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Exotic plant invasion, a global issue, has a tremendous impact on ecology, economy, human, and animal health. Alligator weed (the world’s first aquatic weed) is a serious invasive weed in 32 different countries of South America, Australia, Asia, and North America. Recently, it has been recorded as a threat weed of rice, maize, soybean, vegetables, fruit trees, and pastures, causing 19–45% yield losses in these crops in addition to its infestation in canals, lakes, and ditches. Alligator weed has the potential to ruin agricultural and natural ecosystems and recreational areas. Ability to propagate via vegetative fragmentation, water-borne dispersal of vegetative propagules, and allelopathic potential contribute towards its success as an invasive weed species of terrestrial, semi-aquatic, and aquatic environments. Application of glyphosate, metsulfuron-methyl, dichlobenil, fluridone, hexazinone, triclopyr amine, dimethylamine, imazapyr, diuron, and amitrole herbicides have been found most effective in controlling this weed in different habitats. Agasicles hygrophila, Vogtia malloi pastana, Amynothrips andersoni , and Nimbya alternanthera have been reported as bio-agents for the control of alligator weed. We present a comprehensive review of the biology, interference, and management options of an extremely dangerous invasive weed species. Although management of alligator weed through chemical, biological, and mechanical means are often effective, there is need for well-planned, long-term field experiments to evaluate the role of different factors that are stated to be responsible for its increasing infestation and distribution (e.g., regeneration after damage caused by herbicides, high soil fertility levels, soil disturbances, shallow vs. deep ploughing and grazing management). It is recommended that future research should focus more on the integration of different management approaches in both aquatic and terrestrial ecosystems, and in various ecological regions.

Unoccupied aerial application systems (UAAS) are gaining popularity for weed management to increase applicator safety and to deliver herbicide treatments where treatment sites limit ground-based spray equipment. Several studies have documented UAAS application strategies and procedures for weed control in terrestrial settings, yet literature describing remote spray technology for use in aquatics remains limited. Currently, applicators seek guidance for UAAS deployment for aquatic weed management to overcome site access restrictions, deal with environmental limitations, and improve ground-based applicator safety in hazardous treatment scenarios. In the present case studies, we evaluate a consumer-available UAAS to deliver the herbicide, florpyrauxifen-benzyl, as both foliar and directed in-water spray applications. The first case study showed that the invasive floating-leaved plant, yellow floating heart, was controlled 80% to 99% by 6 wk after treatment (WAT) following UAAS foliar herbicide treatments. The second case study demonstrated that UAAS directed in-water herbicide application reduced variable-leaf watermilfoil visible plant material by 94% at 5 WAT. Likewise, directed in-water applications from UAAS eliminated the need to deploy watercraft, which improved overall operational efficiency. Data from both case studies indicate that UAAS can provide an effective and efficient treatment strategy for floating-leaved and submersed plant control among common herbicide treatment scenarios. Future integration of UAAS in aquatic weed control programs is encouraged, especially among smaller treatment sites (≤4 ha) or where access limits traditional spray operations. Nomenclature: Florpyrauxifen-benzyl; yellow floating heart, Nymphoides peltata (S.G. Gmel.) Kuntze; variable-leaf watermilfoil, Myriophyllum heterophyllum (Michx.)

Water hyacinth (Eichhornia crassipes (Mart). Solms) is a rapidly growing plant that can easily invade water bodies and negatively impact aquatic ecosystems. Cangkuang Lake is currently facing a major issue due to the increased proliferation of this plant species. Although herbicide can be used to manage weeds in aquatic ecosystems to save labor and time, their impact and toxicity on the environment must be considered. Therefore, this study aims to determine the effectiveness of the Florpyrauxifen-benzyl herbicide in controlling water hyacinth in Cangkuang Lake, Garut Regency, West Java, and its impact on water quality. A randomized block design (RBD) was used with eight treatments, and each treatment was replicated four times to obtain a total of 32 experimental plots with a size of 1 m × 1 m. Each plot contained water hyacinth weeds, with a range of 8–10 leaves and a weight range of 250–300 g. The treatment consisted of herbicide with active ingredients Florpyrauxifen-benzyl (5, 15, 25, 35, and 45 g a.i./ha), 2,4-D Dimethyl Amine (DMA) (1200 g a.i./ha), Penoxsulam (25 g a.i./ha), and the control. The study also measured several water quality parameters, including dissolved oxygen (DO), pH, total dissolved solids (TDS), and ammonia levels. The results showed that Florpyrauxifen-benzyl, starting at a dose of 15 g a.i./ha, was effective in controlling E.crassipes weeds with a growth reduction percentage of up to 100% and no weed regrowth at 42 DAA (day after application). However, all water quality parameters were within the standard threshold for the Government Regulation of the Republic of Indonesia No. 22/2021. This study suggests that Florpyrauxifen-benzyl can be an effective herbicide for controlling water hyacinth in Cangkuang Lake, and that its use did not have a negative impact on water quality. However, this study also highlights the importance of considering the potential environmental impact and toxicity of herbicides before their use in aquatic ecosystems.

The foundation of most aquatic weed management programs in Florida is synthetic herbicides because many of these U.S. Environmental Protection Agency (USEPA)-registered products are effective, selective, and inexpensive compared with other strategies such as mechanical harvesting. However, stakeholders have expressed concern regarding their use and managers are interested in exploring alternative methods for aquatic weed control. To that end, we evaluated the efficacy, selectivity, and costs of the “natural” products acetic acid and d-limonene (alone and in combination with each other and citric acid) on the invasive floating plants waterhyacinth ( Eichhornia crassipes ) and waterlettuce ( Pistia stratiotes ), and the native emergent plants broadleaf sagittaria ( Sagittaria latifolia ) and pickerelweed ( Pontederia cordata ). These products, plus an industry-standard synthetic herbicide (diquat dibromide), were applied once as foliar treatments to healthy plants, which were grown out for 8 weeks after treatment to allow development of phytotoxicity symptoms. A 0.22% concentration of diquat dibromide eliminated all vegetation, but neither “natural” product alone provided acceptable (>80%) control of floating weeds, even when applied at the maximum concentrations under evaluation (20% acetic acid, 30% d-limonene). Citric acid (5% or 10%) had no effect on the activity of acetic acid or d-limonene, but some combinations of acetic acid and d-limonene controlled floating weeds effectively without causing unacceptable damage to native plants. However, these treatments are much more expensive than the synthetic standard and managers would realize a 22- to 26-fold increase in product cost alone without factoring in other expenses such as additional labor and application time. Combinations of acetic acid and d-limonene may have utility in some areas where the use of synthetic herbicides is discouraged, but broad-scale deployment of this strategy would likely be prohibitively expensive.

Aquatic weeds, including invasive species, are a worldwide problem. The presence of aquatic weeds poses several critical issues, such as hindering the continuous flow of water in irrigation channels and preventing the proper distribution of adequate water quantities. Therefore, effective control measures are vital for agriculture and numerous downstream industries. Numerous methods for controlling aquatic weeds have emerged over time, with herbicide application being a widely used established method of weed management, although it imposes significant environmental risks. Therefore, it is important to explore nonchemical alternative methods to control existing and emerging aquatic weeds, potentially posing fewer environmental hazards compared with conventional chemical methods. In this review, we focus on nonchemical methods, encompassing mechanical, physical, biological, and other alternative approaches. We primarily evaluated the different nonchemical control methods discussed in this review based on two main criteria: (1) efficiency in alleviating aquatic weed problems in location-specified scenarios and (2) impacts on the environment, as well as potential health and safety risks. We compared the nonchemical treatments with the UV-C-radiation-mediated aquatic weed control method, which is considered a potential novel technique. Since there is limited published literature available on the application of UV-C radiation used exclusively for aquatic weed control, our review is based on previous reports of UV-C radiation used to successfully control terrestrial weeds and algal populations. In order to compare the mechanisms involved with nonchemical weed control methods, we reviewed respective pathways leading to plant cell death, plant growth inhibition, and diminishing reemergence to justify the potential use of UV-C treatment in aquatic habitats as a viable novel source for aquatic weed control.

New arylpicolinate herbicide chemistry under development for rice, aquatic weed management, and other uses was evaluated using five aquatic plants. The herbicide 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)-5-fluoro-pyridine-2-benzyl ester—also identified as XDE-848 BE or SX-1552 (proposed International Organization for Standardization common name in review; active tradename RinskorTM)—and its acid form (XDE-848 acid or SX-1552A) were evaluated on three dicots: (1) Eurasian watermilfoil (EWM), (2) megalodonta, and (3) crested floating heart (CFH), and two monocots: (1) hydrilla and (2) elodea. A small-scale Organization for Economic Cooperation and Development (OECD) protocol developed using EWM for registration studies was utilized. EWM and megalodonta were also evaluated in larger-scale mesocosms for comparison. In-water concentrations between 0.01 and 243 μg ai L−1 as SX-1552 or SX-1552A were applied under static conditions for 14 (growth chamber) or 28 d (mesocosm). EWM was susceptible to both SX-1552 and SX-1552A, with dry-weight 50% effective concentration (EC50) values of 0.11 and 0.23 μg ai L−1 under growth chamber conditions. Megalodonta had EC50 values of 11.3 and 14.5 μg ai L−1 for the SX-1552 and SX-1552A. CFH was more sensitive to SX-1552 (EC50 = 5.6 μg ai L−1 ) than to SX-1552A (EC50 = 23.9 μg ai L−1). Hydrilla had EC50 values of 1.4 and 2.5 μg ai L−1, whereas elodea was more tolerant, with EC50 values of 6.9 and 13.1 μg ai L−1 for SX-1552 and SX-1552A, respectively. For EWM mesocosm trials, EC50 values for SX-1552 and 1552A were 0.12 μg ai L−1 and 0.58 μg ai L−1, whereas the megalodonta EC50 was 6.1 μg ai L−1. Activity of SX-1552 on EWM, hydrilla, and CFH merits continued investigation for selective aquatic weed control properties. Results suggest that the OECD protocol can be used to screen activity of herbicides for multiple aquatic plant species. Nomenclature: 4-Amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)-5-fluoro-pyridine-2-benzyl ester; crested floating heart, Nymphoides cristata (Roxb.) Kuntze; elodea, Elodea canadensis Michx.; Eurasian watermilfoil, Myriophyllum spicatum L.; hydrilla, Hydrilla verticillata L.f. Royle; megalodonta, Bidens beckii Torr. Ex Spreng.

Pondweed is a rhizomatous perennial weed of aquatic habitats that recently adapted to rice ecosystems in northern Iran. Two field experiments were conducted at the Rice Research Institute of Iran to determine the impact of pondweed on rice yield and identify effective herbicides for pondweed control. The focus of the first study was to evaluate the herbicides commonly used in Iranian rice, including butachlor, pretilachlor, oxadiargyl, pendimethalin, thiobencarb, and bensulfuron-methyl. None of these herbicides effectively controlled pondweed, except bensulfuron, which reduced pondweed biomass by ≥95% and produced 26% higher rough rice grain yield than the nontreated plots. The second experiment evaluated the performance of acetolactate synthase–inhibiting herbicides on pondweed control, rough rice yield, and pondweed regrowth. Herbicide efficacy on pondweed varied from 36% to 100%. Five preemergence herbicides, bensulfuron at 45 g ai ha–1, flucetosulfuron at 30 g ai ha–1, triafamone plus ethoxysulfuron at 40 g ai ha–1, and metsulfuron-methyl at 15 g ai ha–1, provided ≥98% control of pondweed. Use of postemergence herbicides penoxsulam at 35 g ai ha–1, bispyribac-sodium at 30 g ai ha–1, and pyribenzoxim at 35 g ai ha–1 provided 36%, 89%, and 93% pondweed control, respectively. Rough rice yields ranged from 107% to 124% in herbicide-treated plots compared with the nontreated plots. Soil-applied herbicide treatments produced higher (≥119%) yield than the hand-weeded control or foliar-applied herbicides. Pondweed regrowth was affected by herbicides and was variable. Soil-applied residual herbicides metazosulfuron, flucetosulfuron, and metsulfuron provided complete control of pondweed and prevented regrowth. In contrast, pondweed regrowth in other soil- and foliar-applied herbicide treatments occurred, indicating their lesser translocation to underground vegetative rhizomes. This study shows that although most sulfonylurea herbicides can control pondweed effectively to achieve high rough rice yield, only a few soil-applied herbicides were able to prevent pondweed regrowth. Nomenclature: Bensulfuron-methyl; bispyribac-sodium; butachlor; flucetosulfuron; metazosulfuron; metsulfuron-methyl; oxadiargyl; pendimethalin; penoxsulam; pretilachlor; pyribenzoxim; thiobencarb; triafamone plus ethoxysulfuron; pondweed, Potamogeton nodosus Poir. ‘PTMNO’; rice, Oryza sativa L.

Water hyacinth (WH) is one of the rapidly spreading aquatic weeds globally including Ethiopia, causing adverse effects on the water body ecosystems and human benefits. Although composting the weed is one of its management techniques, there is inadequate information on the level of its effectiveness in managing weed infestation and the nutrient content of its compost. The study was carried out to determine the feasibility of WH composting in managing its infestation while producing quality compost at Lake Koka of Central Rift Valley in 2019. Treatments of WH, WH + effective microorganism (EM), cow manure (CM), CM + EM, 75:25% WH + CM with EM, and 75:25% WH + CM were replicated three times and applied in a randomized complete block design. A total of 1500 m 2 of water bodies were cleaned from WH infestations by utilizing the weed plant as organic material to produce 1‐ton compost. The highest soil pH, total nitrogen, CEC, and available potassium of 8.52, 0.81%, 51.86 meq/100 g, and 2550 cmol kg −1 , respectively, were obtained from 75:25% WH + CM with EM compost. The highest total content of 749 mg kg −1 available phosphorus was recorded from 100% WH with EM compost. Therefore, future research should be directed toward the evaluation of compost prepared from 75:25% WH + CM with EM on the yield and yield components of major crops around Lake Koka.

Purpose The study was conducted to develop and assess the feasibility of the low-cost mechanical interface as an alternative to the conventional land-based bin type vermicomposting process. The idea was to reduce the drudgery, enrich the nutrient status and reduce the cost of preparation of vermicompost.Method A smart vermicomposting bin comprising of Arduino, feeding hopper, shredding rollers, spiral mixing unit, degradation bin and harvesting gate was fabricated for the preparation of vermicompost from Dal Lake aquatic weed in Kashmir valley. Eisenia fetida earthworm facilitated the degradation process.Results The Dal lake aquatic weed was degraded in the smart vermicomposting bin. The turning frequency was set as 10 days and 20 days. The performance parameters at 10 days turning interval were pH 7.05, electrical conductivity 0.837 dSm-1, available nitrogen 1.15%, available phosphorus 0.06%, available potassium 1.91%, organic carbon 26.2% and C:N ratio 16.3:1 after 60 days degradation period. The comparative evaluation revealed that increase in available nitrogen, phosphorus and potassium at 10 days turning interval was higher by 4.01%, 6.06%, 4.94% than 20 days turning interval. The benefit â cost ratio was 0.45 in first year and 1.78 in second year with a pay-back period of 19 months. The unit cost of vermicompost production was Rs. 13 per kilogram.Conclusion The involvement of mechanical intervention in vermicomposting can help in reducing the dependence on scarce land and addressing the issue of peak labour shortage. Moreover, the automation of the system can reduce the human errors.

While numerous examples exist of freshwater species from aquaculture facilities establishing non-indigenous populations following intentional release, and unintentional escape, clear links between invasions of non-target ‘hitchhiker’ species and this vector are to date are far less convincing. We examined zooplankton from nine New Zealand fish farms, including those with traditional outdoor pond systems, modern Recirculating Aquaculture Systems (RAS), and of zooplankton cultured as food for fish, to determine the prevalence of non-indigenous species among these facilities. Several non-indigenous species were found during our surveys, from all three sources, indicating that freshwater aquaculture provides invasion risks for non-native zooplankton in a variety of ways. Significantly, the North American calanoid copepod Skistodiaptomus pallidus was recorded at five farms with pond operations, greatly strengthening the link between the establishment of this species in New Zealand lakes with the release of grass carp for aquatic weed control. Traditional pond systems were commonly found to contain large populations of non-indigenous species, with risk seemingly greatest where fish are released from these operations. RAS operations contained relatively low numbers of individuals overall, suggesting a movement to this form of aquaculture from pond systems will greatly reduce the invasion risk from the freshwater aquaculture industry. We recommend a tightening of regulations regarding fish release from aquaculture ponds, following the determination of best practice methods to reduce the potential movement of hitchhiking taxa.