What Is Making My Sycamore Sick?

Are there spots on the leaves, younger leaves may have turned brown and fell off?

Are the leaves pale, mottled, and dropping early?

Does the trunk and the branches have holes, tree look weakened, twigs may be dropping?

Does the tree have fewer, smaller leaves, blue or black stains may be present on the bark?

Are the leaves covered with white powder?

Is the tissue on the leaf edge brown, then turning yellow as it moves toward the green center of the leaf?

Anthracnose is the most serious disease of sycamores. Symptoms show an individual or small clusters of leaves suddenly turning brown and dying before they fully emerge. Later, developed leaves show triangular dead spots between their veins. Then cankers appear on twigs and leaf stalks, girdling them. Collect and discard all fallen leaves, twigs, and other tree debris from under and around the tree to prevent the spread of the fungal spores. Prune off any visibly infected twig or branch. Spray healthy foliage with sulfur spray labeled for this use and use it according to label instructions.

Lace bugs are flat, dark-colored insects with lacelike wings that feed on the undersides of leaves. They cause leaves to turn yellow, then brown, and eventually die. Treat plants with a commercial pyrethrin spray or dust if the damage is severe.

Numerous borers attack woody plants, mining the inner bark and wood of branches and trunk. Prune off borer-infested branches. If you see borer holes in your trees, probe into them with a flexible wire or inject a solution of parasitic nematodes. After treatment, seal holes with putty.

The fungal disease Cankerstain is a major problem of London planetrees, cousins of American sycamores which are only mildly susceptible to it. The fungus enters trees through bark injuries caused by saws, ropes, lawnmowers, pruners, or something similar. It causes cankers, or swollen sores, to form on trunks and major limbs of trees. Remove and destroy affected trees as soon as this fungal disease is diagnosed. Disinfect all tools and equipment used on the tree in a solution of hot water and household bleach or disinfectant spray to avoid spreading the fungus. Avoid injuring healthy trees. Keep them vigorous and healthy by proper feeding, watering, and mulching.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.

Bacterial leaf scorch is caused by Xylella fastidiosa, a bacterium that is spreading across the eastern and southern United States. Leaf scorch starts at the edges or margins of the leaf and produces browned edges while the center remains green. There is often a yellow band of tissue between the brown edges and the green center. There are no chemicals or cultural methods for treating bacterial leaf scorch. Pruning infected branches can only slow its spread.

Along streets and occasionally in yards, sycamores are plagued with repeated exposure to dog urine on the lower two feet of their trunks. This causes cankers, or sores, that promote rot in tree tissues. Trees whose trunk diameters measure 6 inches or less can be killed. Shielding trunks of trees frequently visited by dogs with metal collars provides some protection against the cankers, but the urine will run down the shield and still soak into the soil and damage tree roots.