Clean planting material to combat Moko disease of plantains in Latin America

Moko bacterial wilt is the principal bacterial disease limiting plantain production in Latin America and the Caribbean, and it is primarily spread between farms and regions via planting material. Moko disease can destroy up to 75% of crop production in an affected area and annual losses in the region have been calculated to be more than USD $100 million. Most farmers use chemical products, such as disinfectants, herbicides and insecticides to prevent disease dissemination.

Through RTB, CIAT is collaborating with Bioversity and IITA on introducing hybrids and evaluating them for their agronomic performance; resistance to diseases, including Moko and Sigatoka diseases; and acceptability to farmers for consumption or agroindustry in Colombia.

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A plantain cultivar susceptible to Moko disease (left), compared with a resistant plantain hybrid (right), both established in sites with presence of Ralstonia solanacearum, the bacterium that causes Moko disease

With combined funding from FONTAGRO and RTB, interdisciplinary teams of scientists from CIAT, CIRAD and regional and national partners, have been working on improving the production of clean planting material through the development of innovative and cost-effective mass propagation systems as part of a disease management strategy.

A significant development is the use of thermotherapy chambers for mass propagation of disease-free planting materials. CIAT designed and piloted an inexpensive, efficient and completely automatic system to produce clean planting materials: Using corms, which are first disinfected in a solution of insecticide and fungicide, and then subject to the technique of accelerated reproduction of planting material, the thermal chambers clean infected material by heat generated with a polyethylene cover and solar radiation. The plants stay inside the chamber around 20 days at a temperature of 51 – 55 °C.

Once the conditions needed to propagate planting materials were determined, a larger thermal chamber was constructed that is currently producing pathogen-free planting material for 7,000 farmers in central Colombia.

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The thermotherapy chamber implemented in central Colombia guarantees farmers access to clean and high quality planting material

“I produce my own planting material in the thermal chamber and obviously it comes out very clean”, narrates Silverio González, an agronomist at the National Federation of Plantain Producers of Colombia (FEDEPLÁTANO). “This is an innovative system for large-scale production. The planting materials are completely homogeneous and the production with thermotherapy assures that it happens in a pathogen-free environment.”

“After planting the clean planting materials in the field there are no losses and replanting becomes unnecessary, as it presents better establishment in the field”, adds Alejandro Montaña, a Colombian producer. “Further, the first production cycle is shortened by 1.5 months and the production of suckers starts earlier in comparison with crops established using suckers or in vitro plants as planting material”.

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Dr. Rony Swennen, IITA Breeder (left), Elizabeth Alvarez, CIAT Plant Pathologist and Silverio Gonzalez, Plantain Producer, in front of a plantain genotype resistant to Moko disease at Armenia, Quindio farm in Colombia

The technology has since been adopted by at least 10 nurseries or planting material production centers in Colombia. CIAT scientists helped nursery entrepreneurs to improve their production processes and scale the technology out, while involving female household heads in preparations for planting material production and caring for plantlets.

Conducted trials to evaluate the propagation rate inside the thermotherapy chamber found that monthly production increased by as much as 90 plantlets, from 15 suckers per square meter. A total production of 980,000 plantlets was propagated and distributed to farmers in 2014.