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Index : Pests
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- 4. Organic Control of Garden & Landscape Insect Pests - Top
- As the weather warms and plants begin growing again, so do the insects that feed on them. But in nearly all cases, it’s not necessary to use harsh chemical sprays to keep the population of harmful insect pests in check. Most problems can be dealt with using safe organic or biological controls.
Certain insect pests require no control measures at all! Thrips, tiny flea-like insects that feed on flowers and in leaf buds can disfigure petals and leaves but have no effect on the overall health of plants. They are most common on roses and citrus where they cause a curious cupping, puckering and streaking of flower petals and leaves. Aphids are also common garden insects requiring no control. They too cause cupping and curling of new leaves.
Aphids are small, soft-bodied insects, usually green or yellowish-green. They secrete a clear, sticky substance called ‘honeydew’, the presence of this varnish-like substance on leaves of plants is an indication of their presence. Although the sucking damage of aphids causes no real injury to plants, they can be eliminated by simply using a strong spray of water from a garden hose to wash them from the leaves.
One garden pest that does warrant control measures is the cutworm. This 2 inch long, dull grayish-brown worm crawls on the ground cutting off the stems of young vegetable plants it comes in contact with, killing them. The best way to prevent cutworm damage is to provide a physical barrier around young vegetable transplants. Remove the bottom from a paper or styrofoam cup and place the cup over the young seedling, pressing it down into the soil and inch or so. The cup will provide a barrier to keep the crawling cutworm away from the stem. After the plant has grown for a couple of weeks the stem will be to tough and large for the cutworm to damage and the cup can be removed.
Other worms feed on various garden and landscape plants. They include tomato hornworms, orange dog citrus caterpillars, grape leaf caterpillars and Texas mountain laurel caterpillars. Tomato worms and orange dog caterpillars are rarely numerous enough to require anything more control than hand picking and disposal in a plastic bag. But Texas mountain laurel and grape leaf caterpillars are numerous and persistent. Fortunately there’s an organic control for both! It’s a product called ‘BT’, a bacteria deadly only to leaf-feeding caterpillars. BT (Bacillus thurengensis) has no harmful effects on birds, wildlife, pets or humans. Just ask for BT at local garden stores.
A great organic control for a large range of insect pests is a product called Neem. It’s a natural extract from the Neem tree, indigenous to India, and discovered to have excellent natural insecticidal properties. Neem oil is effective in the control of soft bodied insects such as aphids, whiteflies, and mealy bugs. Another material derived from the Neem tree is a type of growth regulator effective in the larval control of moths, butterflies, beetles, flies, true bugs. In addition, it contols aphids, thrips, mealybugs and leaf miners. Neem growth regulator is sold under several brand names including; Neemix, Bionim, Neemazol and Neemactin. Most garden centers have some form of Neem available.
In it’s native land, the stems of neem trees are used my millions of Indians as an antiseptic tooth brush. It’s oil is used in the preparation of toothpaste and soap. An assortment of it’s parts including; bark, leaves, flowers and fruits are used to treat a wide range of diseases.
Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona,
520-626-5161.
- Updated: March 12, 2006
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