Apple Scab


Apple-scab Venturia inaequalis is a fungal disease that affects leaves, fruit, and twigs. This disease not only affects edible fruit bearing apple trees, but ornamental crabapples as well. Apple scab can diminish the aesthetic quality of an apple tree by early defoliation and unsightly blemishes on leaves and fruit. In some cases branch dieback can occur as the disease progresses. The disease rarely kills, but it can severely affect the health of the tree by reduced growth, vigor, and fruit production. Repeated infections can weaken the tree and make it a susceptible host to other diseases and or pests.

Affected trees:  edible and ornamental crabapples, mountain ash, cotoneaster, pear, and hawthorn.

Noticeable Signs

Common signs of Apple scab tend to show:

  • brown to olive lesions on leaves in late spring eventually turning black.
  • heavily infected leaves turn yellow and then defoliate.
  • fruit can also display similar symptoms as to those on leaves.
  • Lesions on fruit will unevenly mature, crack, and turn brown and corky.


Reduction of infection and ultimately the amount of fungicidal spray applicant needed, can accomplished by raking and proper disposal of leaves in fall, watering at ground level, and proper pruning for better air circulation.

Two to three fungicidal spray applications in the spring, starting at bud break and continuing every 7 to 14 day intervals for fruit trees and 21 days for ornamentals. If wetter conditions exist, for proper control, a forth spray in-fact may be necessary.