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Index : Pests
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- 22. Garden Chemicals Can Be Confusing - Top
- Many chemicals are available to the home gardener. They control a host of garden and landscape insects, weeds and diseases. But knowing which one to choose for the job at hand can be very confusing.
To simplify the process, first determine whether you really need a garden chemical at all! Insects and weeds are the most common pest problems facing Tucson gardeners. Most insects are beneficial; not plant feeders! Those that do bother plants, like aphids and thrips, do little more than cosmetic injury. Weeds are more of a problem, but often can be dealt with by hand weeding, hoeing, or preventing weed growth with surface mulches.
Many good non-chemical controls are available and should be tried first. A strong spray of water from a garden hose is often enough rid plants of aphids and mites. And no, once they're sprayed off they don't crawl back. Soap sprays will do an even better job and will also help control whitefly and thrips.
If stronger measures are needed, first make sure you know what your trying to control. Most insect pests are either sucking or chewing and the chemical controls for each type are very different. Weed controls are also very different depending on the type. Annual weeds growing from seed can be controlled with pre-emergent weed killers, like Surflan. Perennial weeds growing from roots and rhizomes require post emergent systemic herbicides, like Roundup. Then there are broadleaf weeds which differ in control from grasses and sedges. The point being: know the pest and you'll find the solution!
With the pest identified, search the garden shelves for the chemicals that list that particular pest. The chemical should also list the plant or type of plant you wish to treat. For instance, if you wish to spray eggplant to control flea beetles, flea beetles should be listed on the label among the insects controlled and eggplants or vegetables among the crops or plants to be treated.
Protect the environment and yourself! If you have a choice, always use the safest, least toxic material. For instance; caterpillars can be controlled with B.T. (Dipel) or Sevin. Bacillus thurengensis (B.T.) is a biological control, deadly to caterpillars but harmless to humans and wildlife. Sevin is a chemical insecticide. Therefore, B.T. is the best and safest choice.
Chemicals labeled for use in vegetable gardens are among the least toxic. Sevin insecticide; although a chemical; can be applied to edible crops like grapes, eggplants, and others. Diazinon is another common vegetable garden insecticide. So even when spraying non-edible plants like flowers or shrubs, if the pest is on the label, garden insecticides are a safer choice than non-garden types.
Another more exacting measure of a chemicals relative toxicity is the signal word listed clearly on the label. The least toxic chemicals are designated and labeled with the word "Caution". Those which are more toxic display the "Warning" label. And finally, the most toxic: "Danger" with the skull and cross bones symbol. When there's a choice, choose the product labeled with "Caution".
All chemicals, regardless of their toxicity, can be dangerous if mishandled! Always read the entire label before using any product. Follow the application procedures listed, including the use of all specified safety equipment! If no safety equipment is specified, at least wear a long-sleeved shirt and long pants, solid leather shoes, and chemical resistant gloves. A hat, and eye goggles offer added safety. Always mix sprays outdoors with the wind to your back. Mixing is the most likely time for accidents, so be extra careful!
Chemicals are sold under various brand names and at various concentrations. If you know the common chemical name you can sort out the best values. For instance, Weed Stop and Weed-Be-Gon are two trade names the Ortho Chemical Company uses for the same chemical: 2,4-D. If you know that 2,4-D is the chemical you need for broadleaf weed control, then you'll know that either product can be used. It's just a matter of selecting the strength or concentration and the price you wish to pay.
Higher concentrations of a chemical are usually less expensive overall than lower concentrations of the same product. Roundup weed killer is sold in various concentrations ranging from 1% to 41%. A 41% concentrate Roundup product may cost 4 times what a 1% pre-mixed and ready-to-use Roundup product costs, however, it makes 20 times more spray than the 1% product!
The informed shopper can make wise decisions about the purchase of garden chemicals. Knowing the pest and the product is the best way for home gardener to safely and effectively deal with pest problems.
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Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on October 11, 1998
- Updated: October 11, 1998
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