Response of Spring Canola Yields to Foliar Boron Application.

Canola (Brassica napus L.) is Canada’s major oilseed crop, and now rivals wheat as the country’s most valuable cash crop.  Foliar boron (B) is sometimes applied to canola during early flowering, but research data demonstrating the benefit of this practice are rare.  We conducted replicated small-plot field experiments at two locations in Ontario in each of 2007 and 2008, and farm-scale strip trials at nine locations in 2008 to investigate the benefits of foliar B applied to canola.  In 2007, a hot, dry year, foliar B applications produced large (over 400 kg / ha) and statistically significant (P<0.10) yield benefits at both locations.  In 2008, a cool year with adequate precipitation, no benefits of foliar B could be detected in the small plot experiments.  However, a small (86 kg) and statistically significant (P<0.10) yield increase was seen with foliar B when data were averaged across the nine strip trial locations in that year.  Location differences in yield responses to B were not related to B soil test results. In experiments established in 2009, at one location we were able to detect the effects of B on canopy colour one week after B application, using canopy reflectance spectroscopy methods.  Yield data from the 2009 small plot trials will also be presented.