as home and garden uses, golf courses, and other landscaping—virtually all seed is purchased.

Private-sector plant-breeding R&D has been growing rapidly. In nominal terms, private-sector spending on plant breeding rose from $6 million in 1960 to $400 million in 1992 (Economic Research Service 1995). In real terms, private-sector spending increased by a factor of about 13 over this period (an average annual growth rate of 8.3%).

The public and private sectors also differ substantially in the types of breeding R&D undertaken. The public sector concentrates primarily on basic breeding R&D, notably basic research on breeding methods and germplasm enhancement. Each of those general categories accounts for about 30% of public-sector breeding effort, but only 10% of private-sector breeding effort (Frey 1996). The private sector concentrates primarily on cultivar development, that is, preparation of varieties for commercial release.

R&D on transgenic plants exhibits similar differences between the public and private sectors. Most studies have used the number of field trials of transgenic plants as an indicator of R&D effort (Huttner et al. 1995; Ollinger and Pope 1995).

From 1987 to the end of May 1999, the USDA Animal and Plant Health Inspection Service (APHIS) approved 6,531 applications for field trials of transgenic agronomic crops. Data provided by APHIS list the crops involved in 6,522 of them and the types of traits in 6,516. Field trials conducted by private industry focused on herbicide and insect resistance, both of which complement existing product lines of the agrichemical companies responsible for the overwhelming majority (81%) of the trials (table A.3). Universities and nonprofit research institutes focused relatively more effort to basic research (for example, on marker genes) and traits like viral resistance and bacterial resistance, for which pesticidal chemicals are not marketed. Private-sector field trials focused overwhelmingly on corn, which accounted for almost half the industry total (table A.3). Four other major crops—soybeans, cotton, potatoes, and tomatoes—accounted for virtually all of the remainder. The public-sector effort was distributed somewhat more evenly across crops.

USDA estimates that in 1997 US farmers spent $6.7 billion on seed and $8.8 billion on pesticides for agronomic crops alone (Economic Research Service 1997). Seed and pesticide sales have been increasing during the 1990s (figure A.1). Corn, soybeans, wheat, cotton, and potatoes comprise the largest farm-sector markets for seed (table A.2). Corn, soy-