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Factors Associated with the Resistance of Barley to Helminthosporium teres. B. L. Keeling, Former Research Fellow, Department of Plant Pathology, University of Minnesota, now Research Plant Pathologist, Southern Region, Agricultural Research Service, United States Department of Agriculture, Stoneville, Mississippi 38776 ; E. E. Banttari, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Phytopathology 65:464-467. Accepted for publication 7 November 1974. DOI: 10.1094/Phyto-65-464.

Helminthosporium teres caused smaller and fewer lesions on resistant, than on susceptible, barley. Sporulation of the fungus on excised leaves was less on resistant lines than on susceptible ones. No differences were found in spore germination, germ-tube growth, or number of penetrations by the fungus on leaves of resistant and susceptible barley. After penetration, however, the growth of the fungus was inhibited in resistant C.I. 4976 tissue, in which many infections did not progress beyond the penetrated cell. At least one factor in the resistance of barley to net blotch appears to be the formation of an antifungal substance(s) produced as a result of the host-parasite interaction.