Fusarium oxysporum. f. sp. cubense
Author: Mpoki Shimwela, University of Florida
Reviewed by: Jeffrey Rollins, University of Florida
Pathogen
Fusarium oxysporum f. sp. cubense (Foc) (E.F. Smith) Snyder. & Hansen is the causal agent of Banana Fusarium wilt, also known as Panama disease of banana. Further, the pathogen is categorized into races based on the differential responses of cultivars. Races 1, 2, and 4 are pathogenic only to bananas (Musa spp.) and race 3 is pathogenic only to Heliconia spp.
Race 1 strains cause disease in Gros Michel, Silk, Pome, and Pisang awak cultivars.
Race 2 strains cause disease in Bluggoe and closely related cooking cultivars.
Race 3 strains are reported to cause disease in Heliconia spp.
Race 4 strains cause disease in Cavendish cultivars
The pathogen strains are divided based on the vegetative compatibility groups (VCGs).
Symptoms and Signs
Symptoms include yellowing and wilting of the older and lower leaves, which progresses to the younger leaves. This eventually results in death of the entire plant. Wilt is accompanied by internal discoloration of the vascular system of the banana plant, as a large portion of the xylem turns a brick red to brown color.
Ecology and Spread
The pathogen can remain immobile in soil or plant debris as chlamydospores for up to 30 years. The chlamydospores can be stimulated to germinate by host exudates or by the contact with susceptible health tissue. Mycelia and conidia are produced 6-8 hours after chlamydospore germination. Infection takes places through secondary or tertiary feeder roots, but not through the main root unless there is exposition of the central core. The pathogen passes to the vascular zone of the rhizome and then to the adjacent parenchyma in advance stages of the disease. Conidia and chlamydospores are produced and released to the soil to begin a new cycle.
The pathogen is introduced into disease free areas through movement of infected planting materials (e.g., rhizomes). Within the field, the pathogen moves in soil, running water, and on farm implements and machinery. Warm, wet weather is favorable for Foc infection and spread.
Geographic Distribution
Widespread in all banana-producing regions except the Mediterranean, Melanesia, and Somalia.
Management
Management of this disease should involve use of: resistant cultivars, certified clean planting materials, biological control (e.g., Trichoderma spp.), and quarantine measures. There are no effective chemical available to control banana Fusarium wilt.
Diagnostic Procedures
Pathogenic Foc can be isolated from pseudostem or roots of the wilted banana plant.
Diagnostic features include:
- presence of chlamydospore and
- presence of macroconidia and microconidia.
This fungus grows well on media such as PDA and Komadas.
Resources and References
1. Fourie, G., Steenkamp, E. T., Ploetz, R. C., Gordon, T. R., and Viljoen, A. 2011. Current status of the taxonomic position of Fusarium oxysporum formae specialis cubense within the Fusarium oxysporum complex.Infection, Genetics and Evolution, 11: 533-542.
2. Ploetz, R. C. 2006. Panama disease, an old nemesis rears its ugly head: part 2, the cavendish era and beyond. Plant Health Prog March, 1-17.
3. Stover, R. H. 1972. Banana, Plantain, and Abaca Diseases. Commonwealth Mycological Institute, Kew, England.
