Spot Form of Net Blotch Resistance in a Diverse Set of Barley Lines in Australia and Canada.

The responses of 95 barley lines and cultivars to spot form of net blotch (SFNB) caused by Pyrenophora teres f. maculata were analyzed as seedlings and adults in Australia and Canada. Cluster analyses revealed complex reaction responses. Only 2 lines (Esperance Orge 289 and TR3189) were resistant to all isolates at the seedling stage, whereas 15 lines and cultivars (81-82/033, Arimont, BYDV-018, CBSS97M00855T-B2-M1-Y1-M2-Y-1M-0Y, C19776, Keel, Sloop, Torrens, TR326, VB0111, Yarra, VB0229, WI-2477, WI2553, and Wisconsin Pedigree) were resistant toward the two Canadian isolates and mixture of Australian isolates at the adult stages. In Australian field experiments, the effectiveness of SFNB resistance in three barley cultivars (Barque. Cowabbie, and Schooner) and one breeding line (VB9104) with a different source of resistance was tested. Barque, which possessed a resistance gene that provided complete resistance to SFNB, was the most effective and showed no effect on grain yield or quality in the presence of inoculum. Generally, cultivars with seedling or adult resistance had less disease and better grain quality than the susceptible control. Dash, but they were not as effective as Barque. A preliminary differential set of 19 barley lines and cultivars for P teres I. maculata is proposed

Validation of a new spot form of net blotch differential set and evidence for hybridisation between the spot and net forms of net blotch in Australia

A recently developed spot form of blotch differential set of 16 barley lines was tested for reaction response to 60 Pyrenophora teres f. maculata isolates from geographically disperse barley crops of Australia. Twelve barley lines (Arimont, Barque, Chebec, CI5286, CI5791, CI9214, CII6150, Dairokkaku, Esperance Orge 289, Galleon, Keel, Skiff, Torrens and TR250) provided differential response between the isolates. The susceptible controls Gairdner and Kombar provided indication of isolate virulence or avirulence. Abundant pathogenic diversity was revealed with 33 designated pathotypes, some of which related to geographic region. AFLP analysis also revealed abundant diversity with each of the isolates representing a unique genotype and one isolate that contained both AFLP bands unique to P. teres f. maculata and P. teres f. teres, the cause of spot form and net form of net blotch respectively, suggesting that sexual recombination between the net form and spot form isolates may have occurred naturally in the field

Survey of Fusarium species associated with crown rot of wheat and barley in eastern Australia

Fusarium species associated with crown rot were isolated and identified from 409 wheat, barley or durum wheat crops from the eastern Australian grain belt between 1996 and 1999. Fusarium pseudograminearum was almost the only species isolated from crops in Queensland and New South Wales. F. pseudograminearum was also the most common species in Victoria and South Australia, but F. culmorum was frequently isolated in these states. F. culmorum accounted for more than 70% of isolates from the Victorian high-rainfall (> 500 mm) region and the South-East region of South Australia. F. culmorum comprised 18% of isolates from the Victorian medium-rainfall (350-500 mm) region, and 7% of isolates from each of the Victorian low-rainfall region and the Mid-North region of South Australia. F. avenaceum, F. crookwellense and F. graminearum were isolated very infrequently. The proportion of F. culmorum among isolates of Fusarium from districts in Victoria and South Australia was strongly correlated with climatic conditions around the end of the growing season, especially with rainfall in November