Controlling volunteer herbicide tolerant canola in the subsequent crop year is easy for 75 percent of the prairie canola growers surveyed by the Canola Council of Canada.
The remaining 25 percent said volunteer HT canola in the subsequent year is more of a problem than conventional varieties.
Only 16 percent of the growers cited volunteer canola of either type as the main target of their broadleaf herbicide program. Also, 69 percent of growers surveyed said they had not changed their weed management program because of volunteer HT canola.
The survey of 335 prairie canola growers dealt with the 2004 crop year. Most growers cited wild oats, wild buckwheat and Canada thistle as more significant than volunteer canola.
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JoAnne Buth, vice-president of production for the canola council, said it wanted to find out how growers managed volunteer canola weeds following conventional canola and three HT systems – Roundup Ready, Liberty Link/InVigor and Clearfield.
Buth said the results were no surprise.
“We knew that growers were doing a good job of managing volunteers. There had been some issues in the earlier years with Roundup Ready canola, but there have been very few reports recently of any kind of volunteer canola problem. Growers tell us that controlling volunteer canola is just part of their overall management plan.”
She said the council had done a similar survey in 2000, but that report had overlooked the question of what growers do in the subsequent crop year.
“These are the kinds of questions we get from our overseas customers. We are the global example of the adoption of transgenic canola and herbicide tolerant canola. We often get questions about how growers handle these situations.”
Because volunteer canola is lumped in with all the other weeds that need to be controlled, most of the surveyed growers could not specify what percentage of their weed control dollar was spent on volunteer canola.
Those who could break down their costs reported no incremental application costs to control Roundup Ready volunteers. They just add a low-cost herbicide such as 2,4-D to their glyphosate pre-seed burnoff.
The study revealed no significant differences in costs of volunteer canola control following any of the systems. Estimated control costs were $10-$13 an acre for herbicides and about $5 an acre for tillage control.
In addition, nearly 60 percent of growers who planted HT varieties in 2003 reported a carryover weed control benefit to the 2004 crop.
About half the growers who reported this carryover benefit put a dollar value on it of almost $12 an acre.
