As anticipated for the past few weeks, the fungal leaf spot diseases are wreaking havoc on ornamental and fruit trees alike. The main culprits at this time are anthracnose on good quality shade trees, apple scab on production apple trees and crabapples, and leaf curl on peaches.

The common factors, as in any disease problem, are a susceptible host, weather favorable for the disease, the disease present, and time. The "photo shoot" blog from a couple weeks ago had early infection stages of many of these diseases. Now, the full blown effect is heavy leaf drop.

These diseases are preventable to some extent, but not curable. This doesn't mean you will lose the trees, but young or weakened ones might be at risk. Most healthy trees, especially shade trees, will put out a new set of leaves even this year. It just takes energy out of the tree's system to do this. Preventative fungicide treatments would have been put on even as early as bud swell to help prevent peach leaf curl. With the abnormal amount of rainfall, you may have needed many extra treatments to have had any success.

For further information on fungal infections of shade and ornamental trees, check out the Report on Plant Diseases at http://web.extension.uiuc.edu/forestry/publications/pdf/forest_health/UIUC_Leaf_Spot_Diseases_of_Trees.pdf