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Integrated pest management cuts use of chemicals.

Integrated pest management (IPM), a technique often associated with decreased pesticide use, is gaining favor with producers of some major and minor crops, according to economist Catherine Greene of USDA's Economic Research Service (ERS). IPM involves the control of pests or diseases by using an array of crop production strategies combined with careful monitoring procedures.

A national evaluation in the mid-1980's indicated that producers using IPM on nine major crops earned $54 million more in net revenue annually from decreased chemical costs and similar or increased crop yields than those not using IPM.

In vegetable farming, the increase in IPM methods has been dramatic. "Vegetable growers are experiencing increased public pressure to reduce pesticides, and State and Federal laws have restricted more and more chemical options," Greene says. "Also, some vegetable pests have developed resistance to all pesticides registered for use on those crops."

"Conventional approaches to pesticide use are becoming uncommon for cotton, canning tomatoes, and other crops where IPM is succeeding," Greene adds.

The number of States with vegetable IPM programs rose from only a few before the early 1980's to 17 in 1984 and 22 in 1989.

Greene points out that vegetable area under some form of IPM increased from 742,000 acres in 1984 to nearly 2 million in 1989. These estimates include IPM acreage managed under Extension Service programs, and by private consultants and firms, cooperatives and other grower organizations, representatives of chemical companies, as well as growers and others influenced by Extension recommendations.

"IPM combines the use of pesticides with biological, cultural, and other nonchemical techniques and management practices," Greene says.

Under IPM, pesticides are applied only when the level of pest damage seriously threatens the crop's quality and yield. Determining this level is difficult, however, because it varies according to the individual farmer's pest problems, the stage of crop growth, crop prices, pesticide costs, and other factors. Universities and Extension Services in the States generally provide guidance on the acceptable level ot damage a farmer can sustain without economic loss.

Biological control uses parasites, predators, and pathogens (bacteria or viruses that can cause disease) to reduce pest populations. Cultural controls include crop rotation and field sanitation (destruction or utilization of crop refuse).

Central to IPM is scouting, or monitoring pest populations and applying pesticides only when the population exceeds an economically damaging level. Thus, the IPM approach differs from organic control, which excludes chemical pesticide use, and from conventional control, which uses routinely applied pesticides based on the calendar or when pests are presumed to be at a certain stage of development, without direct observation. Scouting, together with determining the level of economic damage (known as the threshold approach), were the most popular techniques used by growers in the nationwide survey.

In addition to timely scouting assessments of the crop, farmers using IPM must be familiar with pest monitoring techniques and the factors that go into making pest management decisions. IPM also requires timely updates about factors needed to make pest management decisions.

Growers Point to Success

For Randy Stallman, a pecan grower near Las Cruces, New Mexico, the benefits of IPM are mainly economic. He calls his 3,500-acre pecan orchard the 'second largest in the world.'

He points to saving $690,000 a year by importing lady bug beetles and lace wing flies to attack pests rather than buying and applying insecticides. "This amounts to spending about 71 cents an acre compared with $190 an acre--quite a difference! " he says. By 1987, the insecticides Stallman was using to combat the yellow aphid and the complex black pecan aphid were no longer effective because the insects had developed a tolerance. "You sprayed them and they laughed at you," he recalls. Stallman called on the Entomology Department of the New Mexico State University for help, and eventually obtained the aphid predators from an insectary in Ventura, California. His solution falls under the "biological control" category of IPM techniques.

Similarly, Dr. William Moore of the Plant Pathology Department at Mississippi State University reports only one case of cyst nematode damage in 6 years among 7,500 soybean farmers working 1.9 million acres in that State. The farmers rely on crop rotation to keep the nematodes under control.

"In the 1970's, nematodes were a real problem," Moore says. The cyst nematode is a type of worm about one sixty-fourth of an inch long that lives in the soil and attacks soybean roots. Farmers not practicing IPM techniques would find some plants 6 inches tall in one place and 20 inches tall in another place at maturity.

"Alternative planting to such nonhost crops as sorghum, corn, cotton, or even a resistant variety of soybean plant reduces the cyst nematode population," Moore explains.

John Micheli, a fruit grower on a 600-acre farm near Live Oak, California, says IPM techniques "are cheaper than conventional treatment." In the spring, he sprays only the new top growth on his peach trees to eliminate the oriental fruit moth. This practice doesn't affect the beneficial mites on the lower parts of the trees, which then can prey on the harmful spotted mites.

Micheli also ties pheromone dispensers to the trees. The dispensers release the smell of the female oriental fruit moth, confusing the male moth and inhibiting mating.

Limiting spraying and pheromone release were developed with the help of the Extension Service at the University of California, where Micheli learned scouting. "If you don't have this, you don't have anything," says the fruit grower, who now hires entomologists to monitor pests.

IPM techniques also helped some cotton growers control the boll weevil, a pest that has historically caused problems and still ranges from the Atlantic coast to the Imperial Valley of California. In 1978, farmers and public agencies began a program to eradicate the weevil in parts of North and South Carolina.

The boll weevil eradication program resulted in a very high rate of return--97 cents on each dollar spent per year in North and South Carolina during 1978-87. In other words, according to ERS economist John Schaub, each dollar initially invested in the program has returned 97 cents per year ever since--mainly through increased yields, lower pesticide expenditures, and increased value of cotton acreage. Cotton yields rose by 69 pounds per acre, and producers saved about $30 per acre through reduced pesticide use. Cotton land gained $14 an acre in value as farmers switched from less profitable crops.

The program encompassed several IPM procedures. In the first year, the cotton acreage was treated with insecticide to kill any weevils that might survive in stalks or the ground.

In the second year, pheromone traps were placed in the fields. In the spring of that year, fields that showed substantial boll weevil populations in trap catches were treated with insecticides. In the third year, only trap monitoring and cleanup of spot infestations were conducted as needed.

The success of this program led to its expansion on all North and South Carolina cotton acreage in 1983. The program has succeeded in eradicating the weevil, and may eventually be extended across the Cotton Belt.

IPM Outlook Is Bright

IPM research originally focused on field crops, including corn, soybeans, cotton, alfalfa, grain sorghum, and peanuts. But Greene explains that grower interest in using IPM on vegetable crops has surged since the 1980's. "Some analysts think adoption of IPM practices has decreased pesticide use on these crops since the early 1970's," she says.

Greene notes that although most vegetable IPM programs have lowered pesticide use in the States where they've been adopted, there is little pesticide data to document the reduction. IPM studies are not designed to measure the exact volume of pesticides used, but it may be down," she says. "In the future, IPM will likely continue to be an important technique and will minimize the use of pesticides."
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Title Annotation:includes related article
Publication:Frozen Food Digest
Date:Jul 1, 1992
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