Prairie farmers are getting renewed access to Avenge, a wild oat herbicide that BASF took off the market in 1995.
That’s good news in the ongoing battle against herbicide resistance, says a weed specialist with the Saskatchewan government.
The return of Avenge provides growers of wheat, barley and canaryseed with more flexibility in rotating herbicide groups in an effort to prevent the development of resistance among targeted weeds.
“It’s a good viable alternative,” said Clark Brenzil, provincial weed control specialist. “It offers producers a good rotational option.”
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Herbicides are categorized into groups according to the chemical process they use in controlling weeds. Avenge, which goes by the generic name difenzoquat, is a Group 8 herbicide, while most wild oat control products are Group 1 or 2.
Brenzil said herbicide group rotation is one of the key strategies in managing the increasing problem of herbicide resistance.
While the concept has been around for a long time, many farmers have been hesitant to adopt it.
“Human nature is to use what we know and what has worked in the past,” said Brenzil.
However, using the same herbicide product over a long time is asking for trouble, he added.
If herbicide groups are rotated each year, the weeds that develop resistance to one group and survive to the next year can be killed by a different group.
When BASF took Avenge off the market, sales had declined as new and improved products came on the market and the company turned its focus to other products such as Assert, Odyssey and Pursuit.
It brought the product back a few years later as the only herbicide registered for post-emergent wild oats control in canaryseed.
In 2005, BASF sold Avenge to American Vanguard Corp., a California company that specializes in acquiring niche product lines from bigger, often recently merged companies that want to focus on new products.
It is marketed in Canada by United Agri Product, the largest distributor of agricultural and non-crop inputs in North America.
Garth Render, UAP marketing manager in Manitoba, said reintroduction of the product is good news for canaryseed growers and for wheat and barley producers who want to practise herbicide group rotation.
He acknowledged that Avenge, with its older technology, is not as effective as some of the newer wild oat control products, but said it’s effective enough to provide yield benefits.
“If farmers want to preserve Group 1 and 2 chemistries, they need to start looking seriously at rotation to prolong the life of those groups.”
According to Saskatchewan Agriculture, farmers should suspect resistance in their fields under the following circumstances:
- A weed species that was previously controlled by a specific herbicide survives treatment, while other weeds listed on the label are controlled.
- The survival cannot be attributed to adverse weather or post-application emergence.
- Irregular-shaped patches of a weed develop where the herbicide provides no control.
- Records indicate the field has been repeatedly treated with the same herbicide or herbicide group.
If resistance appears, contact a local agricultural office or crop protection company representative for advice.
