First Report of Scald of Triticale Caused by Rhynchosporium secalis in North America. Ronald E. Welty, Research Plant Pathologist (retired),; USDA-ARS, National Forage Seed Production Research Center, Oregon State University, 3450 SW. Campus Way, Corvallis 97331. Robert J. Metzger, Research Geneticist (retired), USDA-ARS, National Forage Seed Production Research Center, Oregon State University, 3450 SW. Campus Way, Corvallis 97331. Plant Dis. 80:1220-1223. Accepted for publication 12 July 1996. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1996. DOI: 10.1094/PD-80-1220.

Scald, caused by Rhynchosporium secalis, was found for the first time on leaves of triticale in the Willamette Valley in Oregon in April 1995. Koch’s postulates were completed and four separate inoculation studies were done with 12- to 17-day-old greenhouse-grown seedlings of triticale lines. Seedlings were examined beginning 3 days after inoculation and at 2- to 3-day intervals until a final rating was made 11 to 20 days after inoculation. Nine to 15 days after inoculation, leaves of susceptible plants of triticale lines 149 TR 3-232, 83 TP 1-121, and 191 TR 2-12 lost turgor, wilted, and collapsed, changing from green to gray to chlorotic. No leaf lesions developed in triticale lines 5735 TW 3-324 and 431 TU 1-22. Seedlings of rye, winter and spring wheat, and barley were also inoculated with conidia of R. secalis. Severe scald developed in rye cvs. Prima and Jingshou and rye semidwarf line SD-152. Some cultivars of inoculated barley developed small lesions along margins of leaves, but were considered resistant to scald. No disease symptoms developed in inoculated wheat. Symptomatic leaf sheaths and blades from triticale line 149 TR 3-232 were dried and deposited in the Herbarium, Department of Botany and Plant Pathology, Oregon State University, Corvallis. A culture of R. secalis from triticale in Oregon was deposited in the American Type Culture Collection, Rockville, MD, as ATCC 96698.