Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, June 23, 1994 TAG: 9407210003
SECTION: CURRENT PAGE: NRV7 EDITION: NEW RIVER VALLEY
SOURCE: Joe Hunnings
DATELINE: LENGTH: Medium
An especially good opportunity for some assistance is to bring your plant pest samples and questions to the Extension Master Gardener Plant Clinic. Master Gardeners are specially trained gardeners who volunteer to help their community through Cooperative Extension horticulture programs.
The plant clinic is held Saturdays in June at the Christiansburg branch of the Montgomery County Public Library from 10:30 a.m. to 1:30 p.m.
Plant clinics are held July 9 and 23 at Laurel Creek Nursery on Virginia 114.
Saturday plant clinics will be held at the Blacksburg branch library during August. Come by and visit.
APHIDS are small, soft-bodied insects that infest new shoots, stems and leaves. There are many species, and they vary in color - yellow, red, green, brown, gray, black - often imitating the color of the plant part infested. Since they shed their "skins" as they grow, white, flaky specks drop onto leaves beneath aphid colonies - a good clue to their presence on the plant. Aphids are sucking insects that excrete sugary honeydew. Honeydew appears as shiny, sticky droplets on foliage beneath aphid colonies in which black or brown sooty mold fungi may develop. Feeding damage causes stunting, curling and distortion of the leaves and new growth.
SPIDER MITES are wingless, eight-legged relatives of insects that are too small to identify without a magnifying glass. They look like black pepper sprinkled on the undersides of the leaves. Feeding damage causes very fine stippling or yellow flecks on the upper leaf surfaces. The mites spin silk strands over their colonies on the leaf undersurface and also in the crotches of petioles and stems when infestations are severe. They attack a wide variety of plants.
MEALYBUGS are small, oval insects covered with white, powdery wax. They are larger than aphids. More-mature mealybugs have filaments of wax projecting from the body margin. They are also sucking insects and produce damage similar to aphids. Mealybugs tend to crawl into cracks, crevices and crotches of petioles and twigs as well as along the veins of leaves and on the buds of new growth.
SCALE INSECTS include the brown soft scale, the hemispherical scale, and the fern scale. The fern scale is small, white, and elongated-oval-shaped as a male, and brownish, oyster-shell-shaped as a female. The other two scales are brown when mature and yellowish-green to tan when young and small. The brown soft scale is oval and flat. Hemispherical scale is what the name suggests - a half-sphere. Both are soft scales and have an extensive list of host plants. The fern scale is an armored scale with a white cover of wax. It is a pest of ferns but also attacks numerous other hosts.
WHITEFLIES have two conspicuous forms: small, white, waxy adults that are active fliers when plants are disturbed; and small, round, sedentary, greenish-yellow nymphs attached by sucking mouthparts to the undersides of the leaves, often by the hundreds. They attack a wide variety of plants.
OTHER PESTS can cause damage occasionally, including cyclamen mites (especially on African violet and cyclamen), thrips, caterpillars, cutworms and slugs. Some insects, such as springtails and fungus gnats, are a nuisance but cause no damage, since they feed on organic matter in the growing medium.
Joe Hunnings is the Virginia Cooperative Extension agent for agriculture in the Montgomery County extension office in Christiansburg. If you have questions, call 382-5790.
by CNB