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Barley varieties of differing fungal disease resistance were grown in triplicate plots at Lacombe and Lethbridge, Alberta with the disease resistant variety (FR) sprayed with a foliar fungicide to maximize differences in field fungal disease. Both varieties were harvested at soft dough and ensiled in minisilos to assess differences in fungal contamination on ensiling properties, nutritional quality, aerobic stability and associated bacterial and fungal microbiomes. Data were analysed as repeated measures with the effect of treatment × time (duration of ensiling or aerobic exposure) included in the model. The percentage leaf area diseased by net form net blotch was higher (p < 0.05) in the untreated barley cv. Sundre (UN, 59.1% leaf area affected at Lacombe and 25.2% at Lethbridge) than in the FR barley cv. Chigwell (0.7% leaf area affected at Lacombe and 0.1% at Lethbridge). Fungal resistant barley had a lower (p < 0.01) acid and neutral detergent fibre content. Relative abundance of Xanthomonadales was higher (p = 0.02) for FR than UN, while Lactobacillales dominated the bacterial microbiome after 60 day of ensiling in both silages. Bacillales dominated both FR and UN after 21 day of aerobic exposure. Fungal resistant fresh barley forage had a tendency (p = 0.10) for a greater relative abundance of Pleosporales, while UN had higher (p < 0.01) Hypocreales. Mould counts were lower (p = 0.01) for FR than UN after 7 day of ensiling. Fungal resistant barley had minimal influence on the fungal community that contributed to the aerobic deterioration of barley silage. [ABSTRACT FROM AUTHOR]

Tan spot is an important foliar disease of wheat caused byPyrenophora tritici-repentis. Eight races of this fungus have been identified based on their virulence on a wheat differential set. Previous surveys revealed that most isolates collected from the Canadian Prairies belong to races 1 and 2 ofP. tritici-repentisand carry theToxAgene. However, pathogen populations from Alberta, a major wheat-producing province, have not been characterized. In this study, the virulence of 45 isolates ofP. tritici-repentisfrom Alberta was evaluated on six differential wheat genotypes. Race 1 was found to be most common, representing 62% of the isolates tested, while race 2 was the second most common (36% of isolates). A single isolate of race 3 was also found (2% of total), but no other races were identified. Polymerase chain reaction and Southern blot analyses withToxAandToxB-specific primers and probes were conducted to confirm the race designations of the tested isolates. TheToxAgene was identified in each isolate classified as race 1 or race 2, but not in the race 3 isolate. Sequencing ofToxAfrom 16 isolates collected in different parts of the province revealed that the sequences were identical. TheToxBgene was not found in isolates classified as races 1 or 2, but aToxBhomologue was identified in the race 3 isolate. These results confirm that theP. tritici-repentispopulations in Alberta follow the toxin or inverse gene-for-gene model, and serve to validate the race-based classification system for this pathogen. [ABSTRACT FROM AUTHOR]

Fusarium head blight, caused by Fusarium graminearum, could potentially become a major concern for the cereal industry in Alberta, Canada. Infested feed grain in feedlot manure may act as a means of spreading the disease when manure is land applied. The ability of manure composting to eradicate the pathogen on infested grain (wheat, barley, corn) was evaluated. F. graminearum and other Fusarium spp. were rapidly eradicated from infested grains buried in compost windrows with no recovery after 2 d where windrow temperature attained 51°C. Under cooler windrow conditions (11.9 to 17.5°C), recovery of F. graminearum reached zero on Day 9 for corn (Zea mays L.), Day 14 for wheat (Triticum aestivum L.) and Day 22 for barley (Hordeum vulgare L.), showing that factors in addition to compost temperature may play a role in pathogen elimination. Composting represents an effective strategy in mitigating the dissemination of F. graminearum via manure should land application occur on fields that are subsequently used for grain production. [ABSTRACT FROM AUTHOR]