Apple scab, Venturia inequalis, affects apple, crabapple, pear and many other species of Malus throughout North America. The cool, wet weather that is common in early spring favors the development of apple scab.
Symptoms first appear in the spring as lesions on the leaf surface. When heavily infected, the leaves become distorted and drop early in the summer. Scab may be controlled by an early injection of either Arborfos (available in both liquid loadable bottles and capsules) or Tebuject 16 (available only in capsules).