• No crop tolerance established, except for rice
• Do not apply to waters used for food crop irrigation until concentration drops below 1 ppb
• No turf irrigation restrictions for penoxsulam concentration < 30 ppb

• Avoid applications within or adjacent to newly planted aquatic revegetation sites

• No issues related to this tool

• No issues related to use patterns with this tool
  • Rainbow trout 96-hr LC₅₀ > 102 ppm
  • Bluegill sunfish 96-hr LC₅₀ > 103 ppm

• No issues related to this tool

• No issues related to this tool

• Bobwhite quail Oral LD₅₀ > 2,025 mg/kg bw
• Mallard duck Oral LD₅₀ > 1,900 mg/kg bw

• May be difficult to maintain effective concentration in flow-through flood control waters
• Used alone, penoxsulam requires contact time of 60-120 days for submersed plant control
  • Depending on plant species and level of plant maturity
• Combining with potassium endothall reduces required contact time to 3-14 days to control hydrilla

• No issues related to this tool

• No crop tolerance established, except for rice
• Do not apply to waters used for food crop irrigation until concentration drops below 1 ppb
• No turf irrigation restrictions for penoxsulam concentration < 30 ppb

• No restrictions related to this tool

• No restrictions related to this tool

• No issues related to this tool

• No restrictions related to this tool, little to no bioaccumulation in fish

• No issues related to this tool

• No swimming restrictions

• Maximum label concentration for controlling hydrilla is 150 ppb per growing season

• Average half-life in water of about 2-4 weeks in Florida waters

• Slow microbial breakdown – minor pathway

• Weakly adsorbed to clay and organic particles in water
• Adsorbs to dry soils and broken down by microbes

• Broken down primarily by sunlight in water
• Half-life 20-50 days

• Not sensitive to hydrolysis

• May dissipate widely with long exposure requirement and extended presence in water column
• Herbicidal activity only in areas where concentration is sufficient for controlling the target plant
• Combine with potassium endothall for submersed plant control in moving or open water
  • Significantly reduces required exposure time to control submersed plants

• Available in liquid formulation

• Available in solid formulation

• Classified in WSSA Resistance Grouping #2
  • Acetolactate enzyme (ALS) inhibitor

• Absorbed by foliar tissues
  • Moves to areas of new growth
• Prevents the formation of essential branched chain amino acids in plants – ALS
  • Without these essential amino acids, the plant cannot make proteins, enzymes, etc.
  • Plant cannot continue growing and eventually starves and dies

• Used as herbicide for aquatic plant control applications in FWC programs
• Functions as growth inhibitor or growth regulator at lower rates

• Resistance to ALS compounds confirmed in terrestrial species
• No evidence of penoxsulam resistance in Florida waters
• Rotate with other compounds for successive large-scale applications, or
  • Use in combination with another active ingredient
    • Most commonly potassium endothall or fluridone for hydrilla control
• Used in combination with flumioxazin or carfentrazone for foliar applications to floating plants

• Amounts used are depth dependent for submersed plant control – see label for chart

• Accurate bathymetry is required to calculate prescribed dose for submersed plant control
• Apply if possible when water level (volume) is lower
  • Reduces the amount of herbicide required

• Avoid using alone for small-scale, open-water submersed plant control
  • Required exposure period may be too long to sustain herbicide in the control zone
  • Consider combining with potassium endothall
• Need 3-14 days of exposure for optimum submersed plant control when combined with potassium endothall

• Slow acting when used alone
• When applied with potassium endothall or other contact type herbicides for submersed plant control, use caution for large control sites and in warmer water to avoid oxygen sags
• DO sags not likely an issue in fall or spring through early summer applications

• No issues related to this tool

• No issues related to this tool

• Dark or tannic stained waters may decrease sunlight and prolong half-life
• Turbidity not an issue related to this tool

• Sand/Clay – no issues related to this tool
• Organic – no issues related to this tool

• No issues related to this tool

• Not used for native aquatic plant control in FWC funded management programs

• Not used for non-native aquatic plant control in FWC funded management programs

• Hydrilla
  • Penoxsulam alone ~30 ppb for young stands of actively growing hydrilla in quiescent waters
    • Stops hydrilla growth immediately
    • Need 60-120 days of exposure for control
    • Extended exposure will also control water hyacinth via root uptake
  • Penoxsulam ~20 ppb + potassium endothall 1-2 ppb
    • Higher rates needed for smaller plots to compensate for dissipation
    • Follow with low concentration of penoxsulam for several months for long term control
• Water hyacinth
  • Control water hyacinth through root uptake in submersed plant applications at 10-20 ppb, or
  • By direct foliar application of 2-4 oz / acre
  • Penoxsulam 2-4 oz / ac + flumioxazin 2 oz /ac for water hyacinth / water lettuce mix
    • Selective control in bulrush
    • Water lettuce control in < 1 wk – hyacinth control ~ 2+ weeks
• Feathered mosquitofern (Azolla pinnata) and Giant salvinia (Salvinia molesta)
  • Penoxsulam alone
    • Containment or eradication applications
    • Applied at 20 ppb in non-flowing waters

• Lower rates may be applicable for young actively growing plants
• Higher rates / longer exposure may be necessary for mature plants or warmer waters

• Good efficacy for small to large-scale areas of hydrilla in quiescent waters
• Combined with potassium endothall to control hydrilla in higher energy lakes and reservoirs
  • Control is faster than with penoxsulam alone
  • Hydrilla mats begin to collapse in as little as two weeks
  • Seasonal control of non-target native submersed plants such as Illinois pondweed (Potamogeton illinoensis)
  • May temporarily impact some emergent plants
    • Spikerush (Eleocharis), soft-stem bulrush (Schoenoplectus), pickerelweed (Pontederia) sp.
    • Thick lush growth usually recovers next growing season
• Minimize non-target effects by applying when native plants are dormant

• Effective for annual control of hydrilla, especially when applied with potassium endothall
  • Regrowth mostly from sprouting turions/tubers
  • Extent of control varies with season and plant growth stage – up to 1-year control
  • Older plants with more carbohydrate reserves require a higher dose or longer exposure
• May provide more than 1-year of control of floating plants especially water hyacinth
  • For in-water or foliar applications

• Apply when wind/wave action is low to minimize dissipation

Seasonally

• Apply alone for hydrilla control during periods of active growth in quiescent waters
• Combine with potassium endothall for year-round hydrilla applications in Florida waters

• Low intensity
  • Reduces submersed plant (hydrilla) ability to recover after application
  • May extend penoxsulam half-life (longer half-life in dark waters or during winter months)

• Apply when water temperature generally above 50°F to ensure active growth of target plants
• Enhanced efficacy when applied during active plant growth

• Generics are not available
• Herbicides with similar mechanism of action or similar efficacy on different target plants are available

• Surface area
  • Disperses widely outside treatment area depending on water movement and length of exposure
  • Acres of submersed plants controlled generally equals acres of plants to which penoxsulam + potassium endothall is applied
• Percent of Water Column – need to treat entire water column

• When applied with potassium endothall, provides 3-8 months of control
  • Relatively fast plant decline (2-4 weeks)
  • Optionally follow by low dose penoxsulam application once hydrilla biomass is reduced
  • Typically, in 1-2 months
• Annual control when hydrilla exposed to low dose of penoxsulam for several months
  • Slow plant decline – recovery generally from tuber / turion sprouting

• Hydrilla growth shuts down soon after exposure
  • May require 60-120 days exposure to achieve complete control
• Fast acting (7-14 days) for submersed plant control when applied with potassium endothall
• Water hyacinth control in 3+ weeks after application

• Apply by hand gun and boat for small acreages of floating plants
• Apply by hoses trailing from boat, or by helicopter for submersed plant control
  • Especially large acreages of hydrilla (500+ acres)