Apple Scab is a leaf and fruit disease found on commercial apples and pears grown for fruit production as well as ornamental apples, crabapples, pears, hawthorn and other closely related members of the apple family.
Species of fungi are the cause of scab diseases. Fungus overwinters on fallen dead leaves and during bud break spores are forcibly discharged into the air. These spores infect emerging leaves by growing within the leaf tissues causing a lesion. The amount of spore production and the infection rate depends on the weather. Wet and cool conditions are favorable for growth.
Detecting Apple Scab
Your apple tree could be infected with Apple Scab if you notice circular lesions appearing on expanding leaves during the spring or summer. Lesions start out as a dark green color and eventually turn black. Leaf lesions may either remain separate or may merge. Dead areas in maturing leaves cause curling and dwarfing in severe infections. Developing fruit may also grow lesions which thicken and become rough or scabby. Mature fruit may be distorted or cracked. You may observe infected leaves and fruit dropping to the ground throughout the summer and fall. Do your best to clean up and dispose the fallen pieces because the ground is where they produce spores for next year's infections.
- Annual fertilizations can go a long way to improve the health and restore your tree's vigor.
- Having your ISA Certified Arborist® prune or thin the tree to allow more air circulation within the canopy is recommended for mature trees.
- Once your tree has been infested with apple scab, fungicide can be applied to control, and/or minimize leaf drop.
- Always rake up and dispose of fallen and diseased leaves and fruit.
If you think you may have a problem with apple scab, contact us at 651-337-4089 or by filling out the form below.