Observations were made on the natural infection of tobacco cultivars and breeding lines grown in replicated trials at Beerwah in the Moreton district of South Queensland. This district is notorious for the regular occurrence of blue mould caused by a strain (A.P.T.2) of the fungus able to infect cultivars resistant to the common Australian strain (A.P.T.1). One breeding line derived by backcrossing from Nicotiana excelsior, one from N. velutina and two from N. debneyi suffered the least damage from blue mould. Cultivars bred for resistance to A.P.T.1 suffered less damage than the susceptible cultivar Hicks. Lines that showed the severest leaf symptoms also suffered most loss from stem infection. Three donor parents (N. excelsior, N. velutina and N. debneyil appear to be equally useful as sources of resistance to A.P.T.2.

(Full article published with kind permission from "Tobacco International")