A number of trees are beginning to display fall coloration, or they are experiencing early leaf drop now. This early leaf drop is mostly due to two sets of divergent weather conditions that we experienced this growing season: rain and cold in the early part of the spring; and the recent stretch of dry, hot weather. Cold, wet spring weather is favorable for the development of many diseases that affect trees and shrubs such as scabs, rusts, anthracnose, and leaf scorches. Many of these diseases impact fruit-producing trees such as apples, cherries, hawthorns, and plums. Much of these diseases will impact the leaf and the fruit of the tree. In the case of a nonresistant apple, the tree begins displaying brown lesions on the leaf and fruit in late summer which can disfigure the fruit and result in early leaf drop. More often than not, the health of the tree is not severely impacted because the defoliation takes place later in the season after the tree has had the opportunity to manufacture and store sugars and starch for the next season.
The hot, dry weather we experienced is causing trees such as tulip poplar, river birch, box elder, and walnut to begin displaying some fall coloration. This is especially the case with the tulip poplar, some of which have bright yellow foliage. This late season leaf drop normally does not impact these trees, either.