Submersed Weeds in Non-flowing Canals and Ditches

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/acre-foot per application; minimum 21 days between applications. Irrigation/spray use of water requires setback distance of 600 to 2,400 ft 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 2,400 ft, 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 ft wide and delay treatment of these for four to five weeks.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

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 Aquatic Herbicide)

Rate 0.5 to 5 ppm for varying exposure times (see label for specifics by target weed).

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

Caution Toxic to fish and wildlife. Not for use in brackish/salt water. Minimum 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. Not effective on elodea or chara. Treat areas with abundant growth of weeds in sections, and 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

diquat (Diquat Herbicide or Reward)

Rate 1 to 4 lb ai/A (0.5 to 2.0 gallons 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 waterbody 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

fluridone (Sonar, Avast!)

Rate 30 to 150 ppb per treated surface acre; maximum application rate or sum of all application rates cannot exceed 150 ppb per annual growth cycle.

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

Remarks Treat when water movement will be minimal. Results are best when fluridone contacts target plants for at least 45 days. Conduct an enzyme-linked immunosorbant assay test (ELISA) to determine the concentration of active ingredient in the water. Use an application pattern that gives uniform distribution; avoid concentrating the herbicide.

Caution Irrigating with treated water may injure crops. See label for irrigation times after application. 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 growing along shoreline. Do not apply at rates greater than 20 ppb within 0.25 miles of any functioning potable water intake.

Site of action Group 12: bleaching; inhibits carotenoid biosynthesis

Chemical family None generally recognized

imazamox (Clearcast)

Rate 50 to 500 ppb surface applied or injected.

Time Apply early in the growing season.

Remarks Surface apply or inject into water column. Injection more effective on some species. Consult label. 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. There are no restrictions on use of treated water for livestock, swimming, fishing, agricultural spray or domestic use, as long as the setback restriction is observed.

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. When treating irrigation canals, the initial flush of recharge water after application must not be used for irrigation purposes. Note label restrictions on setback distances on applications 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 postemergence 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 (enzyme-linked immunosorbent assay test) 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 apply Galleon SC through any type of irrigation system or 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.

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

Chemical family Triazolopyrimidine