Basil: An Herb Society of America Guide

Pests & Diseases

Basil has a reputation as an insect repellent, particularly for mosquitoes. Despite its insect repellent properties, basil is subject to a variety of pests, including Japanese beetles, grasshoppers, slugs, aphids, spider mites, whiteflies, cutworms and nematodes. 

Whiteflies are primarily a problem for young plants in the greenhouse (1, 8). Susan Belsinger and James Adams recommend blasting plants with a stream of water to remove whiteflies (1, 8). The water pressure should be strong enough to eliminate the pests but not so strong that it bruises the plant (45). Susan also suggests using a homemade garlic and hot pepper spray, or a natural insecticidal soap like Safer's (8). 

Cutworms can kill plants in the first few weeks after transplanting (62, 85). To prevent infestation, add wood ashes (38, 62) or diatomaceous earth to soil (31) or place a cutworm collar around the base of the plant (31, 38, 71). Researchers at the University of Hawaii at Manoa have found that adding compost to soil can combat nematodes (79, 81). Slugs can be deterred with 5-inch copper fencing. The copper reacts with the slug's natural body chemistry to create a "non-lethal electrical charge" in the slug's body (24). Many adult insects can be avoided by covering plants with fabric row covers during the day (24, 45).

Pests may vary depending on your region. In the Ozarks, where Tina Marie Wilcox gardens, mealybugs, fungus gnats and spit bugs are a problem. To control mealybugs, Tina deters the ants that carry the mealybugs on to the plants with diatomaceous earth, blasts mealybugs from pots, growing tables, and plant parts with water, sprays with natural Safer's soap, and swabs mealybug egg masses with alcohol (85). According to Tina, "there really is no simple way to control mealybugs. It takes constant attention and action to stay on top of the mealybug pest" (85). Orange oil can also be used to treat mealybugs as well as aphids and white flies (45). 

Grasshoppers and June bugs are the major troublemakers in Texas. Madalene Hill reminds gardeners in her region to avoid planting basil near outdoor night-lights since the lights will attract June bugs. To combat grasshoppers, Madalene and Gwen use Nolo bait, "a grain chaff impregnated with a bacteria that affects only grasshoppers and locusts" (44, 45).

Pests & Diseases continued

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