Environmental concern sparks renewed interest in IPM - the system of pest control called Integrated Pest Management

Food Review, April-June, 1991 by Catherine Greene

Environmental Concern Sparks Renewed Interest in IPM

Environmental movements during the 1960's inspired a system to control crop pests with fewer synthetic pesticides, and the recent revival of concern for the environment has renewed interest in this approach.

The system of pest control called Integrated Pest Management (IPM), partially funded by the Federal Government, is saving participating farmers significant pesticide expense. A national evaluation team has estimated that in the 1980's, total annual benefits to farmers in 15 States using IPM exceeded $500 million.

IPM evolved as entomologists and other agricultural scientists became concerned about the unintended effects of pesticides, such as killing nontarget species, or causing pests to build immunity or create mutations. Today's concerns are about the potential risks from pesticide residues on food and in groundwater supplies, and about the sustainability of heavy pesticide use in agriculture. IPM offers farmers a variety of pesticide-reducing techniques which allow them to produce high quality, abundant food supplies while minimizing environmental impacts.

Although few farmers in the United States use no pesticides, the conventional practice of applying pesticides by the calendar is becoming uncommon for cotton, canning tomatoes, and other crops where IPM is having success. Instead, pesticides are applied only when pests reach economically damaging levels, and pest-resistant varieties, biological control, and other non-chemical techniques are often used as well.

The Federal Government began funding IPM research through several large, nationally coordinated projects in 1972. Funding gradually increased to approximately $7 million annually during the early 1980's, and has remained at that level. State and private funding of IPM research has also been growing. Today, the Federal Government funds IPM research projects for over 100 major and minor crops grown in the United States.

IPM practices have reduced pesticide use, especially insecticides, on some of the major crops such as cotton and soybeans. Although less data are generally available for minor crops, the IPM program for apples in New York, documented since 1975, shows consistently fewer applications of pesticides (figure 1).

A national evaluation of Federal Extension IPM programs conducted during the mid-1980's found that 3,500 farmers of 9 major crops in 15 States earned $54 million more annually in net revenues from decreased chemical costs and increased crop yields than those not using IPM. And the evaluation team found that total benefits to all IPM-using farmers in the 15 States exceeded $500 million.

Scouting is the Cornerstone

IPM uses both efficiency and substitution approaches to control pests. Making better use of synthetic pesticides is the focus of the efficiency approach. Pest populations are monitored and pesticides are applied only when the population exceeds an economically damaging level. This approach, called scouting, has been the cornerstone of IPM for several decades.

The economic threshold, or level, at which pests are damaging depends on crop prices, pesticide costs, the types of pests, pest population densities, and other factors. Because economic thresholds must be developed separately for each crop and each crop pest, researchers have many thresholds yet to develop.

With the substitution approach, a variety of biological, cultural, and other nonchemical techniques and management practices are used to control pests. Biological control uses parasites, predators, and pathogens to lower the population of crop pests. For example, seven parasitic wasps, predators, viruses, and bacteria have been developed to control tomato pests in California, although only two, Trichogramma and Bacillus thuringiensis, are commercially produced and used by growers.

Cultural controls include crop rotation, field sanitation, mechanical cultivation, irrigation, pruning, and other beneficial management practices that reduce or prevent pest problems. Other IPM techniques include the use of pest-resistant varieties, natural chemicals such as pheromones (substances secreted by pests that influence specific behavior patterns by others of the same species) and botanical pesticides (derived from plant sources as opposed to synthetic pesticides made from petro-chemicals). Botanical pesticides, such as rotenone and sabadilla, are generally recognized as breaking down more quickly in the environment than synthetic pesticides.

IPM Funding Expands to Specialty Crops

Annual reports indicate a dramatic increase in the funding and use of IPM for specialty crops during the 1980's. The number of States with Extension IPM programs for vegetable crops increased to 22 by 1989. Combined funding from governments and industry for vegetable IPM projects rose from approximately $64,000 in 1978 to almost $3 million in 1989 (figure 2). During this time, State funding for vegetable projects tripled to almost $500,000 and industry funding quadrupled to almost $2 million. Federal IPM funding of vegetable projects was fairly constant during the 1980's at approximately $500,000 annually, which represents approximately 8 percent of total Federal IPM expenditures.