Red leaf maple trees are popular for their brilliant foliage, but there are a number of diseases that can shorten the life of this beautiful landscaping tree. Knowing the signs and symptoms of these diseases and infections can dramatically improve your red leaf maple tree's chances for survival and keep your yard looking bright and beautiful for years to come.
Anthracnose can cause a variety of problems for red leaf maple trees, including stunting the buds of new branches so that the tree becomes misshapen. Likely the first thing that you will notice, however, is that your beautiful red leaves are developing brown spots and that the veins are becoming a darker purple and getting blotchy. To control this disease, remove affected leaves and dispose of them in garbage bags or burn them. Thin the crown of the tree so that air evaporates off the leaves faster, which will make it harder for the infection to spread. Ensure that the tree is planted in well-drained soil, and water the base of the tree, not the leaves. Fungicides also work against anthracnose. Treat the tree once you discover the infection and again in the early spring when hard spring rains may splash fungal spores onto the tree.
Leaf wilt, also known as maple wilt, is caused by an infection called verticillium. This infection enters the tree by the roots, then spreads upward into sapwood and leaves. Usually the first sign of this infection are scorched, discolored and brown leaves. Branches at the crown of the tree may also start to die off, and the sapwood of the tree--the wood underneath the bark that is carrying nutrients up through the tree--may show olive-green streaks if you cut down to it.
Control leaf wilt in its early stages by pruning the infected branches with a sterile instrument. Fertilize your red leaf maple and keep it well-watered, since your tree will need to establish new nutrient pathways so that it can avoid the infected wood entirely, thereby eventually killing the fungus. If the fungus has taken over large portions of your tree, then you will likely need to remove the tree entirely to prevent a wider infestation.
This fungal infection causes large, black circles to appear on the leaves of the red leaf maple. However, while this is certainly cosmetically unappealing, this infection does not tend to harm the tree. Control the infection by removing affected leaves and branches if necessary. This should remove the issue by the next growing season. However, if you start to notice serious leaf drop, attack the problem with a fungicide.