Powdery mildew is a frequent problem throughout the Pacific Northwest. Although any tree can get this common disease, the ones that are … The first sign of powdery mildew … It is often a serious problem in apple nurseries. Symptoms. A downy white fungal growth, powdery mildew attacks a wide variety of trees and shrubs as well as ornamental plants, indoors or out. Symptoms. Powdery mildew is a common fungal disease of trees and shrubs in Minnesota. But despite the name, it is not only one of the most serious diseases of Apple tree, but also of Pear, Quince, and of Peach tree … Powdery mildew interferes with the proper functioning of leaves, reduces shoot growth, reduces fruit set, and produces a netlike russet on the fruit of some cultivars. Losses are due to its chronic effect on tree vigor and yield in addition to poor fruit finish for highly susceptible cultivars. Disease is often … As resistance to certain fungicides becomes more common integrated management with good resistance management is critical. The Apple Powdery Mildew, which is caused by the ascomycete fungus Podosphaera leucotricha, represents an important disease of the tree and crop.. Powdery mildew … Apple powdery mildew is becoming more problematic as many cultivars preferred by consumers are powdery mildew susceptible. White to gray, powdery spots, blotches or felt-like mats form on leaves, stems and buds of infected plants. Very susceptible apple …