Identify Maple Tree Disease

Asked July 22, 2019, 6:18 PM EDT

Hello. We have an old Maple tree (50+ years old) and this year the leaves from top to bottom of the tree are turning brown (see attached photo). Can you identify the disease and recommend treatment if possible?

Washtenaw County Michigan maple trees

2 Responses

Thank you for your question. Here is an Extension article suggesting two possibilities: https://www.canr.msu.edu/news/maple_leaf_blister_and_anthracnose_two_foliar_diseases_that_can_appear_on_s I suggest you contact your Extension office for advice: https://www.canr.msu.edu/washtenaw/county-extension-office Good luck!

It appears that your maple tree is infected with anthracnose, a disease caused by several different, but related fungi. These pathogens blight foliage and in some cases create cankers on twigs, resulting in dieback. Anthracnose foliar lesions are large, irregularly shaped areas of necrotic tissue along the leaf margins and between the veins. Leaf blighting typically begins on lower branches and spreads upward. With a hand lens, you may be able to see the fungal fruiting bodies along the veins of infected foliage.

Newly emerged foliage is more susceptible to infection. In general, fungicides are not recommended for control of shade tree anthracnose. Large well established trees that are otherwise healthy can withstand the damage without serious long term affects. In time, severely infected plants will push forth a new flush of growth from buds that would otherwise have remained dormant.

Remember that sanitation is very important. High humidity and rain help spread spores to the newly emerging foliage. Fallen leaves should be raked up and removed; spores of the pathogen remain viable on this dead foliage even throughout the winter.

Management Of Anthracnose:
  1. Prune out and destroy dead branches and twigs.
  2. Rake and destroy fallen leaves around susceptible trees that have branches close to the ground.
  3. When a specimen tree must be protected, fungicides can be applied. Spraying must begin at bud break and be repeated on a weekly or biweekly schedule until the weather warms, daily temperatures averaging above 60°F. There are some cases where a fungicide can be injected into a tree in order to protect it for more than one year.
  4. Most hardwoods develop new leaves quickly enough to prevent serious damage when defoliated early in the summer. If defoliation is not severe and twig death is has not occurred or if defoliation does not occur frequently or if the tree is not of very great value, spraying is not recommended.
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