Soybean south april 2018

ONE GROWER PUBLISHING, LLC

Weed resists multiple herbicides Rotate effective modes of action to thwart new pigweed biotype

APRIL 2018

SS0418 Layout_CF 11/13 template 3/21/18 2:33 PM Page 2

SS0418 Layout_CF 11/13 template 3/21/18 2:33 PM Page 3

Talk about fast delivery.

52-7' 25 58& /+' 2 12 5207 582'1-2 25 (5*+7))&2*1' 81)2102 65 8 * + 52 1& 57'2(5 2 5 2 /523'1*361-'2&1 25 (5* 2 '2/1 8 2+' 5762 10267& 2-+ /2 ' 85(+62 6 5®2+' 5* +*+65 2 552+ 20182&1 8 5)027 2ExpectFaster.com.

® 98765478321029/52.1-2,/54+*7)2,14(7'&2%$.1-#"21827'270!)+7 562*14(7'&2102.1- 2 ' 85(+62 6 52+ 2'1 285 + 585620182 7)52182 52+'27))2 7 5 2,1' 7* 2&1 82 7 52(5 +*+65285 )7 18&27 5'*&2 1265 584+'52+0272 (816 * 2+ 285 + 585620182 7)52182 52+'2&1 82 7 5 2 )-7& 2857627'6201))1-2)7 5)26+85* +1' 2 2.1-2 81 *+5'*5 2 ,222 2% "2 222. 9

ONE GROWER PUBLISHING, LLC

APRIL 2018

The more we know about pigweed, the more we don’t know

Weed resists multiple herbicides Rotate effective modes of action to thwart new pigweed biotype

CONTENTS

6 Weed resists multiple herbicides Be diligent rotating MOAs to thwart new pigweed biotype.

5 Industry News 8 Irrigation trials In MSU trials, furrow irrigation beats flood irrigation by a nose.

Cover photo by Vicky Boyd

DIGITAL EXTRAS

Soybean South: Covering Southern Soybean Production Soybean South is a supplement to the Mid-South and Southeast versions of Cotton Farming magazine and Rice Farming magazine.

If you would like to receive Soybean South, visit www.SoybeanSouth.com and click on “Subscribe to Soybean South.” Add your email address to the E-News list to have exclusive content delivered directly to your inbox.

Palmer amaranth, which has been dubbed a “super weed” by some, is definitely living up to its reputation.

The weed already has documented resistance to six different modes of action: glyphosate, ALS-inhibitors, HPPD-inhibitors, PPOs, microtubule inhibitors like Treflan, and photosystem II inhibitors like atrazine and metribuzin. At least a few biotypes have resistance to multiple modes of action at once.

Scientists are still unsure of the mechanism behind the resistance in some cases. Work at the University of Illinois last year found Palmer amaranth resistant to PPOs also had a genetic mutuation that allowed it to withstand glyphosate. With each successive generation, the mutation frequency was higher, meaning it Vicky Boyd took higher rates of PPO herbicides to control it.

Editor In other cases, they haven’t pinpointed the exact change within the weed that allows it to withstand herbicide applications. It also appears that some Palmer amaranth populations resistant to glyphosate have more tolerance to other herbicides. Whether this is true resistance or the herbicide was never really effective on Palmer remains unanswered.

But you don’t have to be a scientist to realize that Palmer pigweed resistance to herbicides is a growing problem and one that shouldn’t be taken lightly.

Extension weed specialists such as Bob Scott with the University of Arkansas continue to preach overlapping residuals and rotating effective modes of action. That’s the operative word: effective modes. You’d be just wasting money if you rotated ALS-inhibitors and glyphosate in a field with multiple resistance to those herbicides.

Even with the most diligent integrated weed program that includes mechanical control and crop rotation, the job won’t be easy. A single female Palmer pigweed plant under optimum conditions can produce up to 460,000 seeds annually, according to University of Georgia research. Preventing the plants from going to seed in the first place should be job one.

The glyphosate-resistance trait also can be carried on pollen at least 1,000 feet to fertilize susceptible female plants. As a result, a portion of the offspring will be glyphosate resistant.

In addition, University of Missouri research has found that geese and ducks can spread resistance by feeding on glyposate-resistant amaranth seed, traveling to another location and passing it out the other end.

Growing up, we liked to joke that should a nuclear explosion go off, two things will survive: cockroaches and my mom’s fruitcake. Based on the research of weed scientists, I think Palmer pigweed should be added to that list.

Vicky

Follow Soybean South on Twitter @soybeansouth

4

SOYBEAN SOUTH

|

APRIL 2018

Send your comments to: Editor, Soybean South Magazine, 6515 Goodman Road, Box 360, Olive Branch, MS 38654. Call 901-767-4020 or email vlboyd@onegrower.com.

SOYBEANSOUTH.COM

■ Valent launches two soybean products Walnut Grove, California-based Valent U.S.A. has introduced Fierce MTZ Herbicide Co-Pack and Aveo EZ seed treatment this season.

The Fierce co-pack offers three different effective modes of action contained in Zidua, Valor and Mauler herbicides or pyroxasulfone, flumioxazin and metribuzin, respectively, says Frank Carey, Valent field market development specialist. The active ingredients belong to the Weed Science Society of America’s groups 14, 15 and 5.

Fierce is active on small-seeded broadleaf weeds and grasses, whereas the metribuzin controls large-seeded broadleaf weeds, including morningglory — one of Fierce’s weakness, he says. Zidua brings in a different mode of action to control small-seeded broadleaf weeds, including ALS-, glyphosate- and PPO-resistant Palmer amaranth.

Carey says Aveo EZ is a biological nematicide applied to soybean seed at a very low use rate — 0.1 fluid ounces per 140,000 seeds, according to the product label. It contains the active ingredient Bacillus amyloliquefaciens Strain PTA-4838.

Although the exact control mechanism isn’t fully understood, he says researchers have seen strong activity on soybean cyst nematode, reniform nematode and root knot nematode in soybeans.

“We don’t know exactly what’s going on to protect the root,” Carey says. “What we do know is it reduces the egg counts, and we see the plants grow because they don’t have nematodes.”

Aveo can be tankmixed with most seed treatments as well as Rhizobia inoculants.

■ UT student earns WSSA honors for PPO-resistant pigweed work Drake Copeland, a University of Tennessee graduate, won first place for a poster presentation by a Ph.D. candidate at the recent 2018 Weed Science Society of America meeting.

Copeland took home the top prize with his poster titled, “Influence of Residual Herbicide Application Rate on PPO-Resistant and Susceptible Palmer Amaranth (Amaranthus palmeri) in Tennessee.”

The initial findings of his study suggest Palmer amaranth could be exhibiting greater tolerance and possibly resistance to even more herbicide modes of action.

Copeland is a doctoral candidate with the UT College of Agriculturual Sciences and Natural Resources. His concentration TWITTER: @SOYBEANSOUTH

N E W S

is weed science under the direction of Larry Steckel, professor and Extension weed specialist with UT’s Plant Sciences Department.

Palmer amaranth is currently considered the most troublesome and costly weed in U.S. soybean production. It has developed resistance to the widely used herbicide, glyphosate, and more recently to PPO inhibitors.

Copeland evaluated the efficacy of PPO herbicides on two biotypes of Palmer amaranth — PPO resistant and PPO susceptible. He also evaluated the efficacy of Group

15 herbicides on these weeds.

Data showed that Group 15 herbicides were less effective on PPO-resistant Palmer amaranth than PPO-susceptible Palmer amaranth. The inconsistencies suggest pigweed resistance is continuing to evolve.

The poster was co-authored by Steckel and Matthew Wiggins of FMC Corp.

WHETHER ITS SEED, INPUTS, OR FINANCING, SANDERS HAS BEEN PROVIDING SOLUTIONS TO OUR FARMERS FOR OVER 60 YEARS! MISSION SEED SOLUTIONS’ unparalleled genetics and traits on soybeans offer our growers varieties that are second to none, and are selected based on local needs and performance. Treat, protect and grow your seed utilizing the exclusive line of crop input products from Innvictis Crop Care. These two complementary product lines allow our farmers to grow their maximum yield!

www.MissionSeed.com

www.Innvictis.com

©2018 SANDERS, PINNACLE logo and designs are trademarks owned by Pinnacle Agriculture LLC. INNVICTIS name and logo are registered trademarks owned by Innvictis Crop Care, LLC. MISSION SEED SOLUTIONS name and logo are trademarks owned by Mission Seed Solutions.

All other trademarks are property of their respective owners.

APRIL 2018

|

SOYBEAN SOUTH

5

COURTESY UNIVERSITY OF TENNESSEE

I N D U S T R Y

More questions than answers

VICKY BOYD

New multiple-resistant pigweed biotype proves hard to control, reinforces need to rotate effective herbicide modes of action.

6

SOYBEAN SOUTH

|

APRIL 2018

SOYBEANSOUTH.COM

By Larry Steckel

A

Trials leave many questions

It is unclear at this point how to label this

biotype of Palmer amaranth that resides on both sides of the Mississippi River around and just north of Memphis.

Is it resistant to all those herbicides? Is it just the background tolerance that has always been there?

That is still being determined. The best theory to date is that some kind of metabolic resistance is building in the Memphis-area Palmer amaranth biotype that gives the weed some tolerance to multiple classes of herbicides.

So what is a good approach to control Palmer amaranth in locations where PPO-resistant Palmer amaranth is present?

The graph above shows the results of a comparison of the efficacy of herbicides at a PPO-susceptible (PPO-S) Palmer amaranth site and a PPO-resistant (PPO-R) Palmer location.

Treatments were applied alone or with a sequential application made seven days later.

Example of the 20% survivors in a PPO-resistant Palmer population one week after a treatment of 22 fl. oz./A ExtendiMax. TWITTER: @SOYBEANSOUTH

PHOTO COURTESY UNIVERSITY OF TENNESSEE

survey sponsored by the Tennessee Soybean Promotion Board was conducted last summer to determine the percentage of fields that harbored PPO-resistant Palmer amaranth in West Tennessee. We found that 83 percent of the fields tested had Palmer amaranth infestations that survived a field-use rate of Flexstar (fomesafen).

Recent field research has shown that these populations are also ALS and glyphosate resistant.

Additionally, some of these multiple-resistant Palmer amaranth populations are proving to be difficult to control with a number of herbicides.

As a result, research was conducted to investigate the effectiveness of various herbicides in controlling PPO-resistant (Flexstar-resistant) Palmer amaranth compared to a location where PPO herbicides were still effective on Palmer.

The herbicides tested were applied to pigweeds that were 2 to 4 inches tall.

XtendiMax (dicamba, photo below) and Enlist Duo (2,4-D and glyphosate) provided about 80 percent control of the Palmer amaranth at the PPO-resistant site compared to 100 percent control at the PPO-susceptible site.

Other herbicides that did not perform as well as we would like at the PPO-resistant site were Liberty or glufosinate (90 percent compared to 100 percent at PPO-susceptible site) and Callisto or mesotrione, an HPPD (38 percent compared to 90 percent, respectively).

The only herbicide tested that provided 100 percent control of Palmer amaranth at both sites was atrazine.

Treatments included: XtendiMax at 22 fl. oz./A; Flexstar at a pint/A; XtendiMax followed by Flexstar; XtendiMax followed by Liberty at 32 fl oz./A; and XtendiMax followed by XtendiMax. Flexstar (fomesafen) applied alone provided roughly 28 percent control at the PPO-R location. Hence, the need for auxin-tolerant crops.

Interestingly, Flexstar applied seven days after the initial XtendiMax application controlled Palmer amaranth that escaped the initial dicamba application at the PPO-resistant site.

Even though Flexstar applied alone would not control these Palmer amaranth, it would control them if they were recovering from a dicamba application.

We speculate that the initial application of dicamba affected the mechanism of PPO resistance enough that the Palmer amaranth can then be controlled with a follow-up PPO-inhibiting herbicide.

From a stewardship standpoint, applying an auxin (i.g. dicamba or 2,4-D) in the first post application is the best strategy. Following that application, seven to 10 days later with Flexstar (in soybeans) provides good control of any escapes and potentially removes the need for an application of dicamba later in the season.

This strategy may help avoid off-target movement and is also good resistance management.  Dr. Larry Steckel is a University of Tennessee Extension weed specialist at the West Tennessee Research and Education Center in Jackson. He may be reached at lsteckel@ utk.edu.

APRIL 2018

|

SOYBEAN SOUTH

7

By Dan Roach

W

ith the decreasing water levels in the Mississippi Alluvial River Valley aquifer and state regulators requiring irrigation water-use efficiency practices, the Mississippi State University Irrigation Team was requested in 2016 to investigate furrow and flood irrigated soybeans in the Delta.

During the summers of 2016 and 2017, 16 Delta farms were chosen for a study to compare the water use and yield of furrow- and flood-irrigated soybeans. Each farmer furnished two fields, one furrow irrigated and one flood irrigated. All fields were land-formed clay soils.

The fields were required to be side by side or in relatively close proximity with the same planting date, variety and cultural practices.

The MSU researcher installed Watermark moisture sensors in both fields and recorded soil moisture levels. The researcher made the irrigation decision on the furrow-irrigated field, while the farmer made the decision on

the flood-irrigated field. Irrigation water meters were installed in both fields to measure water use. Combine yield monitors provided yield results.

Surprisingly, water use in both systems was similar. This tells us farmers are doing an extremely good job managing water use in their flood-irrigated fields.

Flood-irrigated yields averaged across locations resulted in a 5.4 bushel decrease over the furrow-irrigated fields. The number of levees, well capacity, saturation and drainage all played a role in this yield reduction.

Total specified expenses for the furrow-irrigated system were $562.43 which reflected the additional cost of the poly tubing, and RISER program equipment (surge valves, sensors, data loggers). Total specified expenses for the flood-irrigated system were $543.23. Net income at $10.54 (March 2018) soybean prices was $213.84 for the furrow irrigation system and $176.02 flood irrigation system.

Although your farm numbers may vary, in this study the furrow system netted a $37.82

VICKY BOYD

Furrow irrigation beats flood irrigation in MSU trials

Despite the added cost for collapsible poly tubing, furrow-irrigated beans netted slightly more return per acre than flood-irrigated beans.

advantage over the flood system. A third year of data will be collected in 2018.

Dan Roach is an Extension associate at MSU’s Delta Research and Extension Center in Stoneville. He may be reached at dan.p.roach@msstate.edu.

LOCAL SEED, LOCAL PEOPLE, LOCAL QUALITY We provide the broadest range of top yielding genetics, while hand selecting only the best seed to perform in your area. Maximize your investment in seed through the latest technology and best partnerships possible- GO LOCAL.

BUY LOCAL! 8

SOYBEAN SOUTH

901-260-6000 |

APRIL 2018

@LocalSeedCo

@localseedco

@LocalSeedCo SOYBEANSOUTH.COM