Why Tree Leaves Fall Before It's Fall
No one enjoys autumn more than Grumpy, but unless you live in Montana or on the Moon, fall ain't supposed to be happening yet. So why are the leaves of your trees turning color and even dropping before September? Here are five possible reasons.
#1 -- Weather stress. Some trees react to long periods of hot, dry summer weather by dropping leaves. Here in Alabama, tulip poplar (Liriodendron tulipifera) and sycamore (Platanus occidentalis) are prime examples of this. The early leaf drop seems to have no lasting health effects, though. Other trees react to stress by showing early fall color. These are generally less drought-tolerant species, such as red maple (Acer rubrum) and flowering dogwood (Cornus florida).
#2 -- Insects and disease. Late summer pest attacks can cause leaves to turn color prematurely and drop. For crepe myrtle, the culprit is Cercospora leaf spot. For river birch (Betula nigra), the villains are aphids. Large trees are too big for homeowners to spray, so you just have to put up with this.
#3 -- Old leaves. Tree leaves are temporary, even on evergreens. They do their thing for a while, get degraded by the elements over time, fall, and are replaced. How can you tell whether dropping leaves are normal or signs of a serious problem? Look at which leaves are dropping. If the older leaves on the inside or lower parts of the tree are dropping, that's normal. If the newest leaves on the tips of the branches are dropping, the tree is in big trouble.
#4 --Your tree ain't from around here. Trees grown from seed collected in the North color up earlier than those grown from seed collected in the South. They drop leaves earlier too and also tend to be more cold-hardy. Southern trees, on the other hand, take heat better. So if you live in Georgia, don't order trees from Minnesota and vice-versa.
#5 -- Your tree is on fire. Smoke, heat, and leaves turning red as they're consumed by flames are definite warning signs that your tree is in distress. Put out the fire immediately.