Winter Wheat Yields Are Increased by Seed Treatment and Fall‐Applied Fungicide

Abstract

Poor stand establishment resulting in lower yield is a major constraint to expanding winter wheat (Triticum aestivum L.) land area across the semiarid temperate regions of the northern Great Plains. We conducted a direct‐seeded study at nine sites across western Canada totaling 26 environments (site‐years) over three growing seasons (2011–2013) to observe the responses of the winter wheat cultivar CDC Buteo to five levels of seed treatment (i) Check–no seed treatment, (ii) tebuconozole [(RS)‐ 1‐(4‐Chlorophenyl)‐4,4‐dimethyl‐3‐(1H, 1,2,4‐triazol‐1‐ylmethyl)pentan‐ 3‐ol], (iii) metalxyl {2‐[(2,6‐dimethylphenyl)‐(2‐methoxy‐1‐oxoethyl) amino} propanoic acid methyl ester], (iv) imidacloprid (N‐{1‐[(6‐Chloro‐3‐pyridyl)methyl]‐4,5‐dihydroimidazol‐2‐yl}nitramide), and (v) dual fungicide/insecticidal seed treatment: tebuconozole, + metalxyl + imidacloprid; and two levels of fall‐applied fungicide (i) Check–no application or (ii) foliar‐applied prothioconazole {2‐[2‐(1‐chlorocyclopropyl)‐3‐(2‐chlorophenyl)‐2‐hydroxypropyl]‐1H‐1,2,4‐triazole‐3‐thione} performed in mid‐October. The check and the fungicide seed treatment, metalaxyl, produced similarly low grain yield resulting in lower net returns, whereas the dual fungicide/insecticide seed treatment provided the highest yield and net returns (CAN+$13 ha−1). Fall‐applied fungicide improved yield (0.06 Mg ha−1), but decreased net returns (–$12 ha−1). Plant density increased slightly (13 plants m−2) when seed treatments included the insecticide component, imidacloprid. Fall foliar fungicides generally improved spring plant density; however, no benefit was observed in seed treatments containing imidacloprid. Greater yield and plant stand stability was observed with fall‐applied foliar fungicide applications; however, fall foliar would be cost prohibitive. The benefits of a fall foliar fungicide application requires further exploration in the context of an added input or as an alternative to a spring application as the net returns of a fall foliar compared to no application in the system render the input cost‐prohibitive.Core Ideas Seed treatment increases winter wheat yield. Fall‐applied fungicide increases winter wheat yield. Seed treatment increases winter wheat net returns.