Louisa Master Gardeners

Pesticides FAQs


  1. When should I use a pesticide?
  2. What alternatives are there to pesticides?
  3. Web Resources for Pesticides





1. When should I use a pesticide?

Before you purchase any pesticide, you should answer some important questions.

Remember, just because you see insects does not mean that insects are a problem. Proper identification of the problem is essential before you select any type of control. There are many excellent resources available to help you identify pests or pest-caused problems, including your local Extension office, trained professionals at nurseries and garden centers, and reference books dealing with plant pests and diseases.

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2. What alternatives are there to pesticides?

There are many alternatives such as biological control already taking place in your garden. You can encourage natural predators, such as preying mantises, ladybugs, lacewings, ground beetles, and others. Purchased natural predators are often ineffective, however, since they tend not to remain in the place where they are put. Research the likes and dislikes of these helpers as to foods, habitat, etc. Provide these conditions where possible. Learn to recognize the eggs and larvae of the beneficial insects and avoid harming them. For example, the tomato hornworm is often seen with a number of white egg cases, a little larger than a grain of rice, on its back. These were laid by a parasitic wasp. The hornworm will die and more wasps will emerge. Obviously, it is to your advantage to leave the worm in the garden, moving it to another place if it is doing a lot of damage.

Spiders, toads, and dragonflies are beneficial and should not be a source of fright to the gardener; in most cases they are harmless to people.

Use various insect traps to reduce the insect population levels. Upturned flower pots, bamboo lengths, boards, etc. will trap earwigs and sowbugs; collect them every morning and feed to pet frogs, toads, turtles, and fish, or destroy with boiling water. Slugs can also be caught by these means and can be killed. Indoors, white flies can be caught with sticky yellow traps, made with boards painted yellow and lightly coated with oil or grease. There are also commercial sticky traps available through some catalogs. Although several Japanese beetle traps are on the market which are effective at attracting beetles, use of these traps has not been shown to be effective in preventing Japanese beetle injury to garden plants, since the traps attract beetles from a wide area. Similarly, light traps and electric "zapper" traps operated at night can capture or kill a large number of insects; however, these devices are indiscriminant -- they kill beneficial as well as pest insects -- and will not aid in control of insect pests.

Natural pesticidal products are available as an alternative to synthetic chemical formulations. Some of the botanical pesticides are fairly toxic to fish and other cold-blooded creatures and should be treated with care. Safety clothing should be worn when spraying these even though their toxicity is low to warm-blooded animals. The botanical insecticides break down readily in soil and are not stored in plant or animal tissue. Often their effects are not as long-lasting as those of synthetic pesticides. Apply insecticides locally, to take care of a specific pest problem, instead of blanketing the entire garden.

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3. Web Resources for Pesticides

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