More information on this destructive disease. Excerpt from the
Popular Garden Series magabook Orcharding with permission from
its publisher, BowTie magazines, a division of BowTie Inc.
Purchase Orcharding here. When talking about disease, it’s
important to start by recognizing that a disease is not the same
as a pathogen. Pathogens (fungi, bacteria and viruses) cause
disease, but in order to do so pathogens require a host and a
hospitable environment. The reason this is so important in IPM
is that if you disrupt any one of those elements, the disease
will not develop. You can change the host by planting resistant
varieties, you can modify the environment or you can attack the
pathogen. Powdery mildew affects apples, peaches, apricots,
cherries, plums and pecans. It causes a powdery, white growth on
leaves and can cause leaves to be stiff and distorted if the
leaves are infected while young. On apples, powdery mildew
causes net-like russeting and overall reduction in yield. On
stone fruit, powdery mildew cause