AboutJim Hyland Expertise I am an expert in Forestry, Forest Entomology, Forest Pest Control, and Forest Health. Extensive knowledge in Identification of insects and diseases of trees. Expert on Bark beetles and other insects that attack forests. Also a Registrated Forester with extensive knowledge in the management and care of forests.
Experience 34 years as State Pest Management Chief in a Southern state. Extensive knowledge in Forestry.
BS with major in Forest Management and Entomology Registered Forester Certified Pesticide Appicator
hi there - I live in canada and our small oak tree in our backyard has small brown/rust spots on almost every leaf. This seems to be every year. And then the leaves fall off quite early in the summer. The tree still seems to be growing well but the foilage always seems to be infected.
Answer These are leaf spots caused by a fungus called leaf blister. Oak leaf blister is a fungal leaf spot disease caused by the fungus Taphrina deformans. It is a spring disease common in Alabama on all oak species. Severe leaf blister can result in widespread early defoliation. With well-established trees, early defoliation will not cause tree death, but it will reduce tree vigor and aesthetics.
Early in the spring, small, rough (concave-convex) spots will begin to appear as the leaves expand. Gradually, the spots will become pale green in color and somewhat thickened. Older spots are brown or greenish brown. Leaves with numerous spots will fall prematurely to the ground. If well-established trees defoliate before midsummer, they will sometimes leaf out later in the season. When defoliation occurs in the late summer, leaf loss will have little impact on the tree's health.
Because oak leaf blister does not seriously affect the overall health of the tree, chemical control measures are usually not recommended. Likewise cultural controls are ineffective because of the nature of the fungus and its method of infection and transmission. The following strategies for limited control of oak leaf blister are recommended:
Collect and discard fallen leaves.
On small, newly established or especially valuable specimen oak trees previously damaged by leaf blister, apply a protective fungicide. Apply the fungicide at bud swell.
The following fungicides are labeled for use on oak to control oak leaf blister: Bordeaux mixture, Daconil Ultrex, Daconil Weather Stik 6F, Rose and Shrub Disease Combo, Dithane M-45 80W, Fore 80W. Always follow label recommendations and precautions.
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