Submersed Weeds in Lakes and Ponds

2,4-D (Hardball)

Rate 2.5 to 6.2 gal/a-ft as concentrate.

Time Apply when plants are actively growing.

Remarks For use in quiescent or slow-moving waters; apply to moving bodies of water only while traveling upstream. No use restrictions for swimming, fishing, watering livestock or domestic purposes other than noted below.

Caution Limited to 2 applications per season; maximum of 10.8 lb ae/a-ft per application; minimum 21 days between applications. Irrigation/spray use of water requires setback distance of 600 to 2400 feet from functional water intakes, a waiting period of 21 days or approved assay of 2,4-D concentrations <100 ppb. Drinking water use requires setback distance from functioning water intakes of 600 to 2400 feet, a waiting period of 21 days from application, or approved assay of 2,4-D concentrations < 70 ppb at water intake. See label for sampling requirements and posting requirements. To avoid oxygen depletion and potential fish kills, treat no more than half the waterbody at a time; for large infestations, leave buffer strips 100 feet wide and delay treating them for four to five weeks.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

2,4-D granules (Aqua-Kleen, Navigate)

Rate 100 to 200 lb product/a.

Time Apply in spring or early summer before plants reach the water surface.

Remarks Susceptible weeds include water milfoils (Myriophyllum spp.) and water stargrass (Heteranthera dubia); higher rates and/or repeat treatments may be required for other weeds. Apply granules uniformly over water surface, either by hand or with a rotary spreader.

Caution Do not apply to water used for watering animals, agricultural sprays, domestic use, or irrigation. If weeds are abundant, treat one-third of the pond or lake at a time to avoid fish kill (due to low oxygen from decomposing weeds). Safe for fish at rate given.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

2,4-D dimethylamine salt (DMA 4IVM, Base Camp and others)

Rate 5.4 to 10.8 lb ae/a-ft

Time Apply in spring or early summer when aquatic weeds appear.

Remarks Apply to obtain a concentration of 2 to 4 ppm. A second application may be needed when weeds show signs of recovery.

Caution Maximum of 10.8 lb ae/a-ft per application; limited to 2 applications per season. Toxic to fish and aquatic invertebrates. Do not treat areas free of weeds. If weeds are abundant, treat 1/3 of the pond or lake at a time to avoid fish kill (due to low oxygen from decomposing weeds). Do not use water for irrigation if approved assay indicates 2,4-D concentration is above 0.1 ppm (100 ppb). Do not use treated water for drinking if approved assay indicates 2,4-D concentration is above 0.07 ppm (70 ppb). See label for sampling requirements and posting requirements.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

bispyribac-sodium (Tradewind)

Rate 15 to 45 ppb

Time Apply in spring or early summer to actively growing weeds.

Remarks Apply as a subsurface application targeting submerged aquatic weeds in slow moving or quiescent bodies of water. Repeat application to maintain desired water column concentration for 60 to 90 days, or until target weed is controlled. The use of ELISA (enzyme-linked immunosorbent assay test) or other analytical methods is recommended to determine if and when it is necessary to make sequential applications. Do not reapply within 14 days after initial application, and do not exceed four applications per year.

Caution Do not apply to flowing water, intertidal or estuarine areas. Do not use treated water to irrigate food or ornamental crops, or as a water source for livestock until the concentration is ≤ 1 ppb. To delay herbicide resistance, alternate non-group 2 herbicides when possible. Consult label for other water use restrictions.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Pyrimidinylthiobenzoate

carfentrazone (Stingray)

Rate 0.05 to 0.2 lb ai/a.

Time Apply in spring or early summer to actively growing weeds.

Remarks Inject into water with a boat-mounted injection system. Material may be applied as a surface spray only in combination with a suitable polymer or similar adjuvant that will ensure rapid sinking and mixing of the spray mix. Apply only to water with little or no outflow.

Caution Moderately toxic to fish. Do not exceed 200 ppb in treated water. Do not apply within 1/4 mile of functioning potable water intakes in flowing or standing water. To avoid oxygen depletion and potential fish kills, treat no more than half the waterbody at a time; wait a minimum of 14 days before treating the remaining area. Consult label for water use restrictions.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Triazinone

dipotassium salt of endothall (Cascade)

Rate 0.5 to 5 ppm spread or sprayed on the water or injected below the water surface

Time Apply as early as possible after weeds appear, while actively growing.

Caution Toxic to fish and wildlife. Minimum of 600 ft setback from functioning potable water intakes. Do not use treated water for animal consumption or other domestic use within 7 to 25 days of treatment, depending on concentration applied. This formulation, at given concentrations, is not effective on elodea or chara. Treat areas with abundant growth of weeds in sections, 5 to 7 days apart to avoid fish kill due to low oxygen level from decomposing weeds.

Site of action Not well understood

Chemical family None generally recognized

dimethylamine salts of endothall (Hydrothol)

Rate 0.5 to 3 ppm sprayed on the water or injected below the surface.

Time Apply in late spring or early summer, while actively growing.

Caution Toxic to fish and wildlife. Fish may be killed at dosages above 0.3 ppm. Not for use in brackish/salt water. Minimum of 600 ft setback from functioning potable water intakes. Do not use treated water for irrigation or agricultural sprays on food crops, watering livestock, or domestic purposes within 7 to 25 days following treatment, depending on concentration applied. Do not treat more than 1/10 of lake or pond at one time with concentrations higher than 1 ppm. Marginal or sectional treatments rather than an overall treatment is recommended.

Site of action Not well understood

Chemical family None generally recognized

diquat (Diquat Herbicide or Reward)

Rate 1 to 4 lb ai/a (0.5 to 2.0 gal per surface acre).

Time Apply when weeds are actively growing and water temperatures are above 50°F.

Remarks Apply only to ponds and lakes with little or no outflow. Use diquat in waters that are totally under your control. In public waters, only federal or state public agencies or contractors under their direct control may use this product. Treat submersed weeds using an invert emulsion applied by either subsurface or bottom applications (surface applications to treat dense submersed weeds or in depths over 2 feet is not recommended). Safe for fish at the rates given. This treatment is not effective on attached algae or chara. There are no swimming or fishing restrictions in treated water.

Caution A moderately toxic herbicide that requires protective gear for handling and application. Toxic to aquatic invertebrates. Do not use treated water for domestic purposes, animal consumption, spraying, or irrigating food crops for 1 to 5 days depending on water use and rate applied. Do not let spray contact skin, eyes, or clothing. Do not breathe spray mist. Do not use in turbid water. To avoid oxygen depletion and potential fish kills, treat no more than half the water body at a time; wait a minimum of 14 days before treating the remaining area.

Site of action Group 22: photosystem I electron diversion

Chemical family Bipyridilium

flumioxazin (Clipper)

Rate 100 to 400 ppb ai

Time Apply in spring or early summer to actively growing plants with limited biomass, and when weeds are growing in lower pH (less than 8.5) waters with high light penetration into the water column.

Remarks Apply in a sufficient volume of water per acre to ensure adequate contact with target weeds. Use higher concentrations when weed biomass is heavy and/or weeds are more mature and topped out. Do not exceed 400 ppb of the active ingredient flumioxazin during any one application. When making applications to water bodies greater than 7 feet deep, do not exceed 14.8 pounds of product per surface acre. Buffer spray solution to pH less than 7.0. Due to photosynthetic processes of submersed plants and algae, water pH tends to be lower in early morning hours compared to afternoon hours. Therefore, in water bodies with a higher pH, apply as early in the morning as possible to maximize the length of time Clipper Herbicide will remain at efficacious concentrations in the water column. To ensure adequate coverage, apply Clipper Herbicide with weighted trailing hoses in order to place the herbicide under the surface and throughout the biomass of aquatic vegetation. Keep swath width to a minimum in order to maximize contact with submersed aquatic vegetation.

Caution Rapid decomposition of vegetation resulting from herbicide treatment can result in loss of oxygen in water. A sudden decrease in dissolved oxygen can result in fish suffocation. If aquatic vegetation is dense, treat floating surface weeds in sections to avoid a rapid decrease in dissolved oxygen. Treat up to half of the water body and wait 10 to 14 days before treating the remaining area. Do not apply to flowing water, intertidal or estuarine areas. Treated water may not be used for irrigation purposes until at least five days after application. Do not re-treat the same section of water with flumioxazin more than 6 times per year. Consult label for water use restrictions.

Site of action Group 14: protoporphyrinogen oxidase (PPO) inhibitor

Chemical family N-phenylphthalimide

florpyrauxifen-benzyl (ProcellaCOR EC)

Rate For in-water applications, the maximum single application rate is 25.0 Prescription Dose Units (PDU) per acre-foot of water with a limit of three applications per year. For aquatic foliar applications, do not exceed 10.0 PDU per acre for a single application, and do not apply more than 20.0 PDU total per acre per year. 0.0052 lb florpyrauxifen-benzyl per PDU

Time For best results, apply to actively growing plants. However, effective control can be achieved over a broad range of growth stages and environmental conditions. Application to mature target plants may require higher application rates and longer exposure periods to achieve control.

Remarks Assumes treated area(s) have the potential to dilute with untreated water. If the treated area is not projected to dilute rapidly, utilize FasTEST to confirm below 2 ppb or verify vegetation tolerance before irrigation use. Consult a SePRO Aquatic Specialist for additional site-specific recommendation

Caution Do not use treated water for any form of irrigation. Irrigating with treated water may injure crops. See label for irrigation times after application. Do not permit ProcellaCOR EC to come into contact during an application with any desirable broadleaf plants, as serious injury may occur.

Site of action Group 4: auxin herbicide chemotype

Chemical family Arylpicolinate

fluridone (Sonar or Avast!)

Rate Ponds 45 to 90 ppb; whole lakes 10 to 90 ppb. Sum of all applications must not exceed 90 ppb/year for ponds; 150 ppb for lakes and reservoirs.

Time For best results, apply just before or just as weeds begin active growth.

Remarks For fluridone, a pond is defined as body of water 10 acres or less. A lake or reservoir is defined as having a surface area greater than 10 acres. Treat when water movement will be minimal. Rate is determined by area and depth of water treated, and density of target vegetation. May be applied to a pond's entire surface area. In lakes and reservoirs, apply to areas greater than 5 acres. Results are best when fluridone is in contact with target plants for at least 45 days. Make an enzyme-linked immunosorbant assay test (ELISA) to determine the active ingredient's concentration in the water. See label for rates for split or multiple applications to whole lakes and reservoirs and for partial lake treatment rates.

Caution Irrigating with treated water may injure crops. See label for irrigation times after applying. Do not irrigate established tree crops for at least 7 days after application. Depending on formulation and application site, do not irrigate other crops for 7 to 30 days after application. May injure vegetation along shoreline. Do not apply within 0.25 miles of any functioning potable water intake at rates greater than 20 ppb.

Site of action Group 12: bleaching; inhibits carotenoid biosynthesis

Chemical family None generally recognized

imazamox (Clearcast)

Rate 50 to 500 ppb broadcast to water surface or injected.

Time Apply early in the growing season.

Remarks Surface apply or inject into water column. May be applied as undiluted product or diluted with water prior to application. When weeds are matted at the surface, imazamox should be injected below the water surface to achieve better distribution. Apply to water with little or no flow. Repeat applications may be made, but do not apply at rates resulting in water concentrations greater than 500 ppb.

Caution Do not use treated water to irrigate greenhouses, nurseries, or hydroponics. Do not use treated water for other irrigation purposes less than 24 hours after application is completed, and only as long as concentrations in water are equal to or less than 50 ppb. Note label restrictions on setback restrictions to potable water intakes.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Imidazolinone

penoxsulam (Galleon SC)

Rate 5 to 150 ppb (0.9 to 26.1 fl. oz/a-ft)

Time Apply only to actively growing weeds.

Remarks For post emergent foliar applications or treatments to exposed sediments, use with a surfactant approved for aquatic use (use with organosilicone surfactants not recommended). May be mixed with other herbicides or algaecides according to label specifications. Single applications should target minimum effective concentration of 25 to 75 ppb; split or multiple applications should target an initial dose of 10 to 30 ppb and subsequent applications to maintain that concentration for a minimum of 60 days (use ELISA or other analytical techniques to determine penoxsulam concentrations).

Caution Maximum target concentration in any treated area is 150 ppb ai per annual growth cycle. Do not use treated water for hydroponic farming, irrigating greenhouses or nursery plants; see label for other crop specific irrigation restrictions. Do not use in areas subject to rapid dilution, such as spot treatments in lakes or other large water bodies.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Triazolopyrimidine

topramezone (Oasis)

Rate 0.094 to 0.135 lb ai per acre-foot (30 to 50 ppb)

Time Apply only to actively growing weeds.

Remarks See label for detailed application remarks

Caution Do not exceed a cumulative total of 150 ppb (0.407 lb ai per acre-foot) per year. Concentrations in food/feed crop irrigation must be monitored until concentrations are 1 ppm or less before treated water may be used for irrigation. See label for more irrigation restrictions.

Site of action Group 27 4-HPPD inhibitor.

Chemical family Pyrazolone

triclopyr (Renovate 3 or Renovate LZR)

Rate 0.75 to 2.5 ppm ae concentration in water; apply as surface or subsurface application.

Time Apply in spring or early summer to actively growing weeds.

Remarks Treat 1/3 to 1/2 of the water body at a time and wait 10 to 14 days between applications to prevent possible fish kills due to oxygen depletion. Rates higher in the range are recommended in areas of greater water exchange. Apply as a surface or subsurface application in water that has little or no continuous outflow. When using liquid triclopyr to treat plants 6 ft below the water surface, use trailing hoses along with an approved aquatic sinking agent. There are no restrictions on recreation, including swimming and fishing, in the treated area or on livestock consumption of water.

Caution Do not apply when conditions favor drift to sensitive areas. Observe minimum setback distances from functional potable water intakes for human consumption. Do not exceed 2.5 ppm per season. Do not apply this product through any type of irrigation system and do not use treated water for irrigation for 120 days.

Site of action Group 4: synthetic auxin

Chemical family Pyridine