5

Evaluation of Pest-Control Strategies

In an effort to identify the circumstances under which chemical pesticides might be required in future pest management, the committee received input from experts during the information-gathering phase of its study. Perspectives were received in the form of invited presentations, written input, and informal responses from university and industrial scientists, pest-management practitioners, policy analysts, and other people with expertise in current practices and impacts of pesticide use. On the basis of input from workshops and other information sources, the committee concluded that the diversity of the US agricultural enterprise and other sectors of pesticide use makes generalizing virtually impossible.

Pesticides are used in a multiplicity of settings—agricultural crop and livestock production, silviculture, homes and lawns, schools, golf courses, rights of way, wildlands, and others. Pest managers use an array of chemical pesticides, cultural practices, biological control, and genetically modified organisms to control a broad spectrum of pest species. Moreover, even in a single production system, the utility of chemical pesticides can vary. Although generalizing is difficult, experts who provided input to the committee agreed that pest-management practices can improve in all managed ecosystems. The intent here is to provide some insights on circumstances in which pesticides are in use and to illuminate the variation in pest-management practices in some managed and natural ecosystems.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 210
The Future Role of Pesticides in US Agriculture 5 Evaluation of Pest-Control Strategies In an effort to identify the circumstances under which chemical pesticides might be required in future pest management, the committee received input from experts during the information-gathering phase of its study. Perspectives were received in the form of invited presentations, written input, and informal responses from university and industrial scientists, pest-management practitioners, policy analysts, and other people with expertise in current practices and impacts of pesticide use. On the basis of input from workshops and other information sources, the committee concluded that the diversity of the US agricultural enterprise and other sectors of pesticide use makes generalizing virtually impossible. Pesticides are used in a multiplicity of settings—agricultural crop and livestock production, silviculture, homes and lawns, schools, golf courses, rights of way, wildlands, and others. Pest managers use an array of chemical pesticides, cultural practices, biological control, and genetically modified organisms to control a broad spectrum of pest species. Moreover, even in a single production system, the utility of chemical pesticides can vary. Although generalizing is difficult, experts who provided input to the committee agreed that pest-management practices can improve in all managed ecosystems. The intent here is to provide some insights on circumstances in which pesticides are in use and to illuminate the variation in pest-management practices in some managed and natural ecosystems.

OCR for page 210
The Future Role of Pesticides in US Agriculture PESTICIDE USE IN MANAGED AND NATURAL ECOSYSTEMS For purposes of classification, the committee used both biological and cultural criteria to recognize six major classes of agroecosystems. In the context of agronomic crop production, biological constraints differ between perennial systems—which include silviculture, orchards and vineyards, forages and turf—and annual systems—which include row crops, vegetables, and cereals. Stored-products systems have unique attributes; climate and temperature are factors for all of the systems, but manifest themselves in unique ways in that stored-products systems are often indoors and spatially constrained. Animal-production systems (including those for swine, ruminants, poultry, such nonfood animals as horses and llamas, and aquaculture) present a different set of biological constraints. Urban pest-management systems—indoors for vermin, structural pests, and companion animals; and outdoors for lawn, garden, golf courses, ornamentals, rights of way, and nuisance insects—present cultural and biological constraints that differentiate the process of management from that in other systems. Finally, wildland systems (including rangelands, forests, conservation holdings, and aquatic systems) often present species-conservation priorities that make nontarget effects important in pest-management strategies. Perennial Cropping Systems The longevity of perennial crop plants (particularly trees) creates a distinctive challenge in that both time and vegetational structure promote biological diversity (Lawton and Gaston 1989). Thus, management decisions in these systems targeted at particular pests often have community-level implications. For example, use of conventional pesticides for control of major pests can preclude adoption of nonchemical alternative methods of controlling other pests (Brunner 1994); use of conventional pesticides remains heavy in these agroecosystems. In 1995, over 90% of acres on which the five most widely grown fruit crops (grapes, oranges, apples, grapefruits, and peaches) were grown were treated with at least one pesticide, and most of the acres received herbicide, fungicide, and insecticide treatment (Economic Research Service 1995). Explanations for the heavy reliance on conventional pesticides are numerous and include shortages of trained consultants, institutional limits on information transfer, and unavailability of pesticides with appropriate specificity (Brunner 1994). Cultural factors enter in as well; because of consumer aesthetic concerns, crops grown for fresh market receive more intensive pesticide use to ensure quality. Among perennial crops,

OCR for page 210
The Future Role of Pesticides in US Agriculture regional and seasonal variation affects the intensity of pesticide use. Disease, weed, and arthropod pest complexes vary with locality, climate, and cultivars grown. For example, in the 1994–1995 growing season, while insecticides were applied to 96% of grape acreage grown in Michigan, they were applied to only 17% of grape acreage in Washington (Economic Research Service 1997). Many of the pesticides traditionally used in tree crop systems raise concerns regarding human and environmental exposure and have been either canceled or substantially restricted (for example, phosalone, ethyl parathion, daminozide, ethion, EBDC, and cyhexatin); positive effects of regulatory action are evident in reduced residue detection (chapter 3). The cancellations, however, have increased reliance on fewer products and raised concerns about the availability and competitiveness of alternatives (CAST 1999) and about increased rates of resistance acquisition. A subject of lingering concern, arising at least in part out of failure to enforce laws, is continuing exposure of applicators and farmworkers to remaining traditional chemical pesticides. Institutional and regulatory barriers constrain adoption of nonchemical alternatives under many circumstances (Brunner 1994). Annual Cropping Systems Because of the vast acreage dedicated to annual crops, variability —in regional, seasonal, climatic conditions and in cultivar availability —characterizes production in these agroecosystems. Consequently, pest-management practices for these crops reflect variability, as seen in Table 5-1 and Table 5-2. Corn is the most widely planted crop in the United States and production is overall chemically intensive; in 1995, herbicide was applied to 98% of corn acreage in 10 states surveyed, amounting to 55,850,000 acres (Economic Research Service 1997). Insecticide use in that year, however, was restricted to 26% of the acreage. Sweet corn, however, which is grown for fresh market, received insecticides in 41% of the acreage in Washington and 82% in Illinois. Soybean crops also are widely planted, in diverse soil types, climate regimes, and biotic communities. Herbicide use after planting is high in soybeans, in general, and rose from 52% of acreage in 1990 to 74% in 1995. The diversity of weeds in the weed seed bank, particularly across the diverse acreages planted in soybean (over 45 million acres in major producing states), presents opportunities for weed species shifts and a challenge to single-strategy management plans (Gunsolus et al., 2000). In contrast with corn and soybean crops, wheat, although one of the largest field crops, currently demands considerably less pesticide use. In 1994, although wheat constituted 29% of all surveyed acreage, it repre-

OCR for page 210
The Future Role of Pesticides in US Agriculture sented only 4% of pesticide use. Season profoundly affects herbicide use in wheat; winter wheat can establish itself over the fall and winter and compete well with spring weeds, but spring wheat is often treated with herbicide to provide seedlings with a competitive edge against weeds. Cotton, another major crop, remains pesticide-intensive at least in part because of geographic and climatic factors. Winter survival of pests, particularly insects, tends to be higher in southern states, where cotton is extensively grown. By virtue of volume alone, pest-management practices on field crops have a high potential for adverse environmental effects. Resistance is a major concern, at least in part because of the intensity of the selection pressure applied to pests. Nontarget effects can be considerable simply by virtue of volume. The fact that corn cultivars producing transgenic Bacillus thuringiensis endotoxin constitute over 20% of planted acres in 1999 has raised concerns that pollen shed by these plants and expressing the toxic protein can have unintended effects on nontarget butterflies on plants growing in the vicinity of cornfields (Losey et al. 1999). Roundup-Ready ® soybeans were planted on more than 25 million acres in the United States in 1998 (K. Marshall, Industry Affairs Director, Monsanto, personal communication, August 8, 2000); there is concern that such herbicide-resistant varieties will not reduce weed control to one herbicide application because of a lack of residual weed control. Although vegetable crops, like field crops, are annuals, characteristics of vegetable production systems resemble tree fruit crops in their diversity and in the cultural constraints on production. More than 60 types of vegetables are grown in the United States (Zehnder 1994); this biological diversity is accompanied by a diversity of crop-specific pest species. Regional, seasonal, and cultivar variation also contributes to the composition of the pest community. Potatoes, for example, differ in their response to defoliation by Colorado potato beetle, depending on the region in which they are grown (Zehnder and Evanylo 1989); composition of the potato pest fauna depends on region (Zalom and Fry 1992). Cultivar differences can also influence the efficacy of different pest-management approaches. For example, low-growing spinach varieties require greater amounts of pesticide for aphid control than do upright varieties because of inadequate coverage by the pesticide. Thus, one barrier to adopting more nonchemical alternative management strategies is the idiosyncratic nature of each crop; integrated pest management (IPM) programs must be both crop-specific and region-specific. Box 5-1 provides an example of a weed management approach that includes the role of timing in effective weed control. Broad-spectrum pesticides thus have considerable appeal to many vegetable growers (Gianessi 1993, Gooch et al. 1998). Yet another factor

OCR for page 210
The Future Role of Pesticides in US Agriculture Table 5-1 Pest Management Practices for Major Field Crops in Major Producing States, 1990-1997a Crop 1990 1991 1992 1993 1994 1995 1996 1997 Wheat   Planted area, 1,000 acres 33,600 26,950 30,400 31,550 29,750 28,840 26,810 29,900 Land receiving herbicides, % 38.2 30 35.2 44.5 49.9 59.3 54.6 46.9 Treatments, average no. 1.1 1.1 1.1 1.1 1.1 1.1 1.2 1.4 Ingredients, average no. 1.5 1.5 1.6 1.8 1.8 1.8 2 2 Acre-treatments, average no. 1.5 1.6 1.6 1.8 1.8 1.9 2 2.1 Amt. of herbicide applied, lb./acre 0.28 0.29 0.29 0.32 0.34 0.26 0.45 0.43 Before or at plant only, % 3.5 2.8 2.5 3.6 5 4.4 5.8 5.2 After plant only, % 33.7 25.8 31.9 39.6 42.9 53 45.2 36.9 Both, % 1 1.4 0.8 1.3 2 1.9 3.6 4.8 Land receiving insecticides, % 4.7 8.1 6.4 2.5 12.9 6.6 13.4 6.5 Treatments, average no. 1.1 1 1 1 1.1 1 1 1.2 Ingredients, average no. 1.1 1 1.1 1 1 1 1 1.2 Acre-treatments, average no. 1.1 1 1.1 1 1.1 1.1 1 1.3 Amt. of insecticide applied, lb./acre 0.46 0.23 0.35 0.27 0.4 0.37 0.38 0.49 Before or at plant only, % 0.2 0.4 na 0.1 0.5 0.2 1.4 0.1 After planting only, % 4.5 7.7 6.4 2.4 12.4 3.4 12 3.4 Spring and durum wheat   Planted area, 1,000 acres 16,700 14,700 16,850 16,800 17,600 17,450 19,350 18,300 Land receiving herbicide, %s 92.3 93.5 90.7 95.2 96.1 94.6 82.9 81.7 Treatments, average no. 1.3 1.3 1.2 1.3 1.2 1.3 1.5 1.5 Ingredients, average no. 1.9 2.1 2.1 2.2 2.2 2.4 2.7 2.9 Acre-treatments, average no. 1.9 2.1 2.1 2.3 2.3 2.5 2.9 3.1

OCR for page 210
The Future Role of Pesticides in US Agriculture Amt. of herbicide applied, lbs./acre 0.59 0.53 0.53 0.53 0.55 0.57 0.74 0.79 Before or at plant only, % 1.1 3.1 5.8 4.3 4.2 1.9 0.7 4.4 After plant only, % 78.4 77.7 76.5 80.2 81 82.9 63.6 55 Both, % 12.8 12.7 8.4 10.7 10.9 9.8 19 22.3 Soybeans   Planted area, 1,000 acres 39,500 42,050 41,350 42,500 43,750 45,150 45,950 49,250 Land receiving herbicide, % 95.8 96.8 98.2 97.5 98.4 97.6 97.4 97.7 Treatments, average no. 1.5 1.5 1.6 1.6 1.7 1.7 1.8 1.8 Ingredients, average no. 2.3 2.3 2.4 2.5 2.7 2.7 2.8 2.7 Acre-treatments, average no. 2.3 2.3 2.4 2.5 2.8 2.8 2.9 2.9 Amt. of herbicide applied, lbs./acre 1.42 1.32 1.14 1.12 1.17 1.1 1.26 1.26 Before or at plant only, % 44.2 39.1 35.9 27.7 28.1 23.4 20.2 16.4 After plant only, % 20.1 26.1 27.9 29.7 28.5 32.1 27.8 33.4 Both, % 31.5 31.6 34.4 35.1 41.6 42.2 49.4 47.9 Amount banded, % 13.2 11.8 11.5 9.5 8.4 8.5 6.7 8 Cottonb   Planted area, 1,000 acre 9,730 10,860 10,200 10,360 10,023 11,650 10,025 9,265 Land receiving herbicides 94.7 91.5 90.6 91.9 93.6 97.1 92.8 96.1 Treatments, average no. 2.1 2.3 2.4 2.5 2.6 2.7 2.6 2.8 Ingredients, average no. 2.3 2.4 2.7 2.7 2.7 2.8 2.8 2.9 Acre-treatments, average no. 2.7 2.9 3.2 3.2 3.4 3.3 3.2 3.4 Amt. of herbicide applied, lbs./acre 1.81 2.07 2.08 2.04 2.33 2.07 1.91 1.98 Before or at plant only, % 57.7 52 49.1 45 41.2 46.3 36.4 34.2 After plant only, % 5.7 5.1 9.2 9.5 6.2 6.7 6.2 4 Both, % 31.3 34.5 32.5 37.5 46.1 44.1 50.2 57.9 Amount banded, % 42.1 42.5 43 44.6 42.9 47.4 48.7 48.6

OCR for page 210
The Future Role of Pesticides in US Agriculture Land receiving insecticides, % na 66.4 64.8 64.9 71 75.3 78.6 73.7 Treatments, average no. na 3 4.5 4.9 5.7 6.1 4.4 4.9 Ingredients, average no. na 2.3 3.2 3.4 3.5 3.8 3 2.8 Acre-treatments, average no. na 3.7 6 6.6 7.6 7.9 5.3 5.4 Amt. of insecticide applied, lbs./acre na 1.49 3.7 3.96 2.47 2.35 1.8 2.33 Land receiving other pesticides, % na 56.5 47.3 63.5 66.8 55.8 60 67.9 Treatments, average no. na 2 1.8 1.7 2 2.1 1.9 1.8 Ingredients, average no. na 2 2 1.9 2 2.1 2.4 2.2 Acre-treatments, average no. na 2.4 2.3 2.2 2.6 2.7 2.8 2.5 Amt. of other pesticides applied, lbs./acre na 1.59 2.29 1.79 1.71 2.44 2.15 1.59 Corn   Planted area, 1,000 acre 58,800 60,350 62,850 57,350 62,500 55,850 61,500 62,150 Land receiving herbicides, % 94.8 95.5 96.9 97.5 97.9 97.5 93.3 96.7 Treatments, average no. 1.4 1.4 1.4 1.4 1.5 1.5 1.5 1.6 Ingredients, average no. 2.2 2.1 2.3 2.3 2.5 2.4 2.6 2.7 Acre-treatments, average no. 2.2 2.2 2.3 2.4 2.5 2.5 2.7 2.8 Amt. of herbicide applied, lbs./acre 3.25 2.97 2.91 2.94 2.8 2.77 2.85 2.77 Before or at plant only, % 39.3 38.4 33 34.7 29.4 30.4 23.4 22.4 After plant only, % 29.1 34.1 36.4 36.8 38.1 37.9 35.4 38.7 Both, % 26.4 23 27.2 25.6 30.2 29 34.5 35.6 Amount banded, % 12.8 13.6 15.2 13.7 13.7 11.6 11.3 10.2

OCR for page 210
The Future Role of Pesticides in US Agriculture Land receiving insecticides, % 32.3 30.5 28.6 28.2 26.6 26.1 29.1 30.4 Treatments, average no. 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.2 Ingredients, average no. 1.1 1.1 1.1 1 1.1 1.1 1.2 1.2 Acre-treatments, average no. 1.1 1.1 1.1 1.1 1.1 1.1 1.2 1.3 Amt. of insecticide applied, lbs./acre 1.18 1.14 0.97 0.94 0.82 0.75 0.67 0.7 Before or at plant only, % 25.8 22.7 22.5 22.3 18.5 18 18.5 19.1 After plant only, % 4.4 5.6 4.9 5.2 6.5 6.8 7.9 8.2 Both,% 2.1 2.1 1.3 0.7 1.5 1.3 2.7 3.1 Fall potatoes Planted area, 1,000 acre 605 620 586 616 640 625 641 609 Land receiving herbicides, % 93.8 90.6 93.1 91.3 91.5 93.6 91.4 88.2 Treatments, average no. 1.3 1.4 1.3 1.4 1.4 1.4 1.2 1.4 Ingredients, average no. 1.6 1.7 1.6 1.7 1.8 1.8 1.8 1.9 Acre-treatments, average no. 1.6 1.7 1.7 1.8 1.9 1.9 1.8 2 Amt. of herbicide applied, lbs./acre 2.18 2.31 1.88 2.13 2.49 2.53 2.58 2.31 Before or at plant only, % 22.5 16.3 18.1 18.3 16.6 11.9 25 15.9 After plant only, % 64.9 67.1 70 64.9 62.3 74.4 62.2 65.9 Both,% 6.4 7.2 5 8.1 12.6 5.3 4.2 6.4 Amount banded, % 4 5.2 1.7 1.9 2 1.4 0.2 0.3 Land receiving insecticides, % 86 92.9 87.6 86.3 82.7 84.6 91.5 90.9 Treatments, average no. 1.9 1.9 2 1.9 2.2 2.1 1.7 2.2 Ingredients, average no. 1.7 1.7 1.7 1.7 1.9 1.8 1.6 1.9 Acre-treatments, average no. 2 2 2.2 2 2.4 2.2 1.9 2.3 Amt. of insecticide applied, lbs./acre 3.62 2.89 3.13 2.89 3.7 2.91 2.15 3.08 Before or at plant only, % 24.6 20 23.2 22.6 25.3 19.7 17 20.2 After plant only, % 45 52.1 46.3 47.3 42 44.7 61.8 32.5 Both,% 16.4 20.8 18.1 16.4 15.4 20.2 12.7 38.2

OCR for page 210
The Future Role of Pesticides in US Agriculture Land receiving fungicides, % 54.5 50.6 57.1 62.3 68.2 74.6 86.3 95.5 Treatments, average no. 2.6 2.5 3.1 3.1 3.5 4.8 4.2 5.6 Ingredients, average no. 1.4 1.5 1.9 1.9 2.1 2.6 2.1 3.1 Acre-treatments, average no. 3.5 3.5 4.2 4 5 6.6 5.7 7.8 Amt. of fungicide applied, lbs./acre 3.19 3.21 3.69 3.65 4.95 5.92 5.03 6.6 Land receiving other pesticides, % 31.4 41 39.1 47.5 57.5 55.8 64.6 64.3 Treatments, average no. 1.5 1.5 1.6 1.4 1.5 1.4 1.4 1.4 Ingredients, average no. 1.2 1.3 1.4 1.2 1.3 1.3 1.3 1.2 Acre-treatments, average no. 1.5 1.5 1.7 1.4 1.5 1.6 1.5 1.4 Amt. of other pesticides applied, lbs./acre 99.8 88.6 120.6 131.5 152.1 133.4 178.5 132.1 aRepresents planted area of corn (IL, IN, IA, MI, MN, MO, NE, OH, SD, & WI), soybeans (AR, IL, IN, IA, MN, MO, NE, & OH), cotton (AZ, CA, LA, MS, &TX), winter wheat (CO, KS, MT, NE, OK, SD, TX, & WA), spring wheat (MN, MT, & ND), durum wheat (ND), and fall potatoes (ID, ME, & WA), which are the surveyed states included in all years. For these crops, the area represented in 1997 was about 167 million acres, 75% of total planted acres of these crops. b1990 survey for cotton collected only herbicide treatments. Source: USDA, ERS, Cropping Practices Surveys, 1990-95 and ARMS, 1996-97.

OCR for page 210
The Future Role of Pesticides in US Agriculture promoting dependence on chemical pesticides is the nature of consumer expectations for vegetables for the fresh market; there is a considerable demand for damage-free produce. In the vegetable-processing industry, federal regulations permit only very low levels of contaminating material, such as insect parts. The US Food and Drug Administration (FDA) identifies acceptable levels for these contaminants—Defect Action Levels—and they are typically measured in either the number of foreign parts per weight of food item or by percentage of foreign contamination by weight of food product (FDA 1998). At the same time, consumer concern about pesticide residues in vegetables and fruits (NRC 1993) can restrict the utility of these chemical pesticides in the future, as might concern about worker exposures, given the nature of nonmechanized harvesting procedures in many cropping systems. Registrations of pesticides for use on vegetable crops are decreasing, in part because of the Federal Insecticide, Fungicide, and Rodenticide Act reregistration process; availability of either chemical or nonchemical alternatives is reduced for many crop systems. Stored-Products Systems Pest problems in stored products are influenced by a number of factors, including time in storage, grain temperature and moisture, and type of management (Kenkel et al. 1994). Moisture and temperature in turn are affected by locality; moisture at the time of harvest of wheat can vary by a factor of almost 2 (Hagstrum and Heid 1988). Problems are more likely to arise in the Southwest (Oklahoma and Texas) than in the relatively cool, dry Great Plains states (North and South Dakota and Montana) (Kenkel et al. 1994). Because chemical costs are low and alternative management practices few in number, use of chemicals predominates. Low cost also promotes scheduled fumigations irrespective of whether pest populations merit treatment. Accordingly, resistance has been a persistent problem, increasing in grain elevators, in flour mills and on farms (Beeman and Wright 1990). Many of the broad-spectrum chemicals on which stored product pest-management practices are based, such as phosphine, dichlorvos, methyl bromide, and ethyl dibromide are under review and, because of adverse health and environmental effects, are unlikely to be registered for many of their current uses (EPA 1999). The lack of ready alternatives, either chemical or nonchemical, is likely to present problems to the industry in the future.

OCR for page 210
The Future Role of Pesticides in US Agriculture TABLE 5-2 Fruit and Vegetable Acreage Treated with Pesticides, Major Producing States, 1992 - 1997   1993 Herbicide Insecticide Fungicide Fruit: Grapes, all types 64 66 93 Oranges 94 90 57 Apples, bearing 43 99 88 Grapefruit 93 93 85 Peaches, bearing 49 99 98 Prunes 40 93 84 Avocados 50 12 10 Pears 44 98 92 Cherries, sweet 45 94 87 Lemons 71 88 14 Cherries, tart 49 98 99 Plums 70 89 79 Olives 67 27 33 Nectarines 84 98 95 Blueberries 75 91 81   Total Application, 1,000 lbs. (1997) 1,000s of Planted Acres No. of States Surveyed Herbicide Insecticide Fungicide (1997)   Fruit: Grapes, all types 1306.4 3552.7 39875.6 893.6 6 Oranges 3399.3 47361.1 2088.6 832.9 2 Apples, bearing 710.6 9459.5 5170 350.8 10 Grapefruit 518.7 10604.5 1056.7 159 2 Peaches, bearing 160.2 2014.6 4376.5 135.9 9 Prunes 90.2 1220 476.2 100.5 1 Avocados 68.8 84.3 95.8 62.5 2 Pears 132.3 4655.9 1335.3 67.9 5 Cherries, sweet 73.5 1108.4 633.7 48 4 Lemons 142.5 6813.2 147 49 1 Cherries, tart 48.6 157.2 872.3 32.4 4 Plums 64.3 1141.8 360.3 44 1 Olives 66.2 162.1 95 37.4 1 Nectarines 75.5 1153.9 273.9 38 1 Blueberries 61.7 127.2 234.5 34.2 5

OCR for page 210
The Future Role of Pesticides in US Agriculture FIGURE 5-2 Equilibrium in output market with change in product quality. early years might be low and the price effect not very significant.Over time, increased adoptions would lead to outward price reduction. The CS can change over time because of exogenous factors, such as population growth. Increased population might tend to increase the demand for a product and the annual CS associated with the pest-control strategy. Final versus Intermediate Good. Many agricultural commodities are intermediate goods for the production of final goods. For example, alfalfa, corn, and soybeans are used as feed products in the production of meats. Therefore, analysis of CS effects have to incorporate factors that affect both the grain market and the final-product market. Knutson et al. (1990) show that a pesticide ban in grain crops will reduce consumer welfare substantially through its impact on the price of meats. They separated the impacts of the ban into impacts on feed-crop growers, livestock operators, and final consumers. When agricultural products go through several stages of processing, intermediate surpluses have to be derived.

OCR for page 210
The Future Role of Pesticides in US Agriculture Environmental and Health Costs (EHC) Pest-control strategies have significant effects on human health and various dimensions of environmental quality. Some of the effects can be quantified and monetized, and the quantification should be incorporated into the cost-benefit analysis. The health costs associated with pest-control strategies are denoted by HC and are in several categories shown below. Worker safety costs (WSC). WSC is the sum of several cost categories. These consist of sick days and their attributed costs (e.g., the costs of medical treatment, earnings lost, and pain and suffering (Viscusi and Magat 1987). An even more sensitive category is statistical mortality, which is multiplied by an attributed value. Zeckhauser (1975) and Thaler and Rosen (1976) provided methodological guidelines to value statistical life, and Cropper et al. (1996) provide an overview of the implied valuation of life associated with existing pesticide policies. (The notion of statistical death reflects the estimate that there is a small probability of accidental death due to worker use of a pest-control strategy. This probability, multiplied by the size of the population involved, provides an estimate of statistical death.) Risk-assessment method have been developed to quantify the various types of accidents associated with different production activities, including pest-control activities. If we consider the number of worker sick-days per period (year) associated with a particular pesticide strategy, SD, where Ai is the acreage in regioni and i is the sick-day-per acre coefficient, SD depends on the material used in the pest-control strategy and the exposure level (which depends on quantity of material used, how it is applied, type of protection gear worn, weather conditions during application, and vulnerability of the exposed population). Food-safety costs (FSC). FSC includes the effects on human health of exposure to materials used in pest-control strategies during and after production. The effects vary with age, location, and individual and are a source of major concern. FSC is also a sum of subcategories, including sick-day costs, mortality costs, and costs of disposal and treatment of contaminated food. For each subcategory of cost, the expected number of accidents is proportional to the quantity of output produced in each region multiplied by coefficients that reflect the risk per unit of output. The coefficients are affected by residue levels, toxicity of materials, and vulnerability to the materials.

OCR for page 210
The Future Role of Pesticides in US Agriculture When it comes to FSC, costs are associated with perceptions and uncertainty. Consumers might view some treatment of food products as less desirable than others because they feel that it makes products less safe or wholesome. Some studies have estimated willingness to pay for pesticide-free food (van Ravenswaay and Hoehn 1991). Assessment of pest-control strategies should take into account that some perceptional cost or benefit is associated with the use of strategies in production of foods. When everything else is equal, these considerations could make some strategies more desirable. Other exposure costs (OEC). OEC include exposure to residues of material used in pest-control strategies. People might be exposed to toxic materials when they enter a sprayed field or fumigated storage area. OEC also includes accidental poisoning associated with mistaken consumption of chemicals. Humans might be exposed to chemical residues in the water or materials carried through the air. Again, assessment of strategies has to recognize the magnitude of accidental effects on third parties. When the effects are deemed substantial, the estimation of mortality and morbidity cases will provide the foundation for computing the OEC. HC can be estimated: HC = WSC + FSC + OHC. Several important issues can arise in quantifying HC. Dynamic Considerations. The health effects of different pesticide strategies might occur at different times, and they require adjustment in computation procedures. Therefore, it could be useful to break each category of HC into annual components. HC is then the discounted sum of the annual costs. Some materials might cause acute problems, others may cause chronic problems that will be discovered years later. There is also the issue of cumulative exposure. It is useful to break the annual health costs into these subcategories. Uncertainty Considerations. Quantification of health risks is an immense challenge, and variances of risk assessment are important. A major problem is that different risk assessment coefficients are estimated at various levels of reliability. For example, some studies provide average risks posed by a particular pest-control strategy, and others provide risk estimates that may not be exceeded at 99 % probability. For consistent quantification, all risk estimates should be converted to the same degree of reliability, say, the mean of a level that is not exceeded at 95 % probability. Harper and Zilberman (1989) demonstrate that the quantitative health risk estimates associated with alternative pesticide use regulations in California's Imperial Valley vary by several orders of magnitude when derived with different degrees of reliability. They and others also demon-

OCR for page 210
The Future Role of Pesticides in US Agriculture strate how tradeoffs between health risks and economic benefits can be meaningful only when all health risk estimates are consistent. Environmental Costs and Benefits (ECB) Several categories of environmental costs can be associated with pesticide strategies. The strategies might also have some benefits relative to an initial situation. The categories of environmental costs and benefits are described briefly below. Nontarget Species Costs (NTC) Environmental nontarget costs are borne by society and distinguished from production nontarget costs (damage to beneficial pests that reduces productivity), which are borne by users. Pest-control activities can harm species that provide benefits through various use categories (for example, hunting, fishing, birdwatching, and pollination), through biodiversity, and through existence (see Randall and Stoll (1983) for discussion of such benefits and how to assess them). NTC can be presented as where βi is nontarget species cost per acre in region i, and it is multiplied by the acreage to provide an estimate of the regional NTC. Damage to Property and Resources (DRC) Various pesticide strategies can lead to residues that contaminate nearby property. For example, aerial spraying of pesticides might cause damage to nearby land and structures. A more severe problem is groundwater and surface-water contamination by chemicals, which can cost hundred of millions of dollars to clean (see Lichtenberg et al. (1988) for studies on the clean-up costs of 1,2-dibromo-3-chloropropane, DBCP). Environmental damage depends on the manner of application. When applying materials like chemicals, one can separate applied input and effective input, and the application technology will determine the input use efficiency (percentage of material that is actually used in production). The residue coefficient is 1 minus the input use efficiency. Higher penalties for environmental contamination would lead to adoption of more precise application technologies that would reduce residues and environmental damage (Khanna and Zilberman 1997).

OCR for page 210
The Future Role of Pesticides in US Agriculture Environmental Costs and Benefits of Resource Use (ECBR) Various pest-control strategies affect directly and indirectly the amounts of resources used in agricultural activities. For example, a pesticide strategy might increase yield per acre substantially and thus reduce agricultural land and water use relative to an initial benchmark. The released land might provide substantial environmental benefits as habitat for wildlife- preservation activities. Another pest-control strategy that might be perceived as environmentally friendly but decreases productivity per acre and lead to expansion of the land base and water resources used. If γi is the environmental cost of an acre added to production in region i because of an environmental strategy, As with other cost categories, dynamic and uncertainty considerations affect environmental costs and benefits. When it comes to the nontarget costs, quantification and monetization present serious problems. It is extremely important in an assessment to at least be aware of the different types of environmental costs and, when possible, quantify them in physical units. Government Net Costs (GNC) Implementation of different pest-control strategies might require substantial government involvement. Government might need to finance some of the basic and applied research that leads to establishment of such strategies and need to spend resources on education, extension, monitoring, and enforcement of regulations. Or, government might receive income through taxes and penalty payments. All those costs have to be taken into account when benefits and costs of various categories are considered. Evaluation All the different benefit and cost items that are associated with a pesticide strategy are summed to generate the net benefit (NB) of the strategy: NB = CS + PS − EHC − GNC. NB equals the sum of consumer surplus and producer surplus, minus environmental health costs and government net costs. Detailed calculations require quantification of each of the subcategories, recognizing time

OCR for page 210
The Future Role of Pesticides in US Agriculture variation and discounting net benefits of different years, and finally adjusting for uncertainty. Such an adjustment can be provided by a range of net benefit values rather than one number. The analysis thus far might have ignored international trade considerations, which can be important in assessing pesticide strategies, especially because more than 50 % of the output of some products is exported. Knutson et al. (1990) developed applications that specifically consider the trade effect of pesticide bans. Our analysis has emphasized the importance of economy wide changes and regional heterogeneity in obtaining realistic assessments of various strategies. For a more detailed understanding of how some of the biological considerations should enter into impact assessment, we present below a farm-level framework of analysis. MODEL FOR DESIGN AND EVALUATION OF PEST-MANAGEMENT STRATEGIES ON THE FARM SCALE A generalized model for design and evaluation of pest-management strategies on the farm scale is based on modification of the model presented by Higley and Wintersteen (1992). The model evaluates the benefits and costs associated with a set of alternative strategies. In addition, it identifies the pest-management strategies that fit some minimal criteria and those which maximize “net good”. Net good could include net economic returns, low environmental impact, maximal durability, or an optimization over a set of these and other criteria. Optimization over all the factors requires a common currency for net good and can be used to determine the pest densities required to use a pesticide on the basis of accumulated costs. For example, the conceptual model can be expressed as follows for a crop on a farm, with the common currency units (in this example, dollars) listed below each parameter: net return = [Agricultural Production × (price received − dockage from pest)] − costs where agricultural production (yield) is a function of pest abundance (here assumed to be additive among different pests), Pest Abundance = (Nw + Ni + Np + Nj)

OCR for page 210
The Future Role of Pesticides in US Agriculture where Nw is weed abundance, Ni is insect pest abundance, Np is pathogen abundance and Nj is any other pest abundance that can have an impact on agricultural production. Costs include all the management costs associated with growing a crop or producing an agricultural product on the farm. The pest-management costs can be summed as follows: Mw + Mi + Mp + Mj where Mw is cost of weed management, Mi is cost of insect management and Mp is cost of pathogen management and Mj is cost of other pest management. The cost associated with the evolution of resistance to a pesticide is referred to as “durability cost” and is the cost difference between the current pesticide and an alternative management method (Md) required after the evolution of resistance in the pest. The cost associated with pest impact on human health (Hp) and pest management on human health (Hpm) can also be included. The cost of environmental degradation associated with pest management (Epm) and associated with the pest itself (Ep) on the farm are also variables that can be included. Higley and Wintersteen (1992) demonstrated the use of contingent valuation surveys to estimate monetary costs associated with environmental degradation resulting from agricultural pest management. The cost of special technology and information for pest management (Tpm), and all other costs associated with growing the crop (O) are additional variables that can be included in the estimation of net return. Net return = [yield × (price received − dockage from pest) − (Hp + Ep)] − [(Mw + Mi + Mp + Mj + Md + Hpm + Epm + Tpm + O)] Assessment with Model If net return (NR) is less than zero across the possible range of pest abundance, the logical conclusion is to reject the pest-management strategy. NR must be greater than zero to conclude that a pesticide is worth using in the system. If NR is greater than zero, then its value relative to other practices assessed in the same manner to manage the same pest(s) determines the relative importance of the pesticide in the management system. This example uses NR as the dependent variable, but other measures of response to pesticides —such as crop yield, environmental quality, or human effects—could be used.

OCR for page 210
The Future Role of Pesticides in US Agriculture Identifying Research Needs The model presented above could be used to identify which parameters and their interactions are most important in determining the net return from a particular pest- management practice. Research would focus on the interrelationships between parameters in the model. Various portions of the model require research: The relationship between cost of management and its impact on the pest needs study. For example, herbicide evaluation is usually based on the proportion of the weed population killed, whereas crop yield might be adequately increased by weed injury that could be achieved with rates of much lower herbicide use. The model provides the ability to quantify interactions among pests (insects, pathogens, and weeds) and their management. Different pests in the same agroecosystem are often managed independently, and this can lead to wasted pesticide applications if there are interactions among the pests or the methods used to manage them. For example, two major pests of dry-land spring wheat are wild oats (weed) and wheat-stem-sawfly (insect). The wheat-stem-sawfly life cycle is broken in the presence of wild oats because the larvae do not survive in the stems of wild oats and there is no selective preference for laying eggs in the wheat or wild oats (Sing et al. 1999). Thus, the weed has positive value for reducing the impact of the insect pest, which would increase the economic injury level for the weed. The model does not include future impacts of pests that are left behind when the current pest density is below the economic injury level (EIL). Studies that determine parameters for pest population temporal and spatial dynamics REFERENCES Babcock, B.A., E. Lichtenberg, and D. Zilberman. 1992. Impact of damage control and quality of output: estimating pest control effectiveness. Am. J. Ag. Econ. 74:163–172. Beeman, R. W., and V. F. Wright. 1990. Monitoring for resistance to chlorpyrifos-methyl, pirimiphos-methyl and malathion in Kansas populations for stored-product insects. J. Kansas Ent. Soc. 63(3):385–392. Brunner, J. F. 1994. Integrated pest management in tree fruit crops. Food Rev. Int. 10:135–157. California EPA. 1997. Overview of the California Pesticide Illness Surveillance Program – 1995. Sacramento: California Environmental Protection Agency, Dept. of Pesticide Regulation . Campbell, J. B. 1994. Integrated pest management in livestock production. Food Rev. Int. 10:195–205.

OCR for page 210
The Future Role of Pesticides in US Agriculture Carlson, G. A. and M. E. Wetzstein. 1993. Pesticides and pest management. Pp. 268–318 in Agricultural and Environmental Resource Economics, G. A. Carlson, D. Zilberman, and J. A. Miranowski, eds. New York and Oxford: Oxford University Press. Carlton, D. W., and J. M. Perloff. 1990. Modern Industrial Organization. Glennview, Ill. and London: Scott, Foresman/Little, Brown Higher Education. Carpenter, J., L. Gianessi, and L. Lynch. 1999. The Economic Impact of the Scheduled US Phaseout of Methyl Bromide . National Center for Food and Agricultural Policy, Report supported by USDA's Economic Research Service. CAST (Council for Agricultural Science and Technology). 1999. The FQPA: A Challenge for Science Policy and Pesticide Regulation . [Online]. Available: HtmlResAnchor http://www.cast-science.org/fqpa/fqpa-06.htm Cropper, M. and A. M. Freeman III. 1990. Valuing Environmental Health Effects. Discussion Paper QE90-14. Washington, D.C.: Resources for the Future, Quality of the Environment Division. Cropper, M. L. 1996. The determinants of pesticide regulation: a statistical analysis of EPA decision making. In The Political Economy of Environmental Protection: Analysis and Evidence , R. D. Congleton, ed. Ann Arbor: University of Michigan Press. Cropper, M. L., L. B. Deck, and K. E. McConnell. 1988. On the choice of functional form for hedonic price functions. Review of Economics and Statistics LXX/4:668–675. Cropper, M., W. N. Evans, S. J. Berardi, M. M. Ducla-Soares, and P. R. Portney. 1992. The determinants of pesticide regulation: a statistical analysis of EPA decision making. Journal of Political Economy 100:(1):175–197. Deepak, M. S., T. J. Spreen, and J. J. Van Sickle. 1999. Environmental Externalities and International Trade: The Case of Methyl Bromide. In Flexible Incentives for the Adoption of Environmental Technologies in Agriculture, C. F. Casey, A. Schmitz, S. M. Swinton, and D. Zilberman, eds. Boston: Kluwer. Economic Research Service. 1995. Agricultural Resources and Environmental Indicators. Agricultural Handbook No. 712, Washington, DC: Economic Research Service (US Department of Agriculture). Economic Research Service. 1997. Agricultural Resources and Environmental Indicators, 1996-1997. Agricultural Handbook No. 712. Washington DC: US Government Printing Office. EPA (US Environmental Protection Agency). 1999a. Implementing the Food Quality Protection Act. EPA 735-R-99001. Washington, DC: EPA, Office of Pesticide Programs. FDA (US Food and Drug Administration). 1998. The Food Defect Action Level Handbook.. [Online]. Available: http://vm.cfsan.fda.gov/~dms/dalbook.html Gadon, M., 1996. Pesticide poisonings in the lawn care and tree service industries . J. of Eco. 38:794–799. Gianessi, L. 1993. The quixotic quest for chemical-free farming. Iss. in Sci. and Tech. 1993:29–36. Gooch, J. J., A. Sray, and C. Greenleaf. 1998. The fight to save OPs, carbamates. Farm Chemicals 161:18–22. Gunsolus, J. L., T. R. Hoverstad, B. D. Potter, and G. A. Johnson. 2000. Assessing integrated weed management in terms of risk management and biological time constraints. Pp. 373–383 in Emerging Technologies for Integrated Pest Management: Concepts, Research, and Implementation, G. G. Kennedy and T. B. Sutton, eds. St. Paul, Minn: APS Press. Hagstrum, D. W., and W. G. Heid, Jr. 1988. US S. wheat-marketing system: an insect ecosystem. Bull. Ent. Soc. Am. 34(1):33–36. Harper, C. R. and D. Zilberman. 1989. Pest externalities from agricultural inputs. Am. J. Ag. Ec. 71(3):692–702.

OCR for page 210
The Future Role of Pesticides in US Agriculture Higley, L. G.,. and W. K. Wintersteen. 1992. A novel approach to environmental risk assessment of pesticides as a basis for incorporating environmental costs into economic injury levels. Am. Ent. 38:34–39. Hueth, D. And U. Regev. 1974. Optimal agricultural pest management with increasing pest resistance . Am. J. Ag. Ec. 56:543–552. Just, R. E., D. L. Hueth, and A. Schmitz. 1982. Applied Welfare Economics and Public Policy. Englewood Cliffs, NJ: Prentice Hall. Kenkel, P., J. T. Criswell, G. W. Cuperus, R. T. Noyes, K. Anderson, and W. S. Fargo. 1994. Stored product integrated pest management. Food Rev. Int. 10:177–193. Khanna, M., and D. Zilberman. 1997. Incentives, precision technology and environmental protection. Ecol. Ec. 23(1):25–43. Knutson, R. D., C. R. Hall, E. G. Smith, S. D. Cotner, and J. W. Miller. 1993. Economic Impacts of Reduced Pesticide Use on Fruits and Vegetables . Washington, DC American Farm Bureau Federation. Knutson, R. D., C. R. Taylor, J. B. Penson, and E. G. Smith. 1990. Economic Impacts of Reduced Chemical Use. College Station, Tex.: Knutson and Associates Lawton, J. H., and K. J. Gaston. 1989. Temporal patterns in the herbivorous insects of bracken: A test of community predictability. J. An. Ec. 58:102–1034. Lichtenberg, E., and D. Zilberman. 1986. The welfare economics of regulation in revenue-supported industries: The case of price supports in US S. agriculture. Am. Ec. Rev. 76(5):1135–1141. Lichtenberg, E., D. D. Parker, and D. Zilberman. 1988. Marginal Analysis of Welfare Costs of Environmental Policies: The Case of Pesticide Regulation. Am. J. Ag. Ec. 70(4):867–874. Lichtenberg, E., D. D. Parker, and D. Zilberman. 1988. Marginal analysis of welfare effects of environmental policies: The case of pesticide regulation. Am. J. Ag. Ec. 70:867–874. Lichtenberg, E., D. Zilberman, and K. T. Bogen. 1989. Regulating environmental health risks under uncertainty: groundwater contamination in California. J. Env. Ec. and Mgmt. 17:22–34. Losey, J. E., L. S. Rayor, and M. E. Carter. 1999. Transgenic pollen harms monarch larvae. Nature. 399:214. Louda, S. M., D. Kendall, J. Connor, and D. Simberloff. 1997. Ecological effect of an insect introduced for biological control of weeds. Science. 277:1088–1090. Maxwell, B. D. 1992. Weed thresholds: the space components and considerations for herbicide resistance evolution. Weed Tech. 6:205–212. McWilliams, B., and D. Zilberman. 1996. Time of technology adoption and learning by using. Econ. Innov. New. Tech. 4(2):139–154. NRC (National Research Council). 1993. Pesticides in the Diets of Infants and Children. Washington, DC: National Academy Press. Onstad, D. W., and M. L. McManus. 1996. Risks of host range expansion by parasites of insects. Bioscience 46(6):430–435. Parker, D. D., and D. Zilberman. 1993. Hedonic estimation of quality factors affecting the farm-retail margin . Am. J. of Ag. Ec. 75:458–466 Randall, A. and J. Stoll. 1983. Existence Value in a Total Valuation Framework. In Managing Air Quality and Scenic Resources at National Parks, R. Rowe and L. Chestnut, eds. Boulder, Col.: Westview Press. Regev, U., A. P. Guitierrez, and G. Feder. 1976. Pests as a common property resource: a case study of alfalfa weevil control. Am. J. Ag. Ec. 58(2):1861–197. Sandmo, A. 1971. On the theory of the competitive firm under price uncertainty. Am. Ec. Rev. 61:65–73.

OCR for page 210
The Future Role of Pesticides in US Agriculture Sing, S., B. Maxwell, and G. D. Johnson. 1999. Wheat stem sawfly-wild oat interactions in Montana dryland spring wheat. Bull. Ecol. Soc. Am. Spratt, D. M. 1997. Endoparasite control strategies: implications for biodiversity of native fauna. Int. J. Parasitol. 27:173–180. Stoneman, P., and N. J. Ireland. 1983. The role of supply factors in the diffusion of new process technology . Ec. J. Supp. Mar. 83:66–78. Sunding, D. 1996. Measuring the Marginal Cost of Non-Uniform Environmental Regulations . Am. J. Ag. Ec. 78:1098–1107. Sunding, D., and J. Zivin. 2000. Insect Population Dynamics, Pesticide Use and Farmworker Health. Am. J. Ag. Ec. forthcoming. Templeton, S., D. Zilberman, and S. J. Yoo. 1998. An economic perspective on outdoor residential pesticide use. Env. Sci. Tech.. 21:416–423. Thaler, R. and S. Rosen. 1976. The value of saving a life. In Household Production and Consumption, N.E. Tereckyj, ed. New York: National Bureau of Economic Research. USDA (US Department of Agriculture). 1997. Agricultural Chemical Usage. Vegetables.1996 Summary. US Department of Agriculture, National Agricultural Statistics Service (NASS), Agricultural Statistics Board. Washington, D.C.: US Government Printing Office. USDA (US Department of Agriculture). 1998. Agricultural Chemical Usage. Fruits. 1997 Summary. US Department of Agriculture, National Agricultural Statistics Service (NASS), Agricultural Statistics Board. Washington, D.C: US Government Printing Office. van Ravenswaay, E. O., and J. P. Hoehn. 1991. Willingness to pay for reducing pesticide residues in food: Results of a nationwide survey. Staff paper no. 91-18. East Lansing: Michigan State University, Department of Agricultural Economics. Viscusi, W. K. and W. A. Magat. 1987. Learning About Risk: Consumer and Worker Responses to Hazard Information . Cambridge, Mass.: Harvard University Press. White, F. C., and M. E. Wetzstein. 1995. Market effects of cotton integrated pest management. Am. J. of Ag. Ec. 77:602–12. Wratten, S. D., and A. B. Forbes. 1996. Environmental assessment of veterinary avermectins in temperate pastoral ecosystems. Ann. Appl. Biol. 128:329–348. Zalom, F.G., and W. E. Fry. 1992. Food, Crop Pests, and the Environment. St. Paul, Minn: American Phytopathological Society. Zeckhauser, R. 1975. Procedures for valuing lives. Public Policy 23:427-464. Zehnder, G. W. 1994. Integrated pest management in vegetables. Food Rev. Int. 10:119-134. Zehnder, G. W., and G. K. Evanylo. 1989. Influence of extent and timing of Colorado potato beetle (Coleoptera: Chrysomelidae) defoliation on potato tuber production in eastern Virginia. J. Ec. Ent. 82(3):948-953. Zilberman, D., A. Schmitz, G. Casterline, E. Lichtenberg, and J.B. Siebert. 1991. The economics of pesticide use and regulation. Science 253:518-522.