Build up the inherent strengths of plant and ecosystem defense systems.

We may think that plants are defenseless, but in fact, they use a variety of natural defense mechanisms to resist attack by pests:

• Healthy crop plants can out-compete a pest by growing rapidly.
• Plants can produce chemicals that discourage insects from feeding on them or that inhibit bacterial or fungal infection.
• Some plants release compounds into the soil that inhibit the growth of other plants nearby (allelopathy).
• Certain plants may emit chemical "help" signals that attract beneficial insects to the field where they can control pest organisms.

As described under ecological principle 4 in the first unit of the course, ecosystems as a whole also have built-in "defenses" that contribute to their stability and durability. In sustainable agroecosystems, farmers and ranchers manage crop systems to maximize these defenses.

Stress the pests.

At the same time we are promoting healthy and vigorous crops, we can also be working to create conditions that make it more difficult for pest organisms to grow and reproduce. The primary strategies that farmers use to accomplish this are to:

• interrupt the life cycles of the pests
• remove alternative food sources and habitat that would attract pests to the area
• confuse pests by stimulating or disrupting their sensory systems.

Enhance the population of beneficial organisms.

The third general goal in developing an ecologically based approach to pest management is to boost populations of beneficial organisms. Farmers and ranchers work toward this goal by:

• providing habitat and alternative food sources for beneficial insects.
• timing field operations carefully in order to avoid harming beneficials.
• eliminating the use of agrichemcials that will kill beneficials as well as pests.