Weed Technology最新文献

{"title":"Target site mechanism confers resistance pattern of ACCase-inhibitors in bearded sprangletop (Leptochloa fusca ssp. fascicularis) from California","authors":"Rasim Unan, Aaron Becerra-Alvarez, Kassim Al-Khatib","doi":"10.1017/wet.2024.33","DOIUrl":"https://doi.org/10.1017/wet.2024.33","url":null,"abstract":"Bearded sprangletop is a problematic native grass weed in California’s rice fields. The widespread and extensive use of Acetyl-CoA carboxylase (ACCase) inhibiting herbicides, such as cyhalofop-P-butyl (cyhalofop), has led to speculation that biotypes of bearded sprangletop have developed herbicide resistance to ACCase. The aim of this study was to evaluate suspected resistant bearded sprangletop biotypes, R1, R2, R3, and the susceptible biotype, S1, in terms of their levels of resistance to three ACCase-inhibiting herbicides and to characterize the molecular mechanisms of resistance. Dose-response experiments suggested that the biotype R1, R2, and R3 had high-level resistance to cyhalofop, and quizalofop-P-ethyl (quizalofop), but not clethodim. It was identified that the resistance to ACCase inhibitors was a target site mechanism resulting from nucleotide substitution. The carboxyl transferase (CT) domain of the ACCase gene’s sequence analysis revealed the substitutions Trp-2027-Cys for R1 and R2 biotypes and Ile-2041-Asn for R3 biotype. This study revealed that presence of target-site resistance to cyhalofop and quizalofop in at least two mutation points in representative biotypes of bearded sprangletop in California. This research highlights the significance of careful herbicide selection due to weed species responding quite rapidly to selection pressure to help manage bearded sprangletop in rice field.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"19 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Response of stevia (Stevia rebaudiana) to reduced risk synthetic and nonsynthetic herbicides applied post-transplant","authors":"Stephen J. Ippolito, Katherine M. Jennings, David W. Monks, Sushila Chaudhari, David Jordan, Levi D. Moore, Colton D. Blankenship","doi":"10.1017/wet.2024.20","DOIUrl":"https://doi.org/10.1017/wet.2024.20","url":null,"abstract":"Greenhouse trials were conducted to determine the response of stevia to reduce risk synthetic and nonsynthetic herbicides applied over-the-top post-transplant. In addition, field trials were conducted with stevia grown in a polyethylene mulch production system to determine crop response and weed control in planting holes to reduced risk synthetic and nonsynthetic herbicides applied post-transplant directed. Treatments included caprylic acid plus capric acid, clove oil plus cinnamon oil, d-limonene, acetic acid (200 grain), citric acid, pelargonic acid, eugenol, ammonium nonanoate, and ammoniated soap of fatty acids. Stevia yield (dry above ground biomass) in the greenhouse was reduced by all herbicide treatments. Citric acid and clove oil + cinnamon oil were the least injurious, reducing yield by 16 to 20%, respectively. In field studies, d-limonene, pelargonic acid, ammonium nonanoate, and ammoniated soap of fatty acids controlled Palmer amaranth > 90% 1 wk after treatment (WAT). In field studies caprylic acid plus capric acid, pelargonic acid, and ammonium nonanoate caused > 30% injury to stevia plant at 2 WAT, and D-limonene, citric acid, acetic acid, and ammoniated soap of fatty acids caused 18 to 25% injury 2 WAT. Clove oil plus cinnamon oil and eugenol caused < 10% injury. Despite being injurious, herbicides applied in the field did not reduce yield compared to the nontreated check. Based upon yield data, these herbicides have potential for use in stevia; however, these products could delay harvest if applied to established stevia. In particular, clove oil plus cinnamon oil has potential for use for early season weed management for organic production systems. The application of clove oil + cinnamon oil over-the-top resulted in <10% injury 28 DAT in the greenhouse and 3% injury 6 WAT POST-directed in the field. In addition, this treatment provided 95% control of Palmer amaranth 4 WAT.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"90 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glyphosate-resistant and susceptible downy brome (Bromus tectorum) management with soil-applied residual herbicides","authors":"Charles M. Geddes, Mattea M. Pittman","doi":"10.1017/wet.2024.22","DOIUrl":"https://doi.org/10.1017/wet.2024.22","url":null,"abstract":"Downy brome is a cleistogamous facultative winter-annual grass weed that invades cropland, pastureland, and ruderal areas in western North America. Glyphosate-resistant downy brome, the first known glyphosate-resistant grass weed in Canada, was confirmed in a glyphosate-resistant canola field in southern Alberta in 2021. A controlled-environment study was conducted to determine the impact of preemergence soil-applied residual herbicides on glyphosate-resistant and susceptible downy brome in two field soils. Flumioxazin/pyroxasulfone (70/89 g ai ha<jats:sup>−1</jats:sup>), carfentrazone/pyroxasulfone (18/150 g ai ha<jats:sup>−1</jats:sup>), sulfentrazone/pyroxasulfone (100/100 or 150/150 g ai ha<jats:sup>−1</jats:sup>), and saflufenacil/pyroxasulfone (36/120 g ai ha<jats:sup>−1</jats:sup>) resulted in excellent (≥90%) visible control and downy brome biomass reduction 8 wk after treatment (WAT). The low rate of carfentrazone/pyroxasulfone (12/100 g ai ha<jats:sup>−1</jats:sup>) resulted in good (≥80%) visible control and biomass reduction 8 WAT, while the low and medium rates of saflufenacil/pyroxasulfone (18/60 or 25/84 g ai ha<jats:sup>−1</jats:sup>) resulted in ≥80% biomass reduction but suppression only (66% to 75%) based on visible control. Flumioxazin alone (105 g ai ha<jats:sup>−1</jats:sup>) resulted in good visible control (81%) 8 WAT in a sandy loam soil, but poor (13%) control in a clay loam soil. Soil type affected plant growth as evidenced by reduced growth in the untreated sandy loam soil compared to clay loam soil. The glyphosate-resistant population emerged and grew more vigorously than the glyphosate-susceptible population resulting in greater plant densities in the untreated control and some less-effective herbicide treatments. These results suggest that mixtures of a protoporphyrinogen oxidase-inhibiting herbicide with the very-long-chain fatty acid elongase inhibitor pyroxasulfone applied preemergence at ≥89 g ai ha<jats:sup>−1</jats:sup> could be effective components of an herbicide layering strategy targeting glyphosate-resistant and -susceptible downy brome.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"59 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrating Cover Crops and Herbicides for Weed Control in Soybean","authors":"Annu Kumari, Andrew J. Price, Audrey Gamble, Steve Li, Alana Jacobson","doi":"10.1017/wet.2024.24","DOIUrl":"https://doi.org/10.1017/wet.2024.24","url":null,"abstract":"In midsouthern, southeastern, and northeastern United States soybean production regions, the evolution of herbicide-resistant weeds has become a significant management challenge for growers. The rising herbicide costs for managing herbicide-resistant weeds are also a growing concern, leading to the utilization of cover crops as an integrated weed management strategy for addressing these challenges. Field experiments were conducted at two locations in Alabama in 2022 to evaluate winter cereal cover crops, including a mixture and herbicide system integration in soybean. Treatments included five cover crops: oats, cereal rye, crimson clover, radish, and a cover crop mixture. Cover crops were evaluated for their weed-suppressive characteristics compared to a winter fallow treatment. Additionally, four herbicide treatments were applied: a preemergence (PRE) herbicide, a postemergence (POST) herbicide, PRE plus POST herbicides, and a non-treated (NT) check. The PRE herbicide was <jats:italic>S</jats:italic>-metolachlor, the POST treatment contained a mixture of dicamba and glyphosate. The PRE plus POST system contained the PRE application followed by POST application. Results show that cereal rye and the cover crop mixture provided weed biomass reduction compared to all cover crop treatments across both locations. Furthermore, we observed greater soybean yield following the cereal rye cover crop than the winter fallow treatment at one location. POST and PRE+POST herbicide treatment resulted in greater weed biomass reduction and improved soybean yield than the PRE herbicide treatment alone and NT check at both locations.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"68 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140629227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of Echinochloa spp. and Leptochloa fascicularis with the Novel Dihydroorotate Dehydrogenase Inhibitor Herbicide Tetflupyrolimet in California Water-seeded Rice","authors":"Matthew A Lombardi, Kassim Al-Khatib","doi":"10.1017/wet.2024.21","DOIUrl":"https://doi.org/10.1017/wet.2024.21","url":null,"abstract":"The spread of herbicide-resistant weeds is considered a major problem for rice production in California and there is a need for new herbicides. Tetflupyrolimet is a new herbicide with a novel dihydroorotate dehydrogenase (DHODH) inhibiting site of action (SOA) that has strong activity on grasses. Three field studies were conducted at the California Rice Experiment Station in Biggs, CA, in 2022 and 2023 to 1) determine control of watergrass species and bearded sprangletop with tetflupyrolimet 2) characterize the effects of tetflupyrolimet combined with other herbicides on weed control and rice, and 3) determine response of rice cultivars to tetflupyrolimet. In the first study, tetflupyrolimet was applied at preemergence (PRE) or at the 1- to 2-leaf stage of rice (POST) at 0.1, 0.125, or 0.15 kg ai ha<jats:sup>-1</jats:sup> followed by carfentrazone. Tetflupyrolimet provided ≥ 99% control of watergrass species and 100% bearded sprangletop control regardless of the rate or application timing, while showing no crop injury symptoms or yield reduction. In the second study, tetflupyrolimet was applied PRE or POST at 0.1 or 0.15 kg ai ha<jats:sup>-1</jats:sup> followed by herbicides labeled for use in California rice production. Tetflupyrolimet provided ≥ 98% control of watergrass species, which was better than the grower standard treatment, and ≥ 97% control of bearded sprangletop. In the third study, tetflupyrolimet was applied PRE or POST at 0.125, 0.15, 0.25, or 0.3 kg ai ha<jats:sup>-1</jats:sup> followed by carfentrazone. The six California rice cultivars evaluated – ‘M-105,’ ‘M-206,’ ‘M-209,’ ‘M-211,’ ‘L-208,’ and ‘CM-203’ – did not show any trend of crop injury caused by tetflupyrolimet. Overall, tetflupyrolimet provided a high level of control of watergrass species and bearded sprangletop without causing visual rice injury or yield reductions, regardless of rice cultivar, when applied alone or in combination with commonly used sedge and broadleaf herbicides in California water-seeded rice.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"49 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140613910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of herbicide programs on control and seed production of multiple herbicide-resistant Palmer amaranth (Amaranthus palmeri) in corn resistant to 2,4-D/glufosinate/glyphosate","authors":"Ramandeep Kaur, Rachel Rogers, Nevin C. Lawrence, Yeyin Shi, Parminder S. Chahal, Stevan Z. Knezevic, Amit J. Jhala","doi":"10.1017/wet.2024.23","DOIUrl":"https://doi.org/10.1017/wet.2024.23","url":null,"abstract":"Multiple herbicide-resistant (MHR) Palmer amaranth is among the most problematic summer annual broadleaf weeds in Nebraska and several other states in the United States. A new multiple herbicide-resistant corn cultivar (2,4-D/glufosinate/glyphosate-resistant, also known as Enlist corn) has been commercially available in the United States since 2018. Growers are searching for herbicide programs for control and reducing seed production of MHR Palmer amaranth in Enlist corn. The objectives of this study were to evaluate herbicide programs applied preemergence (PRE), early-postemergence (EPOST), or PRE followed by (fb) late-POST (LPOST) for the management of MHR Palmer amaranth in Enlist corn and their effect on Palmer amaranth biomass, density, seed production, and corn yield. Field experiments were conducted near Carleton, Nebraska, in 2020 and 2021 in a grower’s field infested with acetolactate synthase-inhibitor/atrazine/glyphosate-resistant Palmer amaranth in Enlist corn. Herbicides applied PRE, such as flufenacet/isoxaflutole/thiencarbazone-methyl, acetochlor/clopyralid/flumetsulam, or acetochlor/clopyralid/mesotrione provided 75% to 99% control of Palmer amaranth 30 d after PRE (DA-PRE). PRE fb LPOST herbicides resulted in 94% Palmer amaranth control 90 DA-LPOST, reduced weed density to 0 to 8 plants m<jats:sup>−2</jats:sup> 30 DA-LPOST, and biomass to 2 to 14 g m<jats:sup>−2</jats:sup> 15 DA-LPOST compared to PRE-only (59% control, 0 to 15 plants m<jats:sup>−2</jats:sup>, and 4 to 123 g m<jats:sup>−2</jats:sup>) and EPOST-only herbicides (78% control, 6 to 30 plants m<jats:sup>−2</jats:sup>, and 8 to 25 g m<jats:sup>−2</jats:sup>). Based on contrast analysis, Palmer amaranth seed production was reduced to 14,050 seed m<jats:sup>–2</jats:sup> in PRE fb LPOST herbicide programs compared with 325,490 seed m<jats:sup>–2</jats:sup> in PRE-only and 376,750 seed m<jats:sup>–2</jats:sup> in EPOST-only programs. Based on orthogonal contrast, higher corn yield of 12,340 and 11,730 kg ha<jats:sup>−1</jats:sup> was obtained with PRE fb LPOST herbicide programs compared to PRE-only (10,840 and 11,510 kg ha<jats:sup>−1</jats:sup>) and EPOST-only programs (10,850 and 10,030 kg ha<jats:sup>−1</jats:sup>) in 2020 and 2021, respectively.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"40 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140613903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of management practices to optimize cereal rye cover crop-based weed mitigation in Canadian sweet corn production","authors":"Hayley L. Brackenridge, Jichul Bae, Marie-Josée Simard, François J. Tardif, Kerry Bosveld, Robert E. Nurse","doi":"10.1017/wet.2024.19","DOIUrl":"https://doi.org/10.1017/wet.2024.19","url":null,"abstract":"Fall sown cereal rye has gained popularity as a cover crop in vegetable production due to its weed-suppressive capabilities. However, previous research has shown that replacing preemergence and/or postemergence herbicide applications with roller-crimped rye has variable success at controlling weeds and maintaining vegetable cash crop yields. The objective of this research was to test roller-crimped rye in sweet corn production to determine whether it can provide season-long weed control and maintain sweet corn yield. Two rye cultivars (early vs. standard maturity) were compared at three seeding rates (150, 300, and 600 seeds m<jats:sup>-2</jats:sup>) for their effect on weed control and sweet corn yield. The trial was conducted at Harrow, ON, and St. Jean-sur-Richelieu, QC, from 2019 to 2021 and at Agassiz, BC, in 2019 and 2021. Results suggest that, although the early maturing cultivar allowed for earlier roller crimping in some locations, it was inferior at weed control and resulted in lower sweet corn yield than local standard cultivars. The average rye biomass was lower than the current literature recommendations, and the resulting level of weed control was not high enough to prevent sweet corn yield loss in cover crop treatments. Weed control provided by roller-crimped rye peaked between crimping and eight weeks after crimping and was highest in the standard cultivars sown at 300 and 600 seeds m<jats:sup>-2</jats:sup>. Preliminary testing of supplemental postemergence weed control showed evidence for sweet corn yields comparable to the weed-free no-cover crop check. However, more research is needed. Overall, it was found that with the cultivars and seeding rates tested, roller-crimped rye is not a suitable stand-alone weed control option in sweet corn. Given the benefits of cover crops, further research should evaluate its potential as a component of an integrated weed management program.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"97 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140600771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of multiple-herbicide-resistant waterhemp with acetochlor-based herbicide mixtures in soybean","authors":"Hannah E. Symington, Nader Soltani, Allan C. Kaastra, David C. Hooker, Darren E. Robinson, Peter H. Sikkema","doi":"10.1017/wet.2024.14","DOIUrl":"https://doi.org/10.1017/wet.2024.14","url":null,"abstract":"<p>Waterhemp has evolved resistance to Group 2, 5, 9, 14, and 27 herbicides in Ontario, Canada, making control of this challenging weed even more difficult. Acetochlor is a Group 15, chloroacetanilide herbicide that has activity on many small-seeded annual grasses and some small-seeded annual broadleaf weeds, including waterhemp. The objective of this study was to ascertain if acetochlor mixtures with broadleaf herbicides (dicamba, metribuzin, diflufenican, sulfentrazone, or flumioxazin), applied preemergence (PRE), increase multiple-herbicide-resistant (MHR) waterhemp control in soybean. Five trials were conducted over 2 yr (2021 and 2022). The acetochlor mixtures caused ≤7% soybean injury, except acetochlor + flumioxazin, which caused 19% soybean injury. Acetochlor applied PRE controlled MHR waterhemp 89% at 4 wk after application (WAA). Dicamba, metribuzin, diflufenican, sulfentrazone, or flumioxazin controlled MHR waterhemp 59%, 67%, 58%, 64%, and 86%, respectively, at 4 WAA. Acetochlor applied in a mixture with dicamba, metribuzin, diflufenican, sulfentrazone, or flumioxazin provided good to excellent control of MHR waterhemp; control ranged from 91% to 98% but was similar to acetochlor applied alone. Acetochlor alone reduced MHR waterhemp density and biomass 98% and 93%; acetochlor + flumioxazin reduced waterhemp density and biomass by an additional 2% and 7%, respectively. This research concludes that acetochlor applied in a mixture with flumioxazin was the most efficacious mixture evaluated for MHR waterhemp control.</p>","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"21 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140600648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water-Seeded Rice Response to Pendimethalin Applied at Different Rates and Timings","authors":"Aaron Becerra-Alvarez, Kassim Al-Khatib","doi":"10.1017/wet.2024.18","DOIUrl":"https://doi.org/10.1017/wet.2024.18","url":null,"abstract":"Currently, there is a limited number of herbicides available in California water-seeded rice, with widespread resistance to most of these herbicides. Because no resistant grasses showed resistance to pendimethalin, a series of studies were conducted to evaluate water-seeded rice response to pendimethalin. In a field study conducted at the Rice Experiment Station at Biggs, California, in 2020 and 2021, three pendimethalin formulations, a granule (GR), emulsifiable concentrate (EC), and capsule suspension (CS), were applied at 1.1, 2.3, and 3.4 kg ai ha<jats:sup>-1</jats:sup> rates, and at 5, 10, and 15 days after seeding onto water-seeded rice. In addition, a greenhouse study was conducted to examine the response of five common California rice cultivars to GR and CS formulation applications. <jats:italic>Echinochloa</jats:italic> control levels were reduced at the 15 days after seeding timing after use of EC and CS formulations compared to earlier timings. In both years, rice grain yields were increased by 3,014 kg ha<jats:sup>-1</jats:sup> after application of pendimethalin at 3.4 kg ai ha<jats:sup>-1</jats:sup> when applied at 15 days after seeding compared to 5 and 10 days after seeding, and similar to 1.1 kg ai ha<jats:sup>-1</jats:sup> applications. The GR and CS were safer formulations based on a reduction in injury and an increase in grain yields compared to the EC. Differences in seedling vigor across cultivars appeared to incur an advantage after a pendimethalin application. However, most cultivars evaluated for stand reduction and dry biomass demonstrated tolerance to GR and CS formulation applications only after rice reached the 3-leaf stage. In contrast, an application at 1-leaf stage rice reduced stand up to 68%. Application rate, timing, and formulation are important factors to consider if the use of pendimethalin in water-seeded rice is to be pursued.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"21 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140600755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EPSPS Gene Amplification Confers Glyphosate Resistance in Palmer Amaranth in Connecticut","authors":"Jatinder S. Aulakh, Vipan Kumar, Caio A. C. G. Brunharo, Adrian Veron, Andrew J. Price","doi":"10.1017/wet.2024.17","DOIUrl":"https://doi.org/10.1017/wet.2024.17","url":null,"abstract":"A Palmer amaranth biotype (CT-Res) with resistance to glyphosate was recently confirmed from a pumpkin field in Connecticut. However, the underlying mechanism (s) conferring glyphosate resistance in this biotype is not known. The main objectives of this research were (1) to determine the effect of plant height (10-, 20-, and 30-cm tall) on glyphosate resistance levels in CT-Res Palmer amaranth biotype, and (2) to investigate if the target-site-based mechanisms confer glyphosate resistance. To achieve these objectives, progeny seeds of CT-Res biotype after two generations of recurrent selection with glyphosate (6,720 g ae ha<jats:sup>-1</jats:sup>) were used. Similarly, known glyphosate-susceptible Palmer amaranth biotypes from Kansas (KS-Sus) and Alabama (AL-Sus) were included. Results from greenhouse dose-response studies revealed that CT-Res Palmer amaranth biotype had 69-, 64-, and 54-fold resistance to glyphosate as compared to KS-Sus biotype when treated at 10-, 20-, and 30-cm tall, respectively. Sequence analysis of the <jats:italic>EPSPS</jats:italic> gene revealed no point mutations at the Pro<jats:sub>106</jats:sub> and Thr<jats:sub>102</jats:sub> residues in the CT-Res Palmer amaranth biotype. The qPCR analysis revealed that CT-Res biotype had 33 to 111 relative copies of the <jats:italic>EPSPS</jats:italic> gene compared to AL-Sus biotype. All these results suggest that the <jats:italic>EPSPS</jats:italic> gene amplification endows a high level of glyphosate resistance in the GR Palmer amaranth biotype from Connecticut. Because of the lack of control with glyphosate, growers should adopt effective alternative preemergence and postemergence herbicides in conjunction with other cultural and mechanical tactics to mitigate the further spread of GR Palmer amaranth in Connecticut.","PeriodicalId":23710,"journal":{"name":"Weed Technology","volume":"27 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140170671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}