Jose C.L.S. Dias, Temnotfo L. Mncube, Brent A. Sellers, Jason A. Ferrell, Stephen F. Enloe, Joao M.B. Vendramini, Philipe Moriel
Sporobolus indicus (L.) R. Br. var. pyramidalis (P. Beauv.) Veldkamp is an invasive species in grasslands, and herbicide application has been the most efficient management method to suppress this weed. Experiments were conducted to determine the effects of wiping glyphosate and hexazinone on S. indicus var. pyramidalis in 2017 and 2018. A dose-response experiment using a hand-held weed wiper was established with twenty treatments comprising two herbicides (glyphosate and hexazinone), uni- and bi-directional wiping methods, and five herbicide concentrations (6.25, 12.5, 25.0, 50.0 and 100% v/v basis). Data were collected 30 and 60 days after treatment (DAT). An ATV-mounted roto-type weed wiper experiment was established in a strip plot arrangement with mowing as the horizontal strip, the wiping method (uni-directional vs bi-directional) randomized as the vertical strip with three dosages of each herbicide for a total of 12 wiping treatments. Data were collected 35 and 90 DAT. The percent plant mortality was calculated using differences in pre- and post-treatment plant counts. Analysis of variance (ANOVA) and log-logistic linear regression were used to analyze the data. The dose-response experiment showed that S. indicus var. pyramidalis mortality increased with herbicide concentration and mortality was greater with the bi-directional wiping method compared to the uni-directional method. Treatments wiped bi-directionally with glyphosate at 70% v/v, hexazinone at 30% v/v and hexazinone at 60% v/v, resulted in S. indicus var. pyramidalis mortality ranging from 75 to 98% by 90 DAT across all locations. The ATV-mounted weed-wiper experiment showed that mowing prior to herbicide application with weed-wipers decreased the efficacy of both herbicides. Overall, both experiments indicate that S. indicus var. pyramidalis should be wiped bi-directionally using either glyphosate (70% v/v) or hexazinone (at least 30% v/v) to obtain satisfactory control. Further work should be conducted to determine if seasonality impacts the response of S. indicus var. pyramidalis to mowing and the application of these herbicides.
Sporobolus indicus (L.) R. Br. var. pyramidalis (P. Beauv.) Veldkamp是草原上的一种入侵物种，施用除草剂是抑制这种杂草最有效的管理方法。2017 年和 2018 年进行了实验，以确定擦草甘膦和己烯雌酚对 S. indicus var. pyramidalis 的影响。使用手持式杂草擦拭器进行了剂量-反应实验，共设 20 个处理，包括两种除草剂（草甘膦和己唑醇）、单向和双向擦拭方法以及五种除草剂浓度（6.25、12.5、25.0、50.0 和 100% v/v 基）。数据分别在处理后 30 天和 60 天收集。在条状小区中进行了全地形车（ATV）安装的旋转式除草机试验，以除草为横向条带，擦拭方法（单向与双向）随机为纵向条带，每种除草剂使用三种剂量，共进行了 12 次擦拭处理。数据收集日期分别为 35 天和 90 天。利用处理前后植物数量的差异计算植物死亡率。采用方差分析和对数线性回归分析数据。剂量反应实验表明，S. indicus var. pyramidalis 的死亡率随除草剂浓度的增加而增加，与单向抹杀法相比，双向抹杀法的死亡率更高。使用草甘膦（浓度为 70% v/v）、己唑醇（浓度为 30% v/v）和己唑醇（浓度为 60% v/v）进行双向擦拭处理，到 90 日龄时，所有地点的 S. indicus var. pyramidalis 死亡率在 75% 到 98% 之间。全地形车载除草机实验表明，在使用除草机施用除草剂之前进行除草会降低两种除草剂的药效。总之，这两项实验表明，要获得令人满意的控制效果，应使用草甘膦（70% v/v）或己唑醇（至少 30% v/v）双向除草。应开展进一步的工作，以确定季节性是否会影响金字塔草（S. indicus var. pyramidalis）对除草和施用这些除草剂的反应。
{"title":"Effectiveness of integrating mowing and systemic herbicides applied with a weed wiper for Sporobolus indicus var. pyramidalis management in Florida","authors":"Jose C.L.S. Dias, Temnotfo L. Mncube, Brent A. Sellers, Jason A. Ferrell, Stephen F. Enloe, Joao M.B. Vendramini, Philipe Moriel","doi":"10.1017/inp.2024.16","DOIUrl":"https://doi.org/10.1017/inp.2024.16","url":null,"abstract":"<jats:italic>Sporobolus indicus</jats:italic> (L.) R. Br. var. <jats:italic>pyramidalis</jats:italic> (P. Beauv.) Veldkamp is an invasive species in grasslands, and herbicide application has been the most efficient management method to suppress this weed. Experiments were conducted to determine the effects of wiping glyphosate and hexazinone on <jats:italic>S. indicus</jats:italic> var. <jats:italic>pyramidalis</jats:italic> in 2017 and 2018. A dose-response experiment using a hand-held weed wiper was established with twenty treatments comprising two herbicides (glyphosate and hexazinone), uni- and bi-directional wiping methods, and five herbicide concentrations (6.25, 12.5, 25.0, 50.0 and 100% v/v basis). Data were collected 30 and 60 days after treatment (DAT). An ATV-mounted roto-type weed wiper experiment was established in a strip plot arrangement with mowing as the horizontal strip, the wiping method (uni-directional vs bi-directional) randomized as the vertical strip with three dosages of each herbicide for a total of 12 wiping treatments. Data were collected 35 and 90 DAT. The percent plant mortality was calculated using differences in pre- and post-treatment plant counts. Analysis of variance (ANOVA) and log-logistic linear regression were used to analyze the data. The dose-response experiment showed that <jats:italic>S. indicus</jats:italic> var. <jats:italic>pyramidalis</jats:italic> mortality increased with herbicide concentration and mortality was greater with the bi-directional wiping method compared to the uni-directional method. Treatments wiped bi-directionally with glyphosate at 70% v/v, hexazinone at 30% v/v and hexazinone at 60% v/v, resulted in <jats:italic>S. indicus</jats:italic> var. <jats:italic>pyramidalis</jats:italic> mortality ranging from 75 to 98% by 90 DAT across all locations. The ATV-mounted weed-wiper experiment showed that mowing prior to herbicide application with weed-wipers decreased the efficacy of both herbicides. Overall, both experiments indicate that <jats:italic>S. indicus</jats:italic> var. <jats:italic>pyramidalis</jats:italic> should be wiped bi-directionally using either glyphosate (70% v/v) or hexazinone (at least 30% v/v) to obtain satisfactory control. Further work should be conducted to determine if seasonality impacts the response of <jats:italic>S. indicus</jats:italic> var. <jats:italic>pyramidalis</jats:italic> to mowing and the application of these herbicides.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"43 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141191521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Florencia Spalazzi, Tomás Milani, Cecilia I. Nuñez, Martin A. Nuñez, François P. Teste
Invasion by nonnative woody species poses a major threat to the environment, biodiversity, and economies worldwide. Nahuel Huapi National Park in Argentina is a protected area for habitat conservation that harbors several invasive Pinaceae species, where Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] is one of the most aggressive and abundant conifer tree invaders. Management of invasions in protected areas must include efficient, easy to deploy, and cost-effective techniques, while reducing the impact on native ecosystems. Because the region has no control measures applied other than conventional felling, we analyzed the effectiveness of two systemic herbicides (glyphosate and aminopyralid + triclopyr) at two different concentrations, applied with the drill and fill method. We then quantified defoliation of P. menziesii trees after 6, 12, and 24 mo after application and performed an economic cost analysis to determine profitability. For the application, the trees were grouped into diameter at breast height classes and randomly assigned to one of the four treatments. Herbicide doses were adjusted according to tree size. We found that glyphosate at high concentrations completely defoliated 33% of the trees after 6 mo and 87% after 12 and 24 mo. Glyphosate at low concentrations defoliated almost 30% of the trees after 24 mo, most of which were smaller trees. The aminopyralid + triclopyr treatment did not produce significant defoliation at any of the tested concentrations. When compared with conventional felling, the drill and fill method was found to reduce removal costs by 98%. We observe that differences in costs are mainly due to dead trees that remain standing, decompose slowly, and do not generate costs associated with their removal and debris management. Drill and fill is a suitable method for treating scattered trees in a native forest community, with reduced environmental consequences compared with other removal techniques currently applied within conservation areas of the Patagonian forest.
{"title":"Injection-based approaches for controlling Douglas-fir (Pseudotsuga menziesii) invasion in conservation efforts of the Patagonian forest","authors":"M. Florencia Spalazzi, Tomás Milani, Cecilia I. Nuñez, Martin A. Nuñez, François P. Teste","doi":"10.1017/inp.2024.11","DOIUrl":"https://doi.org/10.1017/inp.2024.11","url":null,"abstract":"Invasion by nonnative woody species poses a major threat to the environment, biodiversity, and economies worldwide. Nahuel Huapi National Park in Argentina is a protected area for habitat conservation that harbors several invasive <jats:italic>Pinaceae</jats:italic> species, where Douglas-fir [<jats:italic>Pseudotsuga menziesii</jats:italic> (Mirb.) Franco] is one of the most aggressive and abundant conifer tree invaders. Management of invasions in protected areas must include efficient, easy to deploy, and cost-effective techniques, while reducing the impact on native ecosystems. Because the region has no control measures applied other than conventional felling, we analyzed the effectiveness of two systemic herbicides (glyphosate and aminopyralid + triclopyr) at two different concentrations, applied with the drill and fill method. We then quantified defoliation of <jats:italic>P. menziesii</jats:italic> trees after 6, 12, and 24 mo after application and performed an economic cost analysis to determine profitability. For the application, the trees were grouped into diameter at breast height classes and randomly assigned to one of the four treatments. Herbicide doses were adjusted according to tree size. We found that glyphosate at high concentrations completely defoliated 33% of the trees after 6 mo and 87% after 12 and 24 mo. Glyphosate at low concentrations defoliated almost 30% of the trees after 24 mo, most of which were smaller trees. The aminopyralid + triclopyr treatment did not produce significant defoliation at any of the tested concentrations. When compared with conventional felling, the drill and fill method was found to reduce removal costs by 98%. We observe that differences in costs are mainly due to dead trees that remain standing, decompose slowly, and do not generate costs associated with their removal and debris management. Drill and fill is a suitable method for treating scattered trees in a native forest community, with reduced environmental consequences compared with other removal techniques currently applied within conservation areas of the Patagonian forest.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"21 1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141169526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Emmett H. U. Snyder, Ian M. Jones, Melanie A. Sifton, Carla Timm, Courtney Stevens, Robert S. Bourchier, Sandy M. Smith
Invasive plants can gain a foothold in new environments by manipulating soil conditions through allelopathy or through the disruption of associations between native plants and their mycorrhizal associates. The resulting changes in soil conditions can affect the recovery of habitats long after the invasive plant has been removed. We conducted a series of greenhouse experiments to examine the effects of soil conditioned by pale swallow-wort [Vincetoxicum rossicum (Kleopow) Barbarich; Apocynaceae], on the growth of native plants. Additionally, we tested the effects of aqueous extracts of common milkweed (Asclepias syriaca L.; Apocynaceae), a related plant with known allelopathic effects, on the regrowth of V. rossicum from transplanted root crowns. Soil from a 15-yr-old V. rossicum infestation reduced seedling emergence in A. syriaca as well as in V. rossicum itself. Conversely, the same soil had no effect on the growth of mature A. syriaca plants. Soil conditioned by V. rossicum growth in the greenhouse had no effect on the biomass and percentage cover generated by two restoration seed mixes. Soil conditioned by A. syriaca, however, yielded lower biomass and percentage cover from both seed mixes. In contrast to the allelopathic effects of A. syriaca on seedlings, aqueous extracts of A. syriaca increased aboveground plant growth in V. rossicum. Our results suggest that the effects of V. rossicum–conditioned soil on native plants are concentrated at the seedling establishment phase. Additionally, the use of diverse native seed mixes shows great potential for restoring productivity to ecosystems affected by V. rossicum.
入侵植物可以通过等位效应或通过破坏本地植物与其菌根伙伴之间的联系来操纵土壤条件，从而在新环境中站稳脚跟。由此导致的土壤条件变化会在入侵植物被移除后很长时间内影响栖息地的恢复。我们进行了一系列温室实验，以研究苍燕草[Vincetoxicum rossicum (Kleopow) Barbarich; Apocynaceae]调节土壤条件对本地植物生长的影响。此外，我们还测试了普通乳草（Asclepias syriaca L.; Apocynaceae）的水提取物（一种已知具有等位异化作用的相关植物）对从移植根冠中重新生长的燕麦草的影响。15 年的 V. rossicum 侵染土壤降低了 A. syriaca 和 V. rossicum 本身的出苗率。相反，同样的土壤对成熟的 A. syriaca 植物的生长没有影响。在温室中生长的 V. rossicum 所调节的土壤对两种恢复性混合种子产生的生物量和覆盖率没有影响。然而，经 A. syriaca 改良过的土壤对两种混合种子产生的生物量和覆盖率都较低。与 A. syriaca 对幼苗的等位影响相反，A. syriaca 的水提取物却能增加 V. rossicum 的地上部植物生长。我们的研究结果表明，V. rossicum 调理土壤对本地植物的影响集中在幼苗生长阶段。此外，使用多样化的本地混合种子显示出恢复受 V. rossicum 影响的生态系统生产力的巨大潜力。
{"title":"Excising the ghosts of invasions past: restoring native vegetation to soil infested with invasive swallow-worts","authors":"Emmett H. U. Snyder, Ian M. Jones, Melanie A. Sifton, Carla Timm, Courtney Stevens, Robert S. Bourchier, Sandy M. Smith","doi":"10.1017/inp.2024.7","DOIUrl":"https://doi.org/10.1017/inp.2024.7","url":null,"abstract":"Invasive plants can gain a foothold in new environments by manipulating soil conditions through allelopathy or through the disruption of associations between native plants and their mycorrhizal associates. The resulting changes in soil conditions can affect the recovery of habitats long after the invasive plant has been removed. We conducted a series of greenhouse experiments to examine the effects of soil conditioned by pale swallow-wort [<jats:italic>Vincetoxicum rossicum</jats:italic> (Kleopow) Barbarich; Apocynaceae], on the growth of native plants. Additionally, we tested the effects of aqueous extracts of common milkweed (<jats:italic>Asclepias syriaca</jats:italic> L.; Apocynaceae), a related plant with known allelopathic effects, on the regrowth of <jats:italic>V. rossicum</jats:italic> from transplanted root crowns. Soil from a 15-yr-old <jats:italic>V. rossicum</jats:italic> infestation reduced seedling emergence in <jats:italic>A. syriaca</jats:italic> as well as in <jats:italic>V. rossicum</jats:italic> itself. Conversely, the same soil had no effect on the growth of mature <jats:italic>A. syriaca</jats:italic> plants. Soil conditioned by <jats:italic>V. rossicum</jats:italic> growth in the greenhouse had no effect on the biomass and percentage cover generated by two restoration seed mixes. Soil conditioned by <jats:italic>A. syriaca</jats:italic>, however, yielded lower biomass and percentage cover from both seed mixes. In contrast to the allelopathic effects of <jats:italic>A. syriaca</jats:italic> on seedlings, aqueous extracts of <jats:italic>A. syriaca</jats:italic> increased aboveground plant growth in <jats:italic>V. rossicum</jats:italic>. Our results suggest that the effects of <jats:italic>V. rossicum</jats:italic>–conditioned soil on native plants are concentrated at the seedling establishment phase. Additionally, the use of diverse native seed mixes shows great potential for restoring productivity to ecosystems affected by <jats:italic>V. rossicum</jats:italic>.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"28 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dale A. Halbritter, Min B. Rayamajhi, Paul Madeira, Jorge G. Leidi, Telmah Telmadarrehei, Carey Minteer
Stem galls and witch’s broom–like growths are locally abundant on the highly invasive Brazilian peppertree (Schinus terebinthifolia) at field sites in southern Florida where a thrips biological control agent (Pseudophilothrips ichini) is being released to reduce the invasive potential of the plant. Galls have also been observed on potted plants in nursery stock grown to feed laboratory colonies of the agent. Herein, our objective was to isolate and identify the causal agent of the galls and assess its ability to induce galls in naive plants. We obtained stem galls from both field- and nursery-grown plants, aseptically isolated a fungus in acidic potato dextrose agar, and purified fungal colonies. Stems of potted naive saplings were wound-inoculated with purified hyphal fragments from the purified colonies, which readily induced galls like those observed in the field and nursery. Simultaneous molecular analysis of the fungal DNA obtained from the galls of field and nursery plants, experimentally induced galls, and fungal colony isolates identified this gall-inducing fungus as Cophinforma sp. We demonstrated that this Cophinforma sp. can infect S. terebinthifolia stems via mechanical wounds and induce visibly discernible stem galls in saplings within 3 mo. This will serve as a model for galled plant production for assessing the impacts of the gall-inducing fungus on S. terebinthifolia, with potential for further study to investigate interactions between the thrips and this naturalized fungus, which may synergistically and/or additively enhance S. terebinthifolia management efficacy.
在佛罗里达州南部的田间地头，高度入侵的巴西胡椒树（Schinus terebinthifolia）上出现了大量的茎瘿和类似金缕梅的生长，当地正在释放一种蓟马生物控制剂（Pseudophilothrips ichini），以降低该植物的入侵潜力。在苗圃中种植的盆栽植物上也观察到了瘿。在此，我们的目标是分离和鉴定虫瘿的病原体，并评估其诱导幼稚植物产生虫瘿的能力。我们从田间和苗圃种植的植物中获得了茎瘿，在酸性马铃薯葡萄糖琼脂中无菌分离出真菌，并纯化了真菌菌落。将纯化菌落中的纯化菌丝片段伤口接种到盆栽天真树苗的茎上，很容易诱发与田间和苗圃中观察到的相同的虫瘿。我们证明这种 Cophinforma sp. 可以通过机械伤口感染 S. terebinthifolia 的茎，并在 3 个月内诱发树苗出现明显的茎瘿。这将作为产生虫瘿植物的模型，用于评估诱导虫瘿的真菌对 S. terebinthifolia 的影响，并有可能进一步研究蓟马与这种归化真菌之间的相互作用，这可能会协同和/或增加 S. terebinthifolia 的管理效率。
{"title":"Isolation and reinoculation of a gall-inducing fungus in the invasive Brazilian peppertree (Schinus terebinthifolia) in Florida","authors":"Dale A. Halbritter, Min B. Rayamajhi, Paul Madeira, Jorge G. Leidi, Telmah Telmadarrehei, Carey Minteer","doi":"10.1017/inp.2024.3","DOIUrl":"https://doi.org/10.1017/inp.2024.3","url":null,"abstract":"Stem galls and witch’s broom–like growths are locally abundant on the highly invasive Brazilian peppertree (<jats:italic>Schinus terebinthifolia</jats:italic>) at field sites in southern Florida where a thrips biological control agent (<jats:italic>Pseudophilothrips ichini</jats:italic>) is being released to reduce the invasive potential of the plant. Galls have also been observed on potted plants in nursery stock grown to feed laboratory colonies of the agent. Herein, our objective was to isolate and identify the causal agent of the galls and assess its ability to induce galls in naive plants. We obtained stem galls from both field- and nursery-grown plants, aseptically isolated a fungus in acidic potato dextrose agar, and purified fungal colonies. Stems of potted naive saplings were wound-inoculated with purified hyphal fragments from the purified colonies, which readily induced galls like those observed in the field and nursery. Simultaneous molecular analysis of the fungal DNA obtained from the galls of field and nursery plants, experimentally induced galls, and fungal colony isolates identified this gall-inducing fungus as <jats:italic>Cophinforma</jats:italic> sp. We demonstrated that this <jats:italic>Cophinforma</jats:italic> sp. can infect <jats:italic>S. terebinthifolia</jats:italic> stems via mechanical wounds and induce visibly discernible stem galls in saplings within 3 mo. This will serve as a model for galled plant production for assessing the impacts of the gall-inducing fungus on <jats:italic>S. terebinthifolia</jats:italic>, with potential for further study to investigate interactions between the thrips and this naturalized fungus, which may synergistically and/or additively enhance <jats:italic>S. terebinthifolia</jats:italic> management efficacy.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"94 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140629754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fireweed (Senecio madagascariensis Poir.) has invaded and colonized numerous habitats in the coastal areas of southeastern Australia and is a major weed in cultivated lands as well as in poorly grassed, neglected, and highly grazed pastures. To examine the seed germination ecology of two populations (Felton and Gatton) of S. madagascariensis, experiments were conducted in the laboratory and screenhouse. The germination of both populations increased as the alternating temperatures increased from the coolest temperatures (15/5 C) to warmer temperatures (25/15 C). However, the highest temperature regime (35/25 C) resulted in the lowest germination rates. The Gatton population exhibited greater tolerance to higher temperatures, resulting in significantly higher germination (2.4 times) than the Felton population at the highest alternating temperature of 35/25 C. Compared to the Felton population, the Gatton population demonstrated higher tolerance to salt and water stress. In comparison to alternating light and dark periods (12 h each) (97-98%), the germination of both populations of S. madagascariensis was significantly reduced under complete darkness (24 h) (33-39%). A screenhouse seed burial depth experiment revealed similar emergence of S. madagascariensis seedlings between the populations. The maximum emergence (60%) was observed for seeds placed at the soil surface, followed by a dramatic decline in seedling emergence with an increase in depth. No seedlings emerged from a burial depth of 4 cm. With the addition of wheat crop residue to the soil surface at rates comparable to 4 to 8 Mg ha-1, seedling emergence of S. madagascariensis decreased significantly. Information acquired from this study could be utilized to manage and develop effective weed management strategies for controlling S. madagascariensis in different agroecological conditions.
{"title":"Unraveling the influence of environmental factors on fireweed (Senecio madagascariensis) germination and its management implications","authors":"Virender Singh Hooda, Bhagirath Singh Chauhan","doi":"10.1017/inp.2024.8","DOIUrl":"https://doi.org/10.1017/inp.2024.8","url":null,"abstract":"Fireweed (<jats:italic>Senecio madagascariensis</jats:italic> Poir.) has invaded and colonized numerous habitats in the coastal areas of southeastern Australia and is a major weed in cultivated lands as well as in poorly grassed, neglected, and highly grazed pastures. To examine the seed germination ecology of two populations (Felton and Gatton) of <jats:italic>S. madagascariensis</jats:italic>, experiments were conducted in the laboratory and screenhouse. The germination of both populations increased as the alternating temperatures increased from the coolest temperatures (15/5 C) to warmer temperatures (25/15 C). However, the highest temperature regime (35/25 C) resulted in the lowest germination rates. The Gatton population exhibited greater tolerance to higher temperatures, resulting in significantly higher germination (2.4 times) than the Felton population at the highest alternating temperature of 35/25 C. Compared to the Felton population, the Gatton population demonstrated higher tolerance to salt and water stress. In comparison to alternating light and dark periods (12 h each) (97-98%), the germination of both populations of <jats:italic>S. madagascariensis</jats:italic> was significantly reduced under complete darkness (24 h) (33-39%). A screenhouse seed burial depth experiment revealed similar emergence of <jats:italic>S. madagascariensis</jats:italic> seedlings between the populations. The maximum emergence (60%) was observed for seeds placed at the soil surface, followed by a dramatic decline in seedling emergence with an increase in depth. No seedlings emerged from a burial depth of 4 cm. With the addition of wheat crop residue to the soil surface at rates comparable to 4 to 8 Mg ha<jats:sup>-1</jats:sup>, seedling emergence of <jats:italic>S. madagascariensis</jats:italic> decreased significantly. Information acquired from this study could be utilized to manage and develop effective weed management strategies for controlling <jats:italic>S. madagascariensis</jats:italic> in different agroecological conditions.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"20 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140154620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lisa C. Jones, Cody Beckley, Corey V. Ransom, Timothy S. Prather
Taeniatherum caput-medusae (L.) Nevski is an invasive winter annual grass of western North American grasslands and rangelands that negatively impacts forage production, wildlife habitat, and ecosystem processes. Growth regulator herbicides, such as aminopyralid, applied in spring reduce invasive annual grass seed viability in greenhouse and California annual grassland experiments. Beginning in fall 2017, we tested combinations of sequential fall (preemergence, PRE) and spring (postemergence, POST) aminopyralid applications at low (103 g ae ha-1) and high (206 g ae ha-1) rates at two ecologically distinct sites in the Intermountain West. PRE and POST aminopyralid applications at low and high rates controlled T. caput-medusae by 76-100% the second summer after study initiation. At the Utah site (which is warmer, drier, and more degraded than the Idaho site), the high rate resulted in better control. The first summer, POST aminopyralid applications at low and high rates reduced seed viability 47-91% compared to nontreated seeds, with the greatest reductions seen in Utah, which was experiencing drought. Across study sites, reduced T. caput-medusae germination in one year was linked to improved control the following year. The Idaho site also had desirable perennial grasses on which we investigated non-target effects. In general, there was a correlation between high T. caput-medusae control and higher perennial grass cover, indicating that successful control can make desirable perennial grasses more vigorous in this system. The option of a spring aminopyralid application increases the management window for controlling invasive annual grasses by decreasing seed viability, thereby depleting short-lived seed banks.
Taeniatherum caput-medusae (L.) Nevski 是一种入侵北美西部草地和牧场的冬季一年生草，对饲草生产、野生动物栖息地和生态系统过程有负面影响。在温室和加利福尼亚一年生草地实验中，春季施用的生长调节剂除草剂（如氨吡啉酸）可降低入侵的一年生草种子活力。从 2017 年秋季开始，我们在山间西部两个生态不同的地点测试了秋季（出苗前，PRE）和春季（出苗后，POST）按顺序施用氨吡菌酰胺的组合，施用量分别为低（103 g ae ha-1）和高（206 g ae ha-1）。在研究开始后的第二个夏天，低剂量和高剂量的氨吡菌酰胺在施用前和施用后可控制褐飞虱76%-100%。在犹他州的研究地点（与爱达荷州的研究地点相比，犹他州的气候更温暖、更干燥、退化程度更高），高用药量的控制效果更好。第一个夏天，在低施用量和高施用量下施用氨吡菌酰胺后，种子活力比未施用氨吡菌酰胺的种子降低了 47-91% ，其中犹他州的种子活力降低幅度最大，因为犹他州当时正经历干旱。在所有研究地点，头状花序蓟马发芽率的降低与第二年防治效果的改善有关。爱达荷州的研究地点还种植了理想的多年生草本植物，我们对这些草本植物的非目标效应进行了调查。总的来说，T. caput-medusae 的高控制率与较高的多年生草覆盖率之间存在相关性，这表明成功的控制可以使该系统中理想的多年生草更有活力。春季施用氨吡菌酰胺可降低种子活力，从而消耗短寿命种子库，从而增加控制入侵一年生禾本科植物的管理窗口期。
{"title":"Fall or spring aminopyralid applications control Taeniatherum caput-medusae","authors":"Lisa C. Jones, Cody Beckley, Corey V. Ransom, Timothy S. Prather","doi":"10.1017/inp.2024.6","DOIUrl":"https://doi.org/10.1017/inp.2024.6","url":null,"abstract":"<jats:italic>Taeniatherum caput-medusae</jats:italic> (L.) Nevski is an invasive winter annual grass of western North American grasslands and rangelands that negatively impacts forage production, wildlife habitat, and ecosystem processes. Growth regulator herbicides, such as aminopyralid, applied in spring reduce invasive annual grass seed viability in greenhouse and California annual grassland experiments. Beginning in fall 2017, we tested combinations of sequential fall (preemergence, PRE) and spring (postemergence, POST) aminopyralid applications at low (103 g ae ha<jats:sup>-1</jats:sup>) and high (206 g ae ha<jats:sup>-1</jats:sup>) rates at two ecologically distinct sites in the Intermountain West. PRE and POST aminopyralid applications at low and high rates controlled <jats:italic>T. caput-medusae</jats:italic> by 76-100% the second summer after study initiation. At the Utah site (which is warmer, drier, and more degraded than the Idaho site), the high rate resulted in better control. The first summer, POST aminopyralid applications at low and high rates reduced seed viability 47-91% compared to nontreated seeds, with the greatest reductions seen in Utah, which was experiencing drought. Across study sites, reduced <jats:italic>T. caput-medusae</jats:italic> germination in one year was linked to improved control the following year. The Idaho site also had desirable perennial grasses on which we investigated non-target effects. In general, there was a correlation between high <jats:italic>T. caput-medusae</jats:italic> control and higher perennial grass cover, indicating that successful control can make desirable perennial grasses more vigorous in this system. The option of a spring aminopyralid application increases the management window for controlling invasive annual grasses by decreasing seed viability, thereby depleting short-lived seed banks.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"5 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three species of the Old World genus Dipsacus L. are considered invasive in the Americas, yet they may differ in how they spread, reproduce, and in genetic diversity. Differences in invasion method may suggest that different management techniques are needed for each species. We performed genetic analyses on 572 plants in 69 populations from the USA, Argentina, and Eurasia with the goals of analyzing taxonomy, diversity, mode of reproduction, population structure and founder effect of each of these species’ invasions, as well as looking for evidence of recent or ongoing hybridization. We found D. sativus to be lowest in diversity and possibly relying on self-pollination more than the other species, D. fullonum and D. laciniatus. We found no evidence of hybridization within the invasions and no support for D. sativus as a subspecies of D. fullonum. The closest genetic matches of D. fullonum from USA to the native range were with Hungary and Spain, while the closest match for D. fullonum between Argentina and the native range was with Spain. Dipsacus laciniatus from the USA most closely matched with samples from Russia. Population structure information regarding these three weedy Dipsacus species can help us understand their invasive processes as well as give insight into their management and the development of a biological control program.
旧大陆 Dipsacus L.属的三个物种被认为是美洲的入侵物种，但它们在传播、繁殖和遗传多样性方面可能有所不同。入侵方式的不同可能表明每个物种需要不同的管理技术。我们对来自美国、阿根廷和欧亚大陆的 69 个种群中的 572 株植物进行了遗传分析，目的是分析这些物种入侵的分类、多样性、繁殖方式、种群结构和始祖效应，并寻找最近或正在进行的杂交的证据。我们发现 D. sativus 的多样性最低，可能比其他物种 D. fullonum 和 D. laciniatus 更依赖自花授粉。我们没有发现入侵物种内部杂交的证据，也不支持 D. sativus 作为 D. fullonum 的一个亚种。从美国到原产地的 D. fullonum 与匈牙利和西班牙的基因匹配最接近，而从阿根廷到原产地的 D. fullonum 与西班牙的基因匹配最接近。美国的 Dipsacus laciniatus 与俄罗斯的样本匹配度最高。有关这三种杂草 Dipsacus 的种群结构信息可以帮助我们了解它们的入侵过程，并为它们的管理和生物防治计划的制定提供启示。
{"title":"Population structure of three invasive congeneric teasel (Dipsacus) species","authors":"John F. Gaskin, Natalie West, Brian G. Rector","doi":"10.1017/inp.2024.5","DOIUrl":"https://doi.org/10.1017/inp.2024.5","url":null,"abstract":"Three species of the Old World genus <jats:italic>Dipsacus</jats:italic> L. are considered invasive in the Americas, yet they may differ in how they spread, reproduce, and in genetic diversity. Differences in invasion method may suggest that different management techniques are needed for each species. We performed genetic analyses on 572 plants in 69 populations from the USA, Argentina, and Eurasia with the goals of analyzing taxonomy, diversity, mode of reproduction, population structure and founder effect of each of these species’ invasions, as well as looking for evidence of recent or ongoing hybridization. We found <jats:italic>D. sativus</jats:italic> to be lowest in diversity and possibly relying on self-pollination more than the other species, <jats:italic>D. fullonum</jats:italic> and <jats:italic>D. laciniatus</jats:italic>. We found no evidence of hybridization within the invasions and no support for <jats:italic>D. sativus</jats:italic> as a subspecies of <jats:italic>D. fullonum</jats:italic>. The closest genetic matches of <jats:italic>D. fullonum</jats:italic> from USA to the native range were with Hungary and Spain, while the closest match for <jats:italic>D. fullonum</jats:italic> between Argentina and the native range was with Spain. <jats:italic>Dipsacus laciniatus</jats:italic> from the USA most closely matched with samples from Russia. Population structure information regarding these three weedy <jats:italic>Dipsacus</jats:italic> species can help us understand their invasive processes as well as give insight into their management and the development of a biological control program.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"79 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jeremiah R. Foley, Summer E. Stebbins, Riley Doherty, Nicholas P. Tippery, Gregory J. Bugbee
Hydrilla [Hydrilla verticillata (L.f.) Royle], an invasive aquatic weed, has had a rich introduction history into the United States with multiple subspecies being introduced since the 1960’s. The most recent occurred prior to 2016, when northern hydrilla (Hydrilla verticillata subsp. lithuanica) was discovered in the Connecticut River. By 2021, following a three-year survey from Agawam, MA to the Long Island Sound by the Connecticut Agricultural Experiment Station Office of Aquatic Invasive Species, H. verticillata subsp. lithuanica was found in over 113 km of the river, occupying 344 hectares. Since this survey, there has been concern that H. verticillata subsp. lithuanica would spread to nearby waterbodies and have a significant negative impact. Here we report the first documented spread and establishment of H. verticillata subsp. lithuanica from the Connecticut River to five waterbodies in Connecticut and one in Massachusetts. Of the total eight sites where H. verticillata observations were made, 75% (n=6) were confirmed to be H. verticillata subsp. lithuanica and 25% (n=2) to be wandering hydrilla (Hydrilla. verticillata subsp. peregrina). Except for one site, all six locations infested with H. verticillata subsp. lithuanica provide watercraft access through public or private boat ramps. The authors also postulate on the mechanisms facilitating the spread and establishment of this subspecies.
水草[Hydrilla verticillata (L.f.) Royle]是一种入侵性水生杂草，自 20 世纪 60 年代以来，美国引进了多个亚种，历史悠久。最近的一次发生在 2016 年之前，当时在康涅狄格河发现了北部水草（Hydrilla verticillata subsp.到 2021 年，康涅狄格州农业试验站水生入侵物种办公室从马萨诸塞州阿格瓦姆到长岛湾进行了为期三年的调查，在超过 113 公里的河流中发现了石花菜亚种水草，面积达 344 公顷。自这次调查以来，人们一直担心 H. verticillata subsp.在此，我们首次报告了 H. verticillata subsp. Lithuanica 从康涅狄格河向康涅狄格州的五个水体和马萨诸塞州的一个水体扩散和建立的记录。在观察到 H. verticillata 的八个地点中，75%（n=6）被确认为 H. verticillata subsp.除一个地点外，所有六个受 H. verticillata subsp. Lithuanica 侵染的地点都通过公共或私人船坞提供了水上交通工具。作者还推测了促进该亚种传播和建立的机制。
{"title":"Hydrilla verticillata subsp. lithuanica: discovery and establishment outside of the Connecticut River","authors":"Jeremiah R. Foley, Summer E. Stebbins, Riley Doherty, Nicholas P. Tippery, Gregory J. Bugbee","doi":"10.1017/inp.2024.4","DOIUrl":"https://doi.org/10.1017/inp.2024.4","url":null,"abstract":"Hydrilla [<jats:italic>Hydrilla verticillata</jats:italic> (L.f.) Royle], an invasive aquatic weed, has had a rich introduction history into the United States with multiple subspecies being introduced since the 1960’s. The most recent occurred prior to 2016, when northern hydrilla (<jats:italic>Hydrilla verticillata</jats:italic> subsp. <jats:italic>lithuanica</jats:italic>) was discovered in the Connecticut River. By 2021, following a three-year survey from Agawam, MA to the Long Island Sound by the Connecticut Agricultural Experiment Station Office of Aquatic Invasive Species, <jats:italic>H. verticillata</jats:italic> subsp. <jats:italic>lithuanica</jats:italic> was found in over 113 km of the river, occupying 344 hectares. Since this survey, there has been concern that <jats:italic>H. verticillata</jats:italic> subsp. <jats:italic>lithuanica</jats:italic> would spread to nearby waterbodies and have a significant negative impact. Here we report the first documented spread and establishment of <jats:italic>H. verticillata</jats:italic> subsp. <jats:italic>lithuanica</jats:italic> from the Connecticut River to five waterbodies in Connecticut and one in Massachusetts. Of the total eight sites where <jats:italic>H. verticillata</jats:italic> observations were made, 75% (n=6) were confirmed to be <jats:italic>H. verticillata</jats:italic> subsp. <jats:italic>lithuanica</jats:italic> and 25% (n=2) to be wandering hydrilla (<jats:italic>Hydrilla. verticillata</jats:italic> subsp. <jats:italic>peregrina</jats:italic>). Except for one site, all six locations infested with <jats:italic>H. verticillata</jats:italic> subsp. <jats:italic>lithuanica</jats:italic> provide watercraft access through public or private boat ramps. The authors also postulate on the mechanisms facilitating the spread and establishment of this subspecies.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"4 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139771519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
White-tailed deer and invasive plants affect forest understories, but few studies have investigated their interaction. We investigated long-term (11-year) effects of excluding deer and removing the invasive shrub, Lonicera maackii, on plants in southwest Ohio. Deer exclusion enhanced tree seedling richness and density, but reduced annual and bare ground cover. Vine density was reduced by Lonicera, especially where deer were excluded. Seedlings of several tree species, the invasive shrub Euonymous alatus, and the invasive vine E. fortunei, were indicator species of the deer exclosure x Lonicera removal treatment combination. The effect of deer on cover of native species depended on Lonicera treatment: where shrubs were removed, cover was higher where deer were excluded, but where shrubs were present, cover was higher where deer had access. We attribute these interactions to the reduced growth of, and shading by, Lonicera where deer had access and browsed this invasive shrub. Some of these effects were evident in the first 6 years, but are now larger. Other effects were not evident in the earlier evaluation. These findings inform management of areas with high densities of deer and invasive shrubs palatable to deer. Control only of invasive shrubs will reduce native cover and not improve tree regeneration. Managing only deer will increase woody plants but reduce native cover. Management of both stressors is needed to promote tree regeneration and restoration of plant communities.
白尾鹿和入侵植物会影响森林林下植物，但很少有研究调查它们之间的相互作用。我们调查了在俄亥俄州西南部驱赶白尾鹿和清除入侵灌木忍冬对植物的长期（11 年）影响。除鹿提高了树苗的丰富度和密度，但减少了一年生植物和裸露地面的覆盖。忍冬降低了藤本植物的密度，尤其是在驱鹿的地方。若干树种的幼苗、入侵灌木 Euonymous alatus 和入侵藤本植物 E. fortunei 是鹿隔离区 x 清除忍冬的处理组合的指示物种。鹿对本地物种覆盖度的影响取决于忍冬的处理方式：在灌木被移除的情况下，鹿被排除在外的地方覆盖度更高，但在灌木存在的情况下，鹿可以进入的地方覆盖度更高。我们将这些相互作用归因于，在鹿可以进入并采食忍冬这种入侵灌木的地方，忍冬的生长和遮荫能力下降。其中一些影响在最初的 6 年中很明显，但现在的影响更大了。其他影响在早期评估中并不明显。这些发现为管理鹿和入侵灌木密集的地区提供了参考。只控制入侵灌木会减少本地植被，不会改善树木再生。只管理鹿会增加木本植物，但会减少原生植被。要促进树木再生和植物群落的恢复，需要对这两种压力因素进行管理。
{"title":"Long-term interactive impacts of the invasive shrub, Lonicera maackii, and white-tailed deer, Odocoileus virginianus, on a deciduous forest understory","authors":"Marco U. Donoso, Hanna Leonard, David L. Gorchov","doi":"10.1017/inp.2024.2","DOIUrl":"https://doi.org/10.1017/inp.2024.2","url":null,"abstract":"White-tailed deer and invasive plants affect forest understories, but few studies have investigated their interaction. We investigated long-term (11-year) effects of excluding deer and removing the invasive shrub, <jats:italic>Lonicera maackii</jats:italic>, on plants in southwest Ohio. Deer exclusion enhanced tree seedling richness and density, but reduced annual and bare ground cover. Vine density was reduced by <jats:italic>Lonicera</jats:italic>, especially where deer were excluded. Seedlings of several tree species, the invasive shrub <jats:italic>Euonymous alatus</jats:italic>, and the invasive vine <jats:italic>E. fortunei</jats:italic>, were indicator species of the deer exclosure x <jats:italic>Lonicera</jats:italic> removal treatment combination. The effect of deer on cover of native species depended on <jats:italic>Lonicera</jats:italic> treatment: where shrubs were removed, cover was higher where deer were excluded, but where shrubs were present, cover was higher where deer had access. We attribute these interactions to the reduced growth of, and shading by, <jats:italic>Lonicera</jats:italic> where deer had access and browsed this invasive shrub. Some of these effects were evident in the first 6 years, but are now larger. Other effects were not evident in the earlier evaluation. These findings inform management of areas with high densities of deer and invasive shrubs palatable to deer. Control only of invasive shrubs will reduce native cover and not improve tree regeneration. Managing only deer will increase woody plants but reduce native cover. Management of both stressors is needed to promote tree regeneration and restoration of plant communities.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Invasive thistles reduce the productivity of pastures and rangelands because their structural defenses make them unpalatable to grazing livestock. However, plants potentially alter their growth patterns, including their allocation of resources to defense, in response to the presence of competing vegetation. Understanding the effects of competition on the structural defense of problematic pasture weeds can inform management plans that reduce the economic harm caused by these pests. We grew Carduus nutans L. in a fully crossed factorial field experiment in a single abandoned pasture in 2017 with two experimental factors: the level of thistle infestation (1 thistle or 5, resulting in densities of 4 or 20 plants m-2) and the presence or absence of grazing (simulated by weekly trimming of competing vegetation). We assessed the effects of treatments on defense by counting prickles >3 mm long on leaves. Our analysis included leaf age and leaf size as covariates. Competition reduced the number of prickles present on leaves. Regression analysis showed that an increase from, for example, 50 g to 200 g of competing vegetation within 50 x 50 cm study plots reduced the expected average number of prickles on intermediate-aged leaves with average length 25.5 cm by 76.9 prickles/leaf, or 41%. This pattern was similar for leaves of all ages, though the oldest leaves generally had fewer prickles than younger leaves. We did not observe differences in defense structures between plants neighbored by conspecifics and those neighbored by other competitors. Carduus nutans has been previously managed using high densities of grazers, and this practice may be more likely to damage less-defended individuals such as those we observed in our treatments with competition. This finding suggests that maintaining competition in pastures may increase C. nutans’ vulnerability to grazing.
{"title":"Competition reduces structural defense in an invasive thistle in the field","authors":"Rachel Lamb, Joseph Keller, Katriona Shea","doi":"10.1017/inp.2023.33","DOIUrl":"https://doi.org/10.1017/inp.2023.33","url":null,"abstract":"Invasive thistles reduce the productivity of pastures and rangelands because their structural defenses make them unpalatable to grazing livestock. However, plants potentially alter their growth patterns, including their allocation of resources to defense, in response to the presence of competing vegetation. Understanding the effects of competition on the structural defense of problematic pasture weeds can inform management plans that reduce the economic harm caused by these pests. We grew <jats:italic>Carduus nutans</jats:italic> L. in a fully crossed factorial field experiment in a single abandoned pasture in 2017 with two experimental factors: the level of thistle infestation (1 thistle or 5, resulting in densities of 4 or 20 plants m<jats:sup>-2</jats:sup>) and the presence or absence of grazing (simulated by weekly trimming of competing vegetation). We assessed the effects of treatments on defense by counting prickles >3 mm long on leaves. Our analysis included leaf age and leaf size as covariates. Competition reduced the number of prickles present on leaves. Regression analysis showed that an increase from, for example, 50 g to 200 g of competing vegetation within 50 x 50 cm study plots reduced the expected average number of prickles on intermediate-aged leaves with average length 25.5 cm by 76.9 prickles/leaf, or 41%. This pattern was similar for leaves of all ages, though the oldest leaves generally had fewer prickles than younger leaves. We did not observe differences in defense structures between plants neighbored by conspecifics and those neighbored by other competitors. <jats:italic>Carduus nutans</jats:italic> has been previously managed using high densities of grazers, and this practice may be more likely to damage less-defended individuals such as those we observed in our treatments with competition. This finding suggests that maintaining competition in pastures may increase <jats:italic>C. nutans</jats:italic>’ vulnerability to grazing.","PeriodicalId":14470,"journal":{"name":"Invasive Plant Science and Management","volume":"38 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139421763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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