Agricultural pests — insects, weeds, nematodes and disease pathogens — blemish, damage or destroy more than 30 percent of crops worldwide. This annual loss has remained constant since the 1940s, when most farmers and ranchers began using agrichemi-cals to control pests.

Agrichemical methods of protecting crops are costly to the farmer, potentially harmful to the environment and, despite widespread use, have not proved 100-percent effective. Problems persist due to pest resistance and the uncanny ability of pests to overcome single-tactic control strategies.

A National Academy of Science 1997 Proceedings paper, "A Total System Approach to Sustainable Pest Management," called for "a fundamental shift to a total system approach for crop protection [which] is urgently needed to resolve escalatory economic and environmental consequences of combating agricultural pests."

Many farmers are seeking such an approach, one that relies less on ag-richemicals and more on mimicking nature's complex relationships among different species of plants and animals. Known as "ecologically based pest management" or simply "ecological pest management," this approach treats the whole farm as a complex system.

The old approach strives for 100 percent control of every pest using one strategy or agrichemical for each pest. The new approach, ecological pest management, aims to manage the whole farm and keep pests at acceptable populations using many complementary strategies. Ecological pest man-

Dave Clark, USDA ARS

Dave Clark, USDA ARS

A crimson clover cover crop prevents erosion, improves soil, fixes nitrogen and attracts beneficial insects.

agement is a preventive approach that uses "many little hammers" or strategies, rather than one big hammer, to address pest problems on the farm or ranch.

Ecological pest management employs tactics that have existed in natural ecosystems for thousands of years. Since the beginning of agriculture — indeed, long before then — plants co-evolved with pests and with the natural enemies of those pests. As plants developed inherent protective mechanisms against pests, they were helped by numerous partners in the ecosystem, for example:

■ Beneficial insects that attack crop insects and mites by chewing them up or sucking out their juices

■ Beneficial parasites, which commandeer pests for habitat or food

■ Disease-causing organisms, including fungi, bacteria, viruses, protozoa and nematodes that fatally sicken insects or keep them from feeding or reproducing. These organisms also attack weeds.

■ Insects such as ground beetles that eat weed seeds

■ Beneficial fungi and bacteria that inhabit root surfaces, blocking attack by disease organisms

By integrating these natural strategies into your farming systems, you can manage pests in a way that is healthier for the environment and eliminates many of the problems associated with agrichemi-cal use. Knowing the life cycles of pests and understanding their natural enemies allows you to better manipulate the system to enhance, rather than detract from, the built-in defenses available in nature. Another National Academy of Science report (1996), Ecologically Based Pest Management (EBPM), stated that EBPM "should be based on a broad knowledge of the agro-ecosystem and will seek to manage rather than eliminate pests" in ways that are "profitable, safe, and durable."

In addition to reducing pest damage, shifting your farming system to ecological pest management will bring multiple benefits to your operation. For example, moving from monoculture to longer rotations improves water- and nutrient-use efficiency. Cover crops planted to attract beneficial insects also suppress weeds, improve the soil, provide moisture-conserving mulch, fix or store nitrogen for subsequent crops and contribute to overall nutrient management goals.

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