Changes of Magnaporthe oryzae population in Jiangsu Province from 2001 to 2010.

818 monosporous strains of Magnaporthe oryzae were isolated from 1 269 rice blast disease samples in five major rice planting areas in 2001-2010,which were identified by seven Chinese rice cultivars and classified into 7 groups and 40 races.The results revealed that ZG1 and ZB groups were dominant races in Jiangsu Province.ZG1 race exhibited the highest appearance frequency(58.3%) in 2001-2010 and ZB group was the second with 16.9% appearance frequency.The distribution of different M.grisea races varied in five major rice planting areas of Jiangsu Province.The race distribution was relatively simple,just 7 groups and 18 races in Xuzhou and Yancheng areas.However,in the other areas,the distribution was complicated,with 7 groups and 22 races in Nanjing,7 groups and 23 races in Suzhou,7 groups and 21 races in Nantong.In Suzhou,there was as more as had 11 races belonging to ZB group.The dominant race ZG1 kept high appearance frequency,with the highest 73% in 2006 and the lowest 41.4% in 2009.ZB groups reached the highest appearance frequency(31.4%) in 2009.The results indicated that rice cultivars exhibited high sensitivity and affinity to rice M.grisea races in Jiangsu Province.