ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Sunday, July 28, 1996 TAG: 9607300117
SECTION: HOMES PAGE: D-2 EDITION: METRO
COLUMN: Dear John
SOURCE: JOHN ARBOGAST
As the growing season moves into "dog days" with their heat and humidity, insect pests seem to be more numerous, often posing a real threat to continued interest in the garden or landscape.
Well-meaning gardeners and landscape caretakers often intervene to save plants from the "bad bugs" but sometimes make the problems worse. Let's look at insect control, its relation to our plants and how we can combine many facts into our attempt to manage the insects rather than letting them manage us. Please note that the order of the list does not relate to the importance of the facts.
Not all insects are bad. Proper identification of friend or foe is important before we reach for the spray. The term "spray" is used here to mean application of an insect-control product, which might also be a dust form.
Spraying to kill insects that we spot on stressed-out plants also kills beneficial insects, such as spiders that hunt and destroy the insects that are feeding on our plants.
Fertilization of plants in an effort to make them stronger to minimize insect injury doesn't work. It simply gives insects such as aphids and scales that like plant juices a better meal.
No insect controls, either chemical or botanical, are foolproof. Resistance to botanicals can happen.
Insects become resistant when repeated sprays to all the plants of an area are made with the same control product.
Plants need regular inspection for insects, diseases, weeds and other site specific factors that adversely affect plant health.
Spot treatment is important. This means applying controls only to infested plants rather than to a whole landscape.
A lack of water in plants seems to be the biggest factor that makes those plants attractive to borers. Borers also like trees that are wounded.
Ninety percent of insecticide spraying is unnecessary! That shocking statistic was given by Michael J. Raupp, entomologist at the University of Maryland.
Q: I have a Colorado spruce in my front yard that has been planted for about 18 years. This tree is brown in places and is shedding needles; it looks like fresh needles are coming out on it, though. What is wrong? Mrs. C.B.C., Salem
A: The problem sounds like damage from a tiny pest known as the spruce spider mite, a cool-season pest that sucks juices from needles in the spring and early fall but is not active in the summer heat. This mite seems to feed on spruces that are under moisture deficit stress.
Please verify this guess before you do anything. Adult spruce mites won't be active until early fall, so spraying now won't do any good. Check for presence of the mites now by using a strong magnifying glass to look for salt and pepper appearance and possibly webbing on needles and stems on the edge of the brown and green. If this evidence shows up, check again in September or take a sample to the Roanoke County Extension Office in the Brambleton Center, 3738 Brambleton Avenue S.W., Roanoke, before you apply controls.
Send short questions about your lawn, garden, plants or insects to Dear John, c/o The Roanoke Times, P.O. Box 2491, Roanoke 24010-2491. We need your mail, but this column can't reply to all letters. Those of wide appeal will be answered during the weeks that the subject is timely. Personal replies cannot be given.
Please don't send stamps, stamped envelopes, samples, or pictures.
Gardener's checklist
Jobs for late July and early August:
Water to soak landscape plants, especially those planted for two years or less, once a week.
Take soil tests to check soil pH for azaleas.
Root cuttings of woody shrubs and some evergreens from growth shoots made this spring.
Plan late-summer and fall bluegrass or fescue lawn improvements: seeding - mid-August to mid-September; and fertilization - September through November.
LENGTH: Medium: 86 linesby CNB