Maple Tree Leaves Turning Black

Asked July 15, 2019, 9:44 AM EDT

Noticed maples leaves turning black last year. It was healthy in the spring and deteriorated there after. The top 1/3 looks like the photos included. The tree is in Muskegon County, Michigan and is about 10 years old. It is 12-14 feet tall and really hasn't thrived at all. What is the cause of the leaves turning black and what measures should be taken?

Muskegon County Michigan

1 Response

Your maple leaves appear to be infected with one or two fungal leaf diseases, anthracnose and maple leaf blister. The only way to be certain if a tree has one or the other or both is to send samples to a diagnostic services laboratory, such as Michigan State University Diagnostic Services, and have it confirmed. Use the link below to obtain information on how to collect a sample, where to send it, etc.:

There are no fungicides available for treatment as the infection occurred earlier this year during our cool and wet weather. You can help your tree push out a new set of leaves by watering deeply and slowly (a trickle from your hose) and a light application of tree fertilizer.

High humidity and rain help spread spores to the newly emerging foliage. Fallen leaves should be raked up and removed from your property (do not compost); spores of the pathogen remain viable on this dead foliage even throughout the winter.

The information in the links below will give you additional information. (You may need to copy and paste the URL into your search line.)

I can identify what appears to be anthracnose in your photos. To explain quickly it is a condition brought on by the heavy spring rains we’ve been suffering through tjis spring. This fungus follows leaf margins and veins of the leaves. Normally newly emerged foliage is affected. Normally we do not treat healthy trees with this condition as they can withstand this damage without long term effects and possibly even push out new leaves. Application of chemicals to slow the fungus’ spread are sometimes called for with show trees or extreme cases. As mentioned above, sanitation is always a good thing when you are dealing with fungal induced leaf drop so keep the leaves picked up and disposed of.