Many questions of tree health are related to foliage problems. Often people first become concerned about the health of their forest or shade tree in response to symptoms that appear in the leaves. Sometimes leaves will become skeletonized (appear eaten by insect, back to the veins)or develop holes, other times the leaves show signs of wilting and may fall from the tree. While these symptoms are certainly cause for concern and may need to be diagnosed by an expert,trees are also naturally equipped with defense mechanisms.In many cases, foliar problems will be corrected by the tree during the same growing season.
One disease that is causing concern this year among many landowners is fungi disease called anthracnose. Anthracnose is a leaf disease favored by wet, cool weather (especially in the spring) and tends to be most severe on the lower branches where the humidity is highest. It is a fungus-caused disease that typically makes a tree’s leaves rather unsightly and can also cause shoot blight. Trees showing the most severe symptoms include dogwood, maple, oak (primarily white oak) and sycamore, but it can also occur in others, such as ash or walnut.
Not to minimize concerns, but anthracnose typically will not cause permanent damage to well established, vigorously growing trees. Most healthy trees will push out a new crop of leaves by mid-June. There are several practices that can minimize damage from year-to-year. Following leaf emergence in the spring, fertilize trees showing evidence of defoliation. Since anthracnose is a leaf disease and will overwinter in fallen leaves and twigs, raking fallen leaves and branches, and burning or removing them from the site, can help reduce chance of infection. In most all trees except dogwood, spraying with a fungicide is unnecessary. In dogwood, anthracnose is aggressive and can cause permanent damage or death.
The internet is a great source for information on tree diseases and treatments. An excellent site to begin your web surf is the US Forest Service North Central States Forest Health Protection homepage (http://www.na.fs.fed.us/spfo/info_dir.htm).
If you feel you have a disease problem that needs immediate attention, call your local Missouri Department of Conservation or MU Extension office to have someone diagnose your tree’s specific health issue.