Two years of drought hurt trees, but there are ways to repair them

Are we ever satisfied? The other day, I was complaining about the soil in my garden being too wet to till. I am still trying to get the majority of my garden in. This is the latest that I have ever gotten my garden planted.

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Don't get me wrong; I am glad that we are getting the rain, and I hope that it continues the rest of the summer. This spring has been a very different scene from the past two springs and summers, when we did everything -- including begging, pleading and even rain dances -- to try to get some rain. The results of these two years of drought are beginning to show up in our trees.

I am getting numerous calls about trees that have dead limbs at the top, or that put out fewer blooms or leaves than in years past. Large trees have plenty of reserves, so they can still flower and leaf out for a number of years before drought, root damage or something else causes them to suffer.

The drought of the past two years has caused a number of our trees to use up their stored energy, and they are in a state of decline. When the tree starts declining, the area that's the greatest distance from the roots will be hit the hardest. This is why you see the limbs in the top of the tree dying.

Also, stressed trees are more prone to insect and disease problems than trees that are healthy and fast-growing. I am seeing and getting numerous calls about oak and elm trees that have dying limbs. These limbs can be anywhere on the tree, not just in the top. When you look at these trees, you would think that it is a root problem because the edges of the leaves are turning brown and drying out.

This is not a problem with the roots; it is a scale problem. If you look at the end of the branch, you will notice brownish, red bumps on the limbs. These are the scale insects.

They form hard shells to protect themselves. Once they start feeding, they are immovable. They will spend the rest of their lives at that spot. In the spring, their eggs hatch and the young move to find a spot to start feeding. This is called the crawler stage. This is the easiest time to control them.

You can get some control now by using a systemic insecticide that contains imidacloprid. Apply this around the root system, and it moves through the plant and kills the scale as they feed. Another way to reduce the problem is to remove the limbs that have the scale on them. This will work if there are only a few affected limbs. If many limbs have scale on them, it could do more harm to the tree to remove the limbs.

There are a number of things you can do to help your trees recover from the drought. The first is to use mulch around the tree. Mulches help the trees recover by conserving soil moisture and reducing soil erosion and water run-off. In our clay soils, mulches help with soil compaction and with competition from weeds.

Mulches can reduce the summer soil temperature, which creates a better environment for the root system. Large mulched areas also protect the tree from lawn mowers and weed eaters.

The mulch needs to be 3 to 4 inches deep. Start it 4 to 6 inches away from the trunk of the tree. This space allows the trunk to stay dry, and this will reduce disease and insect problems. The mulch needs to extend to the edge of the canopy or farther. As the tree gets larger, increase the size of the mulched area to encompass more of the root system.

Avoid forming tree volcanoes where the diameter of the mulched area remains the same, but the mulch is piled higher on the tree. This practice encourages the root system to grow into the mulch, it can increase the chance of diseases and insects attacking the trunk of the tree, and it reduces the growth of the tree.

The next practice that can help trees recover is to lightly fertilize them with a complete fertilizer. The reason to use a complete fertilizer is that phosphorus aids in root development. Phosphorus is the middle number on the fertilizer bag. If you have grass or shrubs under the tree, the amount of fertilizer that you apply to them will help the tree, and it doesn't need additional fertilizer.

The last thing that you can do is to remove the dead wood from the tree. This will reduce the chance of diseases and insects attacking the tree, and the appearance of the tree will be improved. If it is a large tree, I would recommend having professionals do the work.

Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at charlesp@uga.edu. The Extension Web address is www.ugaextension.com/columbia.