Early prevention can save fruit trees

This past week I noticed white blooms along old fence rows and fields. These white blooms are from pear trees. These wild pears will bloom sooner than other pears and fruit trees. I know the pear trees in my yard are not blooming yet, but the buds are beginning to swell. They will be blooming before long.

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Sometime this spring, I will start getting calls about apple, pear, peach and plum trees that are not growing and producing fruit as they should. Or, the fruit has a disease or an insect problem on them. The caller will want to know how to control or correct these problems.

Most of the time, it is too late in the season to do anything. The problem is easier to prevent earlier in the season. That time is now. What you do for your trees now will show benefits later in the season.

Many of the disease organisms and insects overwinter in dead wood on the tree, in cracks and crevices in the bark, and on fallen leaves under the tree. A good sanitation program will help reduce disease and insect problems.

A good sanitation program includes pruning and removal of diseased or dead limbs, twigs and branches. When pruning, keep a bottle of rubbing alcohol handy. After each cut, wipe the blades of the pruners with the alcohol to kill any disease organisms on the wood. While pruning, it is a good time to remove the dried-up fruit from the previous season. These fruit are loaded with bacteria and fungi that will cause disease problems.

Another way to cut down on disease is to remove old leaves and debris from around the trees. Mowing around the trees and disposing of rotten and/or diseased fruit also can reduce the incidence of diseases and insects.

Some fruit, such as pears, can be grown successfully by using sanitation practices alone. However, most fruit will need a combination of sanitation and chemical or organic pest control to get a desirable fruit.

Before the leaves and blooms appear is the time to start controlling insects and diseases. We call these dormant sprays. There are a number of sprays that can be used. The most important thing to remember is that they should be used a couple of times before the buds begin to break on the trees.

For insect control, use horticultural oil sprays. For these sprays to work best, they should be applied when the temperature is below 70 degrees and above 36 degrees Fahrenheit. If the temperature is too warm, the spray can burn the tree. If it is too low it will be difficult to apply. Horticultural oil sprays are very good at controlling mites, scale and aphids. They work very well on the eggs of these insects.

To start a disease-control program, use a fungicide called Bordeaux mixture. This was first used in the 1700s on grapes in France. The mix is available at some garden centers in the area or can be made with eight tablespoons of copper sulfate and eight tablespoons of hydrated lime. The hydrated lime makes a very hot mix, and care should be taken when using it. The Bordeaux mixture can be used on peaches, plums and pears, and needs to be used before any green leaves appear on the tree.

There is one disease of apples and pears that can only be treated during the bloom stage, and this is fire blight. The symptoms don't appear until May, but infection occurs during the bloom stage.

The severity of fire blight varies from year to year. This is because of the conditions that favor the development of the disease. The bacterium that causes fire blight likes a temperature between 65 and 80 degrees, high humidity or rain. The bacterium is spread by rain drops from the limbs where it overwintered to the blooms. Bees then spread the disease from tree to tree.

To reduce the chance of fire blight, start a spray program at the first sight of white in the buds, called the popcorn stage. There are two products available for this disease. The first is streptomycin sulfate. Apply right before the bloom opens and every three to four days until the petals drop. The second is copper hydroxide, which should be used every five to seven days.

The best control option for fire blight is to plant varieties of pears and apples that are resistant. Fire blight will attack ornamental pears, loquat and pyracantha. The same products used on apples and pears also will control fire blight on these ornamental plants.

The secret to a success with fruit trees is to start insect and disease control early, before the leaves and blooms appear.

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.