Apple Scab in Northern Michigan
Why Are the Leaves Falling Off My Apple or Crabapple Tree?
If your apple or crabapple tree develops olive-green or dark brown spots on its leaves each spring, followed by premature leaf drop during the summer, it may be affected by apple scab.
Apple scab is one of the most common fungal diseases of apple and crabapple trees in Northern Michigan. The fungus infects young leaves and developing fruit during cool, wet spring weather. Although the disease rarely kills an established tree, repeated infections year after year can weaken the tree, reduce flowering and fruit production, and make it more susceptible to other insects and diseases.
Common Signs of Apple Scab
Olive-green, brown, or black spots on leaves
Premature leaf drop, often beginning in mid to late summer
Dark, corky spots on fruit
Reduced flowering or fruit production
Thin or weakened canopy after several years of repeated infection
Is My Tree Going to Die?
In most cases, no. Apple scab is rarely fatal to mature landscape trees. However, repeated defoliation over several growing seasons places the tree under stress, reducing its ability to store energy and making it more vulnerable to drought, insects, and other diseases.
Early diagnosis and properly timed management can greatly reduce future infections.
Can Apple Scab Be Treated?
Yes—but timing is everything.
Fungicides protect new leaves as they emerge during spring. Once leaves become infected, fungicides cannot remove the existing spots or restore damaged tissue. For susceptible trees, several properly timed spring applications are often recommended during periods of active leaf expansion and disease risk.
Good sanitation is also an important part of management. Raking and removing infected leaves in the fall helps reduce the amount of fungal spores available to infect new leaves the following spring.
UFT Recommendation
Not every tree with spotted leaves requires fungicide treatments. At UFT Tree Care Specialists, we begin by identifying the severity of the disease, evaluating the overall health of the tree, and recommending a management plan based on the tree's long-term value and the client's goals.
If you're looking for a Traverse City arborist or professional tree care in Northern Michigan, we can evaluate your apple or crabapple trees and develop a science-based Plant Health Care program designed to improve tree health while reducing future disease pressure.
Related Reading
Sources Consulted
The recommendations in this article reflect generally accepted arboricultural practices and information from:
Michigan State University Extension – Apple Scab management and disease identification
Cornell Cooperative Extension – Apple Scab disease management
University of Minnesota Extension – Apple Scab on ornamental crabapple
ISA Best Management Practices – Plant Health Care and Integrated Pest Management
HEALTHY SOIL. | STRONGER TREES. | LASTING LANDSCAPES.
Concerned about apple scab on your apple or crabapple tree? UFT Tree Care Specialists provides science-based disease diagnosis, Plant Health Care programs, and practical recommendations to help protect valuable trees throughout Northern Michigan.
ufttree.care • ben@ufttree.care • 231-409-0442
