Reassessing pesticides' value.

Farmers worldwide invest some $2.4 billion annually in pesticides to protect rice -- more than growers spend on pest-control chemicals for any other crop. Moreover, rice pesticides "are among the most toxic agrochemicals," according to the Philippines-based International Rice Research Institute (IRRI). And that's important, a new IRRI study argues, because rice farmers waste much of their pesticide investments. Moreover, after factoring the health costs of pesticides into the economic analyses of rice production, "the net benefits of pesticide use in the areas studied were negative," the study concludes.

The new 100-page analysis reviews and synthesizes the findings of a host of published studies and field trials on rice production and associated pesticide-related health effects. IRRI's report indicates that both farmers and the rice-research community exaggerate the threat that rice pests pose -- while largely ignoring the costs, both to health and the pocketbook, of pesticide application.

For instance, IRRI cites one recent Philippine survey that found 31 percent of rice farmers thought all insects are pests, and that 80 percent of surveyed growers spray pesticides when they see what they deem to be pests. Moreover, though these farmers have largely switched in recent years to new pest-resistant cultivars, they "spray as much as they did with nonresistant varieties."

Indeed, some 26 percent of surveyed growers said they sprayed more. Ironically, though Philippine rice growers expected to lose more than 35 percent of untreated crops to insects and other pests -- levels typical of 20 or more years ago -- IRRI cites experiments and trials that demonstrate losses associated with unsprayed, resistant cultivars typically average only 5 to 10 percent annually.

When it balanced the value of crops against the costs of applying pesticides and of treating chemical handlers for pesticide-related health effects, IRRI found that "natural pest control" -- which it described as conserving natural predators of dee pests, usually by avoiding the use of pesticides --"consistently has the highest net benefits." In most years, IRRI calculates, the practice can return almost three times the benefit of spraying fields with the aim of achieving complete pest control.

These findings tend to run counter to those in a major study of pesticides' value to U.S. fruit and vegetable growers. Published last September by the Park Ridge, Ill.-based American Farm Bureau Research Federation, this study found that even a 50 percent cut in pesticide use on nine "minor" crops -- potatoes, oranges, tomatoes, grapes, lettuce, apples, onions, sweet corn, and peaches -- would cut yields dramatically and raise costs to growers and consumers.

Halving pesticide use would cut yields roughly 20 percent for processed vegetables and some 42 percent for fresh vegetables, the Farm Bureau said. Estimates of fruit losses tended to be even higher -- from a 28 percent reduction in oranges to a 59 percent fall in peach yields. Additional drawbacks of reducing pesticide use would include higher labor costs, higher food-processing costs, seasonal gaps in the supply of some fruits and vegetables, and the need to plant more acres, according to Ronald D. Knutson, director of the Agricultural and Food Policy Center at Texas A&M University in College Station, who led this analysis.

The U.S. study did not account for health effects in its analyses. But some have cited concerns over cancer (SN: 7/3/93, p.4&10) and other human-health risks (SN: 1/22/94, p.56). The Farm Bureau asserted such health considerations are driving calls to cut U.S. pesticide use. "Chemical manufacturers, faced with expensive tests to label products for individual commodity use, have generally responded by dropping labels for many low-use commodities" such as produce, the bureau also reports.