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通过对郧县小麦白粉病１３ａ的历史资料的研究分析，初步明确决定病害发生程度的主要因素是当年早春３月上旬末的菌源基数，３月份的平均温度以及３月份降水量与３月份平均温度的乘积，提出了病害发生程度中期预测式：Ｙ＝－２．５３３０７４２２８＋０．０５６１９７７６７２Ｘ１＋０．４９８２１１９８０Ｘ２＋０．００２４３７２４９１８９Ｘ４。历史符合率８４．５％，经１９８５～１９９７年回测检验，结果与发生实际基本一致，其中Ｘ１为３月上旬末病株率，Ｘ２为３月份平均温度，Ｘ４为３月份平均温度与３月份降水量的乘积。
Through the analysis of historical data of wheat powdery mildew in Yunxian County, the main factors that determine the extent of the disease preliminarily are the number of bacteria source base in early March in early March and the average temperature in March, and the average of March rainfall and March average The product of the temperature, the mid-term prediction of the degree of disease was put forward: Y = -2.533074228 + 0.0561977672X1 + 0.498211980X2 + 0.002437249189X4. The historical coincidence rate of 84.5%, back to test from 1985 to 1997 test results and the actual occurrence of the actual, where X1 is the end of March plant disease rate, X2 is the average temperature in March, X4 is the average temperature in March and 3 The product of precipitation in the month.