Evaluation of spring wheat head morphologies on Fusarium graminearum infection and tebuconazole efficacy

Fusarium graminearum is the primary pathogen causing Fusarium head blight (FHB) in Canada. Deoxynivalenol is a mycotoxin produced by F. graminearum in infected plants, and is a concern for food safety, due to its immunosuppressant, teratogenic and embryotoxic potential in humans. Wheat (Triticum aestivum L.) breeders are faced with costly and complex task of breeding for quantitative disease resistance. With limited progress in the commercialization of resistant wheat varieties, growers are applying fungicides where application timing and technique are critical. This thesis investigates the influence of wheat head and plant morphologies on FHB infection and tebuconazole efficacy. Increasing awn length reduced FHB severity, while awn presence interacted with plant height and anther extrusion and also effected the movement of tebuconazole within the wheat head. Tall plants had increased tebuconazole efficacy on FHB severity; dense heads had increased FHB severity; while fully-opened flowering increased FHB indexes. Tebuconazole was more effective against FHB in plants with known resistance QTLs. Morphologies identified in this research could be integrated into breeding programs in an attempt to combine physiological and passive resistance mechanisms.