dark mildew

例句：

1. 1.The dark mildew on the leaves is a sign of poor soil health.
   叶子上的暗霉是土壤健康不良的标志。
2. 2.The farmer sprayed the crops with fungicide to prevent dark mildew.
   农民喷洒了杀菌剂以防止作物上出现暗霉。
3. 3. The dark mildew on the walls was so thick that it was hard to see through.
   墙上的暗霉非常厚，以至于很难透过去。