Combining herbicides in tanks may not suffice in preventing herbicide resistance.

Eight years ago, scientists from the University of Illinois and USDA-ARS scientists turned weed control on its head. More and more herbicide-resistant weeds are emerging, and killing pest plants is becoming more and more difficult. It was clear that farmers could no longer rely on the same chemicals year after year. Industrial campaigners and herbicide users began touting the benefits of rotating herbicides annually to avoid the development of resistance, and rotation soon became common practice.

But in 2015, a team of weed scientists from the U of I and USDA-ARS He studied the effects of herbicide rotation The practice has actually found increased resistance to glyphosate in Waterhemp, a common and destructive weed in the corn belt. What worked, instead, was mixing several herbicides in the same tank and spraying simultaneously. Their large experiment, including 105 grain fields in Illinois, showed that mixing tanks was 83 times more likely to cause glyphosate resistance.

The study had a strong impact, with recommendations changing almost overnight; Mixing the herbicide in the tank is now a must. But one of the study’s authors now urges farmers and industry personnel to remember that mixing tanks only delays the development of resistance.

“I worry that this practice has become overused,” said Aaron Hager, the department’s college herbalist and extension specialist. “It’s too simplistic to think that all you need to solve resistance challenges is to keep using herbicides but in a slightly different way.” Crop Sciences, part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at Illinois. Hajar wrote on the subject in a new way farm condition.

He notes that waterweed is now resistant to herbicides from at least seven modes of action herbicides, despite the advantages of tank mixtures. And some water hyacinth populations are resistant to herbicides to which they have not been exposed before. In other words, herbicide resistance is a complex and fast-moving target. We don’t keep up.

Speaking of targets, Hager points out that the 2015 study focused on one type of herbicide evasion strategy: target site resistance. That’s when the herb’s genetic code mutates so that the chemical no longer fits into the protein’s receptor – the target site – and is engineered to attack.

More often nowadays, including in the case of a cannabis bird that develops resistance to chemicals it has never seen before, weeds use another strategy. It is known as metabolic or off-target site resistance. Here, the weed increases the production of detoxifying enzymes that render the herbicide useless before it kills the plant.

“To our knowledge, there are no data that test the hypothesis that mixtures of herbicides are the most effective way to avoid the development of site-dependent off-target resistance mechanisms,” Hager said. “Without this data, how can we know which herbicides or combinations remain effective against which aquatic weed populations? There is no simple way to know.”

Hager contends that the problem of herbicide resistance is a direct result of an over-reliance on one simple solution: chemical weed control. The problem, in his opinion, will not be solved using exclusively the same tools, but in different ways. Instead, he says, farmers should diversify methods and focus on preventing or eliminating weed seed production.

“Look, herbicides will continue to be valuable tools to help prevent crop yield loss, but we must also consider additional tactics to ensure that waterweed plants are not allowed to produce seed during the growing season. All we know for sure is that if the plants can In order to produce seeds, the frequency of any resistance mechanism cannot change or grow. And even a few seed-bearing sedges left in the field at harvest can have the latest herbicide resistance mechanism,” Hager said. “It bears repeating: consider additional methods to ensure weed seeds are not produced.”