Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Sycamore Anthracnose

Problem
In the spring, buds or expanding shoots turn brown and die. Dead areas appear along the veins of young leaves. As the leaves mature, the spots may expand and cover them entirely. Most infected leaves drop from the tree. Later in the season, twigs and older leaves may be infected. Infected twigs hang on the tree or drop to the ground with the leaves. Larger limbs may die. Dark brown spore-producing bodies appear on the bark and dead leaves. The tree is often stunted and bushy.

Analysis
This plant disease is caused by a fungus (Gnomonia platani) that is the most serious problem of sycamore and causes minor damage to the London plane tree. The fungus survives the winter on fallen leaves and twigs, and in swollen cankers in the tree. During cool (below 55°F), wet weather, spores are blown and splashed onto buds, expanding shoots, and young leaves. The fungus enters the tissue and kills it, causing the buds and shoots to die back. The fungus moves down onto the twigs, and spores develop. The spores may infect mature leaves or any new growth on the tree, causing a sun-scorched appearance. Swollen, cracked cankers develop on infected twigs and branches. When the cankers encircle the wood, the limbs die.

Solution
Prune off and destroy infected twigs and dead branches. In areas where spring is cool and moist, spray with a fungicide containing chlorothalonil when buds begin to grow in the spring. Repeat when leaves reach full size, and again 2 weeks later. When planting new trees, plant the resistant varieties Bloodgood, Columbia, or Liberty.

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