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Leaves turning black on red maple tree #869801

Asked May 23, 2024, 2:29 PM EDT

Hello! I have two established red maple trees in my front yard on a St. Paul city street. The tree trunks are about 20 feet apart, and some of their branches touch each other. For the first time this year, many of the leaves on both trees are developing black spots. This is not occurring on every leaf, but it is widespread throughout each tree. It seems to have developed very recently and quickly. Some leaves just have a few spots, while some turn mostly black and fall off. In all cases, the spots are very dry. Note that I've been watering the trees a lot this year, because they weren't watered enough in previous years. Please see attached photos. Any idea what's going on, how serious it is, and if there's anything I can do to help? Thank you.

Ramsey County Minnesota

Expert Response

Thank you for reaching out to ask2.extension.

I 5ink your tree has tar spot, which is fairly common in shade trees

This disease is usually a cosmetic problem and does not affect the long-term health of the tree. Heavy infections can cause premature leaf drop – a circumstance that causes great consternation to homeowners because lawns are littered and must be raked before autumn typically 

  It’s not anything you’ve done.  

When infected leaves drop, they should be removed and disposed of immediately to reduce the number of fungal spores that can spread to other trees. Raking leaves is traditionally a fall activity but Maple Tar Spot management requires summer leaf raking in synch with the fungus's damage and your tree's leaf drop.

Applications of fungicides are possible when high levels of infection become unacceptable, but control of tar spot is challenging, especially on mature maples. In addition, if others in a neighborhood setting are not managing the disease on their trees with fungicides or proper sanitation, the act of spraying may be a waste of time and money.

It probably wouldn’t hurt to contact a certified arborist for professional suggestions, especially if it gets worse

I hope this helps.

Deb Kroon Replied May 24, 2024, 1:21 PM EDT

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