Synergism of Nitrogen Rate and Foliar Fungicides in Soft Red Winter Wheat

Abstract

Projected global demand for small grain cereals emphasizes the need for sustainable intensi cation with higher crop yields. Field studies on so red winter wheat (Triticum aestivum L.) examined interactions among three fertilizer N rates, eight fungicide application strategies, and various cultivars grown in nine eld environments in Ontario, Canada. A synergistic response occurred when a high rate of N was applied with a fungicide strategy that controlled disease. Overall, compared to a typical N rate of 100 kg ha -1 and no fungicide, yields increased by an average of 1.45 Mg ha -1 when N was applied at 170 kg ha -1 with the most intensive fungicide treatment pooled across sites. is yield response varied from 0.80 to 2.11 Mg ha -1 depending on eld site and pooled across cultivars. Fungicide strategies that included a T2 ( ag leaf timing) or T3 (anthesis timing) produced the highest yields across environments, especially at the high N rate and in most cultivars. e crop response to fungicide depended on the susceptibility of the cultivar to foliar disease and whether the eld environment was favorable for disease development. High N rates increased spike numbers and kernels spike -1 , whereas fungicides mainly increased kernel weight and kernels spike -1 . Prior to an economic analysis, results from this study indicates clear potential for increasing wheat performance by intensifying management with increasing N and deploying fungicide application strategies, especially in some cultivars and in high yielding environments that may be favorable for disease development.

Optimizing inputs for winter durum wheat in Ontario

“…Similar results were reported by May et al (2014) for spring durum wheat in western Canada. In contrast, recent studies with soft red wheat among similar environments in Ontario have shown ''synergies'' between fungicide application and N rate on wheat yield (Brinkman et al 2014). In other words, the grain yield response to foliar fungicides increased with an increase in N rate.…”

“…Variable yield responses to fungicide have been reported elsewhere in Ontario, depending on the cultivar, weather, and environment (Sutton 1985;Brinkman et al 2014). The yield response may be attributed to the control of leaf diseases after the application of fungicides.…”

“…Some key agronomic factors for wheat production in Ontario include: fertilizer nitrogen (N) rate, seeding rate, and application of fungicides (Brinkman et al 2014). Until 2013, the provincial recommendation for N rates for soft winter wheat varied between 75 and 110 kg ha (1 if fungicides are applied at or after flag leaf timing.…”

“…Recent research has shown agronomic advantages for increasing N rates combined when fungicides are applied to control leaf and head diseases (Brinkman et al 2014). High N rates have been reported to increase powdery mildew in wheat (Bainbridge 1974;Roth et al 1983;Cox et al 1989;Olesen et al 2003) and decreased leaf spots in common and durum wheat (Fernandez et al 1998;May et al 2008).…”

“…The study corresponds with Phelps and Campbell (2013), who reported from a Saskatchewan study that fewer plants compared with winter wheat were required to achieve optimal yield i.e., 210 to 250 plants m (2 . Similarly, optimal fungicide management strategies are needed to determine economic thresholds that warrant application (Brinkman et al 2014). Both weather and other environmental factors affect yield responses to fungicides application (Sutton 1985).…”