David B. Langston, University of Georgia, Bugwood.org
Leaf Spot Tree Disease
A leaf spot disease creates spots on foliage. The spots will vary in size and color depending on the plant, the organism involved and the stage of development. Spots are most often brownish, but may be tan or black. Concentric rings or a dark margin around the spot may be present. Over time the spots may combine to enlarge and form blotches. Spots or blotches that are angular and located around the veins are generally referred to as anthracnose. Leaves may yellow and drop prematurely.
Leaf spot fungi overwinter in and produce spores for new infections on the fallen leaves, which should be gathered in the fall and removed from the site or destroyed. Infection occurs when leaf surfaces are moist; improve air circulation by thinning crowded plants and pruning overly dense growth. Avoid overhead irrigation, or water only in the morning to ensure leaves dry quickly.
Good tree care is sufficient for prevention. Avoid crowding plantings too closely. Thin out branches to open up the tree crown, but don't top or dehorn. Rake up leaves in fall and bury or compost them. Plant different kinds of trees in mixture. Fertilize trees in the spring with a complete fertilizer. Water trees deeply during dry spells.
