A check around the Midwest with ag retailers shows that farmers in general are aware that weed resistance to glyphosate herbicide is becoming a problem, even if it hasn't happened in their area, and producers are only starting to adjust their herbicide programs for growing Roundup Ready corn and soybeans.

Even though every herbicide manufacturer competitive to Monsanto has announced some type of alternative to Roundup or glyphosate herbicide alone, there doesn't seem to be a stampede to adopt new programs with chemistry that is mainly older active ingredients combined and repackaged.

Some growers never put all their faith in a continuous glyphosate-only program when growing Roundup Ready crops, and that could be paying off for them. Other farmers, usually in more northern climates, have seen less glyphosate resistance.

A check with Agricultural Retailers Association members serving seven states resulted in interesting contrasts and comments. Arkansas was the most southern state from which comments were gathered. Ben Branch, location manager for Ritter Crop Services at Marked Tree, which is in northeast Arkansas, reported the most glyphosate weed resistance of all the locations surveyed.

"This year we had a dramatic turnaround in the amount of pre-emerge herbicides that we put out. The best thing for glyphosate-resistant weeds is to keep them from coming up; then we don't have to worry about them," Branch said. "We've been preaching use of one or another pre-emerge herbicide to fit specific field situations. Certain situations call for specific programs and products, and we work hard to find the right ones."

Pigweed, marestail and ryegrass have all shown glyphosate resistance in places across Ritter Crop Services's sales area. Branch said that those farmers not using a pre-emerge up front or another herbicide in the tank with the glyphosate are taking a chance. "Some of the guys aren't listening because they say they don't have a problem, but one year more and they'll probably have a big problem."

Up North in Nebraska
Going north to Nebraska and checking in with Robert Maxwell, owner and manager of Madison's Great Western, Ainsworth, found that resistance or low susceptibility to glyphosate is just raising its ugly head.

"We think we're starting to see some resistance on some fields primarily where there have been two shots of glyphosate in corn and two in beans and then two in corn again over multiple years. Having said that, in the last few years, we have been actively promoting farmers use another mode of action herbicide in their glyphosate application, and we also promote putting a pre-emerge herbicide down and coming back with a single shot of glyphosate. We are trying to get multiple modes of action used for grass and weed control," Maxwell said.

Some growers first to grow Roundup crops continuously are saying "my weed control isn't as good as it once was. Their neighbors are seeing it, too, and word travels fast in the ag sector," Maxwell noted. The multiple modes of action message is one farmers are now willing to accept.

As Far East as Ohio
Near Urbana, Ohio, in the service area of Champaign Landmark Inc. of west central Ohio, glyphosate resistance by marestail, lambsquarter and velvetleaf has been discovered, and Mark Secor, the company's agronomy manager, has farmers using pre-emerge herbicides.

"I can't stress enough that we only promote use of a full rate of various pre-emerge herbicides. With problem weeds, if they use a half or low rate, those problem weeds are eventually going to come through," he said.

"We're telling the guys to use full rates of residual herbicides ahead of planting followed by a glyphosate application, and we're also suggesting they add something to the glyphosate for another mode of action for problem weeds."

Secor partially blames glyphosate resistance on farmer use of reduced rates. "If the label was a quart, he went 24 ounces. If the situation called for 22 ounces, he went with 16 or 18 ounces."

As for new weed control programs, Secor doesn't see them as really new. "There is some new stuff coming down the road from manufacturers, but at least a portion of the product is going to still be old chemistry."

Looking at the I-States
At South Whitley, Ind., and AgPlus Inc.'s territory in the northeast portion of the state, Mike Sims, the agronomy manager, notes that the only glyphosate weed resistance verified in the company sales area is a small section of ragweed.

It is typical that one ag retailer will have resistant or lower susceptible weeds while a neighboring retailer will have much more or none. The survey of retailers for this article was as much to determine farmer attitudes as much as control practices being promoted.

"We've been able to keep the farmers using residuals pretty well," said Sims. "This has not been a continuous Roundup alone area. Most of the growers have been putting a residual herbicide down with their corn, and we're getting more and more of them every year to put a residual with their burndown for beans."

Sims notes that as the price of corn and beans fluctuate lower and the price of glyphosate drops, as has recently occurred, it is harder to keep farmers from thinking about cutting back on the residual to save a dollar and take their chances with glyphosate-resistant weeds showing up.
River Valley Cooperative with headquarters at Mt. Joy, Iowa, serves northwest Illinois and Eastern Iowa farmers. Randy Beard reports farmers in this area are showing concern, but not fear of glyphosate-resistant weeds at this time.

"I haven't seen a big move away from Roundup because of weed resistance. I think it is on the top of people's minds, and I think they know the train is coming down the track," he said.

"There is some belief that a few species of weeds are getting harder to control, not that they can't be controlled but that they are being tougher to control," Beard said.

In an area where more than 80 percent of the corn planted is Roundup Ready, "the practice is to put a pre-emerge herbicide ahead of Roundup when planting corn. In beans, there are many farmers that use a pre-emerge herbicide, but it is not the majority," he explained.

Farther south in eastern Iowa, a similar situation was reported by Steve Meyerholz, agronomy manager for Eldon C. Stutsman, Inc. at Hills. Weed resistance has not hit the area. Farmers are not asking a lot of questions or showing concern about glyphosate-resistant weeds.

"We are not having trouble, knock on wood. We have farmers using a whole lot of rotation and different chemistries. We have recommended adding different chemicals to the glyphosate so that it isn't glyphosate, glyphosate, glyphosate alone," Meyerholz said.

A Mixed Bag in Missouri
Missouri has earned a reputation as a state of mixed weed resistance or reduced susceptibility to glyphosate by various weeds. "There is a little bit of waterhemp and marestail coming through," noted Larry Harman, manager of the Salisbury Ag Center, Inc. at Salisbury in north central Missouri. "We're not having a whole lot of such problems, but we are running into some of it.

"We're adding other chemistries to the glyphosate to make it a little hotter. By adding something to the glyphosate, we're able to get some extra control. We also encourage crop rotation as well as not planting Roundup Ready corn following Roundup Ready beans."

Some of the farmers in the Salisbury area are willing to skip Roundup Ready corn, and even a few farmers are trying non-Roundup Ready soybeans. Local farmers are watching the fields of three or four farmers who have planted a portion of their acreage to conventional soybeans in 2009.

Whether new chemistry will allow the experiment to become a more standard practice, is yet to be determined, but Harman remembers how it was much more work to control weeds in soybeans before Roundup Ready beans.

"I don't think it is going to be too interesting if the farmers ask me to kill weeds that come through and they are beyond label recommendations," Harman said. "I remember the old days. With the chemicals we were using, too often we would burn the beans or didn't kill all the weeds."