Effects of sulphur dioxide on the development of fungal diseases of winter barley in an open-air fumigation system

Abstract

The development of fungal diseases was monitored through three consecutive growing seasons (1984–1985, 1985–1986 and 1986–1987) on field plots of winter barley ( Hordeum vulgare L). cv. ‘Igri’ exposed to sulphur dioxide (SO 2) concentrations in the range 0.005–0.048 μl 1 −1 using an open-air fumigation system. In each season the incidence and severity of powdery mildew ( Erysiphe graminis D.C. ex Mérat f. sp. hordei Em. Marchal) increased and leaf blotch ( Rhynchosporium secalis Oudem J.J. Davis) decreased in plots exposed to elevated levels of SO 2 (0.014–0.048 μl 1 −1 SO 2) compared with control plots exposed to background levels of 0.005–0.009 μl 1 −1 SO 2. The apparent infection rate of powdery mildew was also greater in SO 2-treated plots. The effects of SO 2 exposure on eyespot ( Pseudocercosporella herpotrichoides (Fron) Deighton) and black ear moulds ( Cladosporium and Alternaria spp.) were variable. Sharp eyespot ( Rhizoctonia cerealis van der Hoeven), Fusarium foot rot, brown rust ( Puccinia hordei Otth.), Septoria nodorum Berk., net blotch ( Pyrenophora teres Sacc.) and Botrytis spp. infection on the ear were all apparently unaffected by SO 2.