Abstract Liverseedgrass (Urochloa panicoides P. Beauv.) is one of the most important summer grass weed species in the eastern cropping system of Australia. Experiments were conducted to evaluate the effects of temperature, salt stress, water stress, burial depth, and sorghum crop residue load on germination and emergence of U. panicoides and the performance of postemergence herbicides on this weed species. The optimal germination temperature regimes for U. panicoides were 30/ 20 and 35/25 C (alternating day/night temperatures), but seeds also germinated at temperatures occurring in winter, spring, and autumn in Australia (15/5, 20/10, and 25/15 C). A concentration of 48 mM sodium chloride and –0.27 MPa osmotic potential inhibited germination of U. panicoides by 50%, indicating that this weed species is not salt and drought tolerant at germination. The maximum germination was obtained for the surface seeds; a burial depth of 1.9 cm inhibited emergence by 50%. No seedlings emerged from the 12-cm depth, but about 3% of seedlings emerged from the 8 cm depth. The addition of sorghum residue amounts up to 8,000 kg ha–1 to the soil surface stimulated U. panicoides' emergence compared with the no-residue treatment, suggesting that conservation agriculture will promote the emergence of U. panicoides. Several postemergence herbicides were found to be effective in controlling this weed species, especially when applied at an early stage. Information obtained from this study will help to develop effective and sustainable control measures for U. panicoides and other weed species with similar germination requirements.
摘要Liversedsgrass（Urochloa panicoides P.Beauv.）是澳大利亚东部种植系统中最重要的夏季杂草之一。通过试验，评价了温度、盐胁迫、水分胁迫、埋深和高粱作物残留量对圆锥花序发芽和出苗的影响，以及出苗后除草剂对该杂草的性能。圆锥花序的最佳发芽温度为30/20和35/25摄氏度（昼夜交替温度），但种子也在澳大利亚冬季、春季和秋季的温度下发芽（15/5、20/10和25/15摄氏度）。浓度为48 mM的氯化钠和–0.27 MPa的渗透势抑制了50%的圆锥花序的发芽，表明该杂草在发芽时不耐盐和干旱。表层种子发芽率最高；1.9厘米的埋深抑制了50%的出苗。在12厘米深处没有幼苗出现，但约3%的幼苗从8厘米深处出现。与无渣处理相比，向土壤表面添加高达8000 kg ha–1的高粱渣刺激了圆锥花的出现，这表明保护性农业将促进圆锥花的产生。一些出苗后除草剂被发现能有效控制这种杂草，尤其是在早期使用时。从这项研究中获得的信息将有助于制定有效和可持续的控制措施，以控制圆锥花序和其他具有类似发芽要求的杂草。
{"title":"Germination Biology of Liverseedgrass (Urochloa panicoides) and its Response to Postemergence Herbicides in Australian Conditions","authors":"B. Chauhan","doi":"10.1017/wsc.2022.50","DOIUrl":"https://doi.org/10.1017/wsc.2022.50","url":null,"abstract":"Abstract Liverseedgrass (Urochloa panicoides P. Beauv.) is one of the most important summer grass weed species in the eastern cropping system of Australia. Experiments were conducted to evaluate the effects of temperature, salt stress, water stress, burial depth, and sorghum crop residue load on germination and emergence of U. panicoides and the performance of postemergence herbicides on this weed species. The optimal germination temperature regimes for U. panicoides were 30/ 20 and 35/25 C (alternating day/night temperatures), but seeds also germinated at temperatures occurring in winter, spring, and autumn in Australia (15/5, 20/10, and 25/15 C). A concentration of 48 mM sodium chloride and –0.27 MPa osmotic potential inhibited germination of U. panicoides by 50%, indicating that this weed species is not salt and drought tolerant at germination. The maximum germination was obtained for the surface seeds; a burial depth of 1.9 cm inhibited emergence by 50%. No seedlings emerged from the 12-cm depth, but about 3% of seedlings emerged from the 8 cm depth. The addition of sorghum residue amounts up to 8,000 kg ha–1 to the soil surface stimulated U. panicoides' emergence compared with the no-residue treatment, suggesting that conservation agriculture will promote the emergence of U. panicoides. Several postemergence herbicides were found to be effective in controlling this weed species, especially when applied at an early stage. Information obtained from this study will help to develop effective and sustainable control measures for U. panicoides and other weed species with similar germination requirements.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"553 - 560"},"PeriodicalIF":2.5,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49124559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Cover crops enhance the biodiversity of cropping systems and can support a variety of useful ecosystem services, including weed suppression. In California orchards, cover crops are typically implemented as annual plants that can replace resident vegetation in orchard alleyways during the rainy winter season. Our research objective was to evaluate cover crop management factors that support a competitive, weed-suppressing cover crop in the unique orchard systems of central California. We conducted two experiments: an experiment evaluating cover crop management intensification in walnuts (Juglans regia L.) and an experiment evaluating multispecies cover crop mixes and planting date in almonds [Prunus dulcis (Mill.) D.A. Webb]. These experiments demonstrate that timely cover crop planting is important for producing an abundant cover crop, and a variety of cover crop management programs can produce weed-suppressing cover crops. However, cover crops do not result in weed-free orchards and should be considered within the context of integrated management programs. The apparent flexibility of orchard cover crop management provides an opportunity to promote other agroecosystem services, with vegetation management and weed suppression as complementary management goals.
{"title":"Agronomic Cover Crop Management Supports Weed Suppression and Competition in California Orchards","authors":"Steven C. Haring, B. Hanson","doi":"10.1017/wsc.2022.48","DOIUrl":"https://doi.org/10.1017/wsc.2022.48","url":null,"abstract":"Abstract Cover crops enhance the biodiversity of cropping systems and can support a variety of useful ecosystem services, including weed suppression. In California orchards, cover crops are typically implemented as annual plants that can replace resident vegetation in orchard alleyways during the rainy winter season. Our research objective was to evaluate cover crop management factors that support a competitive, weed-suppressing cover crop in the unique orchard systems of central California. We conducted two experiments: an experiment evaluating cover crop management intensification in walnuts (Juglans regia L.) and an experiment evaluating multispecies cover crop mixes and planting date in almonds [Prunus dulcis (Mill.) D.A. Webb]. These experiments demonstrate that timely cover crop planting is important for producing an abundant cover crop, and a variety of cover crop management programs can produce weed-suppressing cover crops. However, cover crops do not result in weed-free orchards and should be considered within the context of integrated management programs. The apparent flexibility of orchard cover crop management provides an opportunity to promote other agroecosystem services, with vegetation management and weed suppression as complementary management goals.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"595 - 602"},"PeriodicalIF":2.5,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44026968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Southern threecornerjack (Emex australis Steinh.) produces both aerial seeds on the branches and subterranean seeds at the base of the plant crown approximately 1 to 2 cm underground. Prior research indicated that seeds buried at a depth of 1 cm have a much higher probability of germinating in the following season compared with seeds on the soil surface. The current research investigated the number of subterranean seeds produced per plant, timing of subterranean seed production, and germination requirements of subterranean seeds compared with aerial seeds. This research demonstrated that E. australis plants from multiple populations produced subterranean seeds beginning at the 4-leaf development stage, before the production of aerial seeds. Individual plants produced a maximum of 30 subterranean seeds. Germination of subterranean and aerial seeds following afterripening over the summer to autumn (December to May) fallow was similar, demonstrating that the different seed types had no differences in dormancy. Further, the subterranean seeds did not have the light requirement for germination observed in aerial seeds. Subterranean seeds had 22.2% and 24.3% germination in light and dark conditions, respectively, compared with aerial seeds, which had 26.9% germination in light conditions and 12.3% germination in the dark. Production of subterranean seeds was low, given that a mature E. australis plant may produce more than 1,100 aerial seeds, but the subterranean seeds formed earlier in plant development. Recommendations for postemergence herbicides are to spray E. australis at the 2- to 4-leaf stage of growth, yet some plants may have already produced mature subterranean seeds by this stage. Further research is required to determine the impact of subterranean seeds on population ecology.
{"title":"Subterranean and aerial seed production of southern threecornerjack (Emex australis)","authors":"C. Borger, N. Wilkins","doi":"10.1017/wsc.2022.44","DOIUrl":"https://doi.org/10.1017/wsc.2022.44","url":null,"abstract":"Abstract Southern threecornerjack (Emex australis Steinh.) produces both aerial seeds on the branches and subterranean seeds at the base of the plant crown approximately 1 to 2 cm underground. Prior research indicated that seeds buried at a depth of 1 cm have a much higher probability of germinating in the following season compared with seeds on the soil surface. The current research investigated the number of subterranean seeds produced per plant, timing of subterranean seed production, and germination requirements of subterranean seeds compared with aerial seeds. This research demonstrated that E. australis plants from multiple populations produced subterranean seeds beginning at the 4-leaf development stage, before the production of aerial seeds. Individual plants produced a maximum of 30 subterranean seeds. Germination of subterranean and aerial seeds following afterripening over the summer to autumn (December to May) fallow was similar, demonstrating that the different seed types had no differences in dormancy. Further, the subterranean seeds did not have the light requirement for germination observed in aerial seeds. Subterranean seeds had 22.2% and 24.3% germination in light and dark conditions, respectively, compared with aerial seeds, which had 26.9% germination in light conditions and 12.3% germination in the dark. Production of subterranean seeds was low, given that a mature E. australis plant may produce more than 1,100 aerial seeds, but the subterranean seeds formed earlier in plant development. Recommendations for postemergence herbicides are to spray E. australis at the 2- to 4-leaf stage of growth, yet some plants may have already produced mature subterranean seeds by this stage. Further research is required to determine the impact of subterranean seeds on population ecology.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"569 - 578"},"PeriodicalIF":2.5,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45247489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chaonan Cai, Jianhua Xiao, J. Wan, Zichun Ren, M. van Kleunen, Junmin Li
Abstract Some parasitic plants are major pests in agriculture, but how this might be affected by climate change remains largely unknown. In this study, we assessed this question for five generalist holoparasitic Cuscuta species (smoothseed alfalfa dodder [Cuscuta approximata Bab.], alfalfa dodder [Cuscuta europaea L.], soybean dodder [Cuscuta chinensis C. Wright], Peruvian dodder [Cuscuta australis R. Br.], and Japanese dodder [Cuscuta japonica Choisy]) and two of their main Leguminosae host crop species (soybean [Glycine max (L.) Merr.] and alfalfa [Medicago sativa L.]. For each of the five Cuscuta species and the two crop species, we ran MaxEnt models, using climatic and soil variables to predict their potential current distributions and potential future distributions for 2070. We ran species distribution models for all seven species for multiple climate change scenarios, and tested for changes in the overlap of suitable ranges of each crop with the five parasites. We found that annual mean temperature and isothermality are the main bioclimatic factors determining the suitable habitats of the Cuscuta species and their hosts. For both host species, the marginally to optimally suitable area will increase by 2070 for all four representative concentration pathway scenarios. For most of the Cuscuta species, the marginally to optimally suitable area will also increase. While the suitable areas for both the hosts and the parasites will increase overall, Schoener's D, indicating the relative overlap in suitable area, will change only marginally. However, the absolute area of potential niche overlap may increase up to 6-fold by 2070. Overall, our results indicate that larger parts of the globe will become suitable for both host species, but that they could also suffer from Cuscuta parasitism in larger parts of their suitable ranges.
{"title":"Implications of climate change for environmental niche overlap between five Cuscuta pest species and their two main Leguminosae host crop species","authors":"Chaonan Cai, Jianhua Xiao, J. Wan, Zichun Ren, M. van Kleunen, Junmin Li","doi":"10.1017/wsc.2022.45","DOIUrl":"https://doi.org/10.1017/wsc.2022.45","url":null,"abstract":"Abstract Some parasitic plants are major pests in agriculture, but how this might be affected by climate change remains largely unknown. In this study, we assessed this question for five generalist holoparasitic Cuscuta species (smoothseed alfalfa dodder [Cuscuta approximata Bab.], alfalfa dodder [Cuscuta europaea L.], soybean dodder [Cuscuta chinensis C. Wright], Peruvian dodder [Cuscuta australis R. Br.], and Japanese dodder [Cuscuta japonica Choisy]) and two of their main Leguminosae host crop species (soybean [Glycine max (L.) Merr.] and alfalfa [Medicago sativa L.]. For each of the five Cuscuta species and the two crop species, we ran MaxEnt models, using climatic and soil variables to predict their potential current distributions and potential future distributions for 2070. We ran species distribution models for all seven species for multiple climate change scenarios, and tested for changes in the overlap of suitable ranges of each crop with the five parasites. We found that annual mean temperature and isothermality are the main bioclimatic factors determining the suitable habitats of the Cuscuta species and their hosts. For both host species, the marginally to optimally suitable area will increase by 2070 for all four representative concentration pathway scenarios. For most of the Cuscuta species, the marginally to optimally suitable area will also increase. While the suitable areas for both the hosts and the parasites will increase overall, Schoener's D, indicating the relative overlap in suitable area, will change only marginally. However, the absolute area of potential niche overlap may increase up to 6-fold by 2070. Overall, our results indicate that larger parts of the globe will become suitable for both host species, but that they could also suffer from Cuscuta parasitism in larger parts of their suitable ranges.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"543 - 552"},"PeriodicalIF":2.5,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46973302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Meyers, JEAN-MARIE ARANa, Brandi C. Woolam, Nathaly Vargas, Laura Rodriguez, Luz Cardona
Abstract There is zero tolerance for dicamba and dicamba metabolite residue in tomato (Solanum lycopersicum L.) fruit following exposure to dicamba. Field trials were conducted in 2020 and 2021 to determine the persistence of dicamba and metabolite (5-hydroxy dicamba and 3,6-dichlor-osalicylic acid [DCSA]) residue in processing tomato shoots and fruits. Dicamba was applied 49 d after transplanting at 0, 0.53, 5.3, and 53 g ae ha–1. Tomato plants were harvested 5, 10, 20, 40, and 61 d after treatment (DAT). No 5-hydroxy dicamba was recovered from any sample. In 2020, the DCSA metabolite was detected from tomato shoot tissue when dicamba was applied at the 53 g ha–1 rate at 0 (14 µg kg–1), 5 (3 µg kg–1), and 20 DAT (5 µg kg–1) and from tomato fruit tissue at 53 g ha–1 at 20 (2 µg kg–1) and 61 DAT (2 µg kg–1). In 2021, DCSA was not detected from tomato shoot or fruit tissues at any harvest date. By 5 DAT, dicamba was only detected from tomato shoot tissues treated with 53 g ha–1. At 0 DAT, dicamba residue was detectable only from tomato fruit on plants treated with 53 g ha–1. Tomato fruit dicamba residue from plants treated with 5.3 g ha–1 had a predicted peak of 19 µg kg–1 at 11.3 DAT. Tomato fruit dicamba residue from plants treated with 53 g ha–1 decreased from 164 to 8 µg kg–1 from 5 to 61 DAT. Furthermore, this study confirms that dicamba is detectable from tomato fruits at 61 DAT following exposure to 5.3 or 53 g ha–1 dicamba. Growers who suspect dicamba exposure should include tomato fruit tissue with their collected sample or sample tomato fruits separately.
摘要番茄（Solanum lycopersicum L.）果实在接触麦草畏后对麦草畏及其代谢产物残留具有零耐受性。2020年和2021年进行了实地试验，以确定麦草畏及其代谢物（5-羟基麦草畏和3,6-二氯-水杨酸[DCSA]）残留在番茄芽和果实加工中的持久性。麦草畏在移植后49天分别以0、0.53、5.3和53 g ae ha–1施用。番茄植株在处理（DAT）后5、10、20、40和61天收获。没有从任何样品中回收5-羟基麦草畏。2020年，当麦草畏以53 g ha–1的剂量0（14µg kg–1）、5（3µg kg-1）和20 DAT（5µg kg-1）施用时，从番茄地上部组织中检测到DCSA代谢产物，并以53 g ha-1的剂量20（2µg kg？1）和61 DAT。2021年，在任何收获日期，都没有从番茄茎或果实组织中检测到DCSA。通过5 DAT，麦草畏仅从用53 g ha–1处理的番茄茎组织中检测到。在0 DAT时，麦草畏残留仅可从用53 g ha–1处理的植物上的番茄果实中检测到。用5.3 g ha–1处理的植物的番茄果实麦草畏残留物在11.3 DAT时的预测峰值为19µg kg–1。用53 g ha–1处理的植物的番茄果实麦草畏残留物从164µg kg–1降至8µg kg-1，从5 DAT降至61 DAT。此外，这项研究证实，在暴露于5.3或53 g ha–1麦草畏后，在61 DAT的番茄果实中可以检测到麦草畏。怀疑接触麦草畏的种植者应将番茄果实组织与他们收集的样本或单独对番茄果实进行采样。
{"title":"Dicamba residue persistence in processing tomato","authors":"S. Meyers, JEAN-MARIE ARANa, Brandi C. Woolam, Nathaly Vargas, Laura Rodriguez, Luz Cardona","doi":"10.1017/wsc.2022.46","DOIUrl":"https://doi.org/10.1017/wsc.2022.46","url":null,"abstract":"Abstract There is zero tolerance for dicamba and dicamba metabolite residue in tomato (Solanum lycopersicum L.) fruit following exposure to dicamba. Field trials were conducted in 2020 and 2021 to determine the persistence of dicamba and metabolite (5-hydroxy dicamba and 3,6-dichlor-osalicylic acid [DCSA]) residue in processing tomato shoots and fruits. Dicamba was applied 49 d after transplanting at 0, 0.53, 5.3, and 53 g ae ha–1. Tomato plants were harvested 5, 10, 20, 40, and 61 d after treatment (DAT). No 5-hydroxy dicamba was recovered from any sample. In 2020, the DCSA metabolite was detected from tomato shoot tissue when dicamba was applied at the 53 g ha–1 rate at 0 (14 µg kg–1), 5 (3 µg kg–1), and 20 DAT (5 µg kg–1) and from tomato fruit tissue at 53 g ha–1 at 20 (2 µg kg–1) and 61 DAT (2 µg kg–1). In 2021, DCSA was not detected from tomato shoot or fruit tissues at any harvest date. By 5 DAT, dicamba was only detected from tomato shoot tissues treated with 53 g ha–1. At 0 DAT, dicamba residue was detectable only from tomato fruit on plants treated with 53 g ha–1. Tomato fruit dicamba residue from plants treated with 5.3 g ha–1 had a predicted peak of 19 µg kg–1 at 11.3 DAT. Tomato fruit dicamba residue from plants treated with 53 g ha–1 decreased from 164 to 8 µg kg–1 from 5 to 61 DAT. Furthermore, this study confirms that dicamba is detectable from tomato fruits at 61 DAT following exposure to 5.3 or 53 g ha–1 dicamba. Growers who suspect dicamba exposure should include tomato fruit tissue with their collected sample or sample tomato fruits separately.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"603 - 609"},"PeriodicalIF":2.5,"publicationDate":"2022-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45233636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Boyd, Marcelo L. Moretti, L. Sosnoskie, Vijay Singh, Ramdas G. Kanissery, S. Sharpe, Thierry E. Besançon, S. Culpepper, R. Nurse, H. Hatterman-Valenti, Elizabeth G. Mosqueda, D. Robinson, Matthew A. Cutulle, R. Sandhu
Abstract Herbicide resistance has been studied extensively in agronomic crops across North America but is rarely examined in vegetables. It is widely assumed that the limited number of registered herbicides combined with the adoption of diverse weed management strategies in most vegetable crops effectively inhibits the development of resistance. It is difficult to determine whether resistance is truly less common in vegetable crops or whether the lack of reported cases is due to the lack of resources focused on detection. This review highlights incidences of resistance that are thought to have arisen within vegetable crops. It also includes situations in which herbicide-resistant weeds were likely selected for within agronomic crops but became a problem when vegetables were grown in sequence or in adjacent fields. Occurrence of herbicide resistance can have severe consequences for vegetable growers, and resistance management plans should be adopted to limit selection pressure. This review also highlights resistance management techniques that should slow the development and spread of herbicide resistance in vegetable crops.
{"title":"Occurrence and Management of Herbicide Resistance in Annual Vegetable Production Systems in North America","authors":"N. Boyd, Marcelo L. Moretti, L. Sosnoskie, Vijay Singh, Ramdas G. Kanissery, S. Sharpe, Thierry E. Besançon, S. Culpepper, R. Nurse, H. Hatterman-Valenti, Elizabeth G. Mosqueda, D. Robinson, Matthew A. Cutulle, R. Sandhu","doi":"10.1017/wsc.2022.43","DOIUrl":"https://doi.org/10.1017/wsc.2022.43","url":null,"abstract":"Abstract Herbicide resistance has been studied extensively in agronomic crops across North America but is rarely examined in vegetables. It is widely assumed that the limited number of registered herbicides combined with the adoption of diverse weed management strategies in most vegetable crops effectively inhibits the development of resistance. It is difficult to determine whether resistance is truly less common in vegetable crops or whether the lack of reported cases is due to the lack of resources focused on detection. This review highlights incidences of resistance that are thought to have arisen within vegetable crops. It also includes situations in which herbicide-resistant weeds were likely selected for within agronomic crops but became a problem when vegetables were grown in sequence or in adjacent fields. Occurrence of herbicide resistance can have severe consequences for vegetable growers, and resistance management plans should be adopted to limit selection pressure. This review also highlights resistance management techniques that should slow the development and spread of herbicide resistance in vegetable crops.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"515 - 528"},"PeriodicalIF":2.5,"publicationDate":"2022-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41608686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Hydrilla [Hydrilla verticillata (L. f.) Royle] is often called the “perfect aquatic weed,” as it has numerous physiological adaptations that make it highly aggressive and competitive. Hydrilla verticillata has historically been managed effectively using fluridone; however, the overreliance on this single mechanism of action (MOA) resulted in evolved fluridone resistance in the late 1990s. Where fluridone-resistant H. verticillata populations evolved, endothall became widely used for H. verticillata control. In 2018, florpyrauxifen-benzyl, a highly active auxin-mimic herbicide, was registered for H. verticillata control, and its use has increased since its introduction. Endothall and florpyrauxifen-benzyl provide two effective MOAs for H. verticillata management, and combining these two MOAs would be an effective strategy to delay further resistance evolution. The objective of this research was to determine whether combining endothall and florpyrauxifen-benzyl would significantly impact the behavior of either herbicide in dioecious (DHV) or monoecious (MHV) H. verticillata compared with their behavior when applied alone. Endothall and florpyrauxifen-benzyl absorption and accumulation alone and in combination were measured over a 192-h time course. Translocation patterns were also determined. Herbicide accumulation in MHV and DHV was not impacted when these herbicides were applied in combination. Endothall translocation from shoots to roots in DHV was not impacted (alone = 18.7 ± 1.4%; combination = 23.2 ± 2.2%); however, endothall shoot-to-root translocation in MHV was reduced from 16.2 ± 1.3% applied alone to 2.2 ± 0.1% when applied in combination with florpyrauxifen-benzyl. Florpyrauxifen-benzyl shoot-to-root translocation was reduced in both MHV and DHV when applied in combination with endothall. Florpyrauxifen-benzyl translocation was reduced by 16- and 6-fold in DHV and MHV, respectively. These data do not suggest that there would be operational impacts from endothall and florpyrauxifen-benzyl mixtures. Still, there appear to be changes in herbicide behavior, primarily shoot-to-root translocation, when these two herbicides are applied in combination.
{"title":"Endothall and Florpyrauxifen-benzyl Behavior in Hydrilla (Hydrilla verticillata) When Applied in Combination","authors":"M. Ortiz, S. Nissen, F. Dayan","doi":"10.1017/wsc.2022.39","DOIUrl":"https://doi.org/10.1017/wsc.2022.39","url":null,"abstract":"Abstract Hydrilla [Hydrilla verticillata (L. f.) Royle] is often called the “perfect aquatic weed,” as it has numerous physiological adaptations that make it highly aggressive and competitive. Hydrilla verticillata has historically been managed effectively using fluridone; however, the overreliance on this single mechanism of action (MOA) resulted in evolved fluridone resistance in the late 1990s. Where fluridone-resistant H. verticillata populations evolved, endothall became widely used for H. verticillata control. In 2018, florpyrauxifen-benzyl, a highly active auxin-mimic herbicide, was registered for H. verticillata control, and its use has increased since its introduction. Endothall and florpyrauxifen-benzyl provide two effective MOAs for H. verticillata management, and combining these two MOAs would be an effective strategy to delay further resistance evolution. The objective of this research was to determine whether combining endothall and florpyrauxifen-benzyl would significantly impact the behavior of either herbicide in dioecious (DHV) or monoecious (MHV) H. verticillata compared with their behavior when applied alone. Endothall and florpyrauxifen-benzyl absorption and accumulation alone and in combination were measured over a 192-h time course. Translocation patterns were also determined. Herbicide accumulation in MHV and DHV was not impacted when these herbicides were applied in combination. Endothall translocation from shoots to roots in DHV was not impacted (alone = 18.7 ± 1.4%; combination = 23.2 ± 2.2%); however, endothall shoot-to-root translocation in MHV was reduced from 16.2 ± 1.3% applied alone to 2.2 ± 0.1% when applied in combination with florpyrauxifen-benzyl. Florpyrauxifen-benzyl shoot-to-root translocation was reduced in both MHV and DHV when applied in combination with endothall. Florpyrauxifen-benzyl translocation was reduced by 16- and 6-fold in DHV and MHV, respectively. These data do not suggest that there would be operational impacts from endothall and florpyrauxifen-benzyl mixtures. Still, there appear to be changes in herbicide behavior, primarily shoot-to-root translocation, when these two herbicides are applied in combination.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"537 - 542"},"PeriodicalIF":2.5,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48050625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Busi, Bowen Zhang, Danica E. Goggin, G. Bryant, H. Beckie
Abstract The control of multiple-resistant wild radish (Raphanus raphanistrum L.) populations in no-till Australian wheat (Triticum aestivum L.) crops has relied upon 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides over the last decade. Two R. raphanistrum populations identified as putatively resistant to pyrasulfotole + bromoxynil in an initial large-scale screening trial were characterized and confirmed to be 5- to 8-fold (comparison of LD50 values) less sensitive than the susceptible control population to the HPPD inhibitor pyrasulfotole when plants were treated at the 4-leaf stage. The two pyrasulfotole-resistant populations exhibited up to 4-fold resistance to the coformulated herbicide mixture pyrasulfotole + bromoxynil and up to 9- and 11-fold cross-resistance to mesotrione and topramezone postemergence, respectively. A small-plot trial was conducted in the field from which of one of the populations suspected of resistance was originally collected. Pyrasulfotole + bromoxynil or topramezone + bromoxynil applied postemergence delivered reduced R. raphanistrum control (79% to 87%), whereas mesotrione applied preemergence was >99% effective. We report here the first case of field resistance to HPPD-inhibiting herbicides in R. raphanistrum, caused by 12 yr of continuous reliance on that mode of action. The mitigation of herbicide resistance in continuous no-till cropping requires a constant optimization of the herbicide technology via alternation and mixtures of multiple sites of action, use of preemergence herbicides, and ensuring postemergence herbicides are applied at the most sensitive plant growth stages.
{"title":"Identification of Field Resistance to HPPD-Inhibiting Herbicides in Wild Radish (Raphanus raphanistrum)","authors":"R. Busi, Bowen Zhang, Danica E. Goggin, G. Bryant, H. Beckie","doi":"10.1017/wsc.2022.42","DOIUrl":"https://doi.org/10.1017/wsc.2022.42","url":null,"abstract":"Abstract The control of multiple-resistant wild radish (Raphanus raphanistrum L.) populations in no-till Australian wheat (Triticum aestivum L.) crops has relied upon 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides over the last decade. Two R. raphanistrum populations identified as putatively resistant to pyrasulfotole + bromoxynil in an initial large-scale screening trial were characterized and confirmed to be 5- to 8-fold (comparison of LD50 values) less sensitive than the susceptible control population to the HPPD inhibitor pyrasulfotole when plants were treated at the 4-leaf stage. The two pyrasulfotole-resistant populations exhibited up to 4-fold resistance to the coformulated herbicide mixture pyrasulfotole + bromoxynil and up to 9- and 11-fold cross-resistance to mesotrione and topramezone postemergence, respectively. A small-plot trial was conducted in the field from which of one of the populations suspected of resistance was originally collected. Pyrasulfotole + bromoxynil or topramezone + bromoxynil applied postemergence delivered reduced R. raphanistrum control (79% to 87%), whereas mesotrione applied preemergence was >99% effective. We report here the first case of field resistance to HPPD-inhibiting herbicides in R. raphanistrum, caused by 12 yr of continuous reliance on that mode of action. The mitigation of herbicide resistance in continuous no-till cropping requires a constant optimization of the herbicide technology via alternation and mixtures of multiple sites of action, use of preemergence herbicides, and ensuring postemergence herbicides are applied at the most sensitive plant growth stages.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"529 - 536"},"PeriodicalIF":2.5,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48588679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. H. Oreja, M. Inman, D. Jordan, M. Vann, Katherine M. Jennings, R. León
Abstract The adoption of dicamba-resistant cotton (Gossypium hirsutum L.) cultivars allows using dicamba to reduce weed populations across growing seasons. However, the overuse of this tool risks selecting new herbicide-resistant biotypes. The objectives of this research were to determine the population trajectories of several weed species and track the frequency of glyphosate-resistant (GR) Palmer amaranth (Amaranthus palmeri S. Watson) over 8 yr in dicamba-resistant cotton. An experiment was established in North Carolina in 2011, and during the first 4 yr, different herbicide programs were applied. These programs included postemergence applications of glyphosate, alone or with dicamba, with or without residual herbicides. During the last 4 yr, all programs received glyphosate plus dicamba. Biennial rotations of postemergence applications of glyphosate only and glyphosate plus dicamba postemergence with and without preemergence herbicides were also included. Sequential applications of glyphosate plus dicamba were applied to the entire test area for the final 4 yr of the study. No herbicide program was entirely successful in controlling the weed community. Weed population trajectories were different according to species and herbicide program, creating all possible outcomes; some increased, others decreased, and others remained stable. Density of resistant A. palmeri increased during the first 4 yr with glyphosate-only programs (up to 11,739 plants m–2) and decreased a 96% during the final 4 yr, when glyphosate plus dicamba was implemented. This species had a strong influence on population levels of other weed species in the community. Goosegrass [Eleusine indica (L.) Gaertn.] was not affected by A. palmeri population levels and even increased its density in some herbicide programs, indicating that not only herbicide resistance but also reproductive rates and competitive dynamics are critical for determining weed population trajectories under intensive herbicide-based control programs. Frequency of glyphosate resistance reached a maximum of 62% after 4 yr, and those levels were maintained until the end of the experiment.
{"title":"Effect of Cotton Herbicide Programs on Weed Population Trajectories and Frequency of Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri)","authors":"F. H. Oreja, M. Inman, D. Jordan, M. Vann, Katherine M. Jennings, R. León","doi":"10.1017/wsc.2022.41","DOIUrl":"https://doi.org/10.1017/wsc.2022.41","url":null,"abstract":"Abstract The adoption of dicamba-resistant cotton (Gossypium hirsutum L.) cultivars allows using dicamba to reduce weed populations across growing seasons. However, the overuse of this tool risks selecting new herbicide-resistant biotypes. The objectives of this research were to determine the population trajectories of several weed species and track the frequency of glyphosate-resistant (GR) Palmer amaranth (Amaranthus palmeri S. Watson) over 8 yr in dicamba-resistant cotton. An experiment was established in North Carolina in 2011, and during the first 4 yr, different herbicide programs were applied. These programs included postemergence applications of glyphosate, alone or with dicamba, with or without residual herbicides. During the last 4 yr, all programs received glyphosate plus dicamba. Biennial rotations of postemergence applications of glyphosate only and glyphosate plus dicamba postemergence with and without preemergence herbicides were also included. Sequential applications of glyphosate plus dicamba were applied to the entire test area for the final 4 yr of the study. No herbicide program was entirely successful in controlling the weed community. Weed population trajectories were different according to species and herbicide program, creating all possible outcomes; some increased, others decreased, and others remained stable. Density of resistant A. palmeri increased during the first 4 yr with glyphosate-only programs (up to 11,739 plants m–2) and decreased a 96% during the final 4 yr, when glyphosate plus dicamba was implemented. This species had a strong influence on population levels of other weed species in the community. Goosegrass [Eleusine indica (L.) Gaertn.] was not affected by A. palmeri population levels and even increased its density in some herbicide programs, indicating that not only herbicide resistance but also reproductive rates and competitive dynamics are critical for determining weed population trajectories under intensive herbicide-based control programs. Frequency of glyphosate resistance reached a maximum of 62% after 4 yr, and those levels were maintained until the end of the experiment.","PeriodicalId":23688,"journal":{"name":"Weed Science","volume":"70 1","pages":"587 - 594"},"PeriodicalIF":2.5,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42849461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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