Maples are beautiful trees that come in a variety of different colors and can be an ideal accent to any lawn or garden. Spread throughout the northeast of the United States, there are a number of different species of maples. From the Japanese maple to the Norwegian, silver maples and the red ones, all can be susceptible to a handful of diseases. Diseases can be merely aesthetic inconveniences, but they can also be life-threatening.
Yellowing of the maple tree's limbs or leaves can signify a big problem: a disease called Verticillium wilt. Often caused by prolonged periods of hot, dry weather when a soil-based fungus begins to grow, Verticillium wilt is an infection that slowly kills trees by first killing their extremities. One of the surest ways to diagnose Verticillium wilt is to look at the wood of some of the dying branches--they will have olive and brown colored streaks running through the wood.
Once Verticillium Wilt infects the soil and the tree, it's almost impossible to get rid of. Pruning obviously damaged branches can help prolong the tree's life, but it's important not to plant other susceptible trees in the vicinity as they will also become infected. (When pruning, be sure to clean tools before using them on another plant as the fungus can be spread via gardening tools.)
Leaf and Tar Spots
Leaf and tar spots can take a number of different forms, but in every case the disease manifests itself as discolored patches on the leaves. These spots can have regular or irregular edges, and they can be brown, tan, yellow or even the color of bruises. Sometimes there are also tiny black dots within the patches. In the case of tar spots, the disease first manifests itself as yellow patches but quickly turns black and resembles the substance it gets its name from.
Spots are also caused by a fungus and can result in the trees shedding their leaves early. In order to help control the spread of the disease, rake and remove infected leaves as they fall. Oftentimes, following a proper regiment of fertilizing, pruning and making sure the tree has plenty of water will ensure that the tree is healthy enough to fight off the infection on its own. Fungicides are rarely necessary.
Anthracnose is another type of fungal disease, but in this case the visible signs are there only when the tree has been badly infected. Blighted, dead leaves, spots on the leaves, abnormally thin leaves and the sudden death of new growth are all common signs of anthracnose. Many times, these signs are only apparent late in the growing season.
Since the disease is caused by a fungus that lives on the leaves, it is important to rake and remove fallen leaves to help prevent the spread of more spores. Anthracnose may cause leaves to fall early. Since visible symptoms appear well after the tree has been infected, fungicides can be applied as soon as they develop. Consistent watering, pruning and fertilizing are also key, as weak or otherwise damaged trees are less likely to fight off the infection on their own.