Agronomic practices to reduce leaf spotting and Fusarium kernel infections in durum wheat on the Canadian prairies

May, W. E., Fernandez, M. R., Selles, F. and Lafond G. P. 2014. Agronomic practices to reduce leaf spotting and Fusarium kernel infections in durum wheat on the Canadian prairies. Can. J. Plant Sci. 94: 141–152. Fusarium head blight (FHB) has become an important disease of durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn] in the humid and sub-humid regions of the prairies along with leaf spots, black point and red smudge. Together, they contribute to lower grain yields and grain quality. The study objective was to determine the effect of seeding rate, nitrogen (N) fertilizer rate, fungicidal treatment, and cultivar on disease severity, crop development, grain yield and quality in durum. A four-way factorial design was used with two seeding rates (150 and 300 viable seeds m⁻²), two N rates (75 and 100% of recommended rate), three cultivars (AC Avonlea, AC Morse and AC Navigator), four fungicide treatments (no application, propiconazole at flag leaf, tebuconazole at anthesis, and propiconazole at flag leaf followed by tebuconazole at anthesis) and three locations (two in Saskatchewan and one in Manitoba) from 2001 to 2003. There were no interactions among fungicide, seeding rate, N fertilizer and cultivar for all measured variables. Foliar fungicide treatments resulted in greater kernel weight, grain yield and test weight than the no-fungicide treatment. The application of tebuconazole at anthesis did not reduce the amount of FDK in the harvested grain. The application of a fungicide increased the percentage of kernels infected by black point from 0.38% to over 0.50% and red smudge from 0.54 to 0.61%. Two fungicide applications increased red smudge to 0.85%. Grain yield increased by 2.4% when the seeding rate was increased from 150 to 300 plants m⁻². Increasing N fertilizer rate increased grain yield by 5.2%, protein concentration by 5.4% and hard vitreous kernels (HVK) by 2.6%, but decreased test weight by 0.5%. Cultivar selection had the largest effect on FDK. In conclusion, effects of a fungicide application on durum wheat did not interact with selection of seeding rates, cultivars or N rates used in this study.