Watch trees to catch diseases early

Mark your calendar that this time next year the calls about tree problems will start coming in. They have for many years, and the calls will continue in the future because there are some problems that show up this time every year.

//

Also, there are natural events occurring in a lot of our trees that make the tree look like they are having problems when they aren't.

The first tree that I have received many calls about is the magnolia. There are a couple of problems affecting magnolias now.

The first is part of the natural cycle of the magnolia tree. Magnolias are evergreen trees. They keep their leaves on year-round, but the leaves are not on the tree forever. They usually stay on the tree for two years. At the end of the second year, they will turn yellow, start drooping and will fall off the tree. This event usually occurs in late April through May.

Not all magnolias lose their leaves at the same time. Most magnolias are individuals, because they are grown from seeds and not cuttings. New leaves will appear and the tree should fill out again.

The second problem with magnolias is whole limbs or the tree itself dying. I have seen this problem all over Columbia County and have had reports of it occurring elsewhere in the local area and state. This problem is associated with last year's drought. Most of the trees that I have seen with this problem have the tops or upper portion of the tree dead or showing damage.

To help correct this, make sure that you have three to four inches of mulch around the tree, and that the mulch goes out to the end of the limbs. Most of the trees showing drought symptoms had very little or no mulch around them, or they had the mulch going up the trunk of the tree instead of covering the root system.

A problem that affects pear and apple trees is fire blight. I have seen two Bradford pear trees showing signs of fire blight. This will cause the end of a limb to start dying from the tip back down the limb. The leaves turn black and look like they have been scorched. This is caused by a bacteria entering the tree through the bloom.

If or when your trees get fire blight, prune the infected limb. To keep from spreading the disease, you need to go down the limb until you find the first green leaf and cut the limb off six inches below that leaf.

After making the cut, wipe the pruning tool with rubbing alcohol or a 10-percent bleach mix before making the next cut to keep the disease from spreading.

If you are thinking about planting any type of pear tree or apple tree, plant a variety that is resistant to fire blight. If you have trees that are susceptible to fire blight, spray them with a fungicide containing copper two times during the bloom. Commercial applicators can use streptomycin sulfate for fire blight control. This product needs to be applied every three to four days during bloom.

Elm trees were hit hard by the drought last summer. Many elm trees were killed or had limbs die from the drought. Again, most of these trees were not mulched properly.

In the next few weeks, the elm leaf beetle will start attacking elms in the larva stage and as an adult.

The first signs of damage will be the skeleton of a leaf. The larva will eat the leaf material around the veins of the leaf, and the leaf will turn brown and fall off. The tree will put on new leaves and will recover. If you notice the problem early, you can use liquid Sevin to control this pest.

The last tree that I have received calls on is the Japanese maple. Japanese maples are relatively disease- and insect-free plants. There are very few problems with them.

However, the main problem is environmental. Japanese maples are sensitive to heat stress and sun scold. Symptoms will be leaves that are grayish in color. This usually occurs around the margins of the leaves, but it can cause grayish spots in the center of the leaf. You can correct this by planting the plant in the right location. Japanese maples like morning sun and afternoon shade. Trees add a lot to our landscapes, and we need to learn what trees we have and the problems they face.

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.