Influence of Carrier Volume and Nozzle Selection on Palmer Amaranth Control

ABSTRACT Palmer amaranth is one of the most troublesome weeds in the southeast. Effective control is essential in order to avoid reductions of crop yield. Due to widespread resistance to acetolactate synthase (ALS)-inhibiting herbicides, postemergence contact herbicides are often the only in-season option to control Palmer amaranth in peanut. Lactofen is a postemergence protoporphyrinogen oxidase inhibiting herbicide that is commonly used to control Palmer amaranth in peanut. Adequate spray coverage is essential for lactofen efficacy and nozzle selection may affect coverage. Extended range (XR) and air induction (AI) nozzles were used to evaluate spray coverage on water sensitive cards. XR nozzles provided more coverage than AI nozzles. A factorial treatment structure of carrier volume (94, 187, 281 L/ha), nozzle selection (XR and AI) and application timing (5 to 10 cm or 15 to 20 cm tall weeds) was conducted in 2008 in Williston, FL and in 2012 in Tifton, GA to determine the best strategy for controlling Palmer amaranth with lactofen. Palmer amaranth control was recorded 7, 14, and 21 days after treatment (DAT). Nozzle selection was not significant in field trials as a main effect or as an interaction at any location; therefore data were pooled across nozzle type. However, the carrier volume by application timing interaction was significant at each location. In 2008 at Williston, FL and in 2012 at Tifton, GA application at 5 to 10 cm tall Palmer amaranth with 94, 187, or 281 L/ha provided >90% control. Applications made to 15 to 20 cm tall weeds provided less control. Applications made to smaller weeds provided sufficient control at any carrier volume tested, while applications made to larger weeds were least effective at 94 L/ha. Despite reduced coverage by AI nozzles, nozzle type did not translate to differences in herbicide efficacy in the field. Carrier volume did not affect control of small weeds, but on larger Palmer amaranth, control was reduced at smaller spray volumes. Growers should apply lactofen to smaller Palmer amaranth plants for the most effective control.

Download Full-text

Palmer Amaranth (Amaranthus palmeri) Control by Glufosinate plus Fluometuron Applied Postemergence to WideStrike®Cotton

Weed Technology ◽

10.1614/wt-d-12-00158.1 ◽

2013 ◽

Vol 27 (2) ◽

pp. 291-297 ◽

Cited By ~ 14

Author(s):

Kelly A. Barnett ◽

A. Stanley Culpepper ◽

Alan C. York ◽

Lawrence E. Steckel

Keyword(s):

United States ◽

Weed Control ◽

Acetolactate Synthase ◽

The United States ◽

Palmer Amaranth ◽

Effective Control ◽

Yield Response ◽

Amaranthus Palmeri ◽

Cotton Yield ◽

Cotton Cultivar

Glyphosate-resistant (GR) weeds, especially GR Palmer amaranth, are very problematic for cotton growers in the Southeast and Midsouth regions of the United States. Glufosinate can control GR Palmer amaranth, and growers are transitioning to glufosinate-based systems. Palmer amaranth must be small for consistently effective control by glufosinate. Because this weed grows rapidly, growers are not always timely with applications. With widespread resistance to acetolactate synthase-inhibiting herbicides, growers have few herbicide options to mix with glufosinate to improve control of larger weeds. In a field study using a WideStrike®cotton cultivar, we evaluated fluometuron at 140 to 1,120 g ai ha−1mixed with the ammonium salt of glufosinate at 485 g ae ha−1for control of GR Palmer amaranth 13 and 26 cm tall. Standard PRE- and POST-directed herbicides were included in the systems. Glufosinate alone injured the WideStrike® cotton less than 10%. Fluometuron increased injury up to 25% but did not adversely affect yield. Glufosinate controlled 13-cm Palmer amaranth at least 90%, and there was no improvement in weed control nor a cotton yield response to fluometuron mixed with glufosinate. Palmer amaranth 26 cm tall was controlled only 59% by glufosinate. Fluometuron mixed with glufosinate increased control of the larger weeds up to 28% and there was a trend for greater yields. However, delaying applications until weeds were 26 cm reduced yield 22% relative to timely application. Our results suggest fluometuron mixed with glufosinate may be of some benefit when attempting to control large Palmer amaranth. However, mixing fluometuron with glufosinate is not a substitute for a timely glufosinate application.

Download Full-text

Effect of dicamba rate and application parameters on protoporphyrinogen oxidase inhibitor-resistant and -susceptible Palmer amaranth (Amaranthus palmeri) control

Weed Technology ◽

10.1017/wet.2020.59 ◽

2020 ◽

pp. 1-5

Author(s):

Wyatt Coffman ◽

Tom Barber ◽

Jason K. Norsworthy ◽

Greg R. Kruger

Keyword(s):

Palmer Amaranth ◽

Research Station ◽

Spray Parameters ◽

Group 14 ◽

Metabolic Resistance ◽

Susceptible Population ◽

Protoporphyrinogen Oxidase ◽

Sites Of Action ◽

Carrier Volume ◽

Nozzle Type

Abstract Throughout eastern Arkansas, Palmer amaranth resistant to protoporphyrinogen oxidase (PPO)-inhibiting herbicides (Group 14 herbicides) has become widespread. Most PPO-resistant Palmer amaranth biotypes possess a target-site mutation, but a metabolic resistance mechanism to fomesafen (Group 14) has also been identified. Once metabolic resistance manifests, plants may also be tolerant to other herbicides and sites of action. To evaluate whether varying spray parameters affected control of PPO-resistant Palmer amaranth in dicamba-tolerant crops, field trials were conducted in 2017 and 2018 at the Lon Mann Cotton Research Station near Marianna, AR, and on-farm in Marion, AR. The experiment included split plot factors of dicamba rate, nozzle type, and carrier volume, with a whole plot factor of population. Dicamba was applied at 560 or 1120 g ae ha−1 through 110015 TTI or AirMix nozzles at 70 or 140 L ha−1 to PPO-resistant or PPO-susceptible Palmer amaranth. Palmer amaranth control 14 d after treatment (DAT) was influenced by an interaction between population and carrier volume. PPO-resistant Palmer amaranth control 14 DAT was 81% regardless of carrier volume, compared with 90% and 95% control at 70 and 140 L ha−1, respectively, of the PPO-susceptible population. An interaction between nozzle type and carrier volume influenced Palmer amaranth control 21 DAT, whereas AirMix nozzles at 140 L ha−1 controlled Palmer amaranth at a greater level (94%) than any other nozzle and carrier volume combination (≤90%). An interaction between population and dicamba rate influenced the relative density of Palmer amaranth 21 DAT. PPO-resistant Palmer amaranth density was less affected by dicamba at either rate than PPO-susceptible Palmer amaranth, relative to the nontreated check. Results concur with those of other research that suggest PPO-resistant Palmer amaranth is harder to control with dicamba. Otherwise, increasing carrier volume affected overall Palmer amaranth control to a greater degree than any other factor.

Download Full-text

Evaluation of Preemergence Herbicide Programs for Control of Protoporphyrinogen Oxidase-Resistant Amaranthus palmeri in Soybean

International Journal of Agronomy ◽

10.1155/2021/6652382 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Michael M. Houston ◽

L. Tom Barber ◽

Jason K. Norsworthy ◽

Trent L. Roberts

Keyword(s):

Acetolactate Synthase ◽

Field Trials ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Long Chain Fatty Acid ◽

Protoporphyrinogen Oxidase ◽

Density Reduction ◽

Glycine Max L ◽

Sites Of Action ◽

Herbicide Programs

Protoporphyrinogen oxidase- (PPO-) resistant Amaranthus palmeri (S.) Wats. (Palmer amaranth) was confirmed in Arkansas in 2015. Field trials were conducted in Crawfordsville, Gregory, and Marion, Arkansas in 2016, and Crawfordsville and Marion in 2017, assessing PPO-resistant Palmer amaranth control options in Glycine max (L.) Merr. (soybean). Twelve trials consisted of 26 preemergence (PRE) treatments, evaluated for Palmer amaranth control and density reduction at 28 days after treatment (DAT). Treatments that consisted of PPO- or acetolactate synthase- (ALS-) inhibiting herbicides such as flumioxazin (72 g ai ha−1) or sulfentrazone + cloransulam (195 g ha−1 + 25 g ha−1) controlled Palmer amaranth <60%. At 28 DAT, treatments including mixtures of a very-long-chain fatty acid (VLCFA) plus the photosystem II- (PSII-) inhibiting herbicide metribuzin provided increased control over single herbicide sites of action (SOA) or herbicides mixtures to which Palmer amaranth was resistant. Pyroxasulfone + metribuzin (149 g ha−1 + 314 g ha−1) controlled Palmer amaranth 91% control across twelve trials at 28 DAT. S-metolachlor alone did not provide consistent, acceptable control of PPO-resistant Palmer amaranth (55–77%); subsequent research has determined that these populations are resistant to S-metolachlor. A minimum of two effective herbicides should be included in soybean PRE programs for control of PPO-resistant Palmer amaranth.

Download Full-text

Multiple herbicide-resistant Palmer amaranth (Amaranthus palmeri) in Connecticut: confirmation and response to POST herbicides

Weed Technology ◽

10.1017/wet.2021.6 ◽

2021 ◽

pp. 1-7

Author(s):

Jatinder S. Aulakh ◽

Parminder S. Chahal ◽

Vipan Kumar ◽

Andrew J. Price ◽

Karl Guillard

Keyword(s):

Cropping Systems ◽

Acetolactate Synthase ◽

Palmer Amaranth ◽

Effective Control ◽

Herbicide Resistant ◽

First Case ◽

Whole Plant ◽

Chlorimuron Ethyl ◽

Als Inhibitors ◽

Als Inhibitor

Abstract Palmer amaranth is the latest pigweed species documented in Connecticut; it was identified there in 2019. In a single-dose experiment, the Connecticut Palmer amaranth biotype survived the field-use rates of glyphosate (840 g ae ha−1) and imazaquin (137 g ai ha−1) herbicides applied separately. Additional experiments were conducted to (1) determine the level of resistance to glyphosate and acetolactate synthase (ALS) inhibitors in the Connecticut-resistant (CT-Res) biotype using whole-plant dose-response bioassays, and (2) evaluate the response of the CT-Res biotype to POST herbicides commonly used in Connecticut cropping systems. Based on the effective dose required for 90% control (ED90), the CT-Res biotype was 10-fold resistant to glyphosate when compared with the Kansas-susceptible (KS-Sus) biotype. Furthermore, the CT-Res biotype was highly resistant to ALS-inhibitor herbicides; only 18% control was achieved with 2,196 g ai ha−1 imazaquin. The CT-Res biotype was also cross-resistant to other ALS-inhibitor herbicides, including chlorimuron-ethyl (13.1 g ai ha−1), halosulfuron-methyl (70 g ai ha−1), and sulfometuron-methyl (392 g ai ha−1). The CT-Res Palmer amaranth was controlled 75% to 100% at 21 d after treatment (DAT) with POST applications of 2,4-D (386 g ae ha−1), carfentrazone-ethyl (34 g ai ha−1), clopyralid (280 g ae ha−1), dicamba (280 g ae ha−1), glufosinate (595 g ai ha−1), lactofen (220 g ai ha−1), oxyfluorfen (1,121g ai ha−1), and mesotrione (105 g ai ha−1) herbicides. Atrazine (2,240 g ai ha−1) controlled the CT-Res biotype only 52%, suggesting the biotype is resistant to this herbicide as well. Here we report the first case of Palmer amaranth from Connecticut with multiple resistance to glyphosate and ALS inhibitors. Growers should proactively use all available weed control tactics, including the use of effective PRE and alternative POST herbicides (tested in this study), for effective control of the CT-Res biotype.

Download Full-text

Control of acetolactate synthase inhibitor/glyphosate-resistant Palmer amaranth (Amaranthus palmeri) in isoxaflutole/glufosinate/glyphosate-resistant soybean

Weed Technology ◽

10.1017/wet.2021.49 ◽

2021 ◽

pp. 1-23

Author(s):

Jasmine Mausbach ◽

Suat Irmak ◽

Debalin Sarangi ◽

John Lindquist ◽

Amit J. Jhala

Keyword(s):

Field Experiments ◽

Cropping Systems ◽

Acetolactate Synthase ◽

The United States ◽

Palmer Amaranth ◽

Effective Control ◽

Synthase Inhibitor ◽

Density And Biomass ◽

Als Inhibitor ◽

Herbicide Programs

Abstract Palmer amaranth is the most problematic and troublesome weed in agronomic cropping systems in the United States. Acetolactate synthase (ALS) inhibitor- and glyphosate-resistant (GR) Palmer amaranth has been confirmed in Nebraska and it is widespread in several counties. Soybean resistant to isoxaflutole/glufosinate/glyphosate has been developed that provides additional herbicide site of action for control of herbicide-resistant weeds. The objectives of this study were to evaluate herbicide programs for control of ALS inhibitor/GR Palmer amaranth and their effect on Palmer amaranth density and biomass, as well as soybean injury and yield in isoxaflutole/glufosinate/glyphosate-resistant soybean. Field experiments were conducted in a grower’s field infested with ALS inhibitor- and GR Palmer amaranth near Carleton, Nebraska, in 2018 and 2019. Isoxaflutole applied alone or mixed with sulfentrazone/pyroxasulfone, flumioxazin/pyroxasulfone, or imazethapyr/saflufenacil/pyroxasulfone provided similar control (86%-99%) of Palmer amaranth 21 d after PRE (DAPRE). At 14 d after early-POST (DAEPOST), isoxaflutole applied PRE and PRE followed by (fb) POST controlled Palmer amaranth 10% to 63% compared to 75% to 96% control with glufosinate applied EPOST in both years. A PRE herbicide fb glufosinate controlled Palmer amaranth 80% to 99% 21 d after late-POST (DALPOST) in 2018 and reduced density 89% to 100% in 2018 and 58% to 100% in 2019 at 14 DAEPOST. No soybean injury was observed from any of the herbicide programs tested in this study. Soybean yield in 2019 was relatively higher due to higher precipitation compared with 2018 with generally no differences between herbicide programs. This research indicates that herbicide programs are available for effective control of ALS inhibitor/GR Palmer amaranth in isoxaflutole/glufosinate/glyphosate-resistant soybean.

Download Full-text

The use of light spectrum blocking films to reduce populations of Drosophila suzukii Matsumura in fruit crops

Scientific Reports ◽

10.1038/s41598-020-72074-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Michelle T. Fountain ◽

Amir Badiee ◽

Sebastian Hemer ◽

Alvaro Delgado ◽

Michael Mangan ◽

...

Keyword(s):

Control Strategies ◽

Field Trials ◽

Biological Data ◽

Insect Vision ◽

Invasive Pest ◽

Effective Control ◽

Fruit Crops ◽

Light Spectrum ◽

Drosophila Suzukii ◽

The Impact

Abstract Spotted wing drosophila, Drosophila suzukii, is a serious invasive pest impacting the production of multiple fruit crops, including soft and stone fruits such as strawberries, raspberries and cherries. Effective control is challenging and reliant on integrated pest management which includes the use of an ever decreasing number of approved insecticides. New means to reduce the impact of this pest that can be integrated into control strategies are urgently required. In many production regions, including the UK, soft fruit are typically grown inside tunnels clad with polyethylene based materials. These can be modified to filter specific wavebands of light. We investigated whether targeted spectral modifications to cladding materials that disrupt insect vision could reduce the incidence of D. suzukii. We present a novel approach that starts from a neuroscientific investigation of insect sensory systems and ends with infield testing of new cladding materials inspired by the biological data. We show D. suzukii are predominantly sensitive to wavelengths below 405 nm (ultraviolet) and above 565 nm (orange & red) and that targeted blocking of lower wavebands (up to 430 nm) using light restricting materials reduces pest populations up to 73% in field trials.

Download Full-text

KIH-485 and S-metolachlor Efficacy Comparisons in Conventional and No-Tillage Corn

Weed Technology ◽

10.1614/wt-05-048r2.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 622-626 ◽

Cited By ~ 38

Author(s):

Patrick W. Geier ◽

Phillip W. Stahlman ◽

John C. Frihauf

Keyword(s):

Weed Control ◽

Field Experiments ◽

Conventional Tillage ◽

Palmer Amaranth ◽

Effective Control ◽

No Tillage ◽

Green Foxtail

Field experiments were conducted during 2003 and 2004 to compare the effectiveness of KIH-485 and S-metolachlor for PRE weed control in no-tillage and conventional-tillage corn. Longspine sandbur control increased as KIH-485 or S-metolachlor rates increased in conventional-tillage corn, but control did not exceed 75% when averaged over experiments. Both herbicides controlled at least 87% of green foxtail with the exception of no-tillage corn in 2004, when KIH-485 was more effective than S-metolachlor at lower rates. Palmer amaranth control ranged from 85 to 100% in 2003 and 80 to 100% in 2004, with the exception of only 57 to 76% control at the lowest two S-metolachlor rates in 2004. Puncturevine control exceeded 94% with all treatments in 2003. In 2004, KIH-485 controlled 86 to 96% of the puncturevine, whereas S-metolachlor controlled only 70 to 81%. Mixtures of atrazine with KIH-485 or S-metolachlor generally provided the most effective control of broadleaf weeds studied.

Download Full-text

Influence of Selected Fungicides on Efficacy of Clethodim and 2,4-DB

Peanut Science ◽

10.3146/ps11-14.1 ◽

2012 ◽

Vol 39 (2) ◽

pp. 121-126 ◽

Cited By ~ 1

Author(s):

Gurinderbir S. Chahal ◽

David L. Jordan ◽

Barbara B. Shew ◽

Rick L. Brandenburg ◽

James D. Burton ◽

...

Keyword(s):

North Carolina ◽

Sampling Interval ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Solution Ph ◽

Affect Control ◽

Solution Preparation ◽

Positive Correlations ◽

Sampling Times ◽

Large Crabgrass

Abstract A range of fungicides and herbicides can be applied to control pests and optimize peanut yield. Experiments were conducted in North Carolina to define biological and physicochemical interactions when clethodim and 2,4-DB were applied alone or with selected fungicides. Pyraclostrobin consistently reduced large crabgrass [Digitaria sanguinalis (L.) Scop.] control by clethodim. Chlorothalonil and tebuconazole plus trifloxystrobin reduced large crabgrass control by clethodim in two of four experiments while prothioconazole plus tebuconazole and flutriafol did not affect control. Palmer amaranth [Amaranthus palmeri S. Wats] control by 2,4-DB was not affected by these fungicides. Although differences in spray solution pH were noted among mixtures of clethodim plus crop oil concentrate or 2,4-DB and fungicides, the range of pH was 4.40 to 4.92 and 6.72 to 7.20, respectively, across sampling times of 0, 6, 24, and 72 h after solution preparation. Permanent precipitates were formed when clethodim, crop oil concentrate, and chlorothalonil were co-applied at each sampling interval. Permanent precipitates were not observed when clethodim and crop oil concentrate were included with other fungicides or when 2,4-DB was mixed with fungicides. Significant positive correlations were noted for Palmer amaranth control by 2,4-DB and solution pH but not for clethodim and solution pH.

Download Full-text

Evaluation of Herbicide-Resistance Status on Populations of Littleseed Canarygrass (Phalaris Minor Retz.) from Southern Greece and Suggestions for their Effective Control

Journal of Plant Protection Research ◽

10.2478/v10045-012-0050-3 ◽

2012 ◽

Vol 52 (3) ◽

pp. 308-313 ◽

Cited By ~ 7

Author(s):

Ilias Travlos

Keyword(s):

Herbicide Resistance ◽

Resistance Index ◽

Acetolactate Synthase ◽

Effective Control ◽

Cross Resistance ◽

Resistance Mutations ◽

Resistance Level ◽

Phalaris Minor ◽

Wide Range ◽

Southern Greece

Evaluation of Herbicide-Resistance Status on Populations of Littleseed Canarygrass (Phalaris MinorRetz.) from Southern Greece and Suggestions for their Effective ControlIn 2010, a survey was conducted in the wheat fields of a typical cereal-producing region of Greece to establish the frequency and distribution of herbicide-resistant littleseed canarygrass (Phalaris minorRetz.). In total, 73 canarygrass accessions were collected and screened in a field experiment with several herbicides commonly used to control this weed. Most of the weed populations were classed as resistant (or developing resistance) to the acetyl-CoA varboxylase (ACCase)-inhibiting herbicide diclofop, while resistance to clodinafop was markedly lower. The results of the pot experiments showed that some of the canary populations were found to have a very high level of diclofop resistance (resistance index up to 12.4), while cross resistance with other herbicides was also common. The levels of resistance and cross resistance patterns among populations varied along with the different amounts and times of selection pressure. Such variation indicated either more than one mechanism of resistance or different resistance mutations in these weed populations. The population which had the highest diclofop resistance level, showed resistance to all aryloxyphenoxypropinate (APP) herbicides applied and non-ACCase inhibitors. Alternative ACCase-inhibiting herbicides, such as pinoxaden remain effective on the majority of the tested canarygrass populations, while the acetolactate synthase (ALS)-inhibiting herbicide mesosulfuron + iodosulfuron could also provide some solutions. Consequently, there is an opportunity to effectively control canarygrass by selecting from a wide range of herbicides. It is the integration of agronomic practices with herbicide application, which helps in effective management ofP. minorand particularly its resistant populations.

Download Full-text

Characterization of Antagonistic Bacillus methylotrophicus Isolated From Rhizosphere and Its Biocontrol Effects on Maize Stalk Rot

Phytopathology ◽

10.1094/phyto-07-18-0220-r ◽

2019 ◽

Vol 109 (4) ◽

pp. 571-581 ◽

Cited By ~ 9

Author(s):

Xingkai Cheng ◽

Xiaoxue Ji ◽

Yanzhen Ge ◽

Jingjing Li ◽

Wenzhe Qi ◽

...

Keyword(s):

Biochemical Characterization ◽

Disease Incidence ◽

Field Trials ◽

Control Measures ◽

Disease Suppression ◽

Effective Control ◽

Stalk Rot ◽

Bacillus Methylotrophicus ◽

Transmission Electron ◽

Potential Biocontrol Agent

Stalk rot is one of the most serious and widespread diseases in maize, and effective control measures are currently lacking. Therefore, this study aimed to develop a new biological agent to manage this disease. An antagonistic bacterial strain, TA-1, was isolated from rhizosphere soil and identified as Bacillus methylotrophicus based on morphological and biochemical characterization and 16S ribosomal RNA and gyrB gene sequence analyses. TA-1 exhibited a strong antifungal effect on the growth of Fusarium graminearum mycelium, with 86.3% inhibition at a concentration of 108 CFU per ml. Transmission electron microscopy showed that TA-1 could disrupt the cellular structure of the fungus, induce necrosis, and degrade the cell wall. Greenhouse and field trials were performed to evaluate the biocontrol efficacy of TA-1 on maize stalk rot, and the results of greenhouse experiment revealed that the bacterium significantly reduced disease incidence and disease index. Seeds treated with a 108 CFU ml−1 cell suspension had the highest disease suppression at 86.8%. Results of field trials show that seed bacterization with TA-1 could not only reduce maize stalk rot incidence but also increase maize height, stem diameter, and grain yield. The lipopeptide antibiotics were isolated from the culture supernatants of TA-1 and identified as surfactins and iturins. Consequently, B. methylotrophicus TA-1 is a potential biocontrol agent against maize stalk rot.

Download Full-text