Play Offense Against Weeds
No herbicide recipe is exactly the same on any operation and no two states are mirrors of weed management, but there is a common thread across U.S. farms: aggression and timeliness. Four growers from Illinois, Indiana, Kansas and Colorado, sound off regarding weed control in 2021.
John Schlessiger, Kansas
In central Kansas, northeast of Great Bend, John Schlessiger and his brother, Joe, grow alfalfa, cereal rye, corn, grain sorghum, soybeans and winter wheat (as well as livestock production). The diverse crop roster is afflicted by a singular weed foe — Palmer amaranth. In alfalfa, for example, the Schlessigers struggle with Palmer after first and second cuttings as weather goes hotter and drier. Wheat fares better regarding Palmer (unless harvest is wet) and the duo lets stubble go.
“We no till for the most part, and stubble stands before beans or milo, but controlling pigweed for the remainder of summer is a tough challenge,” John says.
With corn and soybeans, he goes full-bore after Palmer, dropping pre-emerge with three to four modes of action. “As many pre-emerges and as many modes of action as we can stack is what we’re putting down,” he continues.
On dryland ground going to corn, grain sorghum, or soybeans, the brothers apply a pre-emerge in fall, and return in February or March with another pre-emerge shot, and another at planting. “Then when we post-apply, there’ll always be another pre-emerge,” John explains. “We layer all our pre-emerges, and I’d say milo is the most restrictive crop because there just aren’t many herbicides we can use.”
What is the Palmer and weed presence trajectory over the past five years on the Barton County ground? “I’d say aggression has kept things from getting worse, but they definitely aren’t getting better,” John adds. “Kochia is a distant second as a weed problem, but nothing compares to Palmer.”
Marc Arnusch, Colorado
Outside Prospect Valley, Colo., Marc Arnusch grows 3,000-plus acres of certified seed wheat, certified malt barley seed and grains for craft beer, as well as corn and alfalfa for the dairy industry. Herbicide sprays on his farm focus on a trio of weeds: kochia, lambs quarter and barnyard grass.
“Our strategy differs depending on the crop,” Arnusch says. “Frankly, we’ve had so much trouble with kochia that we’ve had to implement strategic tillage even though it’s choice of last resort for us. Kochia is becoming so much trouble, and it’s already resistant to ALS class herbicides and it’s becoming highly resistant to glyphosate, and now we’re seeing tolerance to glufosinate.”
Every March, weed management begins in Arnusch’s cereal production fields, with residuals to combat grassy species. “We also incorporate residuals into corn. We want protection on top of the seed zone for our strip till acres. That buys us some coverage for a short time, and then we come back with modes like a high rate of glyphosate—usually 5.4 lb. active ingredient, tank-mixed with dicamba chemistry. We plan on an in-crop spray at about V4 with crop nozzles for late emerging grasses that cause trouble in corn.”
Post-harvest, Arnusch avoids tillage, relying on herbicide burndown. “We use more and more atrazine and it seems to really be a great help.”
All his spray efforts are contingent on timeliness, Arnusch emphasize. “It is everything. Timeliness for crop canopy and weed size, especially with kochia. Timeliness is the difference maker for your pocketbook.”
Matt Bohrer, Indiana
Every year Matt Bohrer, who farms near Fort Wayne, Ind., battles giant ragweed, Palmer amaranth, and waterhemp in his corn and soybean fields.
“Early aggression serves us best and that means getting a pre-emerge down right after planting, with multiple modes in beans. We’ll go back in right before canopying and use a Group 15 and get a little more residual down. In corn, we also focus on early post, trying to get control before V4 and use a large amount of glyphosate and a Group 15 and a Group 27.”
Using conventional tillage across his acres, Bohrer gets across his ground in post-harvest fall to bury seed, particularly from an increasing Palmer threat. “We’re constantly looking to tweak our program to do a better job as things evolve. Palmer just keeps getting worse,” Bohrer notes, “and it’s becoming our No. 1 weed problem.”
Kirk Liefer, Illinois
Roughly an hour south of St. Louis, across the Mississippi River, Kirk Liefer farms ground stretched across four counties in southern Illinois. Alongside several family members, he grows corn, soybeans and wheat, and is also involved in seed production of Pioneer hybrids.
Without hesitating, Liefer singles out his main weed nemesis: “Waterhemp. Waterhemp all the way, especially in beans. Get a year like this with adequate rainfall, and you’re guaranteed to see breakouts. We go into every season with a prepared plan for traited beans and we fight post weeds with glufosinate, AMS, and Enlist.”
Atrazine and Callisto, according to Liefer, afford corn a degree of protection from waterhemp, but his soybeans are under persistent assault. “It’s really, really bad in beans. We go out and have a burndown. Then at planting, we burndown again and put down a residual. Then about three to four weeks later we come back with post with another layered residual and monitor from there as to whether to do any spraying for escapes.”
Liefer’s ground is 100% no till, and in the fall some of his farmland transitions to wheat or cover crops, and a portion remains bare. “We let the weeds come up and deal with it in the spring. Something is going to be on all of our ground to prevent erosion.”
As with all farmers, Liefer describes a maddening pattern of unpredictability in weed presence. Expect the unexpected. “Every year is different and there’s nothing you can do about that. Weeds are heavy every year, but the amount of pressure and location is a question mark. One year you get excellent weed control and the next year things get wet and the dynamic changes. That’s why timing and staying on top of the weed situation is crucial.”
