Life Sciences Commons^™

Weed Control With Imiflex In Igrowth Forage Sorghum, R. S. Currie, P. W. Geier, S. H. Lancaster, C. M. Weber

Kansas Agricultural Experiment Station Research Reports

Igrowth (imidazolinone-resistant) forage sorghum hybrids were recently commercialized in Kansas. Even though the active ingredient of the herbicide associated with these systems, imazamox, is used in other crops, data are needed to define best practices for use in forage sorghum. The objective of experiments in Manhattan and Garden City, KS, was to investigate the use of ImiFlex (imazamox) herbicide in Igrowth (imidazolinone-tolerant) forage sorghum. At Garden City, volunteer corn and johnsongrass control 29 days after treatment was 90% or greater in all treatments that included ImiFlex. Similarly, Palmer amaranth control 28 days after treatment was 91% or greater at Manhattan. …

Residual Herbicides As Single And Sequential Treatments For Efficacy In Corn, Randall S. Currie, Patrick W. Geier

Kansas Agricultural Experiment Station Research Reports

This research investigated the use of sequential applications of residual herbicides for the weed-free period in corn. The objective of the study was to compare residual herbicides as either preemergence (PRE) alone or split applications (PRE followed by postemergence). All treatments controlled Palmer amaranth, common lambsquarters, Russian thistle, and green foxtail 90% or more, and kochia 95% or more. Johnsongrass control early in the season was 91% or more regardless of treatment. However, no herbicide controlled johnsongrass as much as 80% late in the year.

Efficacy And Crop Response With Firstact In Accase-Tolerant Grain Sorghum, Randall S. Currie, Patrick W. Geier

Kansas Agricultural Experiment Station Research Reports

This research was conducted to determine the efficacy of quizalofop (FirstAct) herbicide in herbicide-tolerant grain sorghum. FirstAct herbicide was evaluated for efficacy and crop response in Double Team (ACCase-tolerant) sorghum. All herbicides controlled Palmer amaranth 90% or more and volunteer corn 95% or more late in the season. Johnsongrass control was 86 to 91%. Minor sorghum injury early in the season did not persist. Sorghum receiving FirstAct late postemergence yielded more grain than the nontreated control or sorghum receiving Parallel Plus preemergence.

Efficacy Of Impact Mixtures And Timings In Field Corn, Randall S. Currie, Patrick W. Geier

Kansas Agricultural Experiment Station Research Reports

The objective of this research was to determine the utility of topramezone (Impact) herbicide for efficacy in corn. An experiment evaluated Impact with various tank mix and premix partners at several application timings for weed control in corn. Most herbicides provided excellent control of Palmer amaranth, common lambsquarters, and green foxtail. When Impact alone was applied late postemergence (LPOST) following Dual II Magnum (metolachlor) applied preemergence (PRE), kochia and Russian thistle control was less than 85%. Herbicides applied early postemergence (EPOST) or postemergence (POST) provided the best johnsongrass control early in the season, but no treatments controlled johnsongrass more than …

Fall-Planted Cover Crops For Weed Suppression In Western Kansas, S. Dhanda, V. Kumar, A. K. Obour, A. Dille, J. D. Holman

Kansas Agricultural Experiment Station Research Reports

The widespread evolution of herbicide-resistant (HR) kochia and Palmer amaranth warrants the use of alternative ecological-based strategies for weed management in no-tillage (NT) dryland cropping systems in western Kansas. A field study was established in the fall of 2020 at Kansas State University Agricultural Research Center near Hays, KS, to determine the impact of fall-planted cover crop (CC) mixture on 1) kochia and Palmer amaranth suppression (density and biomass reduction), and 2) Palmer amaranth emergence dynamics in subsequent grain sorghum. A CC mixture of winter triticale, winter pea, radish, and rapeseed was planted in wheat stubble in the fall of …

Glyphosate-Resistant Palmer Amaranth Control In Xtendflex Soybean, R. Liu, V. Kumar, T. L. Lambert

Kansas Agricultural Experiment Station Research Reports

XtendFlex soybean is a triple-stacked trait technology that allows growers to use dicamba (XtendiMax) and glufosinate (Liberty) for in-season control of glyphosate-resistant (GR) weed species, including Palmer amaranth. A field study was conducted at the Kansas State University Agricultural Research Center (KSU-ARCH) near Hays, KS, to determine the effectiveness of POST applied XtendiMax and Liberty alone or in sequential applications for GR Palmer amaranth control in XtendFlex soybean. The study site had a natural infestation of GR Palmer amaranth. Results showed that early post-emergence (EPOST) applications of XtendiMax or Liberty followed by (fb) a late post-emergence (LPOST) application …

Efficacy Of Late-Season Herbicide Programs For Controlling Palmer Amaranth In Postharvest Wheat Stubble, R. Liu, V. Kumar, N. Aquilina, T. Lambert

Kansas Agricultural Experiment Station Research Reports

Late-season control of Palmer amaranth in wheat stubble is a challenge for Kansas producers. The objective of this study was to determine the effectiveness of POST herbicide programs (with multiple modes of actions) for late-season control of Palmer amaranth in postharvest wheat stubble. The study was conducted at the Kansas State University Agricultural Research Center in Hays, KS, in 2019. The study site had a natural seedbank of Palmer amaranth that emerged immediately after wheat harvest. All selected herbicide programs were tested 3 weeks after wheat harvest, when Palmer amaranth plants had attained a height of 2 to 2.5 feet …

Control Of Multiple Herbicide-Resistant Palmer Amaranth In Enlist Corn, R. Liu, V. Kumar, T. Lambert

Kansas Agricultural Experiment Station Research Reports

Recent evolution of multiple herbicide resistant (MHR) Palmer amaranth [resistant to 2,4-D, glyphosate (Roundup), chlorsulfuron (Glean), atrazine (Aatrex), and mesotrione (Callisto)] is a serious threat to newly developed stacked trait technologies, including Enlist crops (tolerant to 2,4-D, glyphosate, and glufosinate). Field experiments were conducted in 2019 at the Kansas State University Agricultural Research Center near Hays, KS, to determine the effectiveness of various preemergence (PRE) followed by (fb) postemergence (POST) herbicides (multiple modes of action) for controlling this MHR Palmer amaranth in Enlist corn. The study was established in no-till dryland wheat stubble where MHR Palmer amaranth seeds …

Influence Of Cultural Practices And Herbicide Programs For Managing Glyphosate-Resistant Palmer Amaranth In Cold-Tolerant Sorghum, R. Liu, V. Kumar, R. Perumal, T. Lambert, T. Ostmeyer

Kansas Agricultural Experiment Station Research Reports

The widespread evolution of glyphosate-resistant (GR) Palmer amaranth (Amaran­thus palmeriS. Wats) has become a serious management concern for grain sorghum producers in western Kansas. To develop an integrated weed management (IWM) system, a field study was conducted at the Kansas State University Agricultural Research Center (KSU-ARC) in Hays, KS, in 2018, to evaluate the effect of sorghum hybrid, row spacing, and herbicide programs on GR Palmer amaranth control, shoot dry weight reduction, and sorghum grain yield. Treatments included two cold-tolerant grain sorghum hybrids: Pioneer 87P06 (commercial check) and ATx645/ ARCH12012R (developed by the KSU-ARC breeding program); row spacing …

Characterization And Management Of Glyphosate- And Hppd-Inhibitor-Resistant Palmer Amaranth In Kansas Corn Production, V. Kumar, R. Liu, T. Lambert

Kansas Agricultural Experiment Station Research Reports

Multiple herbicide-resistant (MHR) Palmer amaranth is an increasing management concern for Kansas grain producers. The main purpose of this research was to 1) char­acterize the resistance levels to glyphosate (Roundup PowerMax) and mesotrione (Callisto) in an MHR Palmer amaranth population collected from Stafford County, KS, compared to a known herbicide-susceptible (SUS) population; and 2) to evaluate the effectiveness of preemergence (PRE), PRE followed by (fb) early post emergence (EPOST), and PREfblate POST (LPOST) herbicide programs for controlling this MHR population in Roundup Ready and LibertyLink corn. To achieve these objec­tives, a whole plant dose-response study was …

Integrating Half Rates Of Dicamba And Atrazine With Increasing Sorghum Density And Nitrogen Rate For Palmer Amaranth Control, I. B. Cuvaca, A. J. Foster, R. Currie

Kansas Agricultural Experiment Station Research Reports

Sorghum is an important crop in Kansas. However, in-season weed control options for sorghum are limited. This limitation is exacerbated by Palmer amaranth season-long interference and resistance to multiple herbicide modes of action.

This 2-year study investigated the ability of a contrasting combination of cultural and chemical practices to control Palmer amaranth while maintaining or improving sorghum grain yield. Particular research emphasis was to evaluate the effect(s) of integrating half rates of dicamba and atrazine applied as PRE with increasing sorghum density and nitrogen rate on Palmer amaranth control and grain yield in an irrigated environment.

Palmer Amaranth Populations From Kansas With Multiple Resistance To Glyphosate, Chlorsulfuron, Mesotrione, And Atrazine, V. Kumar, P. W. Stahlman, G. Boyer

Kansas Agricultural Experiment Station Research Reports

Multiple herbicide-resistant (MHR) Palmer amaranth poses a serious management concern for growers across the United States. Since 2014, several Palmer amaranth populations with suspected resistance to most commonly used herbicides were collected in random field surveys across Kansas. This study aimed to characterize the resistance levels to glyphosate (EPSPS inhibitor), mesotrione (HPPD inhibitor), chlorsulfuron (ALS inhibitor), and atrazine (PS II inhibitor) in three suspected MHR Palmer amaranth populations (KW2, PR8, and BT12) compared to a known herbicide-susceptible (SUS) population. Dose-response studies revealed that PR8 and BT12 populations had 7- to 14-fold level resistance to glyphosate, and up to 12-fold level …

Palmer Amaranth (Amaranthus Palmeri) Suppression With Half Rates Of Dicamba And Atrazine With Increasing Sorghum (Sorghum Bicolor) Density And Nitrogen Rate, I. B. Cuvaca, R. Currie, A. J. Foster

Kansas Agricultural Experiment Station Research Reports

Palmer amaranth (PA) competition can result in severe yield loss in grain sorghum. Increasing sorghum density and nutrient supply could promote early/rapid canopy closure and therefore reduce the amount of light that could otherwise penetrate the canopy and promote PA growth in sorghum. A study was conducted at the Southwest Research-Extension Center near Garden City, KS, to determine if PA could be suppressed with dicamba and atrazine applied as PRE at half rates combined with increasing sorghum density (60,000, 90,000, and 120,000 seeds/a), and nitrogen rate (0, 100, 200 lb/a). Preliminary results indicate that increasing plant density and nitrogen rate …

Sequential Weed Control Programs In Liberty Link Soybeans, D. E. Peterson, C. Thompson, C. L. Minihan

Kansas Agricultural Experiment Station Research Reports

The development of glyphosate-resistant weeds has greatly complicated weed control in soybeans. Liberty Link soybeans provide growers an alternative herbicide option for postemergence weed control in soybeans. Liberty Link programs can provide effective weed control in a sequential weed-control program that includes effective preemergence residual herbicides at planting time followed by timely applications of Liberty.

Comparison Of Different Weed Control Technology Programs, D. E. Peterson, C. Thompson, C. L. Minihan

Kansas Agricultural Experiment Station Research Reports

The development of glyphosate-resistant weeds has greatly complicated weed control in soybeans. Roundup Ready 2 Xtend and Liberty Link soybeans provide an alternative postemergence herbicide options for weed control in soybeans. Liberty Link and Roundup Ready 2 Xtend programs provided better overall weed control and slightly higher yields than Roundup Ready 2 Yield programs in this experiment. Yields of Roundup Ready 2 Yield soybeans were likely influenced by more weed competition and possibly crop injury from spray tank contamination by dicamba. Dicamba injury from tank contamination to Roundup Ready 2 Yield soybeans decreased with each subsequent treatment and also with …

Weed Control Programs For Xtend Soybeans In No-Tillage, D. E. Peterson, C. Thompson, C. L. Minihan

Kansas Agricultural Experiment Station Research Reports

The development of glyphosate-resistant weeds has greatly complicated weed control in soybeans. Roundup Ready 2 Xtend (dicamba tolerant) soybeans provide growers an alternative herbicide option for preplant and postemergence weed control in no-tillage soybeans. Preplant programs that included dicamba provided excellent control of giant ragweed. All sequential programs provided excellent control of the weeds present in the experiment.

Two Pass Weed Control Programs In Conventional Tillage Xtend Soybeans, D. E. Peterson, C. Thompson, C. L. Minihan

Kansas Agricultural Experiment Station Research Reports

The development of glyphosate-resistant weeds has greatly complicated weed control in soybeans. Roundup Ready 2 Xtend (dicamba tolerant) soybeans provide growers an alternative herbicide option for postemergence weed control in conventional tillage soybeans. Two pass programs consisting of preemergence residual herbicides followed by postemergence Roundup Power Max plus dicamba provided excellent weed control, superior to a single postemergence treatment with Roundup Power Max plus dicamba.

Sequential Weed Control Programs In No-Tillage Xtend Soybeans, D. E. Peterson, C. Thompson, C. L. Minihan

Kansas Agricultural Experiment Station Research Reports

The development of glyphosate resistant weeds has greatly complicated weed control in soybeans. Roundup Ready 2 Xtend (dicamba tolerant) soybeans provide growers an alternative herbicide option for preplant and postemergence weed control in soybeans. Preplant programs that included dicamba provided excellent control of giant ragweed. Sequential programs consisting of Envive or Enlite plus glyphosate and dicamba preplant followed by postemergence treatments that included glyphosate and dicamba provided excellent control of henbit, giant ragweed, Palmer amaranth, and large crabgrass.

Alternatives To Glyphosate For Palmer Amaranth Control In Wheat Stubble, D. E. Peterson, C. Thompson, C. L. Minihan

Kansas Agricultural Experiment Station Research Reports

Glyphosate-resistant Palmer amaranth has become a serious weed problem in fields following wheat harvest. A field experiment was established in 2016 near Manhattan, KS, to evaluate herbicide alternatives to glyphosate for Palmer amaranth control in wheat stubble. The two most effective postharvest herbicides for control of Palmer amaranth were Gramoxone (paraquat) or Sharpen (saflufenacil). Clarity (dicamba) and 2,4-D treatments provided suppression of Palmer amaranth, but were inconsistent, and often some plants survived and produced viable seed. The tank-mix of Clarity plus 2,4-D was more effective than either herbicide alone, but not as good as Gramoxone or Sharpen.

Palmer Amaranth (Amaranthus Palmeri) Suppression With Half Rates Of Dicamba And Atrazine With Increasing Sorghum (Sorghum Bicolor) Density And Nitrogen Rate, I. B. Cuvaca, R. Currie, A. J. Foster

Kansas Agricultural Experiment Station Research Reports

Palmer amaranth (PA) competition can result in severe yield loss in grain sorghum. Increasing sorghum density and nutrient supply could promote early/rapid canopy closure and therefore reduce the amount of light that could otherwise penetrate the canopy and promote PA growth in sorghum. A study was conducted at the Southwest Research-Extension Center near Garden City, KS, to determine if PA could be suppressed with dicamba and atrazine applied as PRE at half rates combined with increasing sorghum density (60,000, 90,000, and 120,000 seeds/a), and nitrogen rate (0, 100, 200 lb/a). Preliminary results indicate that increasing plant density and nitrogen rate …

Weed Control And Crop Injury With Single Or Sequential Herbicide Applications In Grain Sorghum, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

The preemergence application of Dual II Magnum (S-metolachlor) improved the over­all weed control compared to single postemergence treatments. Excessive rainfall after preemergence application compromised all treatments, producing abnormally low weed control.

Weed Control With Postemergence Applications Of Status, Armezon, Atrazine, Corvus, Verdict, And Roundup Powermax In Irrigated Corn, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

All postemergence herbicides provided greater than 98% control of quinoa, common sunflower, Palmer amaranth, and green foxtail. Crabgrass and Russian thistle were more difficult to control. All postemergence herbicides except Roundup PowerMax (glypho­sate) alone controlled Russian thistle and crabgrass greater than 89%. Diflexx (dicamba) plus Roundup PowerMax was slightly more efficacious on kochia than Status (diflufen­zopyr + dicamba) plus Armezon (topramezone) with atrazine and Roundup Power­Max, and all other herbicides were intermediate for kochia control. Corn yields did not differ between herbicide treatments. However, all herbicides increased grain yields.

Weed Control With Single Or Sequential Herbicide Applications In Acetolactase Synthase-Tolerant Grain Sorghum, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

Palmer amaranth control was best when Resolve (rimsulfuron) plus Harmony GT (thifensulfuron) and Abundit Extra (glyphosate) were applied 15 days preplant fol­lowed by Zest (nicosulfuron) and atrazine postemergence, or by Zest plus atrazine alone postemergence. Palmer amaranth control was less than 80% with all other herbicide treatments. Preemergence herbicides alone provided less than 60% green foxtail control at 53 days after postemergence applications, and Zest plus atrazine alone postemergence controlled green foxtail 70%. Sequential applications of preemergence and postemer­gence herbicides were needed to provide the best green foxtail control. The relatively low weed control provided by these treatments may be …

Preemergence Weed Control With Fultime Nxt And Competitive Standards In Grain Sorghum, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

At 71 days after treatment, FulTime NXT (acetochlor + atrazine) at 2.5 or 3.0 qt/a and Lumax EZ (S-metolachlor + atrazine + mesotrione) at 2.0 qt/a were the only treatments to control Palmer amaranth at 90% or more. All treatments provided similar velvetleaf control. Green foxtail control was 75 to 83% with all rates of FulTime NXT or Lumax EZ. Sorghum receiving FulTime NXT at 2.5 or 3.0 qt/a or Lumax EZ yielded significantly more than the control treatments.

Efficacy Of Anthem Maxx, Solstice, Cadet, Roundup Powermax, And Competitive Standards In Irrigated Corn, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

Control of Palmer amaranth and green foxtail was generally best when herbicides were applied as sequential treatments of preemergence (PRE) followed by late postemergence (LPOST) or as postemergence (POST) alone. Velvetleaf and puncturevine control was 95 and 93% or more, respectively, regardless of herbicide or application timing. Corn receiving herbicide treatments yielded 42 to 72 bu/a more grain than non-treated corn.

Efficacy Of Preemergence Or Early Postemergence Weed Control With Keystone Nxt, Hornet Wdg, Atrazine, Surestart Ii, Lumax Ez, And Resicore, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

Control of buffalobur was complete regardless of herbicide used. Velvetleaf and punc­turevine control, although not perfect, was excellent by all herbicides. The premix of SureStart II (acetochlor + flumetsulam + clopyralid) with atrazine and Durango DMA (glyphosate) applied early postemergence and the preemergence herbicides Resicore (acetochlor + mesotrione + clopyralid) with atrazine and Lumax EZ (S-metolachlor + atrazine + mesotrione) provided excellent Palmer amaranth control. The early pos­temergence treatment of SureStart II plus atrazine and Durango DMA was the only treatment to provide excellent control of green foxtail.

Efficacy Of Preemergence And Sequential Applications With Corvus, Atrazine, Starane, Balance, Anthem, Capreno, Diflexx And Halex Gt In Irrigated Corn, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

Control of kochia and quinoa was 98 to 100% regardless of herbicide treatment at 48 days after post applications (DAPT), and 95% or more with all herbicides for Russian thistle. Palmer amaranth control was slightly less with preemergent (PRE) treatments alone compared to sequential treatments. Corvus (isoxaflutole + thiencarbazone) plus atrazine, Starane Ultra (fluroxypyr), and nonionic surfactant preemergence controlled crabgrass by 88%; whereas all other treatments provided 91% or more crabgrass control. Corn with the best herbicide treatments yielded 33 to 66 bu/a more than untreated corn.

Weed Control With Accent, Callisto, Isoxadifen, Impact, Cinch, Dicamba, And Atrazine In Irrigated Corn, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

Some timings and combinations of the herbicides tested in this study controlled Palmer amaranth, kochia, quinoa, Russian thistle, and green foxtail from 95 to 100% 51 days after postemergence application (DA-B). Accent (nicosulfuron) plus Callisto (mesotri­one) and isoxadifen alone postemergence provided 88% Palmer amaranth control at 51 DA-B. Kochia control was 92 and 90% when Accent plus Callisto and isoxadifen alone or with atrazine and Dicamba XP (dicamba) was applied postemergence following Cinch (S-metolachlor) preemergence application. Crabgrass control with preemergence followed by postemergence treatments exceeded 89%. Crabgrass control was 83 and 88% when no preemergence herbicide was applied …

Herbicide Evaluation For Control Of Kochia And Palmer Amaranth In Teff Grass, J. D. Holman, C. Thompson, T. Roberts, S. Maxwell

Kansas Agricultural Experiment Station Research Reports

Eleven postemergence herbicide treatments were applied to teff grown for forage to evaluate Palmer amaranth and kochia control, as well as crop tolerance. Effective Palmer amaranth control was achieved with all herbicide treatments, while less than satisfactory kochia control was obtained with atrazine and Harmony. Clarity, 2,4-D, and Huskie applied alone appeared to control kochia, but kochia density was low in the plots. Had the kochia population been higher, similar efficacy ratings may have been attained. Huskie or atrazine caused the most injury to teff. The first harvest suggests these herbicides reduced forage yield to less than 3,000 lb/a.

Weed Control In Irrigated Corn With Combinations Of Corvus, Balance Flexx, Capreno, Laudis, Harness, Atrazine, Glyphosate, Dual, And Diflexx, R. Currie, P. Geier

Kansas Agricultural Experiment Station Research Reports

Most preemergence treatments followed by postemergence treatments provided better Palmer amaranth control than preemergence treatments alone or early postemergence treatments alone (Table 2). The better treatments provided good control of Palmer amaranth, kochia, Russian thistle, crabgrass, green foxtail, and shattercane. All treatments elevated yield over the untreated control.