AREI Chapter 4.3: Pest Management Practices

Chapter 1: Land and Farm Resources Chapter 2: Water and Wetland Resources Chapter 3: Knowledge Resources and Productivity Chapter 4: Agricultural Production Management • 4.1 Farm Business Management • 4.2 Soil Management and Conservation • 4.3 Pest Management • 4.4 Nutrient Management • 4.5 Animal Agriculture and the Environment • 4.6 Irrigation Water Management • 4.7 Information Technology Management • 4.8 Production Systems Management • 4.9 U.S. Organic Agriculture Chapter 5: Conservation and Environmental Polices Appendix: Data Sources

Craig Osteen and Michael Livingston

Abstract—Crop producers use pesticides and other practices to manage pests. The quantity of pesticides used on crops was less in 2002 than in 1997. The development and marketing of new pesticides and the adoption of genetically modified seed has resulted in changes to insecticide and herbicide compounds used, while new pest problems can increase pesticide use.

Introduction

Crop producers use pesticides and other practices to manage insects, diseases, and weeds and to prevent crop yield or quality losses. Factors that influence pest management decisions include the extent of pest problems, cost and effectiveness of available practices, regulations on what pesticides can be used and how, and the prices of commodities and inputs. The recent entry of Asian soybean rust into the United States could increase fungicide use.

Pesticide Use

Pesticide use can be measured by expenditures, quantity, and area of use. The measure for which estimates have been available for the longest time is million pounds of active ingredient (a.i.). However, this measure does not capture changes in the use of pesticide compounds applied at different rates (where the area treated is unchanged). Nor is total quantity a good measure of total pesticide toxicity, which varies by pesticide compound, or of risk, which can be mitigated by application practices.

One measure of pesticide area is acre-treatments, which is the product of acreage treated and treatments per acre. We use this measure when discussing market shares of insecticides and herbicides, because some pesticides are applied at low rates per acre and account for small portions of total quantity applied, but large portions of total treatments.

Agricultural pesticide expenditures reached an estimated all-time high of $9 billion in 1997-98 and totaled $8.3–8.5 billion in 2002-2004. Herbicides accounted for two-thirds of those expenditures, while insecticides accounted for about one-fifth in 2000 and 2001 (Kiely et al., 2004). Crop pesticide use peaked at an estimated 579 million pounds a.i. in 1997; in 2004, it was 495 million pounds a.i. (fig. 4.3.1, table 4.3.1).

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In recent decades, the development of new pesticides, increased use of practices such as genetically modified seed, and the regulatory process encouraged shifts in pesticide compounds used. Many, but not all, compounds increasing in total use are applied at lower rates per acre than those declining in total use, resulting in lower pesticide quantity. Rather than discuss hundreds of pesticide compounds, we show use of major insecticide and herbicide families measured by shares of total quantity applied and acre-treatments on five major crops: corn, cotton, potatoes, soybeans, and wheat.

Among insecticides, the organophosphate share of acre-treatments and quantity applied was greater in 2000 than 1996, while pyrethroid and carbamate shares were less (table 4.3.2). Corn and cotton are the major insecticide markets among the five crops. The higher organophosphate share was largely due to higher malathion use on cotton for boll weevil eradication, which has since declined. During 1996-2000, organophosphate and pyrethroid use on corn varied year to year, with no obvious trend. (See "Crop Production Practices" in the ARMS Data Tool.) According to NASS, malathion was used on 11 percent of cotton acres (with 6 treatments per acre) in 1997 and 1998, 40 percent (7 treatments per acre) in 1999, but only 11 percent (5 treatments per acre) in 2003. The U.S. Environmental Protection Agency (USEPA), under a regulatory review of organophosphates (discussed below), determined that malathion use for boll weevil eradication was not a significant dietary and drinking water health risk (USEPA, 2000). The adoption of cotton seed genetically modified to produce the Bacillus thuringiensis toxin may reduce organophosphate, pyrethroid, and carbamate insecticide use for lepidopteran insects, such as bollworms and tobacco budworms (see AREI Chapter 3.3).

Among herbicides, shares of acre-treatments and quantity for phosphinic acids—primarily glyphosate (trade name: Roundup) but also glufosinate-ammonium and sulfosate—were much higher in 2000 than in 1996 (table 4.3.3). At the same time, shares of amides, anilines, phenoxys, and triazines, widely used since the 1960s and 1970s, were lower in 2000. Shares of sulfonyl ureas and other new families increased before 1996, but there was little change between 1996 and 2000.

Phosphinic acid shares were higher in 2000 than in 1996 on all major crops, but especially cotton and soybeans, where adoption of genetically modified seed tolerant to these herbicides has been widespread (see AREI Chapter 3.3). Phosphinic acids were the most used herbicides on cotton and soybeans in 2000; their share of herbicide acre-treatments increased from 4 percent in 1996 to 30 percent in 2000 on cotton and from 10 to 42 percent on soybeans, while shares of other major herbicide families were stable or declined. The higher application rates with phosphinic acids contributed to the higher soybean herbicide quantity in 2002 relative to previous years (table 4.3.1). The phosphinic acid share of herbicide acre-treatments increased from 2 percent in 1996 to 6 percent in 2000 on corn, 7 to 13 percent on winter wheat, 3 to 7 percent on durum wheat, and 4 to 10 percent on other spring wheat. However, shares of sulfonyl ureas and other new herbicide families on corn and wheat were higher in 2000 than in 1996. (see "Crop Production Practices" in the ARMS Data Tool.)

Since some producers used phosphinic acids and other newer post-emergence herbicides (applied after weed emergence) instead of older pre-emergence herbicides, the shares of corn, cotton, soybean, and spring wheat acres receiving post-emergence applications were higher and acres receiving pre-emergence applications lower in 2000 than in 1996. While producers treat many acres with both pre- and post-emergence herbicides, the shares of acres receiving post-emergence applications only were higher in 2000 than 1996, with the share of soybean acreage almost doubling from 28 percent in 1996 to 50 percent in 2000. (See "Crop Production Practices" in the ARMS Data Tool.)

Pesticide Prices

The USDA/NASS agricultural chemical price index was relatively stable from 1996 through 2003, while the herbicide price index declined by 4 percent, the insecticide price index increased by 17 percent, and the fungicide/other index was stable (table 4.3.4). Prices of individual pesticides may behave differently, responding to different factors. The price for glyphosate fell by 22 percent from 1996 to 2003, which may reflect marketing strategy as well as its patent's expiring in September 2000. The lower price may have encouraged producers to use glyphosate and genetically modified herbicide-tolerant seed. The price for methyl bromide increased by 147 percent from 1996 to 2003, because EPA required supply reductions to implement the Montreal Protocol phaseout, beginning in 1999. Higher prices encouraged producers to use other pesticides, and focused methyl bromide use on crops and acres with higher returns.

Based on USDA/NASS indices, pesticide prices have risen more slowly than wages, fuel prices, and crop prices since the late 1990s, which departs from the post-1980 trend of pesticide prices rising faster than crop and fuel prices (fig. 4.3.2, table 4.3.4). Pesticide prices have risen more slowly than crop prices since 2000 and fuel prices since 1998. Recent trends could encourage producers to substitute pesticides for fuel- and labor-intensive practices, but the slowdown in pesticide prices could also reflect declining demand.

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Pest Management Practices

Growers use biological and cultural practices and information to improve the cost effectiveness of pest management, often coordinating their use through Integrated Pest Management (IPM). Use of practices varies by crop because of different pests and production requirements. Cotton growers use many practices, especially insecticide applications, more intensively than do growers of other crops because of the crop's high value and its vulnerability to pests (especially insects). (See "Crop Production Practices" in the ARMS Data Tool.)

Corn, cotton, soybean, and wheat growers reported tilling, chopping, mowing, or cleaning equipment for pest control on more than 30 percent of acres in 2000, but cotton growers reported the highest proportions. Cultivation for weed control was higher in 1996 than in 2000 on cotton (89 percent of acres versus 65 percent) and soybeans (30 percent versus 17 percent). This may reflect increased use of genetically modified herbicide-tolerant seed and post-emergence herbicides. The share of corn acres cultivated for weed control was higher in 2000 (38 percent) than in 1996 (32 percent).

Among other practices, growers reported adjusting planting or harvest dates to manage pests on about 20 percent of cotton and wheat acres in 2000–more than on corn or soybeans. Growers reported alternating pesticides to prevent pest resistance on 30 percent or more of corn, cotton, soybean, and spring wheat acres in 1996 and 2000, but only about 10 percent of winter wheat acres. (Pesticides are generally applied to 50 percent or less of winter wheat, but to 90 percent or more of the other crop acres.) Cotton growers reported protecting beneficial organisms on the highest proportion of acres, approximately 50 percent in 1996 and 2000.

Cotton growers reported more scouting for insects and reliance on independent consultants or scouts than did growers of other crops in 1996 and 2000 (See AREI Chapter 4.7). Corn, cotton, soybean, and wheat growers reported scouting for weeds, insects, and diseases on 50 percent of acres or more. With the exception of scouting for insects on cotton, operators, partners, or family members scouted the most acreage for insects and weeds, more so than farm supply/chemical dealers and independent consultants and scouts. Independent consultants or scouts had the largest role on cotton, scouting for insects on about 50 percent of cotton acres and weeds on 20-25 percent. On corn, they scouted about 10 percent of acres for insects and 12 percent for weeds.

Farm supply or chemical dealers were identified by growers as primary pest management information sources on corn, soybean, and wheat acreage, ranging from 40 percent on wheat to over 60 percent on corn and soybeans in 1996 and 2000. Cotton growers relied more on independent crop consultants or pest control advisors (30 percent of acres in 2000), Extension (17 percent), and commercial scouting (10 percent) than did growers of other crop