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New races of rust attack coffee in Latin America and the Caribbean
- The rust fungus became more virulent, generating new breeds that are causing symptoms of the disease in resistant varieties.
June 27, 2019. Recently, in several coffee-growing areas of Latin America and the Caribbean, some varieties of F1 Hybrids of coffee, catalogued with resistance to rust, with symptoms of the disease, began to be reported. This is due to the fact that the fungus causing the rust has experienced changes, generating new breeds.
"Several F1 Hybrids presented resistance to rust for almost 20 years, until now some of them began to present symptoms. This does not mean that the hybrids have lost their resistance, the genes of resistance to rust are still present in them, what happens is that being its resistance in a single sense (vertical), when the fungus of rust mutated and a new race appears more aggressive, this if it can affect the hybrids," explained William Solano, plant breeder of CATIE (Tropical Agricultural Research and Higher Education Center).
Elías de Melo, CATIE coffee researcher, explained that despite what has happened, hybrids are even more tolerant to rust than other varieties of coffee, because although some have symptoms of the disease its severity is very low in most situations. "Any material with resistance, even when it can be affected by new races of rust, will always have a better response to the management and control of the disease," said the expert.
The publication F1 Coffee Hybrids, Rust Resistance and Future Strategies explains that new rust breeds arise for several reasons:
- Because the number of rust fungus factors increased, creating new stronger or more powerful combinations.
- Due to the extensive use of a single variety (as it occurred in Honduras with the Lempira variety)
- Failure to implement preventive measures such as applying fungicides, giving good nutrition to the coffee plant, using adequate shade, among others.
This provides ideal conditions for the rust fungus to develop and multiply.
In order to reduce or avoid the impact of rust and its new breeds, even if resistant varieties are available, de Melo recommends that coffee growers use integrated coffee management practices such as: fertilize (organically or inorganically) coffee plants to keep them well nourished, which will make the plants better able to fight back the attack of new races of rust; plant or maintain trees (leguminous, fruit or timber well distributed and managed) in the coffee plantation that provide a uniform shade (covering less than 50%); and use chemicals or bio-pesticides preventively to reduce favorable conditions for the fungus and use fungicides when necessary.
Solutions from science and development
Given what is presented, from the point of view of genetic improvement, Solano mentioned that CATIE, in the last 5 years, has been creating new F1 coffee hybrids with new sources of resistance genes, not previously used. Also, the strategy of creating hybrids is changing to include several rust resistance genes (and not just one), with the purpose of accumulating different sources, thus providing more sustainability to the resistance of coffee to rust.
In addition, within the framework of the Central American Program for Integral Management of Coffee Rust (PROCAGICA, its Spanish acronym), in partnership with PROMECAFE, the Agricultural Research Centre for International Development (CIRAD, its French acronym) and the coffee institutions of Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Panama and the Dominican Republic, a platform is being coordinated to follow up and monitor studies of rust races.
An important part of this initiative is the constant monitoring of the incidence of rust in different varieties of coffee, thus maintaining a continuous vigilance in the different countries.
If you are interested in learning more about this topic we invite you to watch the following video, Are F1 Hybrids losing their resistance to rust?
Elías de Melo
Agriculture, Livestock and Agro-forestry Program
Karla Salazar Leiva
Information Technology and Communication