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Arkansas research on red rice Clearfield/Liberty Link crops

If you're looking for it, you'll find Ronnie Helms' research farm a few miles south of Stuttgart, Ark. The well-tended 150 acres is home to contract research projects, but the plots Helms is showing today — undoubtedly of interest to rice and soybean producers — were installed out of simple curiosity.

Clearfield/Liberty Link

The two sets of rice plots near Helms' headquarters will never be harvested. The farmer, researcher and consultant with G&H Associates expected the plots would be destroyed before the end of July. There's good reason for this.

“We've done red rice/Clearfield (IMI) rice research for a few years now,” says Helms standing in front of several treatment studies. “We've seen a little red rice tolerance to Newpath developing.”

Helms reported this to Ford Baldwin, a consultant and weed scientist (and Delta Farm Press contributor). “Ford walks fields all the time and he's seen the same. He said, ‘Over the years, I've collected seed from panicles from herbicide misses.’ He gave us some of that seed. That's what we used in these plots to see what would happen. We didn't know if we'd be able to control the red rice.”

The first set of plots was planted in Clearfield 131.

“Then, we thought, ‘eventually, we may get Liberty Link rice.’ So we worked with Bayer to get the same amount of seed (in the second set of plots) as we have in the Clearfield plots.”

There are seven treatments in the Clearfield test (see photos).

  • First, is the untreated check.

  • Second, is the typical application — 4 ounces of Newpath followed by another 4 ounces. “We got, basically, zero control of red rice.”

  • The third plot takes advantage of the BASF stewardship program (4 ounces of Newpath twice followed by 5 ounces of Beyond). “The Beyond is supposed to take out any red rice stragglers. As you can see, there isn't much difference.”

  • The fourth plot shows a little less red rice but would still be considered a failure in a Clearfield system. “This one had 6 ounces of Newpath followed by 6 ounces of Newpath. That increased rate approach was just approved this year.”

  • The fifth plot had 6 ounces of Newpath applied followed by another 6 ounces followed by 5 ounces of Beyond.

  • The sixth plot had 8 ounces of Newpath applied followed by 8 ounces Newpath.

  • The seventh plot had 8 ounces of Newpath applied followed by another 8 ounces followed by 5 ounces of Beyond.

The obvious red rice misses point to the need to take care of the Clearfield technology.

“To take care of red rice, this is it. It's the best thing we've ever had and no one should take for granted that it'll always be here. We've used the Clearfield system on our own farm and work with growers who also use it. The system works if managed correctly. What this shows is the value of these technologies.

“Admittedly, we're just small-area research folks and this is an exaggerated situation.” But outcrosses happen and unless red rice is managed properly, “we'll lose this vital system.”

Helms sees things in Clearfield rice production that are very worrisome.

“I've seen fields with irregular shapes. Planes can't get into an odd corner and part of the field misses a Newpath application. If red rice is heading out there and is synchronized with the rice crop, then out-crossing can happen and cause problems.”

Then, there are other farms that can't grow soybeans well because they flood out.

“Those are in continuous rice and red rice has become a problem. Throw Clearfield varieties in that situation and you'll eventually see trouble.”

Since it's a genetically modified organism (GMO), Liberty Link rice isn't currently commercially viable for growers. But some day markets may accept it, so Helms was curious how it would perform in the potentially tolerant IMI red rice.

The Liberty Link study (see photos) included the following:

  • A check. “This check has the same amount of red rice as the Clearfield check.”

  • The second plot had one application of Ignite early at 22 ounces. This resulted in no red rice but some sprangletop escapes.

  • The third plot had one Ignite application at 29 ounces. Again, no red rice but some sprangletop escapes.

  • The fourth plot had 22 ounces of Ignite applied early and then pre-flood. This took care of red rice and other weeds.

  • The fifth plot had 29 ounces applied early and then pre-flood.

  • The sixth plot had 22 ounces applied early, 22 ounces pre-flood and 22 two weeks post-flood. “For the last application there wasn't any red rice or other weeds but we sprayed it anyway.”

  • The last plot had 29 ounces applied early, another 29 ounces pre-flood and 29 ounces post-flood.

The test showed two applications of Ignite at 22 ounces controlled red rice as well as other weeds, including barnyardgrass, sprangletop, coffeebeans and smartweed.

“Doing this certainly opened my eyes to the possibilities. If the markets ever come around, farmers might consider rotating Clearfield and Liberty Link varieties. You could rotate a Clearfield, a Roundup Ready soybean and then Liberty Link. That would provide three modes of action that would, hopefully, take care of resistance issues.”

Permit is a broadleaf herbicide used in rice and marketed by Gowan. It's a sulfonylurea herbicide, “the best we have for yellow nutsedge control in rice,” says Helms. “It also has other broadleaf activity like on coffeebean, joint vetch, and morning-glory — an array of weeds that produce black seeds which cause rice grade reductions.”

But Permit will injure soybeans. That's a big deal in these times of drift problems.

However, it turns out some soybean varieties are more tolerant of the Permit herbicide than others. So Helms, with Gowan's encouragement, began identifying those varieties.

“By now, most farmers have heard of STS or sulfonylurea-tolerant soybeans. In soybean variety studies soybeans are screened for susceptibility to propanil. We wanted to know if any of the STS varieties were tolerant of Permit.”

What soybean varieties might be best to plant next to rice?

“What we've done here is screen beans,” says Helms. “The far left is an untreated check — the plot holds a Roundup STS bean that's tolerant to Permit (see photo). The second plot is 1.3 ounces of Permit over-the-top to an STS-tolerant variety. The third plot is an STS soybean with no tolerance to Permit applied at a tenth of a rate (.13 ounces). The fourth plot is 1.3 ounces of Permit applied to a non-tolerant STS soybean.

“Obviously, there is tolerance of Permit from certain beans.”

How do you get away from drift issues and still control yellow nutsedge? This study might point towards an answer.

Drift issues continue to plague the Mid-South and drove Helms to this research.

“We have tested five STS beans and found tolerance in three of them — two D&PL and one Asgrow. Gowan, because it's a new company with this product, was curious itself. It just acquired Permit from a Japanese company after it had been a Monsanto product. I told Gowan about this test and the company was intrigued.

“This is just expanding the research database with its recently acquired product. It's very impressive to me that there's no injury from Permit on these beans.”

In additional plots, Helms has conducted burndown studies.

“We put the product out three days after planting and five days after planting. The tolerant beans emerged well. Gowan may try to pursue an expanded Permit label for burndown applications or a label for some of these STS beans for over-the-top Permit for yellow nutsedge control.”

What's next?

“We need to find what Roundup Ready/STS beans are available for the Delta that fit our maturity group needs. This information is just something else for farmers to consider. And I suspect they'll be happy to at least have another option.

“If a grower says, ‘I have a nutsedge problem in my rice,’ I can say, ‘you need to look hard at these three Roundup Ready/STS soybean varieties. You can plant the soybean varieties 5 feet from your rice and not injure them when you apply Permit for nutsedge control.’”

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