downy mildew

例句：

1. 1. The downy mildew on the leaves is a sign of poor growing conditions.
   叶子上的霉病是生长条件不佳的迹象。
2. 2. The farmer sprayed the crops with fungicides to prevent downy mildew.
   农民用杀菌剂喷洒作物以防止霉菌病。
3. 3.The greenhouse was filled with downy mildew, making it difficult for plants to grow.
   温室充满了霉菌病，使得植物难以生长。