SURVEY OF THE INCIDENCE OF WHITEHEADS IN WHEAT CROPS GROWN IN NORTHERN NEW-SOUTH-WALES, 1976-1981

The incidence of whiteheads in wheat in the northern areas of the wheat belt in New South Wales was surveyed from 1976 to 1981. Whiteheads were associated with plants affected by crown rot and were common in wheat crops in the survey areas, although the incidence was low (less-than-or-equal-to 5%) in most crops. There was a high incidence of whiteheads ( > 5%) in a small number of crops in each year. The mean incidence of whiteheads was highest in 1977 and was generally higher in the western, lower rainfall areas than in the other areas each year. The predominant crown rot pathogen Fusarium graminearum Group 1 was isolated from 97% of 1450 stem bases collected from plants with whitehead symptoms. A fallow of 18 months was not always associated with a reduction in the incidence of whiteheads.