
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: SUNDAY, June 3, 1990                   TAG: 9006040346
SECTION: HOMES                    PAGE: E-1   EDITION: METRO 
SOURCE: John Arbogast
DATELINE:                                 LENGTH: Medium

WOUND PREVENTION STOPS WOOD BORERS

At this time of year homeowners may be concerned about borers in trees and woody ornamental plants. The damage from these insects is caused by their boring habits either in the larval (young stage, often a grub or worm) or in the adult (often a beetle) stages.

Tree and shrub borers are secondary enemies of plants, meaning these borers attack only those trees and shrubs that are wounded or weakened or dying. Because of this, the primary emphasis should be placed on maintenance of plant vigor and wound prevention to prevent attack from borers.

It's not always obvious that trees and shrubs are in a weakened condition just by looking at their leaf color or overall appearance. Hot summer weather and dry soil may be all that is needed to weaken landscape trees like white birches. Lawn mower bumps can cause all the injury that is needed to lead borers to dogwood trees.

If borers are discovered in a woody plant and the plant is not too far gone to save, prune out the damaged and dead parts. Lindane, which has a relatively short chemical life, has been the recommended insecticide for borers for years, but determining the best time to apply it can be difficult. The premise of spraying is to control the insects (adults laying eggs or the young) before they get into the trunk or limb, but since borers feed and live most of their lives out of sight, it becomes difficult to bring them in direct contact with insecticides.

Q: I have two pyracanthas planted two years ago on the north side by a fireplace chimney. They were doing well until this early spring freeze. Now, some green is showing around the lower portion of the shrubs, but the upper portions seem dead and the branches are brittle. Also, what could be wrong with my house cactus that continues to survive even though the ends of the foliage wilt and fall off. Last week one bud emerged but soon fell off as well. R.W.S., Christiansburg

A: Cut the winter-killed portion of your pyracanthas out now. You may need to do a second pruning in early summer to direct the new lower growth to achieve the branch arrangement you want.

The wilting and loss of the new growth of your indoor cactus could indicate a moisture problem, probably too little watering, although too much water can injure the roots and cause similar symptoms. When cactuses are making new growth, they need much more frequent watering than when they are in a state of no growth. The symptoms indicate root deterioration, so it would be a good idea to carefully take your cactus out of its pot, prune off any dead-looking or decayed roots, and repot in a smaller pot if necessary.

Got a question about your garden, lawn, plants or insects? Write to Dear John, c/o the Roanoke Times & World-News, P.O. Box 2491, Roanoke, Va. 24010.

Gardener's checklist

Continue plantings of warm season vegetable crops, such as bush beans, summer squash and tomatoes. Use the space where one of the spring crops, like radishes, has been harvested for one of the summer vegetable crops.

The leaves of silver maple trees may develop red or green colored round warts at this time of year that look alarming, but are nothing to worry about. These funny growths are called maple bladder galls and were caused by tiny mites irritating the young leaves as they first began growth. Spraying is not necessary.

by CNB