Researchers tackle tricky question of when to reseed canola

INDIAN HEAD, Sask. — Many producers have been stuck in situations that have left them wondering whether it’s worthwile to reseed their canola.

Researchers in Saskatchewan are examining that question.

The early returns on the project indicate growers might be able to salvage respectable yields from fields with lower plant populations without reseeding, said Chris Holzapfel, research manager for the Indian Head Agricultural Foundation.

“If you have 20 plants per metre squared, I probably wouldn’t even think about reseeding at that point,” he said.

Holzapfel spoke to producers about the project during a field tour of the Indian Head Research Farm last week.

“The biggest challenge with canola is just getting that good strong start. Getting a good establishment — even, uniform, adequately high plant population,” he said. “Once you’ve got that it’s a relatively easy crop to grow.”

The Indian Head site is one of five participating in the trials, now in its third year, examining the performance of hybrid varieties. At the end of this growing season, researchers will have “15 site years” of data.

In May, Holzapfel said researchers seeded a number of plots, which were terminated and reseeded in June with Invigor 5440, as well as a Polish variety, ACS-C18 — “Typically not something that guys would grow around here unless they do start getting late into the season when they’re worried about maturity,” said Holzapfel — and the early maturing Proven 9350.

After two years of trials, Holzapfel said early June did appear to be a “very viable” time for reseeding canola.

The yields for sites reseeded later in June were always lower than if they had harvested a crop with less than 20 plants per metre squared, he said.

“So far the results have been quite good for that reseeding date,” said Holzapfel. “5440 was always the best. (There’s a) bit of a yield drag when we went to 9350 and more so with the Polish (variety). As we got into June 15 and beyond, then it was a different story. That was never economically viable.”

According to IHARF’s 2011 annual report, averaged data from across all the sites shows plant densities lower than 20 to 24 plants per metre squared resulted in yield reductions.

“It is difficult to make a general conclusion on the plant density at which reseeding would be recommended as the plant density which yields were severely reduced ranged between sites,” reads the report, which notes another year of research will assist officials.

“Another year of research will allow for better predictions of which environmental conditions require higher seeding rates in order to maximize yield.”

Researchers, however, have been able to achieve 90 percent of maximum yields with as little as 20 to 24 plants per metre squared, said Holzapfel.

“Which is considerably less than our minimum recommendations,” he said, “but, word of caution, we did see increased green content at those numbers.”

There were other problems too, including an increase in days to maturity — up to 10 days, he said — and numbers may have been skewed by moisture. Under drier conditions, he didn’t expect to see the same results.

“Just because the yield potential is there doesn’t mean there aren’t other problems,” he said.

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