The best way to control insects and disease problems is to prevent them before they get a foothold in your garden.
Maintain a slightly acid soil (around pH 6.5). If in doubt, have a soil analysis done through your local Extension office, by a private lab, or with a commercial soil test kit. Lime can be used to increase soil pH and sulfur can lower it.
Maintain adequate levels of soil fertility through additions of potassium and phosphorus releasing materials, such as commercial fertilizers or animal manures. Soil testing should be done every three years to determine levels of these important nutrients.
Build a biologically active, healthy soil through regular addition of organic matter, such as yard waste, compost, and manure.
For planting areas not being cropped, grow annual cover crops, such as clover or rye grass, to provide additional organic matter.
Till the soil in the fall to expose pests living near the surface to natural enemies and weather, and to destroy insects overwintering in crop residues.
The most effective and most important of all practices is careful observation in the garden. Many serious disease or insect problems can be halted or brought under control early by the gardener who knows what to look for and regularly visits the garden for trouble-shooting.
Naturally occurring predators and parasites are found in gardens, orchards, and fields. Learn to properly identify these species as benefits of your environment. Avoid using pesticides around them. They are as susceptible to insecticides as the pests.
Many species of beneficial insects and mites can be purchased. Beneficial insects are target specific, and require gardener knowledge of existing pests. Timing of release is an important factor, and if pests are not present, neighboring gardens may benefit more than your garden. In general, these insects have specific requirements for long-term survival, and may need to be released anew each season.
||Assassin bug - Reduviidaye - The assassin bug feeds mainly on aphids, caterpillars, Colorado potato beetles, Japanese beetles, leafhoppers, and Mexican bean beetles.|
||Damsel bug - Nabidae - The damsel bug feeds on aphids, leafhoppers, mites, and caterpillars.|
||Big-eyed bug - Lygaeidae - Big-eyed bugs feed on aphids, caterpillar eggs and larvae, immature bugs, leafhoppers, and spider mites.|
||Predacious stink bug - Pentatomidae - Predacious stink bugs feed on Colorado potato beetles and various caterpillar larvae.|
||Syrphid fly larvae - Syrphidae - Fly larvae of this species feed on aphids and mealybugs.|
||Lady beetle - Hippodamia convergens - The lady beetle feeds mainly on aphids and other soft-bodied insects, such as mealybugs and spider mites.|
||Green lacewing larvae - Chrysopa camea - Lacewing larvae, known as aphid lions, feed on insect eggs, aphids, spider mites, thrips, leafhopper nymphs, and small caterpillar larvae. Adult lacewings are not predacious.|
||Predatory mites - Phytoseiulus persimilus and several other species feed on many mite pests, including the two-spotted spider mite.|
||Trichogramma wasp - Trichogrammatidae - This tiny wasp attacks eggs of more than 200 pest species, including cutworms, corn borers, corn earworms, armyworms, codling moths, and cabbage moths. Release time is critical for their effectiveness since they only attack pest eggs.|
||Encarsia wasp - Encyrtidae - The greenhouse whitefly is parasitized by this wasp in third and fourth larval instars when Encarsia lay their eggs inside the whitefly scale.|
For more information on selection, planting, cultural practices, and environmental quality, contact your local Virginia Cooperative Extension Office. If you want to learn more about horticulture through training and volunteer work, ask your Extension agent about becoming an Extension Master Gardener. For monthly gardening information, subscribe to The Virginia Gardener Newsletter by sending your name and address and a check for $7.00 made out to "Treasurer, Virginia Tech" to The Virginia Gardener, Department of Horticulture, Virginia Tech, Blacksburg, VA 24061-0349. Horticultural information is also available on the Internet by connecting with Virginia Cooperative Extension's server at http://www.ext.vt.edu.
The original development of this series was funded by ESUSDA Smith Lever 3(d) National Water Quality Initiative Funds and the Virginia Department of Conservation and Recreation, Division of Soil and Water Conservation. This publication was updated by Tony Bratch, Extension specialist, Vegetables and Specialty Crops.
If a pest problem requires chemical controls, use the least toxic materials according to the label. A certified nurseryman or Extension agent can help you identify the proper and legal pesticide and the method to use it.
Reviewed by Allen Straw, Extension Specialist, Southwest Agricultural Research and Extension Center
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Interim Administrator, 1890 Extension Program, Virginia State University, Petersburg.
May 1, 2009