Canadian growers have come to rely on glyphosate for inexpensive, broad-spectrum weed control in their crops. While there is no question that glyphosate has been an effective and reliable herbicide, it's clear now that an increasing number of weeds are becoming tolerant to its application through high intensity use. In fact, only 35 weed species worldwide were listed as showing a resistance to herbicides in 1982. By 1995, that number reached 214 and now there are more than 300 species on the list.

While agricultural crop protection companies are continually working to develop a new broad-spectrum solution, some have also chosen to reinvest in proven and tested technologies that can be combined with today's most effective solutions.

One product that has found new life through reinvestment is Prowl H2O by BASF. The product is an improved formulation of an already proven herbicide, Prowl EC. The new water-based formulation of Prowl H2O results in reduced odour during application and less equipment staining than the original formulation.

"Growers using the same chemistry year after year should expect to see some resistance," says Dr. Trevor Kraus, BASF Supervisor of Research & Commercial Development and Technical Development for Eastern Canada. "One of the best things growers can do to combat resistance is to rotate their chemistry and include additional herbicides that can be mixed with glyphosate, especially those with different modes of action. Just as drivers rotate their tires for even wear and longer life on their vehicles, growers need to rotate their chemistry to maintain the weed control they have come to expect."

Although Canadian growers are not yet seeing the same level of resistance as their American counterparts, the problem is growing. Glyphosate-resistant giant ragweed and Canada Fleabane have been confirmed in Ontario and growers are going to have to change their practices to stay ahead of the problem. By treating crops with different herbicides, especially those with different modes of action, growers can expect to have better control in their fields.

"Glyphosate is effective at killing many weeds that have already emerged but does not have any residual soil activity to manage weeds that are not yet visible. Prowl H2O provides the residual activity on a variety of tough weeds, making it an excellent complement to glyphosate," says Kraus. "Reintroducing proven products that are improved to meet the needs of today's growers is an important step in combating herbicide resistance."

By treating crops with different herbicides, especially those with different modes of action, growers can expect to have better control in their fields and utilize best practices in their operations. A proactive approach to herbicide resistance now will save growers time and money in the future.

© 2011 BASF Canada Inc.