananatopics 25:12-14.
14. Ploetz R. et al. 2015. Tropical race 4 of Panama disease in the Middle East. Phytoparasitica, 43:283-293.
16. CNN news published 22 July 2015
19. ABGC release on suspected Panama TR4 case in Queensland posted on 4 March 2015
21. News on agricultural quarantine measures on bananas in the 5 September 2012 edition of muscatdaily.com
22. Distribution of TR4 on the Banana Fusarium wilt in Africa website
24. Houbin, C., Chunxiang, X., Qirui, F., Guibing, H., Jianguo, L., Zehuai, W. and Molina, A.B. 2005. Screening of banana clones for resistance to fusarium wilt in China. p.165-174 in Proceedings of Proceedings of the 3rd BAPNET Steering Committee Meeting.  Molina, A.B., Xu, L.B., Roa, V.N., Van den Bergh, I. and Borromeo, K.H. (eds.) INIBAP-ASPNET, Los Baños, Philippines.
25. Risk assessment of Eastern African Highland Bananas and Plantains against TR4, a poster presented at the 2012 International Banana Symposium in Taiwan.
26. Ploidy of Ibwi in MGIS
27. Growing Cavendish in the presence of TR4 in the 10 December 2012 issue of InfoMus@'s News and analysis
28. Huang, B.Z., Xu, L.B. and Molina, A.B. 2005. Preliminary evaluation of IMTP-III varieties and local cultivars against Fusarium wilt disease in southern China. Proceedings of the 3rd BAPNET Steering Committee meeting held in Guangzhou 23-26 November 2004. A.B. Molina, V.N. Roa, I. Van den Bergh and K.H. Borromeo (eds). Advancing Banana and Plantain R&D in Asia and the Pacific, Vol. 13:187-191. INIBAP, Los Baños, Laguna, Philippines.
30. Catching up with Fusarium wilt in the May 2010 issue of InfoMus@
31. Ploetz, R.C. 2009. Assessing threats posed by destructive banana pathogens. Proceedings of the International ISHS-ProMusa Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods held in White River, South Africa, 10-14 September 2007. Jones, D.R. and Van den Bergh, I. (eds).  Acta Horticulturae 828:245-252.
32. FAO and partners call for a global response to deadly banana disease published 23 December 2014. Retrieved 14 January 2015.
33. Panama disease tropical race 4: Standards and guidelines published by Biosecurity Queensland, 20 May 2015 (PDF 655.3KB)
34. Molina, A.B., Fabregar, E., Sinohin, V.G., Yi, G. and Viljoen, A. 2009. Recent occurrence of Fusarium oxysporum f. sp. cubense Tropical Race 4 in Asia. Proceedings of the International ISHS-ProMusa Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods held in White River, South Africa, 10-14 September 2007. Jones, D.R. and Van den Bergh, I. (eds.). Acta Horticulturae 828:109-116. ISHS, Leuven, Belgium.
35. Farquhar, I. 2012. Bananas in China. Report on a visit to three banana producing provinces of China by Dr. Iain Farquhar on behalf of Banana Link and the Steering Committee of the World Banana Forum. 35 pp.
39. Containing TR4 by Altus Viljoen, a presentation given at the 2015 Congress of the Australian Banana Idustry.
40. Global Blight Threatens Bananatastrophe in Mozambique, 28 October 2015 in Voice of America
41. AC4TR4 on the website on Fusarium wilt in Africa
42. Website of the BAPNET network
44. Biosecurity Queensland's response to TR4
45. TR4 response on the website of the Australian Banana Grower's Council
46. Dita, M., Echegoyén Ramos, P.E. and Pérez Vicente, L.F. 2013. Plan de contingencia ante un brote de la raza 4 tropical de Fusarium oxysporum f. sp. cubense en un país de la región del OIRSA. OIRSA, San Salvador, El Salvador. 155p.
47. TR4's transcontinental leap in the November 2013 issue of InfoMus@
50. Research projects led by Wageningen University scientists

See also on this website

News and blogs on TR4:
Photos on the symptoms of Fusarium wilt in the Musarama image bank
Video on the symptoms, transmission and prevention of Fusarium wilt in the Musarama video bank
Musapedia page on an INREF-funded research project managed by Wageningen University & Research Centre - Panama disease: Multi-level solutions for a global problem

Further reading

Tropical race 4 grower kit, series of documents produced by Biosecurity Queensland to help Australian banana growers protect their farms
Contingency plan (in Spanish) on TR4 for OIRSA countries
Diagnostic manual and links to presentations given at a 2014 FAO-CARDI regional workshop on the prevention and diagnostic of Fusarium wilt
Fact sheet on Panama disease (8MB PDF) on the Plant Health Australia website
Fusarium wilt of banana laboratory diagnostics manual (1.8MB PDF) on the Plant Health Australia website
Datasheet on Fusarium oxysporum f. sp. cubense in CABI's Invasive Species Compendium
Panama disease: an old nemesis rears its ugly head, Part 1: The beginnings of the banana export trades Part 2: the Cavendish era and beyond
Research projects on Fusarium wilt that are managed by Wageningen University & Research Centre: panamadisease.org
Response to TR4 on the website of the Australian Banana Growers' Council
Response to TR4 on the website of Biosecurity Queensland
Website of the Banana Asia-Pacific Network (BAPNET) network