Not highly competitive | Weed treatments wipe out volunteers
Farmers might like camelina sativa for its big oilseed yields, but many worry about the large number of seeds the combine leaves behind.
With 7,500 seeds per sq. metre missing the hopper, that could produce a massive weed crop in future years.
However, a University of Alberta researcher says camelina growers can rest easy: the seeds don’t survive long, produce weak offspring and are easily managed.
“The seeds exited the seed bank within one year, although surface seeds tended to persist a bit longer,” Kimberly Walsh said during the Canadian Weed Science Society’s annual meeting in Winnipeg Nov. 14.
Camelina seeds are about one-third the size of canola seeds and easily escape from the combine. They can germinate in the autumn and lie dormant over the winter, or they can germinate in the spring if sufficient moisture is present.
“There definitely is a flush,” said Walsh.
However, a pre-seeding treatment of glyphosate wipes out most of the volunteer camelina, and an in-crop weed treatment tends to eliminate the rest. The seed’s general low survivability means there’s almost none by the second year.
“My research shows that volunteer populations can be eradicated to near extinction within two years,” Walsh said in an interview.
Still, farmers can reduce the potential for camelina appearing as a weed by fine-tuning the mechanics of their harvesting, from slowing down to adjusting settings.
Walsh was asked why she considers camelina to have a low potential for weediness when it was considered a weedy crop that could go feral in the 1930s and 1940s. She said present camelina varieties have been bred for domestic conditions.
“I did not find that camelina is a highly competitive crop.”
Even volunteer flushes ignored by farmers tend to do poorly against other crops and weeds. Shepherd’s purse and stinkweed outcompete camelina.
Walsh said her research allows her to conclude that farmers should be able to grow camelina without its large seed loss creating a significant volunteer problem.
However, farmers need to do their part by cleaning fields the year after growing the crop.
“Weed control in the year following harvest is critical for the control of camelina volunteers and the mitigation of gene flow,” she said.