Plant Problems: Disease

Powdery Mildew

Powdery mildew is most likely to develop during cooler temperatures and in higher humidity, but it can still develop in the arid climates of the intermountain west.

Powdery mildew appears as springklings of white or light gray, fuzzy spots on leaves and stems. It looks almost like someone has sprinkled powdered sugar over the plant. Powdery mildew first manifests on the top side of the leaves, near the base of the plant. Regularly and thoroughly checking leaf and stem surfaces will help you identify powdery mildew in time to prevent serious damage to the plants.

Powdery mildew is a fungus, with numerous varieties. Because there are so many varieties of this fungi, some plants are susceptible to one sort and not another. Therefore, do not treat plants for an infection unless you have seen the signs of the fungus.


Powdery mildew can be treated by using a fungicide. Diamond Bar Gro-Systems carries a select supply of fungicides, insecticides, and miticides. You can also find fungicides at most garden centers and nurseries. Make sure to buy a fungicide that targets powdery mildew and carefully use it according to the manufacturer’s instructions.

Pythium Fungus