P-102 - Optimizing management of Leptosphaeria maculans in winter canola in northern Idaho

Blackleg of canola, caused by the fungal pathogen Leptosphaeria maculans, was first observed in the Pacific Northwest (PNW) in northern Idaho in 2009. It has since been found in canola growing regions of eastern Washington and parts of Oregon. While the disease incidence and severity are typically low there have been instances where pod infection has occurred leading to seed lots being rejected. Fungicide trials were established to determine the optimal application timing and to evaluate the efficacy of fungicide products. Trials for the fungicide timing study were established at three locations in northern Idaho using winter canola cultivars Mercedes and Amanda. Priaxor Xemium was applied in fall only, spring only or both fall and spring. Disease incidence was significantly reduced on both cultivars with all fungicide treatments, but the dual fall and spring applications provided the best control. When only a single application was made, spring only was significantly better than fall only. A second study was initiated to examine the efficacy of the fungicide products Tilt, Quadris, Miravis Neo and Priaxor applied only in the spring. A dual application of Priaxor in both the fall and spring was included as a control in addition to a non-treated check. While all fungicides reduced the disease incidence, only Miravis Neo and the dual Priaxor applications significantly reduced disease incidence compared to the non-treated check. Data from these trials will aid in making recommendations to maximize control of blackleg in winter canola fields.