Insects, molds, and fungi take a much-publicized toll of farmers' crops. But what of the invisible pests - ozone, sulphur dioxide (SO2), and other air pollutants that now invade the farmlands?
Research over the past half decade has shown increasingly that such air pollution can damage crops and significantly reduce yields.
Recently C.K. Baker, P. Greenwood, and M.H. Unsworth of Britain's University of Nottingham reported in the journal Nature that SO2 exposures normally found on many British farms make some commercially important plants more susceptible to frost damage. They concluded this after carrying out carefully controlled experiments with winter wheat. They add that this supports suspicions that the combined stresses of air pollution and low temperatures are the reason why it now is difficult to establish grasses and trees in upland areas of northern England.
A review of the subject in the September issue of Environmental Science & Technology, an authoritative journal of the American Chemical Society, makes a similar point. Carefully controlled experiments using the National Crop Loss Assessment Network (NCLAN) show beyond reasonable doubt that much US farmland is exposed to levels of ozone and SO2 that can cause significant loss of yields.
This is just the kind of scientific information that the US Environmental Protection Agency (EPA) has said it needs to set air pollution standards intelligently. Yet EPA funding for the work has been substantially cut back.
This seems a foolish economy. The NCLAN has half a dozen research sites in typical farming areas of the country. More research is needed to uncover effects of various pollution levels and of two or more pollutants working together.
Many more research sites and numbers of experiments were originally planned. However, EPA funding for these has been severely limited and the trend is downward. Fiscal 1982 funding was $2.7 million. Only $2 million has been requested for fiscal 1983. An extra few million dollars could make the difference between a thoroughly adequate research program and one which Environmental Science calls ''severely restricted.''
The implications go beyond farming. The Clean Air Act requires that secondary national ambient air quality standards be established to protect the public welfare, including general ecological effects as well as effects on crops. Wild plants and trees, and the wild life that depends on them, are likely to be affected as much, or more, by air pollution as are crop plants.
Environmental Science says damage to the total ecosystem from ozone, especially, ''is probably far greater than the effect on crops alone.'' Such damage should be pinned down.
Study of air pollution damage to plants, such as that carried out by the NCLAN, is in the national interest. It wouldn't cost much - just a few million dollars a year more than now is spent for the purpose. Yet it could help establish better protection standards for the US countryside.