Epidemics of stem rust and their effects on grain yield in the wheat WW15 and some of its derivatives

Abstract

The progress of epidemics of Puccinia graminis tvitici strain 343-Anz-1,2,3,5,6 was examined in field plots of the wheat WW15, its hard-grained derivatives Condor, Oxley and Banks, the slow-rusting cv. Celebration and the fully resistant cv. Timgalen. Additional rust-free treatments were maintained to provide yield and quality comparisons. Severe epidemics developed in WW15, Condor and Oxley, and reduced grain yield in each cultivar by approximately 50 %. Epidemics in Celebration and Banks developed more slowly, and no significant loss in yield occurred. Reduced grain size accounted for most of the yield reduction in WW15, Condor and Oxley. Grain nitrogen concentration was higher in rusted Condor and Oxley than in rust-free treatments. WW15, Condor and Oxley possess little slow-rusting ability and the dependence on Condor and Oxley in the eastern wheat-belt of Australia should be decreased. Banks has effective stem rust resistance and offers potential as a replacement for Condor.