Comparative Effects of Septoria nodorum on Spring Wheat and Barley

Abstract

SUMMARYSpore suspensions of Septoria nodorum isolated from wheat were used to initiate epidemics on the spring wheat cv. Cardinal and the spring barley cv. Proctor in a field trial. Inoculations were made at g.s.5, 9 and 10.5.4. as separate treatments in wheat and at g.s.5, 9 and 10.3 in barley. A multiple inoculation treatment consisting of all three inoculations was also included.Disease symptoms were much more severe on wheat than on barley both on the leaves and the heads. The largest reductions in 1,000 grain weight were caused by the triple inoculations with decreases of 48 per cent in wheat and 31 per cent in barley. Inoculation at g.s.5 affected only the number of grains and the mean yield per ear and then only in wheat. Fertile tiller number was also reduced by this early inoculation but not significantly. The results are discussed both in relation to the differential reactions of the two hosts and in terms of the epidemiological implications of cross‐infection under field conditions.