Controlling foliar blights of wheat in the rice-wheat systems of Asia

Foliar blight caused by Cochliobolus sativus and Pyrenophora tritici-repentis is the main biotic stress of wheat in the rice-wheat systems of South Asia, where it causes, on average, up to 15% yield loss. Increases in food production have to come from higher and sustainable productivity. It requires a multidisciplinary approach combining novel resistance sources and adapted agronomic practices. Better host plant resistance has been achieved by crossing genetic resistance sources or wild relatives to high-yielding cultivars. Germ plasm improvement methods centered on regional partnerships are now more specifically addressing the needs of warmer areas. Observations in long-term trials underline the increasing role of soil fertility in reducing disease severity. Studies focusing on the effect of stress conditions on disease development increase knowledge about the stability of resistance. This makes breeding more efficient and helps recommend better-adapted crop management practices. The adoption of reduced tillage methods and soil conservation practices imply farmers' direct participation in the research process. Foliar fungicide treatments are not a viable alternative for small farmers, but seed treatment may prove useful as part of an integrated disease management approach based on improved genetic resistance and good agronomy.