VIEW ARTICLE

Techniques

Open-Air Fumigation System for Investigating Sulfur Dioxide Effects on Crops. J. E. Miller, Ecologist, Ecological Sciences Section, Radiological and Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439; D. G. Sprugel(2), R. N. Muller(3), H. J. Smith(4), and P. B. Xerikos(5). (2)(3)(4)(5)Assistant Ecologist, Assistant Ecologist, Scientific Assistant, and Scientific Assistant, respectively, Ecological Sciences Section, Radiological and Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439, (2)Present address: Department of Forestry, Michigan State University, East Lansing 48824; (3)Present address: Department of Forestry, University of Kentucky, Lexington 40506. Phytopathology 70:1124-1128. Accepted for publication 7 March 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-1124.

An open-air fumigation system for treating large field plots of crop plants with sulfur dioxide (SO₂) has been designed and tested. The fumigation system consists of an array of pipes suspended over the field plots through which SO₂ gas is released at controlled rates. The data from 2 yr experiments (three plots in 1977 and five in 1978) were examined for temporal and spatial variations in SO₂ concentrations. The SO₂ concentrations in the plots fluctuated with time due to changing wind speed and turbulence, although the SO₂ concentrations could be controlled within given ranges by adjustment of the SO₂ release rates. This fluctuation in SO₂ concentrations resembled that occurring near point sources of pollution. Statistical analysis indicated that the SO₂ concentrations (1-min averages) were neither normally nor log-normally distributed, and generally appeared to be intermediate between the two. Effects of spatial differences in SO₂ concentrations in the plots were minimized by locating the experimental subplots centrally in each fumigation system. The technique is discussed with regard to its suitability for air pollutant-crop effects studies.