Rainfall （ram） of the second month after transplanting, average temperature （℃） at the same period, and rainfall days of the first month after transplanting were selected from 31 factors using anomalous sign method from data in 9 continuous years in Ningyuan county. Alternaria alternata （Fries） Keissler occurrence trend was studied with grade-statistics method. Re- sults showed that back forecasting was in line with the actual value. The accurate percent of forecasting for Alternaria alternata （Fries） Keissle at different counties for ...
