The incidence and control of mercury resistant strains of Pyrenophora Avenae in british and new zealand seed oats

All of 47 samples of British spring oats and 7 out of 31 samples of British winter oats harvested in 1968 and 1969, and 23 out of 156 samples of New Zealand seed oats harvested in 1969 and 1970 were infected with mercury‐resistant strains of Pyrenophora avenae . Infection with these strains ranged from 0.25% to 79% in British spring oats, 0.25% to 1.75% in British winter oats, and 0.25% to 8.50% in New Zealand seed oats. Best control of the fungus in both British and New Zealand seed oats was obtained with seed dressings containing methyl arsenic sulphide. A thiram seed steep did not give complete control.