Fusavium voseum 'Graminearum' was found to be the predominant fusarium associated with crown rot of wheat in the eastern wheat belt of Australia. This conclusion was based on quantitative surveys involving isolations from stem bases of crown rot-affected plants at growth stages 10.5-11 which were collected at random in the 1972, 1973 and 1974 growing seasons. The majority of the isolates of F. roseum 'Graminearum' did not form perithecia in culture or on sterile wheat straw and are referred to as group 1 isolates to distinguish them from group 2 isolates which normally form perithecia in culture. The two groups can also be distinguished on the basis of cultural characteristics. Several group 2 isolates were obtained from wheat stem bases. The results indicate that the incidence and severity of crown rot caused by F. roseum 'Graminearum' was greater in areas where plants were affected by low soil moisture. The disease was found to occur in all areas of the eastern wheat belt which were surveyed.

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The incidence and spatial patterns of wheat plants infected by Fusarium graminearum Group 1 were assessed in six fields in northern New South Wales, Australia, over a four-year period. The incidence of infected plants declined from 1978 to 1981 in fields where wheat was sown each year, where there was a bare fallow of 18 months and where sunflowers were sown in one season. The pattern of infected plants tended to be regular (uniform) where the incidence of infected plants was particularly high (> 96%). In all fields where a clustered (aggregated) pattern was detected, 12% to 64.4% of plants were infected. A random pattern was observed at a number of sites. There was a positive association between loss in potential yield and the incidence of infection, basal browning of plants and whiteheads. Losses of up to 89% were recorded.

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.