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Visual assessment of maize ears and Fusarium spp. isolation from kernels were compared to determine resistance in 20 Zambian maize hybrids. The mean percentage Fusarium spp. isolations in non-inoculated field experiments varied between years (12–62%). Symptomless infection by Fusarium spp. had domination over symptomatic. More than 95% of the Fusarium species isolated were F. vertcillioides. A disease severity index and the percentage of visibly diseased, discoloured and damaged kernels did not differentiate hybrids with respect to Fusarium spp. ear rot under natural conditions. Artificial inoculation provided a good estimate of Fusarium spp. resistance based on visual symptoms in a year of moderate disease pressure, but not in a year of high disease pressure. The percentage Fusarium spp. isolations showed significant differences between hybrids after inoculation, and it was significantly negatively correlated with the number of days from planting to midsilk. Parental line L5522 contributed to hybrid resistance to Fusarium. The hybrids MM 701-1 and MM 752 were the most resistant among the 20 hybrids. [ABSTRACT FROM AUTHOR]

By using multivariate statistical methods an overview was obtained of how size distribution of proteins, surface properties of freeze-dried gluten, sedimentation tests, glutenin macropolymer (GMP, gel protein) properties and dough rheological tests were related to properties of hearth and pan loaves produced by small-scale experimental baking. Both oil absorption capacity and hydration capacity of gluten were positively related to loaf form ratio as well as to mixing properties, the presence of high molecular weight (HMW) glutenin subunits 5+10, the proportion of SDS-insoluble glutenins and the rheological properties of glutenin macropolymer. Within each cultivar, higher flour protein content gave lower oil absorption capacity and hydration capacity. This could be related to the observed increase in the proportion of monomeric proteins, which are likely to have different surface properties than the polymeric proteins. Whereas an increased flour protein content positively affected pan loaf volume, this change in ratio between monomeric and polymeric proteins negatively affected the form ratio of hearth loaf. The results confirmed that hearth loaf provides a better model system than pan loaf for distinguishing between the effects of protein content and protein composition. [Copyright &y& Elsevier]

The pathogenic variability of the barley scald fungus, Rhynchosporium secalis, in central Norway was examined in 1994. The climate in this region is usually cold and wet during the growing season of spring barley. Leaf blotch is prevalent and causes significant yield losses. Forty-two isolates of the fungus, from naturally infected spring barley in four counties, were differentiated into 32 pathotypes by the standard differential set for R. secalis. All pathotypes were complex and had virulence for nine to 22 differentials. The cultivar Osiris was resistant to all isolates tested. The cultivars C.I.8162, Hudson, Atlas 46 and C.I.3515 were resistant to the majority of the isolates. Several differentials with various resistance genes were susceptible to up to 100% of the isolates. Isolates were derived from local cultivars with no known resistance genes, suggesting that R. secolis populations in central Norway are characterized by a high degree of seemingly unnecessary pathogenicity. Because of the great variability and complexity of the pathotypes, traditional breeding methods using single major genes are not likely to be effective in central Norway. [ABSTRACT FROM AUTHOR]

Chilling resistances in moss pathogenic fungi, Pythium ultimum var. ultimum, from Longyearbyen, Svalbard (78 degree N, 15 degree E), located in the Arctic Zone and in the same isolates from Temperate Zone, were determined. Both strains had similar optimum growth temperatures. However, the strains from Svalbard could grow and survive at 0 - 5 degrees C. In addition, chilling treatment induced irregular mycelial morphology in the Arctic isolates. On the other hand, the isolates from Japan did not grow at temperatures below 5C and were destroyed after chilling stress (0 degree C for 3 days or at 4 degrees C for 1 week). The results suggested that isolates from Svalbard highly adapted to the severe spring condition in Polar environments.