For farmers, chemical pest control can itself become a "pest." Poisons and weed killers that protect one type of crop can injure other kinds of crops, sometimes indirectly.
Serious indirect damage can occur when poisons used to protect crops kill off honeybees. Roger Morse, an apiarian scientist at Cornell University, says bee losses now are reaching record proportions, at least in New York State. Last year, over 4,500 honeybee colonies in 164 apiaries suffered pesticide-induced losses.
This threatens such important bee-pollinated crops as almond, alfalfa, apple, and cherry. Indeed, some 50 different crops require bee pollination in the United States.
Morse says: "As American agriculture intensifies and specializes, it becomes more dependent on honeybees in apiaries because other natural pollinators are not as manageable or available and therefore less reliable. Several major apiarists are considering relocation. This could hurt New York which, after Washington, is the second largest apple-producer among the 50 states.
Meanwhile, a different kind of problem is demonstrated in the Vale of Evesham in England where drifting herbicides and herbicide vapors seriously injure tomatoes, lettuce, and other market garden crops. As biologist Graham R. Martin of the University of Birmingham recently reported in New Scientist, the pattern of farming in the Vale highlights the trouble.
There, market gardens are side-by-side with grain fields receiving herbicides. Both crops are important to the Vale's farming economy so that the damage can't be dismissed as a lesser evil of modern agriculture. Also, Martin notes, it is recognized that the injury to vegetable and berry crops indicates a larger environmental danger. Thus the problems of the Vale are a general warning.
The common element in these reports is that the productivity of some parts of modern farming, especially grain production, has come to depend on chemicals with little thought being given to effects on other types of farming. There is no easy remedy.
It is not a simple matter of curbing "careless" use of chemicals or of banning certain formulas. Beekeepers actually suffered when DDT was banned. Their bees could detoxify DDT but not the chemical Sevin which replaced it. Indeed, Morse notes that suspicion of pesticides has restricted the variety available and discouraged development of new formulations. "This leaves farmers with less flexibility in choosing ones to use," he says.
Clearly, this is a case where the impact of new farming technology has not been foreseen even for farming, let alone the environment at large. However, there now are enough warnings to justify priority research efforts to determine the wisest means of pest c ontrol compatible with the health of agriculture as a whole.