Basal glume rot (Pseudomonas syringae pv. atrofaciens) on wheat and barley in FRG and resistance screening of wheat¹

Abstract

A survey in 1987 and 1988 revealed that basal glume rot, caused by Pseudomonas syringae pv. atrofaciens , occurred nearly everywhere in FRG. The symptoms of the disease usually consisted of water‐soaked dark green to brown lesions on unripe wheat heads, mainly at the basal end of the glumes, which later became dark brown. Forty‐six isolates of P.s. atrofaciens were obtained from glumes, seeds and leaves of wheat and barley. For a fast identification of the isolated bacteria, a bio‐assay was developed. Four to five‐day‐old wheat seedlings, grown on wet filter paper in Petri dishes, were pricked at two‐three sites with a dissecting needle contaminated with bacteria. After 2–3 days, pathogenic isolates induced brown to black spots. The bacterial isolates from wheat inhibited the growth of several fungi grown on potato dextrose agar. In contrast, an authentic isolate of P.s. syringae obtained from wheat showed no inhibitory effect. During screening for resistance, several cultivars of spring and winter wheat were tested in the greenhouse and/or field tests. The results revealed marked differences in the susceptibility of different cultivars.