Herbicide Rate |
- 40 oz/ac in 14-day sequential applications for seasonal torpedograss control
- 3-5% v/v for spot treatments can be done with sequential applications
- Longer retreatment intervals need to be examined
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Breakdown / Inactivation |
- Degraded rapidly by microbes and photolysis
- Half-life in the field ranges from 5 to 25 days on soils
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Microbial |
- Microbial metabolism is primary degradation pathway
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Adsorption |
- Weak tendency to adsorb to soil particles
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Photolysis |
- Degraded rapidly through photolysis – within an hour
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Hydrolysis |
- Not sensitive to hydrolysis
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Dissipation |
- No issues related to this tool
- Not used for submersed applications
- Degrades in as little as one hour in water
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Formulation |
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Liquid |
- Available only in liquid formulation
- Contains 1.5 lb active ingredient / gallon
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Solid |
- Not available in solid formulation
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Mechanism of Action
|
- Classified in WSSA Resistance Group #1
- Acetyl CoA carboxylase enzyme inhibitor
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Mode of Action |
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Systemic |
- Absorbs rapidly through leaf surfaces, transported in xylem and phloem, and accumulates in meristematic tissues
- Leads to failure of cell membrane integrity, especially in regions of active growth
- Results in cessation of shoot and rhizome growth, leading to necrosis and death of shoot meristems and rhizome buds, and ultimately plant death
|
Plant Growth Regulator |
- Not used as a plant growth regulator in Florida aquatic plant control applications
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Stewardship |
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Herbicide resistance |
- Group 1 herbicide – repeated use may lead to the selection of resistant biotypes
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Waterbody Parameters | Management Considerations |
Hydrology |
|
Water depth |
- Mesocosm studies indicate control is lower for torpedograss grown at a water depth of 30 cm compared to saturated conditions.
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Water volume |
- No issues related to this tool – not used for submersed applications
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Water movement |
- No issues related to this tool – not used for submersed applications
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Water chemistry |
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Dissolved oxygen (DO) |
- No issues likely related to this parameter
- Anticipated control sites are spot, band or fringe treatments, or marshes with low DO
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pH, alkalinity, hardness |
- No issues related to this tool for application or mixing water
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Nutrient content |
- No issues related to this tool – primarily used for small-scale control
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Water transparency |
- No issues related to this tool – applied directly to emergent leaves
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Sediment characteristics |
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Composition |
- Sand/Clay – no issues related to this tool
- Organic – no issues related to this tool
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Potential for re-suspension |
- Does not adsorb to suspended material
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Plant Physiology Parameters | Management Considerations |
Plant origin / growth potential |
|
Native |
- May occasionally be used to control native grasses in unwanted areas (e.g. boat ramps)
- Does not control cattail, sedges, or other non-grass species
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Non-native |
- May occasionally be used to control non-native grasses in unwanted areas
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Invasive
|
- Registered in Florida to provide a new mode of action for invasive grass control
- Evaluation underway for torpedograss, paragrass and West Indian marsh grass control
- Will evaluate control for Tropical American water grass, in ponds, lakes, swamps, riparian areas, wetlands, marshes, reservoirs, and other areas adjacent to aquatic sites
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Plant growth stage (target/non-target) |
- Need actively growing plants for herbicide uptake
- Most effective control by applying postemergence applications early in the growing season (late spring), when perennial grasses leaf out and annual grass weeds are small
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Plant susceptibility (target/non-target)
|
- Apply to actively growing target plants
- Use methylated seed oil at a mixing rate of 1% volume/volume
- Torpedograss – 2 applications sethoxydim @ 40 oz/ac broadcast or 3-5% v/v for spot control
- For application by boat or ground equipment
- Use a minimum of 20, up to 100 gallons of water per acre to ensure uniform coverage
- Increased water volume if grass foliage is dense
- Non-target co-mingled grasses will likely be suppressed or controlled
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Potential for regrowth (target/non-target) |
- Seasonal control of torpedograss with sequential applications ~14 days apart
- Longer retreatment intervals need to be evaluated
- Sethoxydim efficacy less than glyphosate/imazapyr, but more selective for non-grass species
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Climate Parameters | Management Considerations |
Weather |
Daily
- Apply only when the wind speed is 10 mph or less
- Produce larger droplets to reduce drift potential
- Rain-fast in one hour
- Avoid wash-off from application boat or recreational boats for one hour
Seasonally
- Apply to actively growing plants in late winter / early spring increases efficacy
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Light intensity |
- Rapidly broken down by photolysis – early season applications may produce better results
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Water temperature |
- No issues related to this tool – not used for submersed applications
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