Soybean south may 2016 by One Grower Publishing

ONE GROWER PUBLISHING, LLC

MAY 2016

Survey ranks Palmer amaranth as most troublesome weed

Get a jump on resistance

Tankmix or rotate chemistries to fight frogeye leaf spot

SS0516 Layout_CF 11/13 template 4/20/16 1:41 PM Page 2

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ONE GROWER PUBLISHING, LLC

MAY 2016

Survey ranks Palmer amaranth as most troublesome weed

Get a jump on resistance

Tankmix or rotate chemistries to fight frogeye leaf spot

CONTENTS

4 Get a jump on resistance Plant frogeye leaf spot-resistant varieties and avoid solo QoI fungicide applications.

6 Industry News Cover photo courtesy United Soybean Board

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.

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No surprise — Survey ranks Palmer amaranth as most troublesome weed You undoubtedly have seen headlines, such as “10 worst cities in which to live” or “Top 10 worst cities for car theft,” in the popular press or online. The Weed Science Society of America has its own survey in which being No. 1 is a notorious honor. It should come as no surprise that Palmer amaranth was ranked the most troublesome weed in 2015 across 26 different cropping systems in the United States. After all, this member of the pigweed family reproduces faster than rabbits, taking over fields in just a few years. It also has become resistant to many of today’s common herbicides. Coming in as the most common weed was foxtail. Three weeds — common lambsquarter, morningglory species and Palmer amaranth — were in the top five of Vicky Boyd both the most troublesome and most common weeds. Editor WSSA defines common as “those weeds you most frequently see,” whereas troublesome weeds are “those that are most difficult to control but may not be widespread.” Participants in the survey included university and Extension personnel, crop consultants and scouts, industry and government representatives, and land or water managers. What is a bit odd, until you consider the survey covered all of the United States and not just the South, is marestail was ranked the most troublesome weed and foxtail the most common weed in soybeans. When you delve deeper and look at the state-by-state data, Palmer amaranth is definitely one of the more common weeds in Southern and Mid-South soybean states. But it may not be the tops. In Louisiana, for example, participants listed Italian ryegrass and barnyard grass as the most common weeds in soybeans. But look at the most troublesome weed, and Palmer amaranth is either the top offender or one of top two offenders in every Southern and Mid-South soybean state. The 2015 survey of 26 different crops, non-crop, aquatic and natural areas established a baseline of weed species that will help researchers in the future gauge shifts in populations and management practices, says Lee Van Wychen, science policy director for national and regional weed science societies. “When you look at the Southern Weed Science Society, Palmer amaranth wasn’t even on their radar screen when they started out in the 1970s. It slowly started to grow over the decades.” WSSA plans to rotate the weed survey every three years, focusing on a portion of the cropping systems annually to avoid overwhelming participants. This year, it is seeking input for weeds of fruits, vegetables, and broadleaf crops including soybeans. In 2017, the survey will focus on weeds in grass crops, pastures and turf. And in 2018, the survey will examine weeds in aquatic systems, non-crop and natural areas. You can view the complete survey results on the WSSA’s website, http://bit.ly/1Wa1SUH.

Vicky 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. SOYBEAN SOUTH MAY 2016

Get a jump on resistance Plant frogeye leaf spotresistant varieties and avoid solo QoI applications if fungicides are needed. By Vicky Boyd Editor

sissippi River, as of April 1. The region includes most of the Southeast where soybeans are grown. The fungal pathogen that causes FLS is called Cercospora sojina. It primarily attacks soybean foliage, causing circular or angular spots on the leaf surface that resemble frog eyes. Symptoms begin as dark brown, water-soaked spots and mature into lesions with tan or brown centers and a narrow reddish-brown to purple margin. In severe cases, the disease can cause premature defoliation, significantly reducing photosynthesis and yields. Although less common, disease symptoms also may be found on pods, seeds or plant stems Optimum conditions for FLS infection and development are temperatures between 77-85 degrees Fahrenheit and high moisture, such as from heavy dews or prolonged periods of light rains. The organism also can survive from one season to the next on infected seed and plant material.

Fungicide resistance continues to expand Strobilurin-resistant FLS has been found in 178 counties in 12 states east of the Mis-

Resistant varieties have improved Although host-plant resistance tops Extension recommendations for managing FLS, many growers in the past have shied away

SOYBEAN SOUTH MAY 2016

COURTESY MISSISSIPPI STATE UNIVERSITY

s strobilurin-resistant frogeye leaf spot (FLS) continues to expand across much of the Southern soybean production region, Extension specialists say using resistant varieties remains a grower’s best option. “The No. 1 recommendation I will always make to growers is to use host-plant resistance,” says Travis Faske, University of Arkansas Extension plant pathologist based in Lonoke. “That’s the best, most economical option they have.” If scouting indicates a fungicide is warranted for FLS, Faske and colleagues now recommend against using strobilurins — also known as QoIs — as a stand-alone treatment. “What I’ve been telling producers, county agents and crop consultants I believe every field (in Tennessee) most likely has some level of resistance, so don’t plan on using a solo QoI in soybeans to control frogeye leaf spot,” says University of Tennessee Extension plant pathologist Heather Kelly. Instead, she and others advise growers to switch to a fungicide with another mode of action, such as an MBC (methyl benzimidazole carbamate) or DMI (demethylation inhibitor). Better yet, they say, is to use a premix or tankmix that contains two different modes of action, one of which can be a strobilurin. “Even though the QoI won’t control frogeye leaf spot, there are other pathogens that it will take care of and help manage,” says Kelly, based at the West Tennessee Research and Education Center in Jackson. Growers also should apply fungicides at labeled rates. In addition, Kelly recommends incorporating other non-chemical resistance-management practices, such as crop rotation and debris management, into production regimes.

Frogeye leaf spot typically attacks foliage. in severe cases, it can cause premature defolliation, significantly reducing photosynthesis and yields.

from these varieties because they didn’t yield as well as those without the genetic attribute. But Kelly says that is changing, and she cites yield data from the past three years of variety trials conducted at the UT Ag Research & Education Center at Milan — considered an FLS hotspot. “In general, I’ve seen some very high yielding, very highly resistant frogeye leaf spot varieties of soybean in my trials over the last three years, so more breeders are incorporating FLS resistance into their genetics,” she says. Faske agrees and notes that Asgrow 4632, a variety with FLS resistance, also produced more than 100 bushels per acre in the Arkansas Soybean Yield Challenge last season. “I think they’re improving in that (yield) area, and I hope the trend continues,” he says. Under severe disease pressure, the resistance trait still may not protect the soybean plant entirely from infection, but it should help. “If you invest in the genetics and a resistant FLS variety, you’re less likely to need a fungicide application to protect yield from FLS,” Kelly says. “It depends on how the year plays out. In drier years, we don’t always have fungal diseases develop that will rob yield.”

Dr. Binbin Lin, a post-doctoral researcher. Spore traps work on the same premise as other pest traps. In this case, they measure the amount of inoculum present and can alert growers seven to 10 days before FLS symptoms appear in the crop. “We know to use a moth trap around nonBt corn — once you get to a certain level,

• Choose a soybean variety with frogeye leaf spot (FLS) resistance. If in doubt, check university soybean research verification trial results as many also contain FLS ratings. • Start with clean, disease-free seed since the FLS pathogen can overwinter on seeds and plant debris. • Rotate crops and use tillage methods to manage plant residue. • Scout fields regularly to catch the disease early. Fungicides work best when applied as a preventive treatment. • If you need to use a fungicide, rotate or tankmix chemistries and avoid using a stand-alone strobilurin fungicide application. Apply fungicides at labeled rates and at the proper timing.

then it triggers an insecticide application,” she said. “With frogeye leaf spot, it will be more complex. You have the level of resistance in the variety to consider as well as crokplping and disease history of the field. We’re finding higher disease pressure in sites that had continuous soybeans with highly susceptible varieties planted.”

HEATHER KELLY, UNIVERSITY OF TENNESSEE

Disease risk model in the works To help growers and consultants better gauge the risk of FLS developing in their soybean crops and when to spray, Kelly is leading a research project to develop a forecasting model. Her first attempt looked at using a simple model to predict when weather conditions would be conducive for disease development. The results were inconsistent. But Kelly is working on a more complex model that will factor in field disease history, field cropping history, varietal genetics, weather parameters and possibly spore trap catches. Assisting her is Jamie Jordan, a research associate also pursuing his Ph.D., and

Take these steps to fight FLS

HEATHER KELLY, UNIVERSITY OF TENNESSEE

Scouting remains the best way to catch the disease early, Kelly says. Fungicides are most effective when applied preventively or shortly after infection. So it’s best if growers apply them before fungal infection or at the onset of symptoms to protect the plant. Based on averages from numerous field trials, the “sweet spot” timing to apply an FLS treatment is R3 when pods are just beginning to form, she says. “When you start to see the disease, you try to figure out what level and how quickly the disease will develop,” Kelly says. “In some instances, we can find the disease and it very slowly develops. Other times after finding it at low levels and the right conditions occur, it’s really blown up.”

Optimum conditions for frogeye leaf spot development are temperatures between 77-85 degrees Fahrenheit and high moisture, such as from heavy dews or prolonged periods of light rain.

SOYBEAN SOUTH MAY 2016

2016 Georgia Farmer of the Year John McCormick (center) and his wife, Paula McCormick, accept his award from Gov. Nathan Deal (far left). Screven County Extension Coordinator Ray Hicks and Georgia House Majority Leader, Rep. Jon Burns, are on hand to congratulate them.

■ Soybean producer named Georgia Farmer of the Year For John McCormick, farming is a tradition. His ability to help his farm evolve over the years earned him the title recently of “Georgia Farmer of the Year.” He will represent the state at the Swisher Sweets/Sunbelt Expo Southeastern Farmer of the Year competition in Moultrie, Ga., in October. The Sylvania, Ga., corn, peanut and soybean farmer was honored recently by Gov. Nathan Deal during the state’s Ag Awareness Day at the Georgia Capitol. McCormick’s wife, Paula, four sons and daughters-in-law were on hand as well. Ray Hicks — University of Georgia Cooperative Extension coordinator for Screven County — nominated McCormick, who pio-

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■ Natural enemies suspected in kudzu bug numbers dip University of Georgia researchers suspect that declining kudzu bug numbers may be due to natural enemies, but they don’t know for sure. “We can’t positively say it’s due to their natural enemies, but kudzu bug populations are decreasing,” Ian Knight, a graduate student in UGA’s College of Agricultural and Environmental Sciences, said in a news release. The decline began in 2014 and is believed to have been caused by a naturally occurring fungus and a wasp. The fungus, Beauveria bassiana, affects most Southeastern insects. But the wasp, Paratelenomus saccharalis, was found in America after kudzu bugs were discovered here. The wasp lays eggs inside the egg case of kudzu bugs, preventing large numbers of the pest from developing.

COURTESY UNIVERSITY OF GEORGIA

neered use of new technologies, such as GPS-guided machinery and variable-rate irrigation, in southeast Georgia. “He is a very diversiﬁed farmer who has used modern technology to help improve the proﬁtability and sustainability of this farm,” Hicks says.

■ Bayer seeks hearing before EPA judge over Belt Bayer CropScience has taken what it calls the “unprecedented step” and requested a formal hearing before an Environmental Protection Agency administrative law judge over the agency’s proposed cancellation of ﬂubendiamide insecticide. Bayer markets the active ingredient as Belt Insecticide, and it is labeled to control worm pests on several crops, including soybeans. “EPA is trying to cancel the products through a streamlined hearing in an effort to shield its science from independent peer review and to avoid other government and stakeholder input on its approach,” Bayer said in a letter to its customers. “We disagree with this and are exercising our right to request that (an) EPA administrative law judge hear both sides and issue an initial determination on what process should be followed.” The EPA claims use of the insecticide may harm benthic organisms — microscopic organisms that live in ocean ﬂoor sediments. After the administrative law judge issues an initial decision, the EPA Environmental Appeals Board will review it. The entire process typically takes about 75 days. In the meantime, retailers can continue to sell the insecticide and growers can continue to use it according to label. ■ Monsanto OKs $975 million expansion of dicamba plant Monsanto Co.’s board of directors recently approved a $975 million expansion at the company’s Luling, La., site that manufactures dicamba herbicide. Upon completion in mid-2019, the facility is expected to supply 25 to 35 percent of the demand across the Americas for dicamba, which is part of the Roundup Ready Xtend Crop System. The Environmental Protection Agency has yet to register over-thetop applications of dicamba on any crop. Monsanto has submitted registration applications for Roundup Xtend with VaporGrip technology, a low-drift premix formulation of glyphosate and dicamba, and XtendiMax with VaporGrip, a standalone dicamba that can be tankmixed with other herbicides. The herbicides will be paired with Roundup Ready 2 Xtend soybeans, which are tolerant to both glyphosate and dicamba.

Keep ‘eyes on the field’ to protect the bottom line CLEMSON UNIVERSITY/USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

In the South, consultants keep a sharp lookout for economic thresholds of insect pests and take action when necessary to keep them under control. By Carroll Smith

oybean insects are monitored closely throughout the season in the South to spot populations that have the potential to aversely affect yields. Stink bugs, bean leaf beetles and the worm complex typically are the likely suspects. Damaging thresholds trigger insecticide applications to protect yield and, ultimately, the farmer’s bottom line. Some of these pests feed on foliage, others on pods and some on both foliage and pods. In the worm complex, foliage-feeders, such as soybean loopers and armyworms, can appear early and cause extensive “stripping” of the soybean plant if they show up in high enough numbers. The general threshold for these worms is 35 percent defoliation before bloom and 20 percent after bloom. Crop consultant Tucker Miller, owner of Miller Entomological Services in Drew, Miss., says it’s important to consider the soybean growth stage at which soybean loopers appear. “A massive population of loopers can cause a huge yield loss if they strip the foliage off the plant when soybeans are at the R5 or R5.5 stage,” he says. “They can skeletonize the plant in two to three days. If you lose all of your leaves and the pods or the soybeans inside the pods are immature, they won’t fill out.” Scout for corn earworms The corn earworm will feed on leaves, flowers and pods. Miller says corn earworms in soybeans are erratic in his area, but when they do appear in high numbers, they can cause substantial yield loss. “Corn earworms, for the most part, are

The corn earworm, which has a voracious appetite, can cause serious damage to soybean pods.

pod-feeders, but I have seen them come in early and feed on leaves and blooms,” he says. “We typically don’t have to spray for them at this time, but we do watch closely to make sure they don’t reach the 35 percent defoliation level. “If corn earworms begin to attack small pods, we apply an insecticide with fast knockdown. In our area, one application is usually enough to control them unless another generation appears. In that case, an additional spray is a possibility.” Other modes of action replace pyrethroids For many years, pyrethroids were the goto treatment for soybean worm pests. However, as these products began to lose efficacy, other modes of action for worm control were brought to market. For example, Dow AgroSciences introduced an insect growth regulator called Intrepid 2F, which was effective against many species of lepidopteran insects, including the soybean looper. But it didn’t control corn earworm. However, it did provide good residual control on treated foliage.

To boost the efficacy of this product, the company added another mode of action. “Intrepid Edge has two modes of action, spinetoram (Radiant in cotton) and methoxyfenozide, that are proprietary to Dow AgroSciences,” says Drew Ellis, market development specialist. “In our trial work, we have seen 70 percent mortality in 24 hours on corn earworm. “The new mode of action brings fast knockdown on a broader spectrum of pod-feeding worms, while the mode of action from Intrepid 2F still provides the residual on foliage-feeding pests that farmers and consultants have been accustomed to. The recommended application rate for Intrepid Edge is 4 to 6.4 ounces per acre.” As the 2016 season gets underway, consultants will have “eyes on the field” to detect potentially damaging insect levels and make insecticidal recommendations when necessary. To be able to walk out in the field soon after an application is made and not see any worms is a good way to achieve peace of mind during the fast-paced soybeangrowing season. SOYBEAN SOUTH MAY 2016

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