Powdery mildew appears as a white, dusty growth on the undersides, or both the tops and bottoms of leaves, and on new growth of apple, cherry, and sometimes pear trees. Leaves turn yellow and drop, stunting growth. Fruit may be stunted, shriveled, or cracked. Prune out distorted or badly mildewed twigs as you notice them. Plant resistant varieties like 'McIntosh' and 'Delicious' apples. Regular spray programs should help, too. For severe infestation, spray with lime sulfur, benomyl, or another fungicide.
