| Herbicide Rate |
- Maximum rates
- Submersed applications – 500 ppb (173 fl oz / ac ft)
- Foliar broadcast – 1 gpa
- Spot applications – up to 5% by volume
- Generally applied at:
- 8-16 oz / ac for water hyacinth control
- ~32 oz / ac for primrose willow and cattail control
|
| Breakdown / Inactivation |
|
| Microbial |
- Not sensitive to microbial breakdown
|
| Adsorption |
- Weakly adsorbed to clay and organic particles
|
| Photolysis |
- Broken down by sunlight – primary pathway
|
| Hydrolysis |
- Not sensitive to hydrolysis
|
| Dissipation |
- Soluble in water
- May dissipate widely in submersed applications depending on water movement
- Herbicidal activity only in areas where concentration is sufficient to control target plant
|
| Formulation |
|
| Liquid |
- Available in liquid formulation
|
| Solid |
- Available in granular formulation
- Granular formulation used for spot and large-scale submersed plant applications
|
| Mechanism of Action |
- Classified in WSSA Resistance Grouping #2
- Acetolactate synthase (ALS) enzyme inhibitor
|
| Mode of Action |
|
| Systemic |
- Quickly absorbed by leaves and shoots
- Moves to areas of new growth
- Shuts down plant growth almost immediately
- Acts like contact herbicide in this regard
- Control may take 2-6 weeks
- 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
|
| Plant Growth Regulator |
- Not currently used as a plant growth regulator in FWC programs
- Functions as growth inhibitor or growth regulator at lower rates of 50-150 ppb
- May provide 3-6 months growth suppression at lower rates
|
| Stewardship |
|
| Herbicide resistance |
- Resistance to ALS compounds confirmed in terrestrial species
- No resistance reported in Florida aquatic plants
- Rotate other compounds for successive control applications, or
- Use in combination with other active ingredients
|
| Waterbody Parameters | Management Considerations |
|---|
| Hydrology |
|
| Water depth |
- Amounts used for submersed applications are depth dependent – see label for chart
|
| Water volume |
- Accurate bathymetry is required to calculate prescribed dose for submersed plant applications
- Apply if possible when water level (volume) is lower
|
| Water movement |
- Need at least 2-3 days of exposure for submersed applications
- Similar to potassium endothall
|
| Water chemistry |
|
| Dissolved oxygen (DO) |
- DO sags not likely an issue with current FWC small-scale use patterns
|
| pH, alkalinity, hardness |
- No issues related to this tool
|
| Nutrient content |
- Slow acting herbicide so nutrient release from decomposing plants is slow
|
| Water transparency |
- Color/tannic content – no issues related to this tool
- Turbidity – no issues related to this tool
|
| Sediment characteristics |
|
| Composition |
- Sand/Clay – no issues related to this tool
- Organic – do not apply granular formulation to flocculent organic sediments
|
| Potential for re-suspension |
- No issues related to this tool
|
| Plant Physiology Parameters | Management Considerations |
|---|
| Plant origin / growth potential |
|
| Native |
- Cattail
- Applied at rates of 16-32 oz / ac with methylated seed oil adjuvant
- Very active on cattail
- 32 fl oz / ac for selective, but slow (~3 months) control when mixed with bulrush
- 64 fl oz / ac for effective control of monocultures, but less selective
- 32 fl oz / ac + 32 fl oz / ac glyphosate for excellent monoculture control, but non-selective
- Much better selectivity than glyphosate or imazapyr alone
|
| Non-native |
- Primrose willow (Ludwigia peruviana)
- Applied alone at 32 oz / ac
- Combined at 32 oz / ac imazamox + 4 oz / ac carfentrazone
|
| Invasive
|
- Uruguayan primrose willow complex
- Applied foliarly alone at 32 oz / ac
- Combined at 32 oz / ac imazamox + 4 oz / ac carfentrazone
- Submersed application – 400 ppb for
- Rosette growth stage or emergent plants less than 15″ tall
- Water hyacinth
- Applied foliarly at 8-16 oz / ac
- May take 2-4 weeks for control
- Wild taro
- Extremely active on wild taro
- Applied at 96-128 oz / ac
|
| Plant growth stage (target/non-target) |
- Lower rates may have greater impact on young actively growing plants
|
| Plant susceptibility (target/non-target) |
- Must be applied to actively growing target plants
|
| Potential for regrowth (target/non-target) |
- May provide more than 1-year control of floating plants during in-water applications
|
| Climate Parameters | Management Considerations |
|---|
| Weather |
Daily
- Apply when wind / wave action is calm for submersed applications
Seasonally
- Apply to actively growing plants
|
| Light intensity |
- Intense sunlight may accelerate photolytic breakdown
|
| Water temperature |
- Apply with water temperature generally above 50º F to ensure active growth of target plants
- Plants must be actively growing to take up herbicide
|
Plant Management in Florida Waters
