Genetic diversity and disease control in rice Controlling disease in rice without using any chemicals. Scientists from the Philippines-based International Rice Research Institute (IRRI) have found a new way to control a major disease in rice without using any chemicals. By planting different types of rice alongside each other, they could almost completely control the spread of rice blast, a disease that can cost the rice industry millions of dollars a year. A small scale experiment in 1997 suggested that interplanting could achieve 92 to 99% control of rice blast, as well as an unexpected double success by boosting farmers’ yields by half a ton to 1 ton per hectare. In 1998, 812 hectares were planted with hybrid rice and glutinous rice, four rows of one and one row of the other. The crop was sprayed with fungicide only once. Yields reached 9 tons of hybrid rice and nearly 1 ton of glutinous rice per hectare. Even more impressive was the fact that, within the interplanted crop, the incidence of blast fell to 5 percent from a common level of 55 percent and the yield loss dropped from 28 percent to nothing at all. In 1999, the area grew to 3,342 hectares, and the farmers involved boasted that interplanting was providing them with about US$150 more income per hectare. By the end of 2000, the IRRI-Yunnan research team plans to extend the scheme to cover up to 60,000 hectares and continue to expand it into the Philippines, Thailand, and other rice-producing nations. IRRI’s Director General Ronald P. Cantrell says, “The days of unsustainable high-input rice production are a thing of the past!” For more information: - Duncan Macintosh, IRRI, MCPO Box 3127, Makati City 1271, Philippines; fax: (63-2) 891-1291; email: d.macintosh@cgiar.org ; http://www.cgiar.org/irri - Youyong Zhu et al. Genetic diversity and disease control in rice. Nature 406, 718-122 (2000), Macmillan Publishers Ltd. << country/story review