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Ornamentals and Turf |
Personnel at the Plant Disease and Insect Clinic at North Carolina State University were excited last week to find vedalia beetles amongst some St. John's Wort (Hypericum) that was infested with cottony cushion scales. The cottony cushion scale is a worldwide pest of citrus. In North Carolina, the only hosts previously recorded were pittosporum, cleyera and nandina. Our only vedalia beetles recorded were from the Wilmington area. In areas further south, the vedalia (a special lady beetle introduced from Australia) keeps the cottony cushion scale under control biologically. Without the vedalia beetles, this scale is very difficult to control because the eggs are protected from insecticides by the cottony egg sac (cushion). Several applications of an insecticide such as malathion, Orthene, were needed to eradicate this pest by using insecticides and waiting 10 days to two weeks between each application. Ornamentals and Turf Insect Information Note No. 51 describes that process in more detail.
Recent news reports have stated that pink hibiscus mealybugs have finally appeared in the United States. Entomologists confirmed the discovery this June in Florida. Despite its name, this mealybug attacks many hosts. It is not certain if this pest can overwinter north of Georgia, but it could certainly survive in greenhouses. This insect has the waxy, woolly appearance of other mealybugs and is quite damaging. Florida entomologists are embarking upon a biological control program using parasitic wasps. For images and more information on the pink hibiscus mealybugs, visit the following web site: http://creatures.ifas.ufl.edu/orn/mealybug/mealybug.htm.
The lesser cornstalk borer is a fairly common pest of field crops, but it attacks other grasses including crabgrass and Johnsongrass (where it is beneficial), Miscanthus, and other ornamentals (where it is a pest!). Damage is more likely to occur in drought-like weather and in plants grown in sandy soils. Lesser cornstalk borers are rare under no-tillage systems apparently because higher moisture and higher amounts of decaying organic matter found in no-till crops suppress development in some manner. Moths emerge in early spring and lay eggs on leaves or stems. A week later they hatch and the larvae feed on leaves or roots. Later they construct underground burrows lined with silk from which they bore into plants near the ground line. The caterpillars become fully grown in 2 to 3 weeks, leave the burrows, and spin silken cocoons under plant material on the surface of the ground. The caterpillars pupate, and the moths emerge in 2 to 3 weeks. At least two generations occur each year in North Carolina. In addition to pesticides usually considered for caterpillar control (Bacillus thuringiensis, Mavrik, Orthene, Sevin, and pyrethrins), Conserve (spinosad) is a relatively new pesticide labeled for the management of caterpillars and other pests.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on August 19, 2002 by Stephen J. Toth, Jr.
