洪雅县地处四川盆地西南边缘，属亚热带湿润气候区，是全省水稻稻瘟病常发县之一。1984一1997年秧田期（4月上旬至5月上旬）发生叶瘟有10年，占71．4％，累计发生叶瘟11．6万亩（l亩一l／15公顷，F同）；发生穗颈瘟有14年，占100％，累计发生穗颈瘟25．6万亩。年均发生叶瘟0．8 Hongya County is located in the southwestern margin of the Sichuan Basin, is a subtropical humid climate zone, is the province one of the frequent rice blast county. The leaf blast occurred in 1984-1997 in the seedling stage (early April to early May) for 10 years, accounting for 71.4% of the total, with a total of 116,000 mu of leaf blast (1 mu per 1/15 hectare, same as F). Occurrence of panicle neck blast for 14 years, accounting for 100% of the total occurred 256000 acres of panicle blast. The average annual occurrence of leaf blast 0.8