DISTRIBUTION OF AND SOURCES OF RESISTANCE TO BIOTYPES OF PYRENOPHORA TERES IN WESTERN CANADA

Abstract

The distribution in western Canada of three biotypes of Pyrenophora teres, the cause of net blotch of barley, was determined. Two of these produced typical net blotch symptoms but differed in virulence and were found throughout the prairies in 1974. The third, which produces spot-like symptoms, was found only in Manitoba and comprised half the total isolates. The incidence of net blotch was higher in fields of two-rowed than in six-rowed barley. Resistance to the three biotypes of P. teres was found in several barley lines when symptom expression and rate of conidial development on infected host tissue were compared. CI 9214 was superior to CI 5791, the resistance source used in some barley breeding programs.