Organic Pest Control for Gardens

Organic pesticides use natural ingredients instead of chemicals.

Organic pest control uses naturally occurring substances and organisms instead of chemicals to reduce pest populations and the damage they cause within the garden. Depending on the particular pests affecting your garden, you can select from a range of organic pesticides, each with distinctive properties, or you can adopt alternative and preventative means of controlling pest problems. For example, companion planting techniques can keep insect pests far away from the plants they love.

Insecticidal Soaps

Soaps and detergents can help to keep away many insect pests. For a simple pesticide solution, mix about one teaspoon of all-natural liquid dish detergent with one cup of vegetable oil and dilute the mix with one cup of clean water. The solution should work to keep away common insect pests, such as spider mites, aphids and white flies. It's particularly effective against pests that attack common vegetables such as carrots, eggplant, peppers and cucumbers. Spray the solution directly on the pests for it to be effective.

Plant-Based Products

Many plants naturally repel harmful insects. For example, you can brew a simple "tea" with raw onions and garlic and spray this solution on roses, fruit trees and flowers to keep away aphids or apple borers. The essential oils of many common herbs also ward off unwanted pests; try spraying solutions of the essential oils of "killer spices" rosemary, thyme, clove or mint to keep your plantings free of insects. Solutions of spearmint, cayenne pepper, ground tomato leaves or tobacco water can also be effective.

Horticultural Oils

Various vegetable-based oils can keep away pesky insects. Depending on the oil, you may use it during the insects' dormant or active periods. Usually, oils for dormancy periods are thicker, to cover and asphyxiate hibernating bugs. Oils for active periods are applied over the plants' foliage, making a lighter solution necessary to ensure the plant's health. The fatty acids present in the oil can also interfere with insect metabolism or disrupt the insects' ability to transmit plant viruses.

Mineral-Based Products

A few effective organic insecticides come from the earth. Diatomaceous earth is an effective pest control, which uses fossilized silica derived from diatoms, a kind of algae. The diatomaceous earth absorbs the insects' outer waxy covering and effectively desiccates the bug. It works especially well on soft-bodied pests, such as slugs, millipedes and sow bugs. It both controls the spread of disease and kills off mites and thrips. Avoid using sulfur in very hot weather or mixing it with other pesticides.

Alternatives to Pesticides

While natural pesticides are a common solution for organic gardeners already facing an infestation, you have many alternatives both before the insects attack and once you discover a population. Companion planting is a preventative strategy of placing insect-repelling plant species alongside plants they protect. For example, planting basil next to your tomato plants keeps away mosquitoes, flies and hornworms. Upon discovering a particular insect pest in your garden, lessen its impact by introducing natural predators. For example, lacewings and lady beetles feed on aphids, mealybugs and the eggs of various insect pests.

References

• Mother Earth News; Guide to Organic Pesticides; Doc and Katy Abraham; February/March 1994
• EurekAlert; 'Killer spices' provide eco-friendly pesticides for organic fruits and veggies; August 2009
• University of Florida IFAS Extension; Natural Products for Insect Pest Management; Eileen A. Buss and Sydney G. Park-Brown; June 2009
• Alabama Cooperative Extension: Comparative Plants
• University of Florida IFAS; Natural Enemies and Biological Control; Hugh A. Smith and John L. Capinera; May 2005

Resources

• Mother Earth News; Carrots Love Tomatoes; Louise Riotte; February/March 1992