Proper control of insects, diseases can mean success with fruit trees
Last week, I wrote about the requirement for chill hours on fruit trees, an important part of producing fruit. Proper care is also important.
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There are a number of fruits that can be grown in our area, but they require different amounts of care. Some plants have a natural resistance to certain insects and diseases that are common in this area, while other species of plants don't have this resistance. These species require more care and spraying to obtain a good fruit crop.
A good insect and disease control program starts now. Waiting until the tree has bloomed and set fruit is too late. Starting early can pre-empt the need for insecticides or fungicides later in the growing season.
A good sanitation program will help reduce the number of pests that overwinter on the trees or in fallen leaves and old fruit on the ground.
A good sanitation program includes pruning and removal of diseased and dead limbs, twigs and branches, raking and removal of leaves and debris, periodically mowing around the trees and disposing of rotten or diseased fruit. Some fruit trees, such as pears, can be grown successfully by using sanitation practices alone. However, most will need a combination of sanitation and chemical or organic pest control to get a desirable fruit.
The first step is pruning. Mid- to late January into early February is the time to start pruning fruit trees. The way to prune depends on the type of fruit tree.
Apple and pear trees are what we call central leader trees. It will have a main trunk with scaffolding branches coming off it. To prune these properly, remove any branches growing straight up and any branch growing toward the center of the tree. Where a limb branches, remove the bottom branch.
Prune peach, nectarine or plum trees in a vase shape. The center of the tree will be open, with three to four main branches coming off the trunk. Again, prune any limbs growing toward the center and any branches growing straight up.
When pruning, it is important to have a bottle of rubbing alcohol handy. After each pruning cut, wipe the blades of the pruners with the alcohol. This will help kill any disease organisms on the wood. Pruning is also a good time to remove dried-up fruit from the previous season. This fruit is loaded with bacteria and fungi that can cause problems.
Control insects and disease before leaves and blooms appear on the tree. We call these dormant sprays. There are a number of sprays available. The most important thing to remember is that they should be used a couple of times before buds begin to break on the trees.
For insect control, use horticultural oil sprays. For these sprays to work they should be applied when the temperature is below 70 degrees and above 36 degrees. If the temperature is too warm, the sprays can burn the foliage; if it is too low, the oil will be difficult to spray. 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 two fungicide products. These are considered organic controls. The first is lime sulfur, which will give some insect control. Spray the whole tree with it. Lime sulfur can be used on trees after leaves have appeared, but some varieties can be damaged by it, so be sure to read the label.
The other fungicide is called Bordeaux mixture. Applied on grapes in France in the 1700s, this was the first fungicide ever used. This mix is available at some garden centers in the area, or it can be made by mixing 8 tablespoons of copper sulfate with 8 tablespoons of hydrated lime. The hydrated lime makes this a very hot mix, and users should be very careful in handling it. Hydrated lime heats up when it comes in contact with a liquid and can burn the skin, so users should always wear rubber gloves. Bordeaux mix is used on peaches, plums and pears.
Charles Phillips is a retired Columbia County Extension Service agent and operates Hort Consulting. He can be reached at cphillipshort@comcast.net.