An Economic Assessment of Foliar Fungicide Application on Multiple Levels of Disease Resistance in Hard Red Winter Wheat Varieties in Texas.

Wheat (Triticum aestivum L.) is planted on more acres than any other crop in Texas at just over six million acres. Leaf (Puccinia triticina) and stripe (Puccinia striiformis) rust are two of the most common diseases affecting Texas wheat and good disease management can have a large impact on statewide production. Newly released varieties offer a wide range of resistance options for these two fungal pathogens and economic returns of a fungicide application often come into question with better resistance. In response, a fungicide trial was conducted over three years in Castroville (29^o20’40N, 98^o47’53W), College Station (30^o30’37N, 96^o25’8W), Farmersville (33^o09’29N, 96^o18’36W), and Chillicothe (34^o11’30N,99^o31’15W), TX to evaluate the impact of tebuconazole on disease control, yield, and test weight of 18 hard red winter wheat varieties. At current costs (Tebuconazole = $3.71 ha^-1, applicator costs = $12.35 ha^-1), a yield response of 2.3 bu ha^-1 would make a single fungicide application cost effective. Based on our findings, applications of tebuconazole significantly improved test weight and yield by more than 2.3 bu ha^-1 for most varieties at Castroville, College Station, and Farmersville over all years regardless of resistance rating. Yield response to tebuconazole was limited in Chillicothe due to drier climate and less disease pressure. In most cases, wheat producers would benefit financially by applying tebuconazole to treat rust in wheat regardless of variety; however, resistant varieties still provide a level of protection if producers are unable to apply a timely fungicide application on their field.