Apple Trees & Small Brown Spots on Leaves

Frogeye leaf spot tends to originate on apple trees during the dormant season.

Apple trees are susceptible to several diseases, many of them affecting the leaves. Luckily, leaf spot diseases do not tend to result in severe damage to apple trees and can be managed quite easily.

Cause

Brown spots on apple tree leaves are typically the result of frogeye leaf spot. Frogeye leaf spot stems from a fungus named Botryosphaeria obtusa, which attacks weak spots on leaves.

Effects

The effects of frogeye leaf spot are typically not too detrimental. However, if leaves are left untreated for a long period of time they will likely yellow and fall from the tree prematurely. It can also lead to black rot, which will cause some fruit on the tree to spoil.

Treatment

Remove all dead and damaged branches from the tree. If leaves with brown spots are seen in the spring, remove them right away. Pruning branches to encourage air circulation can also help to prevent against the fungus, as it thrives in moist conditions. Fungicides are typically not effective against frogeye leaf spot.

References

• University of Kentucky Cooperative Extension Service: Frogeye Leaf Spot, Black Rot and Canker of Apple
• University of Rhode Island Landscape Horticulture Program: Leaf Spot Diseases of Ornamental Trees and Shrubs