A pre-harvest spray to help prepare canola for straight combining may not be required if hot, dry days allow for dry down of the crop and weeds. Two recent studies from Western Canada found situations where these applications were not necessary.
Indian Head Agricultural Research Foundation study
Indian Head Agricultural Research Foundation just finished a three-year study on pre-harvest products applied to canola before straight combining. In the final report, IHARF made this “key finding”:
“With low weed populations, drier late-season weather, and early maturity (i.e. Liberty Link canola at Indian Head and Melita in 2017, Melita in 2018) there was relatively little benefit to using a pre-harvest application. The risks associated with later harvest are (within reason) arguably much lower with modern canola hybrids bred to retain pods and reduce shattering shatter tolerant and pod retaining canola hybrids than straight-combining research preceding this trait has suggested. This is more likely to be the case in more southern environments where both seeding and harvest tend to be earlier and, in general, the growing seasons are longer.
“With this in mind, growers planning to straight-combine shatter tolerant canola hybrids who have seeded early, achieved uniform stands, and kept the crop reasonably free of weeds should consider not spraying as a viable and or even preferable option.
“In contrast, at Melfort in 2019 the canola was prematurely terminated by fall frost and this was followed by unseasonably wet and cold. This resulted in delayed harvest, poor grain quality, and essentially no measurable benefit to the various pre-harvest options with respect to seed and crop dry-down.
“As a further testament to the efficacy of modern shatter tolerant hybrids, no shattering was reported for any treatments at any locations, despite the occurrence of occasional delays and unfavorable weather preceding harvest.”
Prairie Agricultural Machinery Institute study
Prairie Agricultural Machinery Institute (PAMI) ran a trial of pre-harvest aids in 2016, comparing three treatments – Reglone, a Heat/glyphosate tank mix and natural ripening – against swathed checks. The study showed no statistical difference in yield for the four treatments, but treatments did influence harvest timing and combine efficiency.
Reglone-treated plots were ready the same day as swathed treatments. Heat/glyphosate treated plots were harvested three weeks after application (partly due to a rain delay). Naturally ripened plots were ready at the same time as the Heat/glyphosate treatments. For the naturally-ripened canola, high green matter in the stand made harvest difficult.
The PAMI report concluded: “Straight cut treatments with harvest aids had a higher cost of production, but the benefits of timeliness or ease of harvest may provide sufficient benefit to warrant this cost for certain operations.” See the full report.