Resistance to common root rot (Cochliobolur sativus) in wheat in Queensland

Abstract

The field resistance to common root rot (Cochliobolus sativus) of wheat lines, graded for their reaction to this disease in Canada, was determined under Queensland conditions. Several Australian varieties were also examined. Lines considered resistant and susceptible in Canada behaved in a similar fashion under Queensland conditions, while Australian varieties were generally intermediate. Discolouration of the sub-crown internode was the commonest symptom of the disease and was associated generally with a decrease in individual plant yield and in the number of heads on each plant. Discolouration of the sub-crown internode associated with Pyrenochaeta sp. in one experiment gave a varietal reaction pattern similar to that obtained with C. sativus at other sites. There appears little relationship between varietal reaction to common root rot and that previous1 reported to crown rot (Gibberella zeae).