In the Garden:
Northern & Central Midwest
September, 2010
Regional Report

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This stressed red maple has turned to fall color much too early.

Early Fall Color

As I walked the neighborhood the other day, I noticed several trees with yellowing or reddening leaves. This usually leaves me a bit melancholy since I know winter is coming, but I realized that it is too early to see fall colors.

This is the time of year when we start seeing plants begin their slide into dormancy, but there are several signs that plants give us to indicate that they may be in trouble instead of just going through their natural phases. These signs are valuable tools in diagnosing plant problems if you learn to read them correctly.

It's Not Time for Fall Color Yet
Trees and shrubs should not have yellow or red leaves yet and if they do, you need to look at the plant's overall health. We've had a long dry spell, so many plants, such as my river birches, are showing some yellowing. This tells me that I'd better get out the hose. Plants need plenty of water to go in the winter in a healthy state, so make sure to give them long, slow drinks. Newly planted trees really need regular watering, and I am seeing many fall colored leaves on newly planted trees in my neighborhood.

Stressed Plants will Color Early
Another issue I'm seeing is trees that are not newly planted but improperly planted. If they are under stress from being planted too deep, having the burlap still around the root ball or being girdled by twine or tags, they will also start to develop fall color early. If you know your new plant has plenty of water and you see signs of stress, check the way it was planted.

Diseased Plants Will Color and Drop Leaves Early
Some crabapple trees have completely lost their leaves by this time. This is not a natural phenomenon, but rather a disease issue. Older, non-resistant varieties are prone to apple scab, a fungal disease that produces olive spots on the leaves, which then yellow and drop. If your crabapple looks like this, it is telling you that you either need to treat early next spring for the fungus or replace your tree with a more disease resistant variety.

Fungal Diseases
It's not yet time for oaks to drop their leaves, and if yours are, it's probably an indication of another fungal disease. On larger oaks, it's not feasible to spray, but seeing the disease should alert you to the stress the tree is under. You can help the plant by making sure to do all you can culturally to reduce stress. Again, water it well, and next spring consider giving it a good fertilizing.

In fact, this is a good practice for any plant that is showing early leaf drop. Many types of fungal and bacterial leaf spots will cause the leaves to drop early. They do not necessarily need to be treated, but keeping the tree as healthy as possible will help the tree fight these issues by itself.









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