Adjuvant Choice Can Make or Break a Herbicide Mix
Waterhemp must be competing with cockroaches to be the last surviving species on Earth. At least that’s how it seems, given the vile weed’s ability to germinate throughout the growing season, scatter up to a million seeds per plant and develop resistance to multiple herbicides, according to CHS Agronomy.
Paul Fossum, a soybean, wheat and sugarbeet grower who farms about 2,200 acres near Hillsboro, N.D., recently found himself in a pitched battle with waterhemp.
“Waterhemp has become extremely difficult to control,” he says. “The patches were in an area where I couldn’t use dicamba, so I had to find another solution.”
Falling back on glyphosate, but knowing it couldn’t do the job alone, Fossum got an adjuvant recommendation from Craig Moen, his agronomy consultant at CHS Ag Services, based in Warren, Minn.
That decision made all the difference, he says. “I went back a week later and the waterhemp was dead.”
Fossum’s waterhemp-busting herbicide ally was CHS Level Best, a nonionic surfactant, water conditioner and deposition aid.
“Weed control with a contact herbicide is all about coverage,” he says. Fossum also uses the adjuvant with Roundup in sugarbeets and adds it to his desiccant treatment for potatoes.
Works Fast
Rapidly advancing herbicide resistance makes adjuvant choice more critical than ever, says Moen. “Using an adjuvant that gets herbicides into the weed faster helps take down populations before they can spread,” he says
Devin Wirth, a regional technical specialist with CHS Agronomy, who helps develop and support crop protection products for growers in North Dakota and Minnesota, adds:. “When you add it to the tank, you see nearly instant results.” Glyphosate typically controls weeds in 12 to 14 days, he explains, but by adding Level Best, “you could see wilting in five to six days and complete weed death in eight to 10 days.”
A hard-working adjuvant brings out the best in a herbicide mix, says Corey Klaphake, Wirth’s technical counterpart for Iowa and Illinois. Is that difference enough to justify an extra $2 or $3 per acre? “If it gives you peace of mind, it’s worth it,” he says.
“Some adjuvants cost more than we think they should,” Fossum says, “but if an adjuvant like Level Best makes everything better, I’ll continue to use it. We try to have a rough idea of what it will cost per acre to apply a herbicide mix, including the percentage attributed to adjuvants. If the adjuvant enhances the chemistry so it works on problematic weeds, it’s hard to put a value on that.”
Efficacy Wins
“We use a lot of Liberty [glufosinate] in my area,” says Klaphake. “It likes heat and humidity, but we’re often applying it in cool, dry conditions. Adding Level Best allows you to apply Liberty earlier in the day or when the conditions are less favorable.”
And more effective weed control helps prevent resistance development in surviving weed populations, Klaphake adds.
“A small number of weed species have confirmed glufosinate resistance. Let’s steward glufosinate so we can continue to use it.”
Read more at CHS Agronomy.
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