Herbicides for Aquatic Invasive Plant Management:Do We Really Need This Tool in Our Toolbox?

By Marc BellaudPresident

June 8, 2017

Restoring Balance. Enhancing Beauty.

Overview of Presentation

• What is a herbicide?

• Currently registered products

• Types of herbicides

• Application strategies

• Common invasive and nuisance aquatic plants in New Hampshire

• Herbicide treatment options for New Hampshire

• Changes ahead…

What is a herbicide? Approximately 300 registered herbicides in the US,

but less than 15 are registered for aquatic use

Important dates in the regulation of aquatic herbicides

1910 – Federal Insecticide Act 1947 – FIFRA administered by USDA 1962 – “Silent Spring” by Rachel Carson 1970 – EPA created 1972 – Federal Environmental Pesticide Control Act 1988 – FIFRA amended to require re-registration 1996 – Food Quality Protection Act amended both FIFRA and

FFDCA requires EPA to reevaluate all tolerances for pesticides and inerts

2008 – EPA completed reregistration of all products registered prior to 1984; 15-year renewal cycle

2011 – NPDES Pesticide General Permit

Registered aquatic herbicides available in the 1990’s

Compound Year Registered

Mode of Action

2,4-D Ester2,4-D Amine

Navigate(liquids & Sculpin G)

19591976

Systemic – auxin mimic

Copper Komeen, Nautique, etc. 1950’s Contact – phs – membrane

Diquat Reward 1962 Contact – PSII – membrane

Endothall Aquathol K 1960 Contact – Resp.- membrane

Glyphosate Rodeo, etc. 1982 Systemic – protein synthesis

Fluridone Sonar 1986 Systemic – Enzyme inhibitor

Source: USACE, ERDC

Aquatic herbicides registered since 2002Compound Year Registered Mode of Action

Triclopyr Renovate 2002 Systemic – auxin mimic

Imazapyr Habitat 2003 Systemic – ALS inhibitor

Peroxide Green Clean, etc. 2003 (1980s) Contact - algaecide

Carfentrazone Stingray 2004 Contact – Enzyme-membrane

Penoxulam Galleon SC 2007 Systemic – ALS inhibitor

Imazamox Clearcast 2008 Systemic – ALS inhibitor

Flumioxazin Clipper 2010 Contact – protox

Bis-pyrobac Tradewind 2012 Systemic – ALS inhibitor

Topramezone Oasis 2014 Systemic – HPPD inhibitorSource: USACE, ERDC

Why are there so many new herbicides?

Re-registration requirements and costo Aquazine example

Discovery of fluridone(Sonar) resistant hydrilla in Florida in 1999/2000

New herbicide characteristics

• Different mode of action and/or site of action

• Plant-specific impacts

• Lower toxicity

• Lower persistence

Chemical: Contact Herbicides

• Fast acting on plant tissue (~7days)– But can cause DO depletion if not careful

• Causes extensive cellular damage, but not roots • Usually only provides seasonal control • Site-specific • Can be species selective • Examples: diquat, endothall, flumioxazin

Chemical: Systemic Herbicides

• Product is translocated throughout the plant structure• Longer contact time needed, but…

– Slower decomposition has less effect on the lake’s oxygen regime – Often multi-year control of certain species can be achieved

• Tend to be more species selective • Granular formulations useful for site specific or high flow areas • Examples: fluridone, 2,4-D, triclopyr

GranularLiquid

Different Formulations

Graphics courtesy of SePRO

Choosing the Right Product and Formulation

Concentration Exposure Time (CET)

Untreated 1 WAT 4 WAT

Source: US Army Engineers – ERDC

Control PredictionsA: 0 - 70 % (regrowth likely)

B: 70 - 85 % (regrowth potential subject to site conditions)

C: >85 % (limited regrowth potential)

FACTORS FOR HERBICIDE SELECTION• Target species• Size & configuration of treatment area• Selectivity desired or required• Water uses• Flow considerations• Timing• Cost

NEW APPROACHES• New and improved formulations• Treatment timing• Combination treatments • Rotate chemistries

Invasive Aquatic Plants in NH

• Variable Watermilfoil

• Fanwort

• Eurasian Watermilfoil

• Spiny Naiad

• Water Chestnut

• Curlyleaf Pondweed

Variable Milfoil (Exotic)

Fanwort (Exotic)

Eurasian watermilfoil (Exotic)

Spiny Naiad (Exotic)

Water Chestnut (Exotic)

Curlyleaf Pondweed (Exotic)

http://www.des.nh.gov/

organization/divisions/water/wmb/

exoticspecies/index.htm

NH DESExoticSpeciesProgram

Which Herbicide Should I Use?(Submersed Plants)

Plant Contact SystemicVariable Watermilfoil Carfentrazone

Diquat Flumioxazin 2,4-DTriclopyrFluridoneImazamox

Fanwort Flumioxazin FluridoneCurlyleaf Pondweed Diquat

EndothallFlumioxazin

FluridoneImazamox

Eurasian Watermilfoil Diquat Flumioxazin CarfentrazoneEndothall

FluridoneTriclopyr 2,4-D

Variable Milfoil(Myriophyllum heterophyllum)

Decisions driven by SCIENCE, RESEARCHand FIELD EXPERIENCE

2007 Study by the U.S. Army Corps of Engineers on Variable Milfoil from New Hampshire

d

d

Navigate (2,4-D)o Formulation: Granular (BEE)

o Mode of Action: Systemic – auxin mimic, inhibits cell division in new tissue and stimulates growth of existing tissue

o Environmental Fate: Hydrolosis, microbial degradation, photolysis

o Water Use Restrictions: Drinking < 70 ppb, Irrigation < 100 ppb

o Advantages: fairly selective for broad-leaf (dicot) species, multiple year control, effective for spot-treatments

o Limitations: water use restrictions, negative public perception

o Plants Controlled: Milfoil, Water Chestnut, Waterlilies, Watershield

• Treatment timing• Navigate product placement• Concentration exposure time

What have we learned…

Innovating Lake Fronts

• What if Watermilfoil could be eliminated?

– Restoring your pristine lake– Selectively leaving native plants– Protect your property values

Day of Treatment - Eurasian Watermilfoil

14 DAT

• New herbicide active– R&D since 2010

• New systemic technology• Low-dose activity • Fast-acting• Milfoil seeking technology• Excellent human health and environmental

profile– reduced risk in current US EPA review– Fall 2017 registration anticipated

This information is for educational purposes only. PROCELLACOR is not yet registered or approved for sale or use in the U.S.

Northeast Field Demonstration of Invasive Watermilfoil Control

• Cooperative effort with New Hampshire DEC and USACE New England District / APCRP

• 1-acre partial-site application to invasive variable watermilfoil (M. heterophyllum) at the Hopkinton-Everett Flood Control Area

• Special permit from NH Department of Agriculture in consultation with EPA

• Full control of affected water use per experimental testing requirements

Pre-Treatment Conditions in Hopkinton treatment Area (mid July 2016): 3 – 5 feet of water

Remnant VWM condition in treatment area@ 6 weeks post treatment

VWM condition outside treatment area@ 6 weeks post treatment

Partial control of watershield and short-term injury to water water lily in immediate area of application.

No impact to Robbins pondweed, American pondweed, and multiple bladderworts.

3 weeks post treatment

6 weeks post treatment

10 months post treatment

Exceeding Expectations

• Procellacor is a new milfoil herbicide active

– Solitude is a Applicator

– Restores lakes with its plant seeking technology

– Low dose, systemic, and selective

– Protect property values

– The new standard for milfoil management

Questions?