What’s hiding in the leaves?

by | Oct 5, 2016

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Fall is here! It’s time to get excited about cooler temperatures, football and of course, the dreaded raking of leaves from all the beautiful trees surrounding your home. If you need motivation in the task, just think about the attractive trees, flowers and fruits you’ll see next spring and summer. It starts with raking those pesky leaves this fall.

Oak antracnose (top) and ash anthracnose (bottom) cause spotting on tree leaves. Images by Joseph OBrien, USDA Forest Service, Bugwood.org.

Oak anthracnose (top) and ash anthracnose (bottom) cause spotting on tree leaves. Images by Joseph OBrien, USDA Forest Service, Bugwood.org.

While raking is a chore that beautifies your yard, it can also help the health and look of your trees for next spring as well. That’s because a tiny pathogen could be lurking in your leaves. Anthracnose is a common fungal disease that affects many different types of trees. The disease begins when a microscopic fungal spore lands on moist leaves,  killing the surrounding area. This causes spotting on leaves, rotten spots on fruit and cankers on small stems. Typically, this will not kill a tree, but it does cause concern for homeowners because of the unsightly look of the tree during the growing season.

Because this year has seen plenty of rain in portions of our state, trees may be at a greater risk for anthracnose going into next year. These spores thrive in cool, moist environments like we saw this spring. One of the best defenses you have to rake the leaves away from your trees this fall. The fungal spores are cold-hardy and like to hide in the previous years’ leaves. When temperatures warm, they emerge and infect the new leaves in the spring.

Other management strategies for prevention include pruning dead or infected branches from the trees. (Just make sure to clean your tools with alcohol between clippings!) Create good air circulation through pruning of excessive branches which decreases the amount of time leaves remain wet after rainfall. Maintain a vigorous growth cycle through yearly fertilization and weekly watering during periods of drought.

Happy raking!