The reaction of two spring wheat varieties exposed to epidemics of Septoria nodorum and S. tritici of varying intensity and duration

Abstract

Two spring wheat varieties, Cardinal and Kolibri, were inoculated with Septoria nodorum Berk and S. tritici Rob. & Desm. at Growth Stages 3, 7, 10.1 and 10.5 of the Feekes' scale. The treatments included single inoculations at each growth stage and multiple inoculations at 2, 3 and 4 of the above growth stages.Thousand-grain weights of both varieties were reduced by inoculation with either pathogen, S. nodorum causing the largest reduction. Numbers of grain per head in Cardinal were severely reduced by S. nodorum, particularly after the multiple inoculations. In Kolibri, there was evidence of increases in numbers of grain with S. tritici inoculation which nullified the grain size reductions. The results are discussed in relation to compensatory mechanisms and disease tolerance.