Ramularia leaf spot of barley

One of the major issues challenging barley growers in many countries is the control of Ramularia leaf spot (RLS), caused by the fungal pathogen Ramularia collo-cygni. Although the early reports of R. collo-cygni focused on descriptions of the fungal structures the fungus was reported to produce small, elongated brown lesions with pinkish-white sporulating hyphae on the leaf underside of Triticale. Diagnosis of the RLS by visual means has been supplemented by additional tests. Sachs incubated leaves on acidified agar and the resultant reddish colour indicated the presence of the fungus. The initial description of Ramularia leaf spot symptoms was on barley in northern Italy. The fungus is known to infect grass and other hosts and exhibits a non-specific life cycle, which makes control a challenge. Understanding the interaction between the fungus, host and environment has presented researchers with significant challenges. The late season production of symptoms has challenged researchers attempting to define the factors which influence disease epidemics.