Brown spots on tree leaves

Asked October 30, 2017, 7:53 AM EDT

Hi my name is Ken Walters and I plated two trees last year and they are growing but they started to develop brown to black spots on the leaves. I did place fertilizer spikes around the ground around them and I cut out some of the branches to give them more room and air between all of the branches. I think now it's best not to touch them but what do you think? Thanks very much

Monroe County New York

1 Response

It looks like a fungal disease, commonly called rust disease. More below:

Cedar-Apple Rust Disease

(Gymnosporangium juniper-virginianae), and several closely related rust diseases, require two hosts to complete the life cycle of the disease. For cedar-apple rust, or other plant in the rose family, and eastern red cedar (or other juniper) must be present within a distance that allows the spores to travel from one plant to the other. Cedar-hawthorne rust and cedar-quince rust disease affect apples other members of the family rosaceae.

The first symptoms noticeable on an apple tree are yellow leaf spots that appear shortly after bloom. A wet spring, particularly just after leaf buds break, will increase the severity and spread of the infection. Sometimes oozing, orange bumps will form under the leaf spots and then become black. Later in the season, clusters of thread-like fruiting bodies grow from the underside of the leaf spots, as well as twigs and fruit. Spores that infect the needles of the alternate (cedar) host are transmitted in warm, damp weather.

While the cedar host may not be present on the same property (spores can travel for up to 5 miles), the infection on that plant can be identified by the emergence of a gall six months after spores reach it. About 18 months later, brown telial horns emerge from depressions on the gall, elongate and become bright orange and gelatinous in the spring rain. They dry up after releasing spores. Leaves may fall from the tree, especially in dry weather.

Hope this helps.