Disease Note

Unique Symptoms Induced in Ethiopian Barley Cultivars by Rhynchosporium secalis. S. Kelemu, Department of Plant Pathology, Montana State University, Bozeman 59717. E. L. Sharp, Department of Plant Pathology, Montana State University, Bozeman 59717. Plant Dis. 70:800. Accepted for publication 18 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-800a.

Ethiopian barley (Hordeum vulgare L.) cultivars PI 382282, PI 382471, PI 382488, PI 382509, and PI 383036 were resistant to Rhynchosporium secalis (Oud.) J. J. Davis, the causal organism of barley scald. However, unusual scald lesions developed on leaf sheaths of these cultivars when tested in the field with a R. secalis isolate from Bozeman, Montana; the blades remained free from symptoms. Brown discoloration and subsequent wilting of leaf sheaths were noted in seedling tests, whereas the blades were free from scald symptoms. This phenomenon of symptom expression has been previously unreported. Both the leaf sheaths and leaf blades of certain cultivars, e.g., Osiris (CI 1622), were symptomless. Leaf sheath resistance and blade susceptibility were noted in other cases. In powdery mildew of barley, some barley cultivars have resistant leaf sheaths and susceptible blades, and vice versa (J. G. Moseman, personal communication). The relative damage resulting from this type of symptom is unknown but may be considerable, since partial or complete defoliation may occur.