Why Organic

• Gardeners may choose organic methods for a variety of reasons, but the most common include environmental and health impact. Many synthetic pesticides contain elements and compounds that cannot break down or take a long time to decompose, which can damage or even poison water and soil. Organic compounds contain carbon, a naturally-decomposing material that results in less pollution and lower environmental impact.
  
  

Cultural Pest Control

• Organic gardeners should first employ cultural control methods, according to the Vegetable Research and Information Center at the University of California, Davis. Cultural control starts at the crop-planning stage. Instead of planting the same species year after year in the same spot -- a practice that can lead to increased pest populations -- rotate crops and plan planting and harvesting dates strategically. For example, certain plants are more susceptible to infestation when grown early in the season. Cultural control can also include choosing plant varieties most suited to your area, planting diverse species and fertilizing at the correct times. Other cultural controls include providing optimum soil nutrient content so plants stay healthy and less prone to infestation; maintaining correct moisture levels; planting field borders or strips between species, or planting a "trap crop" such as alfalfa that attracts pests away from the main crop.
  
  

Biological Pest Control

• Organic biological control methods involve maintaining or adding to the beneficial species of insects, fungi or bacteria that naturally maintain plant health. Before using biological control methods, research the temperature and time limitations of the control species. Some effective biological controls for aphids include lacewing larvae, ladybugs, syrphid flies and wasp parasites. Control caterpillar infestations with trichogramma wasps or symbiotic fungi (endophytes). Delphastus beetles feed on whiteflies. Microbial controls include Bacillus thuringiensi, a naturally-occuring bacteria that kills pests such as caterpillars, worms, beetles, ungus gnats, blackflies and mosquitoes, but doesn't harm other animals. Fungus controls include Beauveria bassiana, a soil fungus that can control pests such as thrips, aphids, weevils, grasshoppers, ants and mealybugs.
  
  

Mechanical Pest Control

• Mechanical control may require the most effort, but can prove effective. Mechanical controls do not present any negative environmental impact. Mechanical methods include soil tilling, floating row covers, plastic tunnels, weeding and hand-picking pests off plants.
  
  

Chemical Pest Control

• When used as a last resort, chemical controls can provide effective pest control. Chemicals can kill other species, though. Organic pesticides include botanicals, or compounds derived from plants, such as pyrethrin, rotenone and nicotine. Horticultural oils like neem oil soap control pests including aphies, leaf rollers, mites and scales. Other organic pesticides include kaolin clay and sodium bicarbonate.