Leaf Spot Diseases in Illinois
LOWFungus
Leaf Spot Diseases is currently active in Illinois. Watch your susceptible trees closely and act early.
About Leaf Spot Diseases
A broad group of fungal diseases that cause discrete spots on the leaves of deciduous trees. Most are primarily cosmetic and do not seriously harm established trees. They are most common during wet spring and summer weather. Many different fungi cause leaf spots on different tree species.
Symptoms to watch for
Discrete round to irregular spots on leaves, spots may be brown, tan, black, or reddish, spots may have concentric rings or distinct borders, some spots may merge into larger blotches, premature leaf drop in severe cases, mostly cosmetic damage on established trees
Trees at risk in Illinois
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Treatment options
Sanitation and Cleanup
Rake and destroy fallen leaves in autumn to reduce overwintering spore load. Improve air circulation through pruning. Most leaf spot diseases do not require fungicide treatment on established trees.
Recommended Products & Tools
Helpful supplies for managing Leaf Spot Diseases. Always read and follow label directions, and confirm a diagnosis before treating.
Broad-spectrum protectant for many fungal leaf and bark diseases.
Preventive spray for needle cast, leaf spots, and blights.
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Browse all Illinois arborists →Frequently asked questions
Is Leaf Spot Diseases in Illinois?
Leaf Spot Diseases is currently active in Illinois. Watch your susceptible trees closely and act early.
What does Leaf Spot Diseases look like?
Discrete round to irregular spots on leaves, spots may be brown, tan, black, or reddish, spots may have concentric rings or distinct borders, some spots may merge into larger blotches, premature leaf drop in severe cases, mostly cosmetic damage on established trees
What trees does Leaf Spot Diseases affect in Illinois?
It affects Red Maple, Sugar Maple, White Oak, American Elm, Flowering Dogwood. Susceptibility varies by species.
How do I treat Leaf Spot Diseases?
Options include: Sanitation and Cleanup. Confirm the diagnosis before treating, and consider a certified arborist for high-value trees.