Most prairie canola growers surveyed for the Canola Council of Canada report that herbicide tolerant canola volunteers are as easy to manage as conventional canola volunteers.

JoAnne Buth is vice-president of production for the Canola Council. She says the Council commissioned Serecon Management Consulting to call western Canadian canola growers in the summer of 2004 to find out how they managed volunteer canola weeds following conventional canola and three herbicide tolerant (HT) systems - Roundup Ready, Liberty Link/InVigor and CLEARFIELD.

Buth says the results of that survey of 335 farmers combined with the previous three years of information from the federal government's Prairie Weed Survey plus economic modeling of herbicide options and costs showed that “growers have a good handle on controlling canola volunteers following all canola systems”.

Buth says the study revealed more similarities than differences. "We discovered that, regardless of the system, farmers rarely targeted volunteer canola as the primary broadleaf weed to be controlled with a herbicide", she says. "Farmers were more concerned about taking care of wild oats, wild buckwheat and Canada thistle."

The study showed that few canola growers even target herbicide treatments or tillage operations specifically for volunteer canola. And Buth says the majority of canola growers surveyed had not changed their weed management practices to control volunteer HT canola volunteers over conventional canola volunteers.

She says growers reported that controlling volunteer canola is just part of their overall management plan.

In fact, Buth says most of the surveyed growers could not specify how much of their weed control dollar was specifically spent controlling volunteer canola. Those who could break down their costs reported no incremental application costs to control Roundup Ready volunteers. They just added a low-cost herbicide to their glyphosate pre-seed burn-off treatment.

Buth says growers of other systems, including conventional canola, more often added their broadleaf tank-mix to their in-crop grassy weed herbicide treatment.

The study revealed no significant differences in costs of volunteer canola control following any of the systems. "Growers estimated herbicide treatment costs of $10 to $13 an acre for herbicides and about $5 an acre for tillage control," Buth adds.

"This was an important finding and shows that the decision to grow HT canola crops does not result in additional herbicide costs in subsequent years,” she says. “In fact, the previous study the Canola Council conducted showed that using HT canola crops actually resulted in a significant decrease in herbicide costs and increased overall farm profit."

In addition, nearly 60 % of surveyed growers who planted HT varieties in 2003 actually reported a carry-over weed control benefit to the 2004 crop. Buth points out however, that no carry-over weed benefits were detected in the Prairie Weed Survey data.

Buth says about half the growers reporting a benefit put a dollar value on it of almost $12 an acre. "That's roughly the cost of product and application of a typical glyphosate treatment", she figures, “and would offset any incremental cost of controlling the volunteers the next year.”

"All in all," Buth says, "the majority of growers of herbicide tolerant canola continue to support the premise that the benefits of growing these varieties are greater that the benefits of growing conventional canola."

2004 survey results in PDF format: http://www.canola-council.org/PDF/Herbicide_Tolerant_Fact_Sheet.pdf