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.
{"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}
Stephen J. Ippolito, Katherine M. Jennings, David W. Monks, Sushila Chaudhari, David Jordan, Levi D. Moore, Colton D. Blankenship
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.
进行了温室试验，以确定甜叶菊对移栽后顶部施用的风险较低的合成和非合成除草剂的反应。此外，还对在聚乙烯地膜覆盖生产系统中种植的甜叶菊进行了田间试验，以确定作物对种植后直接施用的风险较低的合成和非合成除草剂的反应以及种植穴中的杂草控制情况。处理方法包括辛酸加癸酸、丁香油加肉桂油、d-柠檬烯、乙酸（200 谷物）、柠檬酸、壬酸钾、丁香酚、壬酸铵和脂肪酸氨化皂。所有除草剂处理都降低了温室中甜叶菊的产量（地上干生物量）。柠檬酸和丁香油+肉桂油的伤害最小，分别减少了 16% 到 20% 的产量。在田间研究中，d-柠檬烯、pelargonic acid、壬酸铵和脂肪酸氨化皂在处理后 1 周（WAT）对帕尔默苋的控制率为 90%。在田间研究中，辛酸加癸酸、壬酸钾和壬酸铵在处理后 2 WAT 会对甜叶菊植物造成 30% 的伤害，D-柠檬烯、柠檬酸、乙酸和脂肪酸氨化皂在处理后 2 WAT 会造成 18% 到 25% 的伤害。丁香油加肉桂油和丁香酚造成的伤害为 10%。尽管除草剂会造成伤害，但在田间施用除草剂与未施用除草剂的对照组相比并没有减产。根据产量数据，这些除草剂具有用于甜叶菊的潜力；不过，如果将这些产品用于成熟的甜叶菊，可能会延迟收获。特别是，丁香油加肉桂油有可能用于有机生产系统的早期杂草管理。在温室中，丁香油+肉桂油的顶部施用会导致 10%的伤害（28 DAT），在田间，3%的伤害（6 WAT POST-directed）。此外，这种处理方法在 4 WAT 期对帕尔默苋的控制率为 95%。
{"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}
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−1), carfentrazone/pyroxasulfone (18/150 g ai ha−1), sulfentrazone/pyroxasulfone (100/100 or 150/150 g ai ha−1), and saflufenacil/pyroxasulfone (36/120 g ai ha−1) 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−1) 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−1) resulted in ≥80% biomass reduction but suppression only (66% to 75%) based on visible control. Flumioxazin alone (105 g ai ha−1) 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−1 could be effective components of an herbicide layering strategy targeting glyphosate-resistant and -susceptible downy brome.
绒毛穗禾本科杂草（Downy brome）是一种冬性一年生禾本科杂草，入侵北美西部的耕地、牧场和灌丛地区。2021 年，在阿尔伯塔省南部的一块抗草甘膦油菜田里证实了抗草甘膦绒毛穗草，这是加拿大第一种已知的抗草甘膦禾本科杂草。一项受控环境研究旨在确定两种田间土壤中芽前土壤施用的残留除草剂对草甘膦抗性和易感绒毛膜禾本科杂草的影响。氟草胺/吡唑砜（70/89 克/公顷-1）、氟虫腈/吡唑砜（18/150 克/公顷-1）、磺草酮/吡唑砜（100/100 或 150/150 克/公顷-1）和氟虫腈/吡唑砜（36/120 克/公顷-1）在处理后 8 周（WAT）均能产生极佳的可见控制效果（≥90%）并减少绒毛丛草的生物量。低剂量的氟虫腈/吡嘧磺隆（12/100 克/公顷-1）可获得良好的可见防治效果（≥80%），并在 8 WAT 后减少生物量，而中低剂量的氟虫腈/吡嘧磺隆（18/60 或 25/84 克/公顷-1）可使生物量减少≥80%，但根据可见防治效果，其抑制率仅为 66% 至 75%。在沙质壤土中，单用氟吡甲禾灵（105 g ai ha-1）可在 8 WAT 期获得良好的可见防治效果（81%），但在粘壤土中的防治效果较差（13%）。土壤类型会影响植物的生长，未经处理的沙质壤土与粘壤土相比，植物生长量有所降低。草甘膦抗性种群的出现和生长比草甘膦敏感种群更旺盛，导致未处理的对照组和一些除草剂效果较差的处理组中的植物密度更大。这些结果表明，原卟啉原氧化酶抑制性除草剂与超长链脂肪酸伸长酶抑制剂吡嘧磺隆的混合物在萌芽前施用，施用量≥89 g ai ha-1，可以成为针对抗草甘膦和易感绒毛草的除草剂分层策略的有效组成部分。
{"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}
Annu Kumari, Andrew J. Price, Audrey Gamble, Steve Li, Alana Jacobson
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 S-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.
在美国中南部、东南部和东北部大豆产区，抗除草剂杂草的演变已成为种植者在管理上面临的重大挑战。管理抗除草剂杂草所需的除草剂成本不断上升，这也日益引起人们的关注，因此，人们开始利用覆盖作物作为综合杂草管理策略来应对这些挑战。2022 年，在阿拉巴马州的两个地方进行了田间试验，以评估冬季谷物覆盖作物，包括大豆中的混合物和除草剂系统集成。处理包括五种覆盖作物：燕麦、黑麦、深红三叶草、萝卜和覆盖作物混合物。与冬季休耕处理相比，对覆盖作物的抑制杂草特性进行了评估。此外，还采用了四种除草剂处理方法：萌芽前（PRE）除草剂、萌芽后（POST）除草剂、PRE 加 POST 除草剂以及未处理（NT）对照。萌芽前除草剂是 S-甲草胺，萌芽后处理包含麦草畏和草甘膦的混合物。前处理加后处理系统包括前处理和后处理。结果表明，与两地的所有覆盖作物处理相比，黑麦和覆盖作物混合物可减少杂草生物量。此外，我们还观察到，在一个地点种植黑麦覆盖作物后，大豆产量高于冬季休耕处理。在这两个地点，与单独使用 PRE 除草剂处理和 NT 对照相比，POST 和 PRE+POST 除草剂处理能更有效地减少杂草生物量并提高大豆产量。
{"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}
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-1 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-1 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-1 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.
抗除草剂杂草的蔓延被认为是加州水稻生产的一个主要问题，因此需要新的除草剂。Tetflupyrolimet 是一种新型除草剂，具有新型二氢烟酸脱氢酶（DHODH）抑制作用位点（SOA），对禾本科杂草具有很强的活性。2022 年和 2023 年，加利福尼亚州比格斯的加利福尼亚水稻试验站进行了三项田间研究，目的是：1）确定四氟吡草胺对水草和胡枝子的控制效果；2）确定四氟吡草胺与其他除草剂结合使用对杂草控制和水稻的影响；3）确定水稻品种对四氟吡草胺的反应。在第一项研究中，在水稻出苗前（PRE）或 1 至 2 叶期（POST）施用四氟吡草胺，施用量为 0.1、0.125 或 0.15 kg ai ha-1，然后施用氟乐灵。无论施药量或施药时间如何，Tetflupyrolimet 对水草的控制率≥ 99%，对胡枝子的控制率为 100%，同时没有出现作物伤害症状或减产。在第二项研究中，Tetflupyrolimet 以 0.1 或 0.15 kg ai ha-1 的剂量在水稻收割前或收割后施用，然后再施用标明用于加州水稻生产的除草剂。四氟吡草胺对水草的控制率≥ 98%，优于种植者标准处理，对胡枝子的控制率≥ 97%。在第三项研究中，四氟丙嘧草酯的施用剂量为 0.125、0.15、0.25 或 0.3 kg ai ha-1，施药前或施药后再施用卡芬特酮。接受评估的六种加州水稻品种--"M-105"、"M-206"、"M-209"、"M-211"、"L-208 "和 "CM-203"--没有显示出任何四氟吡草胺对作物造成伤害的趋势。总体而言，在加利福尼亚水稻中单独施用或与常用的莎草和阔叶除草剂联合施用四氟吡草胺时，无论水稻品种如何，四氟吡草胺都能很好地控制水草和胡枝子，而不会对水稻造成视觉伤害或导致减产。
{"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}
Ramandeep Kaur, Rachel Rogers, Nevin C. Lawrence, Yeyin Shi, Parminder S. Chahal, Stevan Z. Knezevic, Amit J. Jhala
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−2 30 DA-LPOST, and biomass to 2 to 14 g m−2 15 DA-LPOST compared to PRE-only (59% control, 0 to 15 plants m−2, and 4 to 123 g m−2) and EPOST-only herbicides (78% control, 6 to 30 plants m−2, and 8 to 25 g m−2). Based on contrast analysis, Palmer amaranth seed production was reduced to 14,050 seed m–2 in PRE fb LPOST herbicide programs compared with 325,490 seed m–2 in PRE-only and 376,750 seed m–2 in EPOST-only programs. Based on orthogonal contrast, higher corn yield of 12,340 and 11,730 kg ha−1 was obtained with PRE fb LPOST herbicide programs compared to PRE-only (10,840 and 11,510 kg ha−1) and EPOST-only programs (10,850 and 10,030 kg ha−1) in 2020 and 2021, respectively.
{"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}
Hayley L. Brackenridge, Jichul Bae, Marie-Josée Simard, François J. Tardif, Kerry Bosveld, Robert E. Nurse
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-2) 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-2. 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.
{"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}
Hannah E. Symington, Nader Soltani, Allan C. Kaastra, David C. Hooker, Darren E. Robinson, Peter H. Sikkema
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.
{"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}
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-1 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. Echinochloa 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-1 after application of pendimethalin at 3.4 kg ai ha-1 when applied at 15 days after seeding compared to 5 and 10 days after seeding, and similar to 1.1 kg ai ha-1 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.
目前，加州水稻可用的除草剂数量有限，而且大多数除草剂都普遍存在抗药性。由于没有抗性禾本科植物表现出对戊唑醇的抗性，因此进行了一系列研究，以评估水播稻对戊唑醇的反应。2020 年和 2021 年，加利福尼亚州比格斯水稻试验站进行了一项田间研究，在水稻播种后 5、10 和 15 天，分别以 1.1、2.3 和 3.4 kg ai ha-1 的剂量施用颗粒剂 (GR)、乳油 (EC) 和胶囊悬浮剂 (CS)。此外，还进行了一项温室研究，考察五种常见加州水稻品种对 GR 和 CS 制剂施用的反应。与较早的时间相比，在播种后 15 天使用 EC 和 CS 制剂后，Echinochloa 的控制水平有所降低。与播种后 5 天和 10 天施用 3.4 kg ai ha-1 的戊唑醇相比，在播种后 15 天施用 3.4 kg ai ha-1 的戊唑醇，水稻产量在这两年都增加了 3,014 kg ha-1，与 1.1 kg ai ha-1 的施用量相近。与 EC 相比，GR 和 CS 是更安全的制剂，因为它们减少了伤害，提高了谷物产量。施用戊唑醇后，不同栽培品种幼苗活力的差异似乎会带来优势。不过，大多数栽培品种在水稻长到 3 叶期后才会表现出对 GR 和 CS 制剂施用的耐受性，以减少立枯病和干生物量。相比之下，在水稻 1 叶期施药可使立秆率降低 68%。如果要在水稻中使用戊唑醇，施用量、施用时间和配方都是需要考虑的重要因素。
{"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}
Jatinder S. Aulakh, Vipan Kumar, Caio A. C. G. Brunharo, Adrian Veron, Andrew J. Price
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-1) 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 EPSPS gene revealed no point mutations at the Pro106 and Thr102 residues in the CT-Res Palmer amaranth biotype. The qPCR analysis revealed that CT-Res biotype had 33 to 111 relative copies of the EPSPS gene compared to AL-Sus biotype. All these results suggest that the EPSPS 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.
{"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}
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