LONG-TERM EFFECTS OF STUBBLE MANAGEMENT ON THE INCIDENCE OF INFECTIONOF WHEAT BY FUSARIUM-GRAMINEARUM SCHW GROUP-1

The effect of 3 stubble management regimes (burning after harvest, inc orporation with a disc plough, retention on the surface) on the incide nce 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 h ad hi-h 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 inc rease in incidence of infection in 2 of 5 years at site A and 3 of 4 y ears at site B. Failure of control in other years was attributed to su sceptible weed hosts and poor bums. When stubble was retained on the p lots at site B that had been burnt, incidence of infection in the next season increased to a level not significantly different from the reta ined 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 treatment s were not significant.