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Crop-specific sales (as % of total herbicide sales)

Figure 1.2 Global sales of herbicides in 1985 for the world's major crops. Data are expressed as percentages of total herbicide sales. (After Jutsum, 1988.)

In the USA, herbicide application to agricultural land has risen nearly fourfold since 1966 (National Research Council, 1989, p. 45), and now exceeds 200 million kg of active ingredients annually (Aspelin & Grube, 1999). Herbicides used for maize, soybean, wheat, cotton, and sorghum account for most pesticides applied to American cropland (Aspelin & Grube, 1999; United States Department of Agriculture, 1999a) (Table 1.1).

Herbicide use is also intensifying in many developing countries. In India, herbicide use increased more than 350% from 1971 to 1987, primarily for wheat and rice production (Alstrom, 1990, pp. 167-8). From 1987 to 1992, herbicide sales in South Asia and East Asia grew about 4% per year (Pingali & Gerpacio, 1997). By the early 1990s, herbicides were applied to half of the area planted with rice in the Philippines (Naylor, 1994) and more than 40% of the land planted with wheat in Punjab and Haranya, the two states that account for a third of India's total wheat production (Gianessi & Puffer, 1993). Sales and application ofherbicides and other pesticides are also expanding in many regions of Latin America and certain areas of Africa (Repetto & Baliga, 1996, pp.3-8).

Multiple factors promote the use of herbicides as primary tools for weed management. Herbicides can markedly reduce labor requirements for weed management in both mechanized (Gunsolus & Buhler, 1999) and nonmecha-nized (Posner & Crawford, 1991) farming systems. Consequently, herbicides

Table 1.1. Estimated applications of pesticidesa used in greatest quantities for crop production in the USA in 1987 and 1997

Active ingredients (millions of kg)

Table 1.1. Estimated applications of pesticidesa used in greatest quantities for crop production in the USA in 1987 and 1997

Active ingredients (millions of kg)

Pesticide

Use

Applied in 1987

Applied in 1997

Atrazine

herbicide

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