Comparison of disease severity caused by four soil-borne pathogens in winter cereal seedlings

Abstract

In Australia, crown rot of cereals is predominantly caused by Fusarium pseudograminearum and Fusarium culmorum, and common root rot by Bipolaris sorokiniana. Fusarium graminearum is an important pathogen causing Fusarium head blight worldwide and has also been reported to cause crown rot of wheat. The comparative ability of F. pseudograminearum, F. culmorum, F. graminearum and B. sorokiniana to cause crown rot and common root rot across a range of winter cereal species requires investigation. In glasshouse trials, we inoculated one cultivar each of barley, bread wheat, durum wheat, oat and triticale with two strains of each of the four pathogens. At 21 days after inoculation, the sub-crown internode and leaf sheaths of each plant were visually rated for brown discoloration. Shoot length and dry weight of inoculated plants were compared with those of non-inoculated controls. Barley and bread wheat had the highest disease severity ratings on leaf sheaths and sub-crown internode (64.7–99.6%), whereas oat had the lowest disease severity ratings across all pathogens (<5%). The shoot length of all cultivars was significantly reduced (by 12.2–55%, P < 0.05) when exposed to F. pseudograminearum. This study provides a comparison of pathogenicity of crown rot and common root rot pathogens and demonstrates significant variation in visual discoloration and host response across a range of winter cereals.