The horse chestnut tree is closely related to the Ohio buckeye tree found in the Central and Southern United States. The tree originated in Europe and is from the family Hippocastanaceae. The limbs of the tree are twisted in appearance making it appealing for landscape design and used for ornamental and shade purposes.
The horse chestnut is a medium size tree that produces large white blooms in spring that hang like a chandelier. Green-colored seed pods appear after flowering and stay on the tree through the fall season. The nuts inside the pod are seeds that can be propagated. The nuts are not edible and should be considered poisonous. Horse chestnut trees grow in zones 3-8 and prefer a full sun environment with well-drained soil. The tree will reach up to 90 feet under optimal conditions.
Leaf blotch is a fungal disease causing red brown blotches with a yellow ring on young leaf growth. The disease continues over winters and will infect trees without treatment. Anthracnose is a fungus that causes the veins, midribs and petioles of the leaves to turn brown. The affected leaves shrink and form fungal bodies that produce spores. Powdery mildew is a fungal disease that produces a white mold growth on the underside of the leaves. Fungal diseases spread during wet conditions.
Leaf scorch occurs under environmental conditions causing the tree to become stressed. The leaf tips of the tree become papery in texture and turn brown, causing the leaves to curl. Weather that is extremely dry and hot is the common cause of this condition, however severely wet conditions may also create leaf scorch.
Fungal infections will either not respond to the application of fungicide or the size of the tree prevents adequate application. It is best to remove all infected areas of the tree and destroy them by burning or burying them. This includes removing dead leaves that have fallen to the ground. Black fungal growth bodies will appear inside the blotches and spores that spread. Initiate re-growth after an anthracnose infection by applying fertilizer and water in spring.
Prevention involves following a treatment plan once the trees have been infected. Do not compost infected leaves and growth as this may not destroy all fungus spores. Space trees when planting and prune when necessary to provide optimum air circulation. Air circulation speeds the drying of wet leaves to reduce the spread of spores.