It's time to check your trees for leaf spot. Leaf spot seems to be a big problem this growing season. It is a that generally makes itself known this time of year.
What is leaf spot? It is a disease caused by a fungus or bacteria that forms spots on the foliage. Color and size of the spots will vary and holes can develop. Often leaves will turn yellow and drop before fall.
How is leaf spot prevented? You will want to avoid crowding your plants (both trees and shrubs). When an area is heavily populated with trees and shrubs, thin out the branches to create better air flow. Plant an assortment of plant varieties. In fall, rake up the leaves to compost or burn. Fertilize in spring with a complete timed release fertilizer. Water deeply during dry periods.
How do you control leaf spot? If leaf spot continues for several years, then it is time for fungicide use. However, you will need to identify the particular leaf spot disease that is attacking your trees. Take several leaf samples to your local agricultural extension agent for identification. Timing is everything with the fungicide applications. Be sure to follow the directions on the fungicide label.
Here is a link to the Missouri Botanical Garden site with an article on leaf spot which includes pictures and more detailed information on this problem. http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/fungal-spots/leaf-spot-shade.aspx