Is it fall yet? We have just experienced one of the hottest and driest Septembers on record. The plants in my landscape were not happy at all with the dry and hot conditions. Even my bermuda grass has been struggling in the oppressive heat. Many of you have noticed that quite a few trees were dropping their leaves early this year. I received more than a few calls from anxious gardeners wondering what was causing this phenomenon and if it would harm the tree.
Leaves drop from trees early for a variety of reasons. If insect pests or fungal diseases have affected those leaves, they will often drop prematurely. Some of the maple trees located on the grounds of the Agricenter have dropped many of their leaves early this year due to tar spot disease. Scales, leafhoppers and mites can also cause leaves to drop early. Always look for pests and diseases early in the season before they become a problem.
I have observed that some trees are just not suited for our hot, dry summers. Many of our trees will drop leaves because of leaf desiccation, the reduction of the photosynthetic process, and slow growth. Anytime there are periods of dry weather in the summer, it will put considerable stress on the trees in our landscapes. Trees need deep watering and layers of mulch (two to three inches) to prevent stress during dry spells.
Will premature leaf drop damage the tree? In most cases, no. The tree should be able to survive without any major problems. Most likely, they have stored up all the carbohydrates needed for spring growth. If early leaf drop happens year after year it could weaken the tree and lessen its chances of survival.
One of the best ways to avoid heat stress is to plant trees that are adapted to our climate and hardiness zone. Remember to keep them watered and do not forget to mulch! Your trees will love you for it!
Until next time, happy fall gardening.