Impact of tillage on lupin growth and the incidence of pathogenic fungi in southern New South Wales

Narrow-leafed lupins (Lupinus angustifolius) were grown in cultivated and direct-drilled plots at 4 field sites in southern New South Wales in 1998 to determine the effect of tillage on seedling vigour, disease and yield. The early growth of lupins in direct-drilled plots was reduced compared with seedlings in cultivated plots at 3 of the sites. However, the biomass of lupin plants in the direct-drilled treatments was 20% greater than in adjacent cultivated plots at harvest. The lower biomass in cultivated plots appeared to be primarily related to an increased incidence and severity of stem rot caused by Sclerotinia sclerotiorum. The increased stem rot in cultivated plots was also associated with a decline in yield of between 16 and 35% across the sites compared with direct-drilled plots. The direct-drilled treatment reduced the severity of brown spot, caused by Pleiochaeta setosa, at the 2 sites where stubble was retained from the previous wheat crop. These results suggest that direct drilling into cereal residue provides benefits over cultivation for the growth of lupins in southern New South Wales where crop infection by Sclerotinia and/or brown spot may be significant.