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TLC for Your Fruit Trees

By John Pohly, Horticulture Agent, Colorado State University Cooperative Extension

If you want to enjoy the fruits of your labor later, give your fruit trees tender loving care. TLC means watering, pruning and spraying to ensure healthy trees and a bountiful crop.

Water is a must for fruit trees because fruit itself is largely water. Water trees thoroughly every other week. If the tree is water-stressed during hot summer weather, fruit will be damaged and might drop prematurely from the tree.

Apple and Pear Trees

Late winter or early spring is the best time to prune apples and pears, but you can prune until mid-summer. Pruning later will stimulate new growth that probably will be damaged by early fall frosts.

Mites and aphids can be serious problems. Mites causes damage to foliage and in some cases to fruit. Aphids suck sap from apple and pear trees. If you had problems with mites or aphids last summer, spray dormant oil on the trees in late winter or early spring before bud swell.

About two weeks after petal drop is the time to control the larvae of codling moths on apples. These pests infest fruit causing the familiar wormy apple. Spray every two weeks with Permethrin or carbaryl (Sevin) to prevent this problem.

You can look for the bacterial disease, fireblight, to be a problem this year if we have a warm, wet spring -- warm enough to bring the bees out. Fireblight is spread by bees, as they visit the flowers. If it's cold and wet, don't worry: The bees won't be out. If you need to spray, use streptomycin sulfate and spray just when flower buds begin to turn pink, before they come all the way out.

Stone Fruits

Stone fruits consist of peach, plum, cherry and apricot.

Peach tree borer is the most serious threat. It attacks peach and cherry trees and, to a lesser extent, plum. This insect larva will burrow into the lower part of the trunk causing damage and, if sufficient numbers invade the trunk, they can kill the tree. Often oozing sap or a wet spot on the bark is an external indication that borers might be present.

Spraying with permethrin, esfenvalerate or some formulations of carbaryl should provide some control. Make the first application around July 4 and the second treatment about August 10. These are the dates when adults should be laying eggs. Once the eggs hatch and the larvae invade the trunk, the sprays won't work. Follow label directions and only spray the lower part of the trunk, avoiding the fruit or foliage.

If you've planted fruit trees in a lawn area, try to keep the grass from growing up to the trunk. Because bluegrass lawns are usually watered heavily, all of this water can cause the trunk of trees, such as apple, to rot and die. By leaving at least a one-foot area around the tree free of grass, you usually can avoid this problem.

These care tips should produce a good fruit crop, assuming that:

  • The tree was planted correctly and it is well established.
  • You planted two varieties of apples, pears, plums and sweet cherries to get cross pollination and a successful crop. Any flowers that did not pollinate drop off soon after petals fall. Only about one blossom in 20 on an apple tree usually produces fruit. Those that did pollinate begin to swell as fruit starts to form. If in doubt about which varieties will cross-pollinate, call the Colorado State University Cooperative Extension office in your county and ask for a fact sheet titled "Pollination of Fruit Trees."

Photograph courtesy of Judy Sedbrook.

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Date last revised: 01/05/2010