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Effects of Open-Air Fumigation with Sulphur Dioxide on the Occurrence of Fungal Pathogens in Winter Cereals. A. R. McLeod, Research officer, Terrestrial Ecology Section, Life Sciences Branch, Central Electricity Research Laboratories, Kelvin Avenue, Leatherhead, Surrey, KT22 7SE, UK; Phytopathology 78:88-94. Accepted for publication 3 June 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-88.

An open-air fumigation system was constructed to determine the effects of sulphur dioxide on the growth and yield of winter cereals. Winter barley (Hordeum vulgare) cultivar Sonja was grown during 1982-1983 and winter wheat (Triticum aestivum) cultivar Rapier during 1983-1984. This paper describes the occurrence of the pathogens Puccinia hordei, Rhynchosporium secalis, and Pseudocercosporella herpotrichoides on barley and Erisyphe graminis, P. herpotrichoides, and Fusarium spp. on wheat at four sulphur dioxide concentrations in the range 0.01-0.06 ppm. The crops were exposed to elevated levels of sulphur dioxide in 30-m-diameter field plots from shortly after emergence in autumn until maturity during the following summer. Interactions were observed between the levels of disease infestation and exposure to sulphur dioxide. The magnitude of the SO_2- pathogen interactions at ambient concentrations and under field conditions suggests that these have considerable importance for plant growth and requirements for disease control measures that may not be apparent from air pollution studies using conventional exposure chambers.