| Herbicide Rate |
- See plant physiology parameter considerations below for current rates by plant species
- 50-200 ppb for submersed applications
- 2-8 oz/ac for foliar applications
|
| Breakdown / Inactivation |
- Short half-life in water depending on season, water depth and especially pH
|
| Microbial |
- Microbial metabolism is the primary degradation pathway in soil – half-life ~45 days
|
| Adsorption |
- Does not bind in sediments or adsorb to soil particles
|
| Photolysis |
- Susceptible to photodegradation with a half-life of ~3 days
|
| Hydrolysis |
- Primary degradation pathway in water – especially sensitive in low pH waters
- Half-life of four days at pH = 5 and minutes at pH = 9.0 in laboratory tests
|
| Dissipation |
- Dissipation is minimal with the very short half-life
|
| Formulation |
|
| Liquid |
- Not available in aqueous formulation
|
| Solid |
- Water dispersible granular herbicide
- Mix with water and apply as liquid solution
|
| Mechanism of Action |
- Classified in WSSA Resistance Grouping #14
- Protoporphyrinogen oxidase (PPO) enzyme inhibitor
|
| Mode of Action |
|
| Contact |
- Inhibits protoporphyrinogen oxidase enzyme important in chlorophyll synthesis
- Absorbed through the leaves – does not move in the plant
- Causes formation of a light-absorbing chlorophyll precursor outside of the chloroplast
- This compound absorbs energy from sunlight, but cannot pass through the Z-scheme
- Energy is passed on to oxygen, creating radical oxygen and cell membrane disruption
|
| Plant Growth Regulator |
- Not used as a plant growth regulator in Florida aquatic plant control applications
|
| Stewardship |
|
| Herbicide resistance |
- No tolerance or resistance issues reported in Florida
- Resistance has been reported for PPO inhibitors in terrestrial applications
- Rotate or combine with other active ingredient where appropriate
|
| Waterbody Parameters | Management Considerations |
|---|
| Hydrology |
|
| Water depth |
- Important to know water depth to calculate appropriate concentration for submersed applications
|
| Water volume |
- Important to have accurate bathymetry to calculate appropriate concentration for submersed applications
|
| Water movement |
- Do not apply to flowing water
- Can be used in slow moving, quiescent waters
|
| Water chemistry |
|
| Dissolved oxygen (DO) |
- Relatively fast-acting contact type herbicide
- Controlling large area may reduce dissolved oxygen level
- Wait 10-14 days if treating as much as half of the waterbody
|
| pH, alkalinity, hardness |
- Half-life is pH dependent in field tests
- Low pH (6.0-6.2) = 39 hours
- Medium pH (7.0-7.2) = 18.6 hours
- High pH (>8.5) = 1.7 hours
- Use buffer if tank mix water exceeds pH 7
- Apply submersed applications early in morning when pH is generally at lower values
|
| Nutrient content |
- No issues related to this tool
|
| Water transparency |
- Higher light intensity usually equates to more robust growth of submersed target plants
|
| Sediment characteristics |
|
| Composition |
- Sand/Clay – no issues related to this tool
- Organic – no issues related to this tool
|
| Potential for re-suspension |
- No issues related to this tool
- Does not adsorb to suspended material in water body or in tank mix water
|
| Plant Physiology Parameters | Management Considerations |
|---|
| Plant origin / growth potential |
|
| Native |
- Fanwort
- Use to control cabomba at about 200 ppb
- Cabomba usually present in lower pH waters
|
| Non-native |
- Ambulia (Limnophila sessiliflora)
- Alone at 200 ppb
- Combination of flumioxazin at 100 ppb + diquat at 370 ppb
- Very active on water lilies at this rate
|
| Invasive
|
- Water lettuce
- 2-4 oz / ac applied foliarly
- 50 ppb for submersed application to control water lettuce
- Need an area >15 ac to compensate for dissipation
- Hydrilla (and Hygrophila (Hygrophila polysperma))
- Alone at 200 ppb
- Combination of flumioxazin at 100 ppb + diquat at 370 ppb
- Ludwigia grandiflora and torpedograss control at 4 oz / ac + 7.5 pt / ac glyphosate
- Increasing use for selective water lettuce control
- ~50 ppb for submersed applications and 2-8 oz / ac foliar application
- 4 oz / ac + 4 oz / ac penoxsulam for water lettuce / water hyacinth mix
- Ludwigia uraguayensis complex and Cuban club-rush
- 4 oz flumioxazin + 96-120 oz glyphosate / ac
- Adding flumioxazin accelerates knockdown – unclear if it increases efficacy
|
| Plant growth stage (target/non-target) |
- Need actively growing plants for herbicide uptake
- Mature plants are more difficult to control due to higher carbohydrate reserve
|
Plant susceptibility (target/non-target)
|
- Good alternative to diquat for controlling water lettuce mixed with bulrush
- Does not cause bulrush stem spotting or browning associated with diquat applications
- Foliar applications when wind speed < 10 mph to reduce damage from drift
- Apply in early fall (Oct/Nov) or late winter (Feb/Mar) for best hydrilla control
- Lower biomass and pH likely lower
- Water lilies in application zone may be impacted
- Especially when applied with diquat for hydrilla control
|
| Potential for regrowth (target/non-target) |
- Thorough water lettuce control
- Regrowth from seed or new plants flushed into control zone
- Regrowth is rapid when applied to mature or slowly growing hydrilla
- Must kill root crowns to slow regrowth from tubers
|
| Climate Parameters | Management Considerations |
|---|
| Weather |
Daily
- Needs 4-8 hours of contact for good herbicidal activity
Seasonally
- Need actively growing target plants for herbicide uptake
|
| Light intensity |
- Higher light intensity usually equates to stronger growth and therefore better control of young submersed plants (hydrilla / cabomba)
|
| Water temperature |
- No issues related to this tool
|
Plant Management in Florida Waters
