Basil Plant and Mites
Basil (Ocimum basilicum), a useful plant in the kitchen, lends its bright aroma and earthy flavor to a variety of dishes, especially those made with tomatoes. In addition, the widely used herb has a reputation for repelling mosquitoes. Relatively easy to grow in the herb garden or in containers indoors and out, basil likes well-drained soil, hot weather and six to eight hours of sunlight per day, reports PlantVillage. Basil varieties range from sweet to spicy and include lemon and cinnamon flavors. Despite its bug-repellent properties, whether real or the stuff of myths, basil may occasionally suffer from insect problems that include infestations of spider mites.
With a few exceptions, spider mites love hot weather as much as basil does. Look for tiny black dots on the basil leaves in summer, when rainfall may be scarce and the ground parched and dusty. The minute, eight-legged arachnids are impossible to see clearly without a fairly strong hand lens, but are still identifiable. Place white paper beneath the foliage and give the basil plant a shake. If small black or reddish-black dots fall onto the paper and move a bit, those are spider mites, says the University of California at Davis IPM. You can also check the basil plant for miniature spider webs. Most spider mites gather in colonies on the undersides of the basil leaves for protection from predators and pesticides. In cold weather, spider mites often hide among fallen leaves or inside plant debris on the surface of the soil in the garden or container. The damage and treatment are the same for all species of spider mites.
Spider mites suck out the basil's vital plant juices. Feeding can cause tiny, light spots on the leaves. As the juices are drained, the leaf curls up and turns yellow or bronze. Damaged leaves may fall off the plant – if the infestation is severe, the basil plant loses vigor and its leaves turn dull. Small populations of spider mites normally do not kill basil plants and often don't cause severe damage if the plant is healthy. Mites often target water-stressed plants.
The fastest, most organic way to get spider mites off basil plants is to hose the plant down with a hard spray of water, being sure to hit the undersides of the leaves. Place container-grown plants in the shower or use the spray attachment at the kitchen sink to knock the mites off the leaves. Repeat every couple of days until the mites are gone. Natural predators often take care of the problem for you. These beneficial insects include lady beetles, thrips and lacewings. Predatory mites are about the same size as spider mites. Mites that are actively moving around are likely predatory mites.
If the infestation is severe, try knocking the mites off the plant, then spray the plant thoroughly with horticultural oil or insecticidal soap, which smothers and kills the spider mites. Neem oil is also effective. These products only kill insects present on the basil plant when you spray; they have no residual effect. Follow label directions carefully. Keep in mind that oils and soaps kill beneficial insects along with the spider mites, so it may be best to let the predators work unmolested.
During hot, dry spells, water the plant as well as nearby areas to keep the ground from becoming dusty. Make sure the basil plants do not become water stressed. Indoors, mist the basil plant, paying special attention to the undersides of the leaves, to keep the plant moist and inhospitable to spider mite colonies. Provide proper fertilizer and monitor growing conditions to keep the basil as healthy as possible. Monitor the plants regularly for signs of spider mite infestation.