Development of Heterodera Avenae On Resistant Wheat and Barley Cultivars

Resistance to a South Australian population of H. avenae was shown in five cultivars of barley: Athinais, Morocco, Nile, Orge-Martin 839 and CI 8147. With wheat grown under field conditions, similar numbers of larvae invaded seedlings of a susceptible (Halberd) and a resistant (AUS 10894) cultivar. The number of nematodes in, and the number of galls developed on roots of Halberd increased during the growing season, but the number of nematodes tended to decrease in, and the number of galls remained the same on, roots of AUS 10894. In the season after AUS 10894 had been grown, the length of flag leaf and number of fertile spikelets and grains per spikelet were increased on Halberd but grain weight was not affected. The increases in growth and components of yield of Halberd were associated with reduction in the density of the nematode following the growth of the resistant cultivar. Halberd, grown after a season of fallow or medic, grew and yielded better than following a season of AUS 10894.