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Know your pesticides

Integrated Pest Management (IPM) is an approach to managing pests (insects, diseases, weeds) that integrates many tools and methods. IPM includes common sense methods, such as choosing resistant plants, keeping plants healthy, rotations, removing damaged parts or sick plants, trapping insects, fencing, row covers, timing of plantings and other intervention. IPM counts on, encourages and protects natural enemies -- the many insects, spiders, birds, toads and more that balance pest populations. IPM practitioners evaluate threshold of tolerance, asking "How important is this plant, this amount of damage, this loss -- and what action is worth taking?" IPM also includes pesticides as one of the tools, with full attention to using the most selective, carefully timed, minimal amount for effectiveness. This is the opposite of spraying by the calendar, for an unknown or anticipated pest, or just in case.

> The law and pesticides

"Cide" as in "pesticide" means "kill." Pesticides kill pests (and non-pests), and that's true whether the product is natural, botanically derived or synthetic. Some gardeners get very comfortable with some pesticides and may not think a lot about it. The law says we must read and obey the label, and we may only use the product if the pest and the plant are both listed on that label. The availability and advertising, which associates the products with happy, green yards, make it easy to forget about the seriousness of the choices. People want easy solutions and quick fixes.

In the big picture, Americans use over 2 billion pounds of pesticides annually at over $7 billion a year. If we are doing that, we probably should know what we are doing, and what are the larger results. Let us proceed with full knowledge.

> Effects of pesticides

I cannot comment on the health or medical effects of cumulative pesticide use, but I can share some consequences of pesticides for pest management. There are many examples of each of these:

* Pesticide resistant populations develop whenever new pesticides are introduced; the more frequent the use, the sooner resistance.

* Persistent pesticides magnify in food chains (i.e. organochlorine pesticides remain in body fat, may be consumed faster than they are metabolized, and the concentration in the body increases up the food chain). Study the Bald Eagle story.

* Broad-spectrum pesticides create secondary pests -- repeatedly shown by experiments. (Commonly, surges of mites, scales, aphids often follow pesticide spraying.)

* Contact insecticides kill natural enemies too, many of them even more sensitive to the products. When the natural enemies are gone, the target pest surges ahead in a rebound effect.

* Immeasurable, less visible effects: Pesticide drift from other yards reaches many living beings. Innocuous-seeming granular pesticides are picked up by birds seeking sand and pebbles for food-grinding. Bees take micro-encapusulated insecticides, collected on pollen, back to their hives.

These are the very short version of a very big picture, which I encourage you to look at critically and carefully as you make your own pest management decisions.

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