Consumer demand for organic food has increased dramatically over the last few decades. Numerous grocery stores and restaurants pride themselves on their selection of organic offerings available to customers. Additionally, home gardeners commonly desire to manage their vegetable gardens organically. While the demand for organic products continues to rise, many believe growing crops organically means they are grown free of pesticides. Is this belief accurate?
Organic farmers and gardeners face the same insect, weed, and plant disease threats as any grower. Sooner or later, pests are going to show up and managing those pests is going to be necessary. Methods of pest management can be organized into four main categories: cultural (crop rotation, resistant varieties), mechanical (discing, screens, traps), biological (beneficial insects and pathogens), and chemical (pesticides). Pest management is more effective, practical, and safer when all four types of management are employed. This is a principle known as integrated pest management (IPM). For more information, see HGIC 2755, Integrated Pest Management (IPM).
Chemical control is an integral component of IPM, even in organic operations. This means pesticides are indeed used in organic crop production. The main difference between organic and conventional production is the type of pesticides that are used.
Conventional (or synthetic) pesticides are materials that are manmade, often from materials found in nature, though their chemical structures have been altered in some way. By altering the chemical structure, certain characteristics can be improved. For example, synthetic pyrethroids are altered to be more stable in sunlight than natural pyrethrin.
Organic pesticides, on the other hand, are considered naturally derived, meaning their chemical structures are unaltered from the way they exist in nature. While the chemical structure is unaltered from its natural form, the material is often processed or extracted to make it more effective or easier to use. Examples of this include azadirachtin derived from neem tree (Azadirachta indica) seeds, or pyrethrin derived from chrysanthemum (Chrysanthemum cinerariaefolium) flowers. Organic pesticides typically break down rapidly in the environment. As a result, when used for persistent pest problems such as plant diseases, organic materials must be applied much more often than their conventional counterparts.
Hundreds of pesticides are approved for organic crop production by the US Department of Agriculture (USDA) and are used regularly by growers. While only the USDA may approve pesticides for organic use, the Organic Materials Review Institute (OMRI) is a non-profit organization that maintains a database of pesticides, fertilizers, cleansers, and other materials approved for use in organic crop production. OMRI is an excellent resource for growers seeking organic options for pest management. To access the OMRI database, visit omri.org.
For more information, see HGIC 2756, Organic Pesticides and Biopesticides.