Xu Junfeng, Bickel Tobias Oliver, Adkins Steve
School of Agriculture and Food Sustainability, The University of Queensland, Brisbane, QLD 4072, Australia.
Invasive Plant Science, Department Agriculture and Fisheries, Brisbane, QLD 4001, Australia.
Biology (Basel). 2025 Aug 8;14(8):1023. doi: 10.3390/biology14081023.
A. Gray (cabomba) is an invasive alien aquatic plant (IAAP) posing a significant threat to aquatic ecosystems in Australia. Its ongoing spread is primarily driven by its rapid growth rate and ability to readily regenerate from stem fragments. Flumioxazin, an effective herbicide for controlling cabomba, has been registered for use in Australia since 2021. However, exposing cabomba to flumioxazin can induce stem fragmentation, potentially facilitating further spread. This study aims to determine whether stem fragments of cabomba following treatment at different flumioxazin doses (i.e., 25, 50, 100, or 200 ppb a.i.) can regenerate new healthy shoots that could contribute to its future spread in a new environment, in either summer or winter. This study also aims to investigate how this regrowth potential changes over time after herbicide application. Results show that flumioxazin suppressed the regeneration of replanted stem fragments in a dose-dependent manner in both winter and summer. In winter, complete regeneration was suppressed at the highest concentration tested (200 ppb a.i.), while low concentrations (25 and 50 ppb a.i.) resulted in an average 45% lower regeneration rate and 93% lower regenerated biomass than the control. In summer, suppression of regeneration was lower; at 200 ppb a.i., partial regeneration (18%) occurred with a 97% biomass reduction. At lower concentrations (25 and 50 ppb a.i.), more stem fragments regenerated (66%) and biomass reduction was lower (69%) compared to winter. Furthermore, in summer, the plants gradually regained their ability to regenerate over time after herbicide exposure, regardless of flumioxazin concentration, while no such recovery occurred in winter at any concentration. The findings show that the highest tested dose (200 ppb a.i.) can effectively suppress cabomba regenerative ability, which will greatly reduce the risk of new infestations caused by dispersed fragments, particularly in winter, when cooler temperatures and lower light are suboptimal for cabomba growth. This suggests that winter may be a more effective season for flumioxazin application. However, since some regeneration still occurred in summer, even at the highest tested dose, the highest registered label rate (400 ppb a.i.) may be necessary to ensure effective suppression under warmer conditions. Further studies are needed to evaluate this higher dose and its long-term efficacy.
A. 水盾草是一种外来入侵水生植物，对澳大利亚的水生生态系统构成重大威胁。其持续扩散主要归因于其快速的生长速度以及从茎段轻易再生的能力。氟草嗪是一种用于控制水盾草的有效除草剂，自2021年起已在澳大利亚注册使用。然而，将水盾草暴露于氟草嗪会诱导茎段断裂，这可能会促进其进一步扩散。本研究旨在确定在不同氟草嗪剂量（即25、50、100或200 ppb有效成分）处理后的水盾草茎段在夏季或冬季是否能够再生出新的健康枝条，从而导致其在新环境中进一步扩散。本研究还旨在探究除草剂施用后这种再生潜力如何随时间变化。结果表明，氟草嗪在冬季和夏季均以剂量依赖的方式抑制重新种植的茎段再生。在冬季，测试的最高浓度（200 ppb有效成分）完全抑制了再生，而低浓度（25和50 ppb有效成分）导致的再生率平均比对照低45%，再生生物量比对照低93%。在夏季，再生抑制较低；在200 ppb有效成分时，出现了部分再生（18%），生物量减少了97%。与冬季相比，在较低浓度（25和50 ppb有效成分）下，更多的茎段再生（66%），生物量减少较低（69%）。此外，在夏季，无论氟草嗪浓度如何，除草剂处理后植物随时间推移逐渐恢复再生能力，而在冬季，任何浓度下均未出现这种恢复。研究结果表明，测试的最高剂量（200 ppb有效成分）能够有效抑制水盾草的再生能力，这将大大降低由分散茎段引起新侵扰的风险，特别是在冬季，较低的温度和光照对水盾草生长不利。这表明冬季可能是施用氟草嗪更有效的季节。然而，由于即使在测试最高剂量下夏季仍有一些再生发生，可能需要最高登记标签剂量（400 ppb有效成分）以确保在温暖条件下有效抑制。需要进一步研究来评估这种更高剂量及其长期效果。
