Chapter 11

Integrated Pest Management on Organic Farms

Integrated Pest Management Control Tactics

A successful IPM program incorporates a variety of pest management control tactics such as cultural, mechanical/physical, biological, biorational, and chemical control tactics individually or in combination. All are equally important in implementing a successful IPM program. Costs, benefits, timing, labor force and equipment as well as economic, environmental and social impacts all have to be taken into consideration. Each control tactic, discussed below, employs a different set of mechanisms for suppressing pest populations. 

Cultural Pest Control

The goal of cultural control is to alter the environment, the condition of the host, or the behavior of the pest to prevent or suppress an infestation. It disrupts the normal relationship between the pest and the host and makes the pest less likely to survive, grow, or reproduce.  Many cultural practices influence the survival of pests. In agricultural crops, selection of crop plant varieties, timing of planting and harvesting, irrigation management, crop rotation, and use of trap crops help reduce populations of weeds, microorganisms, insects, mites, and other pests. Cultivation is one of the most important ways to control weeds.

Mechanical and Physical Pest Control

Mechanical and physical control involves utilizing some physical component of the environment, such as temperature, humidity, or light, to the detriment of the pest. Common examples are tillage, flaming, flooding, soil solarization, and plastic mulches to kill weeds or to prevent weed seed germination.

Biological Pest Control

Biological methods are the use of beneficial organisms that can be used in a greenhouse to reduce insect pest populations. Biological control of greenhouse insect and mite pests can be achieved through release of bio-control agents like predatory mites, pirate bugs, soil-dwelling mites, and parasitic insects. Biological control agents (natural enemies or beneficials) typically will not entirely eliminate the target insect or mite pest. Implementing a biological control program in a greenhouse is management intensive and requires more knowledge on the part of the grower than for traditional pest control programs.

Biorational Pest Control

Pest control materials that are relatively non-toxic to people with few environmental side effects are sometimes called “biorational” pesticides. Biorational pesticides vary in their toxicity and in their potential ecological impact. Biorationals in general have a narrow target range and a very specific mode of action. They are slow acting, have a relatively critical application times, suppress, rather than eliminate a pest population. In addition, they have limited field persistence and a shorter shelf life than conventional synthetic pesticides and present no residue problems. Biorationals fit well into an integrated pest management strategy, which relies on monitoring for early detection of pests and emphasizes the use of selective products that provide control while preserving the ecological health of the farm and minimizing negative effects on beneficial insects that suppress pests. Biorationals encompass a broad array of pesticides which can be classified as follows: 1) microbials, 2) botanicals, 3) spray oils, 4) insecticidal soaps, 5) minerals, and 6) pheromones. A similar term that is used by EPA is “biopesticides” (defined in the following section) and often used interchangeably with the term biorationals.

Biopesticides

Biopesticides, as defined by the Environmental Protection Agency (EPA), are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. Categories of biopesticides include: 1) biochemical pesticides, which are naturally occurring substances that control pests by non-toxic mechanisms, such as sex pheromones that interfere with mating and scented plant extracts that attract insect pests to traps; 2) microbial pesticides, which consist of a microorganism (e.g., a bacterium, fungus, virus or protozoan) as the active ingredient; and 3) Plant-Incorporated-Protectants (PIPs), in which pesticidal substances are produced by crop plants as a result of genetic material being added to the plant (e.g., Bt insecticidal protein). With plant-incorporated protectants, the toxin and its genetic material, but not the plant itself, are regulated by EPA.

Biorationals Approved for Organic Crop Production

Most biorationals are approved for organic crop production, thus they are a logical fit for managing pests in organic crops. However, some formulations are not approved, which can be due to inert materials or synthetic additives. Some biorationals are not allowed under National Organic Program (NOP), for example phosphorus acids and genetically engineered PIPs.

Chemical Pest Control

Conventional chemicals (i.e., synthesized by the agrochemical companies) are used only as a last resort in an IPM program, but sometimes are the most effective means of control. Conventional pesticides are man-made and are the largest group of pesticides used by growers. Major benefits associated with the use of conventional pesticides are their effectiveness, the speed and ease of controlling pests, and, in many instances, their reasonable cost compared with other control options. Because pesticides can be formulated as liquids, powders, aerosols, dusts, granules, baits, and slow-release forms, they are very versatile.

Chemicals Allowed for Organic Crop Production

Organic farmers can use chemicals derived from natural sources and synthetic substances within the regulations of the USDA NOP if other strategies and cultural management practices fail to control pests and diseases. The National List of Allowed and Prohibited Substances managed by the NOP, identifies substances that may or may not be used in organic crop production.

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