Gordon M. Murray

Estimating disease losses to the Australian wheat industry

The incidence, severity and yield loss caused by 41 pathogens were assessed from a survey of 18 wheat pathologists covering the wheat-growing areas of Australia. The survey provided data on the frequency of years that each pathogen developed to its maximum extent, the proportion of the crop then affected in each growing area, and the yield loss that resulted in the affected crops with and without current control measures. These data were combined with crop production and quality data to estimate the value of the losses aggregated to the Northern, Southern and Western production regions. Pathogens were estimated to cause a current average loss of

The incidence and relative importance of wheat diseases in Australia

913 × 106/year or 19.5% of the average annual value of the wheat crop in the decade from 1998–99 to 2007–08. Nationally, the three most important pathogens were Pyrenophora tritici-repentis, Puccinia striiformis and Phaeosphaeria nodorum with current average annual losses of

The risk to Australia from Tilletia indica, the cause of Karnal bunt of wheat

212 × 106,

Prevalence and survival, with emphasis on stubble burning, of Rhizoctonia spp., causal agents of sheath diseases of rice in Australia

127 × 106 and

Studies on the seed transmission of Wheat streak mosaic virus

108 × 106, respectively. If current controls were not used, losses would be far higher with potential average annual losses from the three most important pathogens, P. striiformis, P. triticirepentis and Heterodera avenae, being

Survival of Sclerotinia sclerotia under fire

994 × 106,

Sclerotinia minor on canola petals in New South Wales — a possible airborne mode of infection by ascospores?

676 × 106 and

An enhanced protocol for the quarantine detection of Tilletia indica and economic comparison with the current standard

572 × 106, respectively. The average value of control practices exceeded

A review of the methodology to detect and identify Karnal bunt—a serious biosecurity threat

100 × 106/year for 12 pathogens. Cultural methods (rotation, paddock preparation) were the only controls used for 10 pathogens and contributed more than 50% of the control for a further eight pathogens. Breeding and the use of resistant cultivars contributed more than 50% of control for seven pathogens and pesticides for three pathogens. The relative importance of pathogens varied between regions and zones.

Jan Kuiper, Ing.Agr, 1924–1989

A survey of cereal plant pathologists in each State has shown that stem rust is ranked as potentially the most important foliar disease of wheat in most regions. Other major foliar diseases were stripe rust, flag smut, Septoria tritici blotch and leaf rust. Yellow spot has increased in importance since 1975 with the adoption of stubble retention farming in north-eastern Australia and Western Australia. Root rots of major importance were take-all, crown rot, Rhizoctonia bare patch and cereal cyst nematode. Bunt is potentially the most serious disease of the inflorescence but it is very rare because it is effectively controlled by seed-applied fungicides. Most biotrophic foliar diseases are well controlled by selection for resistance. Cultural practices and crop rotation are the main controls for root diseases, while fungicides are mainly used for control of inflorescence diseases. Regional differences in the severity and incidence are pronounced for several diseases.