With the threat of a major glyphosate-resistant pigweed infestation lurking around the next corner, many anxious farmers are asking themselves, “How much yield can I sacrifice for better weed control?”

Jesse Flye, who farms with his brother, Logan White, and father, Marty White, near Jonesboro, Ark., has been trying to quantify this dilemma for the past two years, by comparing costs and net profits for LibertyLink soybeans versus Genuity Roundup Ready 2 Yield soybeans. They also grow LibertyLink cotton, Clearfield rice and conventional rice.

Many growers, including Flye, have gone to the LibertyLink system because its companion herbicide, Liberty, does a better job of controlling pigweed than Roundup.

But yields in LibertyLink soybeans haven’t caught up to yields in Roundup Ready 2 Yield soybeans.

So, which is the better choice?

In the first year of the study, on a 75-acre plot in 2012, Asgrow AG 4632 RR2Y yielded 69.2 bushels per acre for Flye, while the Halo 4.65 LibertyLink variety yielded 62 bushels, about a 7 bushel advantage for the Roundup Ready 2 Yield variety.

“In 2012, the Roundup Ready 2 Yield variety ended up being a little more costly for us because we missed our Valor and Gramoxone burndown application on part of the field, and we had to put down an extra shot of Flexstar,” Flye says.

“The Flexstar application is a $20 to $25 application. So, our Roundup side ended up being about $20 an acre more than the LibertyLink side in 2012.”

Windy weather was the culprit for missing the burndown, according to Flye. “We got about half the field sprayed with a burndown. Where we started clean — you could tell to the row — there was no pigweed.”

“Flexstar will kill small pigweeds, but if they get much taller than three or four inches, you’re not going to do a very good job,” he says. “It’s a lot better to start clean and do preemergence herbicides after that to keep things clean.”

Applying preemerges “doesn’t bother me,” Flye says. “With all these post- chemicals and technologies and crops, we have to worry more about wind. Getting the preemerge down can make that a lot easier.”

Even with the extra costs in the RR2Y system, he says, “By the time we factor in the 7 bushel increase in yield, our RR2Y plot was still more profitable — and it ended up being cleaner, too.

“We did a better job on the Roundup side. Because of that, we had more RR2Y beans on our farm in 2013. LibertyLink still will have a place on the farm — there’s no doubt — but it’s not quite as much as we thought it would be going into last year.”

Flye says LibertyLink soybeans will be planted “in dryland situations, where we don’t know if we’re going to get rains to activate our preemerge.

“We know if we don’t get a rain, and we get a flush of pigweeds, we can get them with Liberty. That’s a situation where we feel a lot more comfortable with Liberty.

“We also have some farms where the pigweed seed bank is at very high levels, and at some point, preemerges can’t hold them back.

“On those fields, we’ll stay with LibertyLink. Eventually, we want to get the seed bank knocked down so we can use Roundup Ready technology there, because our yield potential is better.”

Flye believes yields will improve in LibertyLink soybeans “as they introduce new varieties.”

The farm also practices zero tolerance, which utilizes chopping and other practices to remove all pigweed plants from the field. While it’s rarely a complete success, after several years, it does reduce the seed bank.

Flye ran side-by-side tests again in 2013. On the preemerge side, he says, “We treated them the same as we did last year — Valor and Gramoxone, preplant on both of them, followed by Prefix on the second trifoliate for pigweed. Then we treated with Liberty or Roundup, as recommended.”

LibertyLink costs were higher in 2013, he says, because he treated the plots with Select for grass. “I didn’t have the Flexstar treatment on the Roundup side.”

The LibertyLink side “was more grown up in pigweed than the Roundup side. I don’t know why — we treated everything else the same. A pigweed can grow pretty fast in 24 hours to 48 hours.

“Maybe the LibertyLink didn’t shade the middle quite as fast, resulting in some breakthroughs. We had chopping costs in that field, too.”

Yield data from the 2013 research plots were not available at press time.

The farm also uses a flagging system developed by the University of Arkansas to make sure the appropriate herbicide is always applied on the correct field.

“This past season was really wet; all the farmers were mostly trying to get their crops in, and were late in getting the flags out.”

As a result, Flye and White made and received numerous phone calls about which technologies were planted where. “Those flags really help, because you can just look at them and know what’s there,” Flye says.

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