Sharing genes: ... volunteers another matter

CHRIS PRESTON of the CRC for Australian Weed Management says recent experience in Canada makes it is clear that pollen can flow between canola crops taking herbicide-resistant genes with it.

"It is likely that canola crops grown next to each other will share genes," he says. "This is not a problem if the two crops are the same variety or have similar characteristics. However, if one of the canola crops contains a herbicide-resistance gene, there is the possibility that pollen 'jumping the fence' will carry that resistant gene to an adjacent crop."

In addition, "canol a volunteers in the following season may be resistant to herbicides where no resistance was expected". Dr Preston says there is no concern with pollen flow from TT varieties because that resistance gene does not move in pollen. The only way that the triazine-resistance gene can get around is through seed movement - for example, seed moved by harvesting equipment or spilled from trucks may move IT canola to new areas.

Other herbicide-tolerant varieties act differently

"In contrast, pollen of the Clearfield canola varieties carries the herbicide-resistance gene. This means it is possible to get imidazolinone-tolerant canola volunteers in a field where the Clearfield varieties have never been grown;' Dr Preston said.

While the distance that canola pollen will move and fertilise other canola plants is being explored in other CRC for Australian Weed Management work (see related story this page), it is wise to consider the resistance status of neighbouring canola crops.

"The safest strategy to minimise resistance genes moving would be not to grow other types of canola in fields adjacent to Clearfield varieties. A cereal or pulse crop should be considered instead.

"The other lesson to be learnt from the Canadian experience is the importance of controlling herbicide-tolerant canola volunteers. This will minimise the risk of herbicide-tolerant canola volunteers infesting other crops."

Program 3 Contact: Dr Chris Preston 08 8303 4455 email christopher.preston@adelaide.edu.au