Brown Leaves in Beech Trees
- Healthy beech leafFeuilles de h?atre image by vigorin from Fotolia.com
American beech (Fagus grandifolia) can live well over 300 years, reaching a height of up to 80 feet. Beech trees tolerate shade, and you'll often find them growing near maples, oaks, hickory and other forest trees. Beechnuts are an important food source for chickadees, who flock to nest in beech branches. It is an excellent shade tree, with oval-shaped leaves that have a serrated edge. Not many pests and diseases will trouble this tree, but there are a few that can cause leaves to wilt and turn brown.
- Sooty mold feeds on the excretions of aphid and scale insects, which can infest beech and many other trees. It's common for sooty mold to grow on trees that are coming up beneath taller infected trees as well. Sooty mold turns leaves grayish brown, but the mold only lives on top of the leaf and doesn't invade or kill it. It does, however, block light from the leaf surface, hurting the tree's ability to produce food through photosynthesis.
Identify the insects that are attracting sooty mold and treat with insecticide, following the timing and proportion instructions on the packaging for best results. Prune away severely affected branches and leaves to increase light and air penetration in the canopy.
- Anthracnose, which also affects maple, birch and dogwood, is caused by fungus. It will seldom kill a beech tree, but may weaken and make it susceptible to other problems. Symptoms include small reddish spots that invade the leaf surface, gradually browning the leaf and causing the center to drop out. Infected leaves tend to drop early, hurting the beech's ability to produce food.
Increase light and air penetration in the canopy by thinning with pruning shears, and cut back surrounding trees so moisture will evaporate more readily. Rake up and destroy prunings to avoid infecting other trees or reinfecting the beech tree.
Leaf Spot Diseases
- Cercospora appears as round, gray or brown spots on the leaf surface. Left alone, the spots will get larger, eventually distorting and browning the leaf. Coccomyces causes a similar, but purplish-brown spotting effect. Gloeosporium produces tan, dark-brown and black spots with an irregular shape and yellowing of the leaf margin. All of these fungal diseases can be treated without chemicals by removing dropped leaves, cutting infected or dead wood and increasing light and air movement with pruning. Cut no more than one third of a beech tree's canopy in any given year.
Drought Stress and Autumnal Changes
- Even short periods of drought can affect beech trees, causing leaf scorch, browning and early drop. When small feeder roots near the surface of the soil don't have enough moisture, the tree responds by shutting down leaf production. Provide water and cultivate carefully around the root zone, which extends to the drip line of the widest branches. Soil that is too compacted will make water run off instead of soaking in. Keep in mind that normal changes in beech trees as winter approaches includes browning and yellowing of the leaves before they drop for the season.