Callaway County
Callaway County
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Jarman's Weekly Agronomy News July 19, 2000 |
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Common Sense Approach to Garden
Pests |
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Garden Pests Jim Jarman |
When it becomes necessary to use chemical control, it is best to use the least toxic, shortest lived pesticide. Try some environmentally friendly chemicals such as insecticidal soaps, horticultural oils, and natural plant products such as pyrethrins, rotenone and sabadilla. Other more traditional insecticides include Sevin, malathion and methoxychlor. Proper insect diagnosis is critical when choosing a control method because insects respond differently to different control approaches. All pesticides chosen must have the target pest included on the label to insure intended control. Mouthparts play a role in how an insect reacts to chemical control. Insects have two types of mouthparts: piercing-sucking or chewing. Insects with chewing mouthparts such as grasshoppers, beetles, and caterpillars have a hardened pair of jaws that saw and grind. Damage caused by insects that chew leaves can be more unsightly than harmful to the plant. Plant feeding insects with piercing-sucking mouthparts include aphids, scales, mealy bugs, leafhoppers, true bugs, and thrips. With these insects, the mouthparts are like a needle that punctures the plant tissue and so the insect can suck fluids from the plant. Some insects with piercing-sucking mouthparts can transmit disease organisms to plants or inject toxic substances into the plant during feeding. Choosing the best chemical for insect control depends in part upon the type of mouthparts. A chemical that kills by contact will kill most insects including ones with chewing or sucking mouthparts. However, a chemical that is dusted on the plant surface and must be eaten so it only works for insects with chewing mouthparts. So, an insect with sucking mouthparts pierces the tissue and does not ingest the dusted chemical. Again, always consult the product label to determine if the chemical is effective against the pest and if the product is safe for the plant that is being damaged. Always follow the application procedures carefully as listed on product labels. With pesticides, more is never better. Some chemicals may have application and use restrictions. For example, some products are not safe to use on tomatoes that are ready to be picked from the vine and eaten. Labels also mention whether or not the particular product may have toxic effects on certain plants and what precautions will prevent that injury. There are many types of control methods that can be used effectively to manage insect pests. Learn when and where pesticides may be needed to control problems. Correct pest identification is extremely important when determining if you need to consider treatment and, if so, what type of treatment. For positive identification of garden pests, you can contact your local University of Missouri Extension county office. The University of Missouri Extension also has guide sheets available in print and on-line at (http://extension.missouri.edu/explore/). These guide sheets help identify common garden pests and treatment options available for those pests. Information for this article is from Mary Kroening, State Master Gardener Coordinator, UMC.
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