ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Sunday, May 19, 1996 TAG: 9605210035
SECTION: HOMES PAGE: D-1 EDITION: METRO
COLUMN: dear john
SOURCE: JOHN ARBOGAST
Identifying the causes of plant problems in the garden, lawn or landscape in order to come up with a realistic remedy is an important concern at this time of year.
Certainly, this task is complicated by the fact that there can be many causes for a given symptom, not all of them related to insects or diseases.
All factors that can influence the health of a plant must be considered in arriving at a diagnosis, including its age, soil nutrition and texture, weather conditions, quality of light, plus all things in the plant's environment and care.
Before going to the garden center chemical shelves or to a plant expert for advice, know the name of the affected plant(s), observe thoroughly for plant abnormalities in addition to the main problem, and recall when the problem was first observed and the stage of the plant's growth and age at that time.
Before reaching for the spray, realize that factors causing plant damage can be grouped into the "living" category, which includes pests and diseases, or the nonliving category, which includes everything in the care of the plant, site-specific conditions and mechanical things such as bumps or breakage.
Q: We like to grow sunflowers for those tall, showy flowers. Other than growing sunflower varieties that are supposed to grow big and tall, how can I encourage my plants to become big and showy? Roanoke
A: I hope you planted your sunflower seeds or transplants where they will have lots of direct sun with little shade and in good, fertile, well-prepared soil. For the best growth, thin the sunflower plants to about 2-21/2 feet apart as soon as you can tell that the plants are strong and established. Also, in addition to mixing low-nitrogen garden fertilizer, such as 5-10-5 or 5-10-10, into the planting site, give each sunflower one gallon of a balanced, liquid fertilizer mixed according to package directions just as soon as the green flower heads start to form.
Sunflowers thrive in hot, dry weather and tolerate droughts, but will benefit from large quantities of water applied as deep soakings every four to seven days during droughts. Don't forget to stake tall plants to help hold up the seed head and prevent wind injuries.
Q: Should evergreen trees be pruned? If so, how much and when? (Hemlock, White Pine, Norway Spruce, Common Spruce, Fir, American Holly) In other words, after a tree is several years old and over 10-12 feet tall, can it be pruned to correct "legginess" or asymmetrical shape? A.A., Radford
A: Evergreen trees can be pruned to promote and maintain a desired size and shape but not to correct for "legginess". Most new growth following pruning of any plant occurs from the buds just under the location of pruning cut; cuts to the upper growth do not stimulate lower buds into growth, thereby correcting a "leggy" plant appearance.
The "how" of your question is controlled by the extent or limits of pruning, which are different for leafy and needled evergreens. For all the needled plants you mentioned, don't prune into the older branch portions, which would be the branch sections where no needles are attached because new growth will not form from there. Hollies can be pruned harder into the areas where no leaves are currently attached.
A general suggestion would be to prune the evergreens you mentioned in the spring.
Send short questions about your lawn, garden, plants or insects to Dear John, c/o The Roanoke Times, P.O. Box 2491, Roanoke, Va. 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.
Gardeners' checklist
(Jobs for mid- to late May)
Prevent squash vine borer damage by applying malathion, methoxychlor or thiodan to the lower section of squash or pumpkin plants four times at seven-day intervals beginning as soon as the vines begin to run or the bush begins to grow. Once the hollowed stems and wilted growth of these plants are noticed in July, control won't be possible.
Check the underside of new growth of azaleas, rhododendrons and pieris, especially those plants that are in mostly sunny locations, for the presence of lacebugs. Control active lacebugs found with Orthene or diazinon.
LENGTH: Medium: 82 linesby CNB