Hot days (28-30°C and up) and warm nights (16°C and up) from bud to mid-flowering stages can increase flower abortion, producing blanks along the stem. Even with a few days of heat, it can take a week for hormone balance and regular pod formation to return. Canola plants can recover from this by flowering longer, but if hot days and warm nights continue throughout the flowering period, it will likely have a significant effect on yield.
Boron treatment shows no clear benefit in Western Canada. When Alberta Agriculture oilseed specialist Murray Hartman ran his meta-analysis of boron studies, he found no boron response – even when temperatures were hot at flowering.
Canola Council of Canada boron trials in 2013-15 found no consistent yield benefit from boron treatment, including in those plots with very high yield results.