The influence of 3 stubble management practices, stubble retention, stubble incorporation and stubble burning, on the incidence of crown rot of wheat (Triticum aestivum L.) caused by Fusarium graminearum Schwabe Group 1, and on plant development and grain yield was examined. The incidence of disease (percentage plants affected) was assessed in a susceptible (cv. Sunstar) and moderately resistant cultivar (cv. Suneca) in 1986. In 1987 Sunstar was planted into stubble of the 2 cultivars to assess the influence of host resistance on disease carryover. Crown rot was highest in the stubble retention plots (81% incidence in 1986 and 59% in 1987), whereas stubble burning decreased disease incidence in both years, with the reduction being greater in the second year (47% and 16%). Stubble incorporation was ineffective in reducing disease levels (76% and 53% in years 1 and 2). The incidence of crown rot did not differ in the 2 cultivars. At the harvest sampling in 1987 there were no differences in crown rot incidence in plants sown into stubble of the 2 cultivars. Grain yield did not differ significantly between treatments, but early season plant dry weight was reduced in the retained plots. Grain protein levels were reduced (P< 0.05) in the stubble burnt plots.

The effect of 3 stubble management regimes (burning after harvest, incorporation with a disc plough, retention on the surface) on the incidence of infection of wheat with Fusarium graminearum Schw. Group 1 was studied for 5 seasons at 2 sites at Moree, New South Wales. One site had high initial incidence (site A) and the other low initial incidence (site B). There were no differences in incidence of infection between retained and incorporated treatments. Stubble burning reduced the increase in incidence of infection in 2 of 5 years at site A and 3 of 4 years at site B. Failure of control in other years was attributed to susceptible weed hosts and poor burns. When stubble was retained on the plots at site B that had been burnt, incidence of infection in the next season increased to a level not significantly different from the retained or incorporated treatments. Incidence of infection at the fourth consecutive wheat crop at both sites was close to the maximum recorded, which was 92% at site A and 65% at site B. There was no evidence of a decline in incidence by the time of the most recent season assessed (eighth year of continuous wheat cultivation at site A, and sixth year at site B). In most years, the differences in yield between treatments were not significant.