Question
Dear Jim, please tell me what to do? My  huge maple has a black round  spots on the leaves,   
and tree started  to loose leaves before even getting yellow.Last summer tree itself looked thinner. Please, give me a good advise how can I safe my tree. Thank You .
Sincerely. Alla. Michigan.

Answer
The spots are a leaf spot fungus which infects the leaves. This fungus normally does not effect the overall health of the tree but will make the leaves drop prematurely. The control for this disease is to spray the leaves in the spring with a fungicide which for this size of tree would be a big job. I recommedn that you rake up the leaves this fall and destroy them --this will greatly reduce the spore from the fungus and cut the infection down for the next year.

Control of leaf spots can be achieved using a multifaceted approach. Thise is often effectively controlled by following good sanitary and cultural practices and are rarely serious enough to warrant chemical control. Since many of these fungi overwinter on fallen leaves, it is important to rake and remove fallen leaves from the vicinity of the tree in autumn. This reduces the number of spores available to infect emerging leaves in spring or during the following growing season. Tree vigor should also be maintained by proper watering, fertilizing, and pruning. Although foliar diseases are usually considered to be more aesthetic than life-threatening, there are situations where they can be serious and cause permanent damage or even tree death. Newly transplanted trees or trees weakened by stress are particularly sensitive to repeated defoliation. In such cases, chemical control can be beneficial. Among the fungicides registered for homeowner use in Connecticut are thiophanate-methyl, chlorothalonil, and mancozeb. The pesticide label will contain information on dosage rates, application intervals, and safety precautions. Since most of these fungi infect in spring as leaves are unfolding, the first fungicide spray is applied at budbreak. Two or three additional sprays are subsequently applied at 7- to 14-day intervals. Additional applications may also be necessary in unusually wet springs. For leaf spots, once symptoms are visible on the leaves it is too late for chemical control.