Potato / Bacterial Wilt /  Bacterial Wilt

Bacterial wilt or brown rot, caused by Ralstonia [Pseudomonas] solanacearum, limits potato production worldwide in Asia, Africa, and Central and South America, where it causes severe crop losses in tropical, subtropical, and warm temperate regions. The disease may also occur in cooler climates such as relatively high elevations in the tropics or higher latitudes. The bacterium affects more than 30 plant families, including crops and wild species. Race 3 (biovar 2A) strains of R. solanacearum, which affect mainly potato but occasionally tomato and other solanaceous crops and weeds, are most common in higher elevations of the tropics (up to 3400 masl). At lower elevations, race 1 strains are most prevalent and affect a wide range of crops and weeds. Crops highly susceptible to race 1 (biovars 1, 3 or 4) of R. solanacearum are potato, tobacco, tomato, eggplant, chili, bell pepper, and groundnut.

Infected seed tubers are the main means of dissemination of R. solanacearum (particularly for race 3 strains). In cool conditions, such as tropical elevations above 2500 m, infected but symptomless plants may harbor the bacterium and transmit it to progeny tubers as latent infection, leading to severe disease outbreaks when grown at warmer locations. The pathogen can survive in soil (mostly on plant debris) and in the rooting system and rhizosphere of many hosts (weeds, other host crops, potato volunteers).

There is no effective chemical control for bacterial wilt. Therefore, its incidence can only be reduced if various control components are combined. This involves mainly the planting of healthy seed in clean soil and the planting of tolerant varieties, in rotation with non-susceptible crops, as well as the application of various sanitation and cultivation practices. Such an integrated disease management approach can lead to significant reduction, or even eradication of bacterial wilt.

CIP's bacterial wilt research aims at reducing losses due to bacterial wilt, a severe disease constraint to potato production in many developing countries. The research is designed to validate and promote integrated management strategies of bacterial wilt in different production systems through the enhancement of farmers and national research and extension organizations knowledge on disease epidemiology and control, and access to technology.

Specifically, it aims at: (i) Documenting control practices used by farmers (rotation, sanitation, seed selection, etc.) in selected potato countries where bacterial wilt is a severe constraint; (ii) Developing and testing new control components (highly sensitive and specific pathogen detection tools, soil treatments or amendments, biological control, rotation and other cultural practices); (iii) Completing the selection of potato progenies with resistance to bacterial wilt produced by past CIP breeding program. Farmers’ practices and effective new control components are subsequently validated in on-farm trials and sets of management options are integrated into potato cropping systems in selected areas.