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.