Response of oat grain yield and quality to nitrogen fertilizer and fungicides

Recently agronomists and producers have expressed interest in combining higher nitrogen (N) rates with a fungicide application even when disease intensity is low. The objective of this study was to evaluate the effect of fungicide application and N rates on grain yield and oat quality (Avena sativa L.). The experimental design was a split plot with fungicide (none, pyraclostrobin, propiconazole + trifloxystrobin) as the main plot, and eight N rates as sub-plots (5, 20, 40, 60, 80, 100, 120, and 140 kg ha(-1)). This study was conducted in 2012 and 2013 at two locations in Saskatchewan, Melfort and Indian Head. Disease intensity was very low for crown rust (Puccinia coronata) and low-to-moderate for all other foliar diseases, and with no large effect on grain yield and quality. No interaction between fungicide and N was observed. A curvilinear increase in grain yield occurred as the N rate increased from 5 to 140 kg ha(-1). Increasing the N rate caused a small linear decrease in test weight. At a low oat price, $130 t(-1), the N rate that maximized economic return was sensitive to N fertilizer price. As the crop price increased the optimum N rate was100 kg ha(-1). In conclusion, our results indicate that using an N rate of 100 kg ha(-1) provided the most consistent economic returns when the crop price is between $162 and $194 t(-1). There is no beneficial interaction between fungicide and N for growers using higher N rates at low disease intensity and resistant genotypes.