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Abstract: A growth chamber study was conducted to determine the effects of Fusarium avenaceum and Drechslera sorokiniana each alone and the two pathogens together on yield, evapotranspiration and stomatal resistance of 6 hard, red, winter wheat cultivars (Payne, Triumph 64, Danne, Vona, Tam 101, and Newton) grown under soil moisture stress conditions. Under soil moisture stress conditions, the pathogens reduced forage and root yields in all the cultivars. Evapotranspiration rate did not differ significantly in any of the treatments of cultivars as compared to their controls. In general, the pathogens had no significant effect on stomatal resistance, but F. avenaceum alone seemed to cause an increase in stomatal resistance while D. sorokiniana alone and the two pathogens together caused a decrease in stomatal resistance. The cultivar, Payne, was consistently superior to the other cultivars in forage and root yields and also gave the lowest stomatal resistance while the cultivar, Newton, consistently gave the lowest yields and the highest stomatal resistance in all treatments. This indicates that Payne is more tolerant to the pathogens under soil moisture stress conditions than the other cultivars while Newton is less tolerant.

Department of Plant Pathology, Oklahoma State University, Stillwater 74078, U.S.A.