Foliar Disease Development in No-till Winter Wheat: Influence of Agronomic Practices on Powdery Mildew Development.
D.K. Tompkins and D.B. Fowler

ABSTRACT

Agronomic practices must be modified to maximize winter wheal (Triticum aestivutn L.) yield in different environments. Changes in crop management may modify the microclimate within the crop canopy thereby influencing the development of foliar pathogens. This study was initiated to determine the effect of cultivar, nitrogen (N) fertility, seed rate (SR) and row spacing (RS) on the severity of powdery mildew (Ervsiphe graminis DC f.sp. tritici E. Marchal) on the upper leaves of no-rill winter wheat grown in the Saskatchewan Parkland region. Average powdery mildew (PM) severity was greater on the upper leaves of the semi-dwarf cultivar Norwin than on the tall cultivar Norstar and increased under conditions of high N fertility. The use of 36 cm RS and 140 kg ha^-1 SR compared to 9 cm RS and 35 kg ha^-1 SR also resulted in increased PM severity. In general, wide RS enhanced spore dispersal and disease progress up the plant while high SR created a more favourable crop canopy microclimate for PM development once (he pathogen was established on a leaf.

Keywords

Wheat (winter). Triticum aestivum L., no-till, powdery mildew, Erysiphe graminis, row spacing, seed rate, nitrogen fertilizer.

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