Controlling Insect Pests

Vegetables and
Annual Flowers

Class 1: Gardening Basics
Class 2: Garden Planning & Design
Class 3: Indoor Seed Starting
Class 4: Planting & Transplanting
Class 5: Maintaining a Healthy Garden
Class 6: Troubleshooting

You’ve monitored your plants, tried barriers, deterrents, and hand-picking. Nothing has worked, and you feel you need to move on to stronger controls. Here are some options. Remember, always start with the least toxic option. Be sure to apply materials evenly and thoroughly, according to label directions. Don’t forget the undersides of the leaves!

Insecticidal soap can be helpful in controlling some soft-bodied insects such as aphids. It can also affect beneficial insects, however, so use with care.

Horticultural oil can also be used to smother some insects, and it’s especially effective on scale and mites.

Biological controls generally target one or a group of pests. Bacillus thuringiensis, or B.t., is sold under various trade names. It is a bacterial control for caterpillars, and it’s especially helpful for cabbageworms, cabbage loopers, corn earworm, and tomato hornworms. It does not affect insects from other families and is considered safe for use around pets and people. Remember, however, that B.t. will affect butterfly larvae as well as "pest" larvae, so use only when necessary. There is also a type of B.t. for potato beetle larvae. Other biological controls include predatory nematodes and milky spore, a bacterial disease targeted to Japanese beetle grubs.

Always read the label of any pesticide, even "natural" ones. Follow directions carefully, and use only on listed pests and plants. This isn't just common sense, it's the law.

Botanical insecticides are substances derived from plants, such as pyrethrum, rotenone, and neem. Botanical insecticides generally break down quickly when exposed to air and light, so they are effective for a limited time after application. This fact is important because it means that they don't "persist" in the environment as some synthetic pesticides do. But most botanicals are broad-spectrum, meaning they will harm both target and non-target insects. And some, such as rotenone, are highly toxic to fish.

Always wear the recommended protective gear, even when applying "organic" controls. Always wear a dust mask when applying powders.

There may be times when you feel compelled to use something "stronger" and more long-lasting. In these cases, there are many synthetic insect control products to choose from. Some are more benign than others, so always check the label for precautions. Your Cooperative Extension office has the latest recommendations. You may find, however, that you can achieve adequate control using careful cultural controls, without resorting to sprays -- either organic or synthetic.

Class 6, Page 1 2 3 4 5 6 7 8 9

Neem
Neem oil is extracted from the seed of the neem tree, a tropical tree native to India. The active ingredient is reputed to have a number of different properties, including repelling pests, suppressing insect feeding, and disturbing insect life cycles. Neem is also being researched for possible fungicidal properties.

Although relatively new to Western gardeners, in its native land neem has been used for centuries against a variety of insect pests.

Pyrethrum Daisy

Just because an insecticide is derived from a plant doesn't mean you should use it freely in your garden. Botanical extracts such as pyrethrum are potent, broad-spectrum insecticides that will harm beneficial insects as well as pests.

Troubleshooting
FAQ #1
When I was growing up in the 40s my father made an insecticide spray with tobacco. What pests was this used to control, and what is the "recipe"?

Answer