ing the amount of active ingredient applied per treated acre. We do that by dividing the total amount of each material used by the number of treated acres, which we estimate by multiplying planted acreage by the fraction of acreage treated. If the fraction of acreage treated is not reported (for instance, for other pesticides used on fruits and vegetables), we use planted acreage instead (Table 2-2). Planted acreage is likely to be larger than treated acreage, because some acreage is not treated, so this procedure can result in an estimate of application rate that is lower than the actual rate.
Potatoes are the most pesticide-intensive US crop, because of their heavy use of soil fumigants (Table 2-3). Other vegetables and apples are the next most intensive, receiving a total of about 20 lb of pesticides per treated acre. Citrus (9.6 lb/acre) is also highly pesticide-intensive. (Lin et al., 1995). In contrast, cotton, the most pesticide-intensive of the major crops, received only about 5 lb/acre, about one-fourth to one-half as much as most fruit and vegetable crops. Corn received less than 3 lb/acre, and soybeans and wheat 1lb/acre or less. Only in the case of herbicides are application rates per treated acre comparable between major crops and fruits and vegetables. Corn and cotton receive roughly the same amounts of active ingredients per acre as potatoes, other vegetables, apples, and other fruits (Lin et al., 1995).
The total amount of pesticides applied to some major crops (Figure 2-2) increased over the last few years after declining for over a decade. Pesticide use in US agriculture increased steadily from the late 1940s until around 1980, because of the spread of herbicide use on corn and soybeans (ERS 1997, Osteen and Szmedra 1989). Pesticide use on major grain and oilseed crops has fallen consistently since the early 1980s. The adoption of pest-management programs that take advantage of the strengths of new pesticides has contributed to decreasing the amount of pesticides used. For example, a 1992 survey showed that pesticide use in Missouri grain crops had decreased by 6% since 1975 while the total quantity of herbicide and insecticide active ingredients had decreased by 38%; the decrease in herbicide use by Missouri corn and soybean farmers from 1984 to 1992 amounted to 3 million pounds. Those decreases were attributable to the availability of more effective herbicides with lower application rates (NAPIAP, 1997). Similarly, a survey in North Dakota in 1996 showed that many farmers had adopted new cultural and management practices that enhanced the effectiveness of pest management. For example, 75% of the farmers surveyed used field monitoring and crop rotation as part of their integrated program. In addition, several thousand wheat growers were trained in field monitoring, insect identification, and other practices, which resulted in a 75% decrease in the number of acres treated for orange wheat blossom midge.