herbicides, waterhemp, weed control, weed management, weeds. For best control, apply a pre-emergence residual herbicide followed by post-emergence applications as needed throughout the growing season. The volume of inquiries about how to control large (taller than 12 inches) horseweed (a.k.a. Group 14 herbicides are likely the best choice for POST-emergence control of glyphosate-resistant waterhemp in Roundup Ready soybeans. Include Group 15 herbicides in the both corn and soybean. New herbicide promises control of waterhemp. The volume of inquiries about how to control large (taller than 12 inches) horseweed (a.k.a. Each is a "contact" herbicide, so thorough coverage of the target vegetation is essential for good control. His research program is focused on improved understanding of weed biology and ecology to develop effective, integrated weed management strategies in corn and soybean production systems of ... ISU Extension and Outreach This article was originally published on April 17, 2020. Products used in the analysis were applied alone as PRE at the labeled field use rates. ( Sonja Begemann ) Waterhemp, Palmer amaranth, redroot pigweed—these words in agriculture are … Although flumioxazin was very effective on waterhemp (>95% control 50% of the time), control fell below 60% in one out of the five years. It’s a premix of three herbicide sites of action aimed at managing problem soybean weeds including Palmer amaranth, waterhemp, and common ragweed. Plus, we give you some tips on identification along with pictures and other helpful information. The economic threshold recommendation is no longer enough. Soybean Pest Beat: Here are tips to get a plan rolling to control waterhemp in 2021. The lowest level of control with pyroxasulfone was 88% at three weeks after application. Authority Edge from FMC contains sulfentrazone + pyroxasulfone (HG 14 + 15) and will be available for use in soybean in 2020. Box and whisker plots showing the variability in waterhemp control at 3 weeks after application of key PRE-emergence herbicides used in soybean over the last five years (2015-2019) in trials conducted by the ISU Weed Science program at the Research Farms. The diphenyl ether herbicides include Blazer/Status, Flexstar/Reflex, and Cobra. Some herbicides perform better than others in variable environmental conditions. If resistant tall waterhemp is present on your farm the herbicide program will be slightly different from a multiple resistant marestail program. The battle against waterhemp is complicated mainly because of its extended emergence period (early May until August). 04 APPLICATION TIMING AND CUTOFFS PG. Links to this article are strongly encouraged, and this article may be republished AVOID WATERHEMP: All three Indiana CCAs agree that planning, residual herbicides and a targeted postemergence approach can control waterhemp in soybeans next year. All rights reserved. These results indicate that while all the PRE herbicides selected can provide effective residual control of waterhemp in soybean, pyroxasulfone, sulfentrazone, and metribuzin provided the most consistent early-season control over the 5-year period. Use full labeled rates; For postemergence treatments, make timely applications and apply to small pigweed (<4 inches tall). Several management considerations need to be addressed with The diphenyl ether herbicides include Blazer/Status, Flexstar/Reflex, and Cobra. The good news is these weeds are easy to control in corn. Waterhemp is a new, aggressive, glyphosate-resistant weed that has swept across the Midwest and made its way into Ontario and Quebec. Waterhemp control (% out of 100) with various preemergence (PRE) soybean herbicides DiFlexx herbicide controls tough weeds including Palmer amaranth, waterhemp, ragweed and lambsquarters, plus over 100 more annual and perennial weeds in corn. soybean herbicides in Roundup Ready (RR) or conven-tional soybean systems. Waterhemp control is an increasing challenge for soybean producers due to the evolution of multiple herbicide-resistant populations. Postemergence herbicides for waterhemp control in soybean are essentially limited to two herbicide families, the diphenyl ethers and glyphosate-type products. If applied too early, the control of Waterhemp declines. Copyright © 2020 Iowa State University of Science and Technology. Resistance to ALS-inhibiting herbicides (such as Raptor and Classic), first confirmed in Illinois during the mid-1990s, has become so widespread that this class of herbicides is largely considered functionally ineffective against waterhemp. Weed control options in soybeans. Purdue Extension also found a similar impact on corn yield. For the complete report, see Managing Waterhemp in Soybean with Layered Residual Herbicides - A Strategy for Controlling ALS and Glyphosate Resistant Waterhemp in Minnesota, 2015 and 2016. Waterhemp can grow at the incredible rate of 1 to 1 1/4 inches per day, so timely herbicide application is critical. These herbicides have been extensively used for postemergence waterhemp control in soybeans with generally good results. Many of the other pre-emerge herbicides can be saved for post, just in case you need them. Since that time, no new postemergence (POST) herbicide modes-of-action (MOA) have been developed. Figure 1. Waterhemp control (% out of 100) with various preemergence (PRE) soybean herbicides AVOID WATERHEMP: All three Indiana CCAs agree that planning, residual herbicides and a targeted postemergence approach can control waterhemp in soybeans next year. Soil-applied herbicide is the first chemical control step in protecting soybeans and corn from Waterhemp. Protect Your Almonds Against Nematodes with Velum One, Protect Your Potatoes Against Nematodes with Velum Prime, International Survey of Herbicide Resistant Weeds, Six Questions to Ask Yourself when Developing Your Weed Control Program, Identifying Pigweed and Keeping Resistance at Bay. Whiskers above and below the box represent upper 25% and lower 25% of the data. To evaluate the performance of commonly used HG 15 herbicides (pyroxasulfone, S-metolachlor, dimethenamid-P, and acetochlor) on waterhemp in Iowa soybean fields, an analysis on weed control data collected from herbicide evaluation trials was conducted by the Weed Science program at Iowa State University Research Farms from 2015 to 2019. June 16, 2016 | Posted in Crop Protection Source: University of Illinois Extension By Aaron Hager, Extension Weed Scientist Waterhemp continues to be one of the most widespread and troublesome broadleaf weed species with which farmers must contend. Soil-applied herbicide is the first chemical control step in protecting soybeans and corn from Waterhemp. Waterhemp control is an increasing challenge for soybean producers due to the evolution of multiple herbicide-resistant populations. A well-thought-out herbicide program, using multiple sites of action, should be implemented to sustainably manage weeds. This was followed by reports of 2,4-D ... help control late-emerging weeds in soybean. Site A was in Seneca County, NY on a field of Odessa silt loam soil where waterhemp had survived various herbicide applications and produced seed in 2018. “You could use glyphosate, but resistance continues to increase every year. 2150 Beardshear Hall The only option is the use of a PPO-inhibiting herbicide such as Flexstar, Cobra, or Ultra Blazer although there are multiple known populations of PPO-resistant Palmer and waterhemp in the state of Kentucky. Control of waterhemp is best achieved with a two-pass herbicide program where the first pass is with a pre-emergence (PRE) soil applied herbicide and the second with a postemergent (POST) herbicide. Not every product is suitable for every situation, and use of the correct application technique will ensure the best results. Ideally, a grower would use both a group 14 and a group 2 herbicide if the waterhemp is glyphosate-resistant to slow the selection pressure for multiple-resistant waterhemp. Use Group 14 (PPO) in soybean followed by Group 27 (HPPD) in corn. We have, however, seen the development of new soybeans with herbicide-resistant traits. Postemergence herbicides for waterhemp control in soybean are essentially limited to two herbicide families, the diphenyl ethers and glyphosate-type products. Waterhemp resistance to HG 15 has not been confirmed yet in Iowa, however it is important to proactively protect the value of these products for waterhemp control in soybean fields. As we get close to soybean harvest, some herbicides can be applied as harvest aids (desiccant) to desiccate weeds and improve harvest operation. and Iowa State University Extension and Outreach. Seedlings are hairless and have leaves that look waxy or glossy. Say goodbye to Palmer amaranth. Diligent™ provides the defense you need, plus the flexibility to tank-mix with glyphosate and other residual herbicides. HG 14 resistant is fairly common in Iowa fields, and while sulfentrazone and flumioxazin still have activity on resistant populations, it usually is shorter-lived than with susceptible populations. Extend weed spectrum and burndown when weeds have already emerged by adding to Roundup herbicide or 2,4-D LVE. Waterhemp management in soybeans was a challenge for several farmers in 2018. Efficacy of HG 14 (flumioxazin), sulfentrazone) and HG 5 (metribuzin) on waterhemp control was also compared over the 5-year period. With dwindling herbicide resources, there is a need to integrate non-chemical strategies into current weed management programs in soybean. Treating new infestations early reduces waterhemp establishment, prevents seed production and greatly improves control. State & National Extension Partners. Weed Technol. Sulfentrazone (HG 14) and metribuzin (HG 5) provided more consistent (smaller size box) PRE waterhemp control compared to flumioxazin (HG 14) over the 5-year period. It is highly unlikely that a one pass, preemergence herbicide application will provide adequate control of resistant tall waterhemp in soybeans. Common waterhemp, giant ragweed, marestail (also commonly known as horseweed) and common lambsquarters are listed among the top problematic weeds for soybeans, according to weed experts in Illinois, Iowa, Kentucky and Minnesota. Group 15 herbicides (HG 15) are commonly used for PRE waterhemp control. Comparison of common waterhemp control with layered (PRE/POST) applications of three Group-15 herbicides and layered (PRE/POST) Group-14 / Group-15 herbicides in soybeans, Rochester, 2016. 29: 716–729. Slated for sale in November for the 2021 growing season, Kyber includes 3 herbicide sites of action—pyroxasulfone (Group 15), flumioxazin (Group 14) and metribuzin (Group 5). Time of application is very important. Farmers who have soybean fields with heavy waterhemp pressure should consider applying HG 5 and HG 14-based PRE products as premixes or in combination with HG 15 to give more consistent early-season residual weed control and manage glyphosate- and PPO-resistant waterhemp. 3 Due to its genetic variability, wide emergence window, vigorous growth potential, and prolific seed production, waterhemp has become a troublesome weed in The blue line within each plot represents the median of data, while the diamond represents the average percent control over the 5-year period. Prior to the evolution of herbicide resistance in waterhemp, ALS-, PPO-, EPSPS- and GS-inhibiting herbicides controlled waterhemp postemergence in soybean. Waterhemp Management in Soybeans Waterhemp Biology • Waterhemp gains a competitive advantage over several more aggressive summer annual weeds through the sheer number of plants that can infest an area. Soybean fields with emerged waterhemp where glyphosate has struggled in the past should get top priority for spraying. Layering herbicides for waterhemp control: Research on the effectiveness of this strategy in Minnesota soybean, including yield and control data. “If left untreated, it will compete with soybeans all season long, and can reduce yield by 44%,” said Jeff Stachler, OSU Extension Educator in Auglaize County, and Weed Specialist. Use effective soil applied herbicides at planting. By Brian Hefty Everyone is talking about Roundup-resistant weeds. Preemergence (PRE) soil residual herbicides serve as a foundation for managing waterhemp, but require follow-up treatments with effective postemergence (POST) products due to late-emerging plants. Waterhemp requires more than twice as many growing degree days to reach 50% emergence as giant foxtail or velvetleaf (Figure 1), resulting in much of the population emerging after mid-June. Waterhemp resistance to HG 15 has not been confirmed yet in Iowa; however, it is important to proactively protect the value of these products for waterhemp control in soybean fields. By Brian Hefty Everyone is talking about Roundup-resistant weeds. Season-long competition by waterhemp (more than 20 plants per square foot) has been shown to reduce soybean yield by 44%. According to the Purdue University Extension, in soybeans, 20 waterhemp plants per square foot can reduce yield by 44 percent. Waterhemp control was more variable (bigger size boxes) with s-metolachlor, dimethenamid-P, and acetochlor. For further information on resistance confirmed by state, visit the International Survey of Herbicide Resistant Weeds. Prior to the evolution of herbicide resistance in waterhemp, ALS-, PPO-, EPSPS- and GS-inhibiting herbicides controlled waterhemp postemergence in soybean. That ugly patch of weeds the combine just tore through is costing farmers money. Waterhemp can grow at the incredible rate of 1 to 1 1/4 inches per day, so timely herbicide application is critical. This is really a worst-case scenario as herbicide options are limited to none. The most troublesome multiple-resistant weeds for North American crop production are 2 pigweed species, common waterhemp and Palmer amaranth. Control of waterhemp is best achieved with a two-pass herbicide program where the first pass is with a pre-emergence (PRE) soil applied herbicide and the second with a postemergent (POST) herbicide. The small-seeded weed is one of the toughest to control. With dwindling herbicide resources, there is a need to integrate non-chemical strategies into current weed management programs in soybean. Include Group 15 herbicides in the both corn and soybean. Soon before or after soybean planting, apply a PRE residual herbicide with good activity on waterhemp. contained within may not be the most current and accurate depending on when it is accessed. Although these three HG 15 herbicides provided 82% or more control 50% of the time, the lowest control fell below 50%. The impact of waterhemp on soybean yields is very real. Among the HG 15 herbicides tested in soybean, pyroxasulfone provided the most consistent waterhemp control over the 5-year period (smaller size Box; Figure 1), with >95% control 50 percent of the time. Waterhemp has been the most troublesome weed for soybean farmers for the last 10 years. ( Sonja Begemann ) Waterhemp, Palmer amaranth, redroot pigweed—these words in agriculture are nearly synonymous with … Soybean fields with emerged waterhemp where glyphosate has struggled in the past should get top priority for spraying. It can be applied at 1.25 to 2 quarts per acre, depending on soil texture and organic matter content. In an effort to use multiple effective SOAs to control waterhemp populations, we evaluated the performance of layering Group-14 Valor® SX followed by Group-15 Dual II Magnum. Marvel™ herbicide protects soybean yields with superior postemergence control of glyphosate-resistant weeds and broad-spectrum control of other key weeds, including waterhemp, Palmer amaranth/Palmer pigweed, lambsquarters, morningglories and velvetleaf. 44 APPLICATION RESOURCES This guide is a comprehensive collection of recommended herbicide programs and options for soybeans, plus other valuable resources to aid in herbicide decision making. Waterhemp is competitive with soybeans and the application of an effective, soil-applied residual herbicide will protect soybean yield from early-season interference. “You could use glyphosate, but resistance continues to … However, an increased selection pressure from these herbicides used in corn-soybean rotations has resulted in the evolution of HG 15 resistance in waterhemp populations, recently documented in Illinois. Tags: Soon before or after soybean planting, apply a PRE residual herbicide with good activity on waterhemp. Figure 1. (And common ragweed. Slated for sale in November for the 2021 growing season, Kyber includes 3 herbicide sites of action—pyroxasulfone (Group 15), flumioxazin (Group 14) and metribuzin (Group 5). Herbicide-resistant waterhemp is already problematic for soybean producers. In the waterhemp seedling stages, look for the following features: In the past, agronomists advised farmers to control waterhemp through visual scouting and considering the economic threshold (dollars spent versus dollars returned) for treatment. Waterhemp competing with soybeans at a farm in Seneca County, NY. “Zero tolerance for adding weed seed to the soil should be every farmer’s goal.”. Palmer amaranth and waterhemp have an amazing ability to develop resistance to herbicides. marestail) and waterhemp in soybean has remained consistent over the past 10 days. When rubbed between the fingers, mature flowers reveal the small, shiny, black seeds found only on female plants. Weed control options in soybeans. Warrant is an acetochlor-based residual herbicide that can be applied post-emergence in soybean after soybeans are completely emerged, but before they reach R2 (initiation of flowering) growth stage. “In today’s environment, there’s no such thing as an economic threshold for control of resistant weeds,” says Dr. Reid Smeda, University of Missouri weed scientist. The small-seeded weed is one of the toughest to control. Herbicide-resistant waterhemp is already problematic for soybean producers. marestail) and waterhemp in soybean has remained consistent over the past 10 days. Soybean fields with emerged waterhemp, where glyphosate has struggled in the past to control the weed, should receive priority for spraying. Never apply glyphosate alone to emerged pigweed The main reason we like the combination we listed is the weed control is superior to anything else. New this year, we’ve added Site A was in Seneca County, NY on a field of Odessa silt loam soil where waterhemp had survived various herbicide … Group 14 herbicides are likely the best choice for POST-emergence control of glyphosate-resistant waterhemp in Roundup Ready soybeans. If applied too early, the control of Waterhemp declines. This strategy will aid in delaying emergence of waterhemp until soybean canopy closure when the crop will be more competitive, thereby reducing selection pressure on POST herbicides and reducing crop-weed competition and protecting against soybean yield losses. Farmers also can use several cultural practices to control waterhemp. Take Home Message. Ames, IA 50011-2031 Procedures: Objective 1. And waterhemp.). without further permission if published as written and if credit is given to the author, Integrated Crop Management News, This premix combines three modes of action, each effective individually, to control resistant weeds. Waterhemp: Best=Flexstar, 2=Marvel (Flexstar/Cadet premix), ... Darren and I have put together the best weed control programs in corn, soybeans, and wheat for all the weeds I have listed above, as well as many more. The first step is to verify you’re actually dealing with waterhemp. Although there are many ways weeds escape control in crop fields, one of the leading causes of waterhemp control failures is emergence of plants following postemergence herbicide (POST) treatments. the author is required. Nicholas J. Arneson, Daniel H. Smith, Ryan DeWerff, Maxwel Coura Oliveira, and Rodrigo Werle. “The ALS inhibitors (Pursuit, Scepter) are almost completely ineffective against waterhemp in Illinois now,” Hager says. Use effective soil applied herbicides at planting. Say goodbye to Palmer amaranth. Subscribe to receive email alerts when new information is posted. Think about waterhemp, lambsquarters, common ragweed, giant ragweed, palmer pigweed, velvetleaf, and marestail. It’s a premix of three herbicide sites of action aimed at managing problem soybean weeds including Palmer amaranth, waterhemp, and common ragweed. If you’re a soybean grower, you really have only four classes of postemergence herbicides to throw at waterhemp. Results from 2015 are described in the Crop News article, Manage waterhemp in soybean with layered residual herbicides. Glyphosate-resistant waterhemp and Palmer amaranth are widespread and if they were not controlled early in the season, they can interfere with soybean harvest (Figure 1). Control waterhemp before it reaches 4 inches in height to achieve timely and effective herbicide application. This premix combines three modes of action, each effective individually, to control resistant weeds. Postemergence Herbicides for Soybeans. Herbicide program approaches for managing glyphosate-resistant palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus and Amaranthus rudis) in future soybean-trait technologies. Waterhemp is an annual weed with enormous genetic diversity. Never apply glyphosate alone to emerged pigweed Authority Edge has Waterhemp management in soybean was challenge for several Wisconsin farmers in 2019. If this article is to be used in any other manner, permission from As we finalize harvesting our crops, it’s important to properly map the fields infested with waterhemp and start developing an effective management plan for 2019. Group 14 herbicides are likely the best choice for POST-emergence control of glyphosate-resistant waterhemp in Roundup Ready soybeans. Kyber ™ herbicide is the comprehensive solution to difficult-to-control weeds in soybean fields. Before applying any herbicide, please read the entire label for the best possible results and to confirm that the product is effective on the weeds you wish to control. Every meeting I went to this winter, every conference I attended, and every farm magazine I picked up, Roundup-resistant weeds were there.