Identification and population dynamics of bacteria in symptomatic oat leaves

Bacteria isolated from symptomatic oat leaves included pseudomonads,Erwinia herbicola, and others.Pseudomonas coronafaciens was isolated predominantly from leaves with halo blight symptoms or necrotic spots. Leaves with red leaf symptoms yielded many types of bacteria, including saprophytic pseudomonads,P. syringae, E. herbicola, Bacillus sp.,Micrococcus sp.,Corynebacterium sp., a yeast, and other unidentified species. Only isolates ofP. coronafaciens were pathogenic on the plant hosts tested. The bacteria associated with red leaf symptoms exist as saprophytes and/or epiphytes on leaves with those symptoms. It is concluded that bacteria do not contribute to red leaf symptom development in oats, but symptomatic leaves provide an environment for their growth.