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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.

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The influence of grazing management, herbicide and fertiliser on botanical change in two perennial grass based pastures was assessed over six years at two sites in central New South Wales. Ten treatments at both sites compared continuous grazing, three seasonal rests from grazing (autumn, winter, summer), and herbicide application for seedling grass control, each at two levels of fertiliser addition (nil, recommended). These treatments were designed to screen options for management rather than devise complete systems. In a degraded perennial pasture dominated by annual grasses, the proportion of perennial grasses and forbs increased with summer rests, especially at the recommended fertiliser level. Legumes increased with herbicide application, and annual grasses remained high in the continuously grazed control and other treatments. There were no significant effects on composition from autumn or winter rests. On the summer rest treatment at the recommended fertiliser level, perennial grasses (mostly cocksfoot) increased from 11% to 30% compared with the control where perennial grass declined below 5%. The increase was due to both recruitment and increase in size of existing plants, as a consequence of resting the perennial grasses when actively growing, flowering and setting seed, in favourable seasons. In contrast, on the better quality perennial pasture dominated by phalaris, there were limited management effects and perennial grasses increased on all treatments over time. The absence of a response at this site was attributed to a lenient stocking rate, dominant perennial grasses and limited rainfall during periods when active growth might be expected. Summer rests in this case also led to a small increase in forbs. The data suggest that perennial grasses can be encouraged with a conservative stocking policy that maintains the available feed-on-offer above 1 t DM/ha through seasons of active growth.