Emergent Weeds along Drainage Ditches

2,4-D (Hardball)

Rate 1.15 gal/a (2 lb ae/a) with 100 to 400 GPA spray mixture with power sprayers

Time Apply in spring or early summer; if needed, a second treatment may be applied before September.

Remarks Applications should be made when leaves are fully developed, above the waterline, and actively growing. Do not apply when wind speeds are at or above 10 mph (ground/surface applications) or 5 mph (aerial applications). See label for instructions on use of drift control agents and equipment to prevent drift to sensitive crops.

Caution Limited to 2 applications per season; maximum of 1.15 gal/a (2 lb ae/a) per application; maximum of 2.25 gal/a (4 lb ae/a) per season; minimum 30 days between applications. Do not use on small canals with flow rates < 10 cfs where water will be used for drinking water purposes. Do not overspray to opposite bank or allow boom spray to be directed onto water surface; allow no more than 2 foot overspray onto water with an average of less than one foot overspray.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

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

Rate 2 to 4 pints/a

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

Remarks Repeat as necessary to kill regrowth or missed plants; use 4 pints/a rate when plants are mature or dense.

Caution Maximum of 8 pints/a per application; limited to 2 applications per season, a minimum of 21 days apart. Toxic to fish and aquatic invertebrates. Do not treat areas free of weeds. If weeds are abundant, consider partial treatments 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. Do not use on small canals with flow rates < 10 cfs where water will be used for drinking water purposes. Do not overspray to opposite bank or allow boom spray to be directed onto water surface; allow no more than 2 foot overspray onto water with an average of less than one foot overspray.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

bispyribac-sodium (Tradewind)

Rate 0.05 to 0.1 lb ai/a (1 to 2 oz/a)

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

Remarks When applying to dense foliage of actively growing weeds, a second application may be required to ensure adequate coverage. Use with an adjuvant approved for aquatic use. Allow 30 days between applications, apply no more than 8 oz of product per acre per year, and do not exceed 4 applications per year. Bispyribac may be mixed with other registered foliar-applied aquatic herbicides for enhanced control of floating and emergent weeds.

Caution With aerial applications do not spray within 200 feet of dwellings, adjacent sensitive crops or environmentally sensitive areas. Consult label for water use restrictions.

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

Chemical family Pyrimidonylthiobenzoate

flumioxazin (Clipper)

Rate 6 to 12 oz/a

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

Remarks It is most effective when applied to young, actively growing weeds in water with a pH less than 8.5. Clipper Herbicide breaks down rapidly and loses herbicidal effectiveness in high pH water (pH greater than 8.5). When applying to dense foliage of actively growing weeds, a second application may be required to ensure adequate coverage. Application of Clipper Herbicide during early morning hours may enhance weed control. Use with an adjuvant approved for aquatic use. Buffer the spray solution to pH less than 7.0. Do not re-treat the same section of water within 28 days of application. Flumioxazin may be mixed with other registered foliar applied aquatic herbicides for enhanced control of floating and emergent weeds.

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. With aerial applications do not spray within 200 feet of dwellings, adjacent sensitive crops or environmentally sensitive areas. Consult label for water use restrictions.

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

Chemical family N-phenylphthalimide

glyphosate (Rodeo, AquaNeat, AquaPro, AquaMaster, Cinco, or Accord Concentrate)

Rate 0.75 to 3.75 lb ae/a (1.5 to 7.5 quarts/a) applied as a broadcast spray or 0.75 to 2.0% solution in water applied through hand-held or high-volume equipment

Time Apply when weeds and brush are actively growing.

Remarks See label for application rate and growth stage of weed and brush species. If water is in the area to be sprayed, add a surfactant labeled for use in water at the manufacturer's surfactant label recommendations. Surfactant must be at least 80% ai. In dry ditches or after drawdown, allow seven days after treatment before reintroducing water; treat within one day after drawdown to ensure weeds are actively growing. Apply as a 33% solution through wiper-type applicators. May be applied through hand-held or high-volume equipment as a 0.75 to 1.5% solution.

Caution Rain within 6 hours after application may reduce effectiveness. Do not apply within 0.5 miles upstream of potable water intakes. Apply to moving bodies of water only while traveling upstream. Do not overlap bank side applications more than 1 foot into open water. Do not exceed 3.75 lb ae/a in a single application being made over water. Take care to avoid drift to desirable plants. With bankside applications, do not overlap more than one foot into open water. Do not spray where weeds do not exist.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

imazamox (Clearcast)

Rate 0.125 to 0.5 lb ai/a (16 to 64 oz product/a)

Time Apply as a foliage spray to actively growing emergent and floating plants.

Remarks Rate depends on species to be controlled. Postemergence applications require adding a spray adjuvant approved for use in aquatic sites. There are no restrictions on livestock watering, swimming, fishing, or domestic use as long as the setback restriction is observed, or for agricultural sprays.

Caution Do not use treated water to irrigate greenhouses, nurseries, or hydroponics. Do not use treated water for other irrigation purposes unless 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

imazapyr, isopropylamine salt (Arsenal, Habitat, Polaris AQ)

Rate 0.5 to 1.5 lb ae/a (2 to 6 pints/a), applied with surface or helicopter equipment in minimum of 2 gal water/a. For low volume foliar applications, use 0.5 to 5% concentration (without applying more than 6 pints/a per year).

Time Apply to vigorously growing emergent and floating vegetation.

Remarks Controls several annual, biennial, and perennial grass and broadleaf species. Rate depends on weed species and growth stage at time of application. Postemergence applications require adding a spray adjuvant (such as a nonionic surfactant or methylated seed oil) approved for use in aquatic sites. Controls emerged and floating vegetation that has most of its foliage above the water surface. No restrictions on recreational or livestock use of treated water. Moisten, but do not drench, target vegetation.

Caution Do not apply more than 1.5 lb ae/a (6 pints/a product) per year. Do not apply to canals or ditches unless a 120 day restriction on irrigation water can be observed or residual levels of imazapyr are determined by laboratory analysis to be less than 1 ppb. Do not apply to dry irrigation canals or ditches. Do not apply within 0.5 miles downstream of an active irrigation water intake. Applications upstream of active irrigation water intakes must be turned off for a period of time sufficient to allow treated water to completely flow past the intake (determined by water velocity, distance and length of water treated). To avoid oxygen depletion, treat no more than half a waterbody at a time, waiting 10 to 14 days between treatments. Do not spray where weeds do not exist.

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

Chemical family Imidazolinone

penoxsulam (Galleon SC)

Rate 2 to 5.6 fl oz/a with at least 10 GPA for aerial foliar applications and up to 100 GPA for ground foliar applications. For pre- or post-emergence applications to exposed sediments, use 5.6 to 11.2 fI oz/a in a total spray volume of 20 to 100 GPA.

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 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

topramezone (Oasis)

Rate For foliar applications apply up to a maximum of 16 fl oz/acre (0.35 lbs ai free acid/ac)

Time Apply only to actively growing weeds.

Remarks Use with an aquatic approved surfactant.

Caution See label for irrigation restrictions.

Site of action Group 27 4-HPPD-inhibitor

Chemical family Pyrazolone