Lack of new pulse herbicides force revisit to tried and true

What’s old might be new again, says a weed management re-searcher at the University of Sask-atchewan.

“We’re doing a fair amount of work just looking at older herbicides again that aren’t used quite as much but still may have some utility in crop production,” said Eric Johnson of the university’s agriculture college, whose weed research program recently re-ceived $2 million in funding over five years from Saskatchewan Pulse Growers.

The funding will be used to look for effective solutions for long-term weed management. Pulse production relies on herbicides because they are not competitive.

“Weed control is still a very important component of pulse production,” said Johnson.

Problem weeds include wild mustard, kochia and cleavers.

Johnson said the funding is in addition to SPG weed research funding, which focused on herbicide screening and finding other modes of action for pulse crops.

“We’ve been looking for alternative groups that might work and we’ve identified some,” he said.

“Now what we want to do is take that information further and work out systems — so integrating herbicides and cultural practices and good agronomy to come up with good weed control systems for growers.”

Results from the past program included “reducing the sulfentrazone re-cropping interval for canola to 12 months after application and lentils to 24 months, improving the tolerance of field peas and assisting with the development of IMI-tolerant chickpeas,” according to the news release that announced the funding.

Further success included managing cleavers in high organic matter soil by “herbicide layering,” which is combining pre-seed short-term soil residual herbicides with post-emergence in-crop treatments.

The research program will now focus on establishing new minor use herbicide registrations for pulses, improving knowledge of competitive traits in pulses for incorporation into future varieties, providing new integrated weed management options for growers and understanding the impact of soil residual herbicides on re-cropping restrictions for newly emerging pulse crops such as fababeans.

The program will also explore technologies such as robotics.

Johnson said the research has focused on groups 14 and 15.

The lack of new groups is a big challenge, he added. There hasn’t been a new mode of action in more than 20 years, while the number of new herbicides continues to grow, contributing to the risk of herbicide resistance. He said this has been motivating researchers to go back to the drawing board stage to look at herbicides and alternative modes of action that were first introduced in the 1970s and 1980s.

“We don’t overlook anything these days right now,” he said.

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