My trees have dark black spots on the leaves. What does this mean?

Answer 1

Depending on the tree species, it could be several things. From University of Missouri:

"Leaf spot is a common descriptive term applied to a number of diseases affecting the foliage of ornamentals and shade trees. The majority of the leaf spots are caused by a variety of fungal pathogens but some are caused by bacteria. Anthracnose is a term for a group of loosely related fungal diseases that often cause irregular blotches on leaves."

Check the site for more info, or search on "black spots " to find other sites to help you, once you have identified the type of tree you have.

Hope this helps!

Answer 2

There are many possibilities including leaf spot and anthracnose. In the case of anthracnose you would notice the spreading of the disease through the vein structure of the leaf. The discoloration can be seen without a microscope or lens. In most cases these spots are not harmful to established trees. The best solution is usually to gather up the infected leaves at the end of the growing season, dispose of them so they do not re-infect the tree the following year, and consider taking a sample to your local county extension office if symptoms persist into the following year.