落叶松褐锈病对林木当年生长无明显影响，但对第二年生长影响显著。连年发病损失量剧增；不同病情指数（Ｘ）每公顷材积生长损失量为Ｙ＝１９４／１＋ｅ５４９３３７－００６８９３Ｘ；该病为害指标———病情指数为３６。立木林价、防治效果和成本分别为Ｃ、Ｑ、Ｅ时，防治指标方程为：１９４Ｃ［１／１＋ｅ５４９３３７－００６８９３Ｘ－１／１＋ｅ５４９３３７－００６８９３（１－Ｑ）Ｘ］－Ｅ＝０；前一年９月份降水量（Ｘ３）、当年５月份平均气温（Ｘ１）和８月份相对湿度（Ｘ２）为测报因子。预测区域平均病情指数Ｙ＝５１８５＋３２５９６Ｘ１－０４２１０５Ｘ２＋００８６２７Ｘ３±６９。 Larch rust had no significant effect on the growth of forest trees, but had a significant impact on the second year’s growth. The incidence of disease in consecutive years increased sharply. The volume growth loss per hectare for different disease index (X) was Y = 194 / 1 + e549337-006893X. The disease index of disease --- disease index was 36. When the stand price, control effect and cost were C, Q and E, the control index equation was: 194C [1/1 + e549337-006893X-1/1 + e549337-006893 (1-Q) X] -E = 0; Precipitation in September of the previous year (X3), mean temperature in May of that year (X1) and relative humidity in August (X2) are the forecasting factors. The predicted regional average disease index Y = 5185 + 32596X1-042105X2 +008627X3 ± 69.