Post on 14-Mar-2018
Evaluation of Herbicide Applications for Control of Aquatic Invasive Species
Michelle NaultWDNR Research
John SkogerboeU.S. Army Corps of Engineers
APM in the Ceded TerritoryLCO Convention Center
December 5, 2012
EWM Distribution
CLP Distribution
Research Questions About EWM & CLP
1) Ecology-What are the possible outcomes when EWM or CLP is introduced to a lake?
-What factors contribute to different outcomes?-Interannual variation?
2) Management-Past management (non-strategic) = short term nuisance relief?
-Future management (strategic) = long term reduction and restoration?
Implementation Considerations
• Management tool(s)• Management goal(s)• Timing (seasonality, weather, water temps)• Herbicide products and formulations• Application rates• Flowing water, water level management• Lake type, size, bathymetry, water chemistry• Target and non-target plant species
NR 107 Aquatic Plant Management –Chemical Use.
“NR 107.01. Purpose. The purpose of this chapter is to establish procedures for the management of aquatic plants and control of other aquatic organisms pursuant to s. 227.11 (2) (a), Stats., and interpreting s. 281.17 (2), Stats. A balanced aquatic plant community is recognized to be a vital and necessary component of a healthy aquatic ecosystem. The department may allow the management of nuisance-causing aquatic plants with chemicals registered and labeled by the U.S. environmental protection agency and labeled and registered by firms licensed as pesticide manufacturers and labelers with the Wisconsin department of agriculture, trade, and consumer protection. Chemical management shall be allowed in a manner consistent with sound ecosystem management and shall minimize the loss of ecological values in the water body.”
Engineer Research and Development CenterUS Army Corpsof Engineers
Objectives of Invasive Aquatic Plant Management Using Herbicides
1. Efficacy: Control invasive exotic aquatic plants
2. Selectivity: Minimize adverse impacts to native plants, protect native aquatic plants from invasives
Engineer Research and Development CenterUS Army Corpsof Engineers
US EPA
University of Florida,Center for Aquatic &
Invasive Species
US Army Engineer Research and Development
Center
Lewisville Aquatic Ecosystem
Research Facility
Eau Galle Aquatic Ecosystem
Research Facility
US Army Engineer Research and Development Center (ERDC)
Engineer Research and Development CenterUS Army Corpsof Engineers
Research Partners
Engineer Research and Development CenterUS Army Corpsof Engineers
Primary Invasive Species and Aquatic Herbicides
Eurasian Watermilfoil & Hybrid milfoil
1. 2,4-D
2. Endothall
3. Triclopyr
4. Fluridone
5. Diquat
Curly-leaf pondweed
1. Endothall
2. Fluridone
3. Diquat
Engineer Research and Development CenterUS Army Corpsof Engineers
Indoor Growth Chambers and GreenhouseGrowth Chambers, Vicksburg, MS
Greenhouse,Lewisville, TX
• Wide range of herbicide conc. and exposure times
•Replicated studies
•Temperature
•Light intensity and duration
•Water quality
Environmentally Controlled
Engineer Research and Development CenterUS Army Corpsof Engineers
Outdoor Mesocosms
•30, 7000 L tanks
•Flow rate controls
24, 1100 L shallow tanks
Engineer Research and Development CenterUS Army Corpsof Engineers
Eurasian Watermilfoil Efficacy2,4-D Concentration/Exposure Time Relationship
J. Aquat. Plant Manage 30: 1-5
Engineer Research and Development CenterUS Army Corpsof Engineers
Concentration/Exposure Time RelationshipEndothall (Aquathol K)
J. Aquat. Plant Manage 30: 1-5
•Degradation vs dissipation
•Project scale
Engineer Research and Development CenterUS Army Corpsof Engineers
Herbicide Selectivity
> 85% Control
Eurasian watermilfoil
American elodea
J. Aquat. Plant Manage 30: 1-5
Engineer Research and Development CenterUS Army Corpsof Engineers
Herbicide Selectivity
•Concentration, Exposure Time
•Species sensitivity
Engineer Research and Development CenterUS Army Corpsof Engineers
Minimum Exposure Time Requirements for Eurasian Watermilfoil Control
• 2,4-D: > 18 hours• Endothall: > 18 hours• Triclopyr: > 18 hours• Fluridone: > 60 days• Diquat: > 1 hour
Engineer Research and Development CenterUS Army Corpsof Engineers
Herbicide Treatment Categories
• Whole Lake Treatments
• Spot Treatments
• Micro Spot Treatments (< 5 acres ?)
• Flowages (Mohawksin, WI) and Complex Mega Lakes (Lake Minnetonka, MN)
Herbicide Monitoring Project Lakes•Legend, Menominee•Connors, Sawyer•Lower Spring, Jefferson•Kathan, Oneida•Enterprise, Langlade•English, Manitowoc•Forest, Fond du Lac•Wilson, Price•Antigo, Langlade•Washington, Shawano
•Monona (Turville), Dane•Tomahawk/Sandbar, Bayfield•Eagle, Racine•Half Moon, Eau Claire•Loon, Shawano•Big Sand, Vilas•Long, Vilas•South Twin, Vilas•North Twin, Vilas•Little St. Germain, Vilas•Eagle River Chain, Vilas•Frog, Florence•Jordan, Adams•Kettle Moraine, Fond du Lac•Metonga, Forest•Minocqua, Oneida•Kawaquesaga, Oneida•Tomahawk, Oneida•Bridge, Oneida/Lincoln •Mohawksin, Lincoln
•Tomahawk/Sandbar, Bayfield Co.•South Twin, Vilas Co.•Forest, Fond du Lac Co.
•Connors, Sawyer Co.•Little St. Germain, Vilas Co.
Small
Scale
Whole
Lake
Whole Lake Small Scale
Case Studies
•Wilson Lake, Price Co.Flowage
Flowage
2,4-D Concentration/Exposure Time
Green & Westerdahl, 1990JAPM 28:27-32
Recommended label rate: 2.0 – 4.0 ppm
ppm
ae
2.0
0.5
1.5
1.0
(Hours) 1.0 ppm = 1.0 mg/L = 1000 ppb
‘High’ doseShort exposure
‘Low’ doseLong exposure
Herbicide Exposure Time
• Dissipation– Water flow– Wind– Treatment area relative to lake– Water depth
• Degradation– Microbial– Photolytic
Application Timing/PhenologyEarly Spring Herbicide Applications
•Exotic species are small and most vulnerable
•Many native species are dormant
•Cool water temperatures result in slower microbial degradation
•Minimize biomass decomposition
Herbicide Water Sample Collection
Immunoassay Test (ELISA)
Aquatic Plant Surveys – Hauxwell et. al 2010
Survey Methods
2,4-D Concentration/Exposure Time
Green & Westerdahl, 1990JAPM 28:27-32
Recommended label rate: 2.0 – 4.0 ppm
mg/
L ae
2.0
0.5
1.5
1.0
Whole Lake Treatments
(Hours) 1.0 mg/L = 1.0 ppm = 1000 ppb
1) What are the effects of early season 2,4-D on Eurasian watermilfoil?
2) What about native plants?
Approach: Monitor annual changesin plant communities in experimental lakes (herbicide or reference)
Sandbar/TomahawkWDNR, Army Corps of Engineers, Town of Barnes,
Bayfield County
No Treatment
2,4-D Treatment
Study design
• Low dose liquid 2,4-D (0.5 ppm) treatment to whole lake (May 20, 2008)
• Aquatic plant surveys conducted 2006-2012
• Biomass collected during 2007-2012 surveys
• Reference lake – no treatment (2007 - 2010)
• Low dose liquid 2,4-D (0.275 ppm) treatment to whole lake epilimnion(spring 2011)
• Aquatic plant surveys and biomass collected during 2007-2012
Tomahawk Sandbar
Tomahawk vs. Sandbar, Bayfield Co.July 2007 Summary Stats
Tomahawk Sandbar
Lake size (ha) 53.1 51.3
Maximum depth (m) 12.8 14.9
Maximum depth of plant colonization (m)
6.8 7.0
Percentage of littoral zone vegetated 86.4 86.8
Number of species 20 17
Mean number of species per site (littoral)
2.6 2.8
Simpson’s Diversity Index 0.90 0.89
Eurasian watermilfoil frequency of occurrence within littoral zone (%)
39.9 25.8
Tomahawk Lake, Bayfield Co.2006 - 2012 Summary Stats
0
10
20
30
40
% F
requ
ency
of O
ccur
renc
es (L
ittor
al)
Species
Tomahawk Lake, Bayfield Co.Species % Frequency of Occurrences
2006200720082009201020112012
* = p ≤ 0.05** = p ≤ 0.01
*** = p ≤ 0.001
*
***
***
******
***
***
***
****
**** *
***
**
*****
***
*
**
*
*
**
***
*
Herbicide Sample Locations
Collected pre-, 1, 2, 3, 5, 7, 14, 21, 28, 35, 42, 49, 56+ days after treatment
Tomahawk 2,4-D Concentrations
0
100
200
300
400
500
600
700
800
900
1000
0 20 40 60 80 100 120 140 160 180
Days after treatment
2,4-
D re
sidu
es, u
g/L
T1T2T3T4T5
Application Rate = 0.5 ppm (500 µg/L)
Sandbar Lake, Bayfield Co.2007 - 2012 Summary Stats
0
10
20
30
40
50
60
% F
requ
ency
of O
ccur
renc
es (L
ittor
al)
Species
Sandbar Lake, Bayfield Co.Species % Frequency of Occurrences
200720082009201020112012
* = p ≤ 0.05** = p ≤ 0.01
*** = p ≤ 0.001
*
***
********
*
***
Sandbar EWM
Sandbar 2,4-D ConcentrationsSandbar Lake 2,4-D Herbicide Concentrations, 2011
Application Rate = 0.275 ppm (275 µg/L)
Sandbar 2,4-D ConcentrationsSandbar Lake 2,4-D Herbicide Concentrations, 2011
Application Rate = 0.275 ppm (275 µg/L)
Stratified Lake
Mixed Lake
Lake Depth Stratification
No TreatmentTomahawk Sandbar 2,4-D
Treatment2,4-D Treatment
Water Quality
1) What are the effects of early season 2,4-D on Eurasian watermilfoil?
2) What about native plants?
Approach: Monitor annual changesin plant communities pre- and post-treatment
South Twin Lake, Vilas Co.WDNR, Army Corps of Engineers, Onterra LLC
2,4-D Treatment
South Twin, Vilas Co.• EWM discovered July 2001
• Spring 2009: Liquid 2,4-D applied to EWM areas at 1.75 ppm (lakewide target = 0.167ppm)
• May 2010: Liquid 2,4-D applied to EWM areas at 2.5 ppm (lakewide target = 0.24 ppm)
• Pre- and post-treatment aquatic plant surveys 2008-2011 by Onterra LLC
SOUTH TWIN, VILAS
Lake size (acres) 627.71Max depth (ft) 43
Avg depth 20Lake type Drainage
South Twin Lake, 2010 2,4-D Herbicide Residuals
0
500
1000
1500
2000
2500
0 7 14 21 28 35 42
Days after treatment
Con
cent
ratio
n (µ
g/L
ae)
Mean TreatedMean UntreatedLakewide TargetIrrigation Limit
Lakewide DissipationSouth Twin Lake, 2010
2,4-D Herbicide Concentrations2.5
2.0
1.5
1.0
0.5
0
Con
cent
ratio
n (p
pm)
South Twin – Chi Square
Forest Lake, Fond du Lac Co.• EWM first discovered 1992 • DNA analysis confirmed as
M. spicatum X M. sibiricum• Liquid 2,4-D applied to five
sites at 0.6 ppm on May 18, 2011
• Whole-lake target = 0.305 ppm• Lake volume factored in
stratification at ~15 feet• EWM surveys pre- and post-
treatment by Onterra LLC
FOREST, FOND DU LAC
Lake size (acres) 51
Max depth (ft) 32
Avg depth 11
Lake type Seepage
Forest 2,4–D ConcentrationsForest Lake 2011, 2,4-D Herbicide Concentrations, <10 feet deep
Forest Lake 2,4-D Herbicide Residuals
0
50
100
150
200
250
300
350
0 7 14 21 28 35
Days after treatment
Con
cent
ratio
n (µ
g/L
ae)
5 ft10 ft15 ft20 ft25 ftTarget Conc.
Lake Stratification
Forest Lake, 2,4-D Herbicide Concentrations
Forest LakeHybrid EWM Spring 2011
Legend
EWM Rake Fullness = 1!(
EWM Rake Fullness = 2!(
EWM Rake Fullness = 3!(
73%
23%
4%
Spring 2011Courtesy of Onterra
Forest LakeHybrid EWM Summer 2011
Legend
EWM Rake Fullness = 1!(
EWM Rake Fullness = 2!(
EWM Rake Fullness = 3!(
89%
10%
1%
Summer 2011Courtesy of Onterra
Wilson Lake, Price Co.• EWM first discovered August
2002 • Spring 2012: Liquid 2,4-D
applied to three sites at 1.0-1.7 ppm
• Whole-lake target = 0.331 ppm• Aquatic plant surveys pre- and
post-treatment by Onterra LLC• Herbicide concentration data
collected within and outside treatment areas
WILSON, PRICE
Lake size (acres) 348
Max depth (ft) 11
Avg depth 6
Lake type Drainage
Wilson Lake, Price Co.
Wilson Lake, Price Co.
Wilson Lake, Price Co.
Wilson Lake, Price Co.Statistically Valid p-value
Myriophyllum spicatum Eurasian w ater milfoil 11.7 0.0 -100.0 ▼ Yes 0.000Ceratophyllum demersum Coontail 44.4 9.7 -78.2 ▼ Yes 0.000Nymphaea odorata White w ater lily 9.2 9.7 5.6 ▲ No 0.863Nuphar variegata Spatterdock 2.6 2.0 -20.0 ▼ No 0.736Brasenia schreberi Watershield 1.0 0.5 -50.0 ▼ No 0.562Myriophyllum sibiricum Northern w ater milfoil 0.5 0.0 -100.0 ▼ No 0.317Utricularia vulgaris Common bladderw ort 0.0 0.5 100.0 ▲ No 0.317Potamogeton robbinsii Fern pondw eed 33.7 14.3 -57.6 ▼ Yes 0.000Potamogeton zosteriformis Flat-stem pondw eed 12.2 1.0 -91.7 ▼ Yes 0.000Potamogeton pusillus Small pondw eed 5.6 0.5 -90.9 ▼ Yes 0.003Chara spp. Muskgrasses 3.1 0.0 -100.0 ▼ Yes 0.014Najas flexilis Slender naiad 3.1 0.0 -100.0 ▼ Yes 0.014Vallisneria americana Wild celery 2.0 0.0 -100.0 ▼ Yes 0.044Elodea canadensis Common w aterw eed 9.2 4.6 -50.0 ▼ No 0.073Potamogeton amplifolius Large-leaf pondw eed 4.6 7.7 66.7 ▲ No 0.206Nitella spp. Stonew orts 4.1 6.1 50.0 ▲ No 0.359Lemna trisulca Forked duckw eed 3.1 0.5 -83.3 ▼ No 0.057Potamogeton epihydrus Ribbon-leaf pondw eed 2.6 0.5 -80.0 ▼ No 0.100Spirodela polyrhiza Greater duckw eed 2.0 0.5 -75.0 ▼ No 0.177Potamogeton natans Floating-leaf pondw eed 1.5 2.0 33.3 ▲ No 0.703Eleocharis palustris Creeping spikerush 1.0 0.0 -100.0 ▼ No 0.156Eleocharis acicularis Needle spikerush 0.5 0.0 -100.0 ▼ No 0.317Potamogeton spirillus Spiral-fruited pondw eed 0.5 0.0 -100.0 ▼ No 0.317Sagitaria sp. (rosette) Arrow head rosette 0.5 0.0 -100.0 ▼ No 0.317Sagittaria rigida Stiff arrow head 0.5 0.0 -100.0 ▼ No 0.317Typha spp. Cattail spp. 0.5 0.0 -100.0 ▼ No 0.317Lemna turionifera Turion duckw eed 0.0 1.0 100.0 ▲ No 0.156Schoenoplectus acutus Hardstem bulrush 0.0 0.5 100.0 ▲ No 0.317Sparganium emersum Short-stemmed bur-reed 0.0 0.5 100.0 ▲ No 0.317
2011 & 2012 N = 196LFOO = Littoral Frequency of Occurrence▲ or ▼ = Change Statistically Valid (Chi-square; α = 0.05)▲ or ▼ = Change Not Statistically Valid (Chi-square; α = 0.05)
Chi-square AnalysisScientific Name Common Name
Dic
ots
Non
-dic
ots
2011 LFOO 2012 LFOOPercentChange Direction
EWM Control
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7Mean 2,4-D Concentration 0-7 DAT (ppm)
EWM Control
High level of control
Damage to natives
No control
Seasonal control
Damage to some natives
???
Focus area
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7Mean 2,4-D Concentration 0-7 DAT (ppm)
Native Species
Preliminary Findings• Recommended label concentrations may not be
applicable for whole lake or large scale treatments • Herbicide dissipation is rapid and large scale treatments
can result in a whole-lake treatment if the scale of the treatment area is large compared to the overall lake volume
• Lake stratification and water temperature are important to consider when calculating volume
• Early spring, large scale treatments may result in longer persistence of herbicides than expected; may exceed 100 ppb (0.1 ppm) for >21 days
• EWM control looks promising, however short-term damage to certain native species may occur and long term effects on biotic and abiotic parameters is uncertain
• Hybrid watermilfoils need to be better documented and studied in both field and laboratory studies
• Herbicide monitoring is important, both to understand treatment efficacy, as well as ecological risks
2,4-D Concentration/Exposure Time
Green & Westerdahl, 1990JAPM 28:27-32
Recommended label rate: 2.0 – 4.0 ppm
ppm
2.0
0.5
1.5
1.0
(Hours)
Small scale Treatments
1.0 ppm = 1.0 mg/L = 1000 ppb
Connors – Treatment Map
Connors – 2,4-D ConcentrationConnors Lake, Sawyer Co.
2,4-D Herbicide Residuals 2010
0
200
400
600
800
1000
1200
0 24 48 72 96 120 144 168
Hours After Treatment (HAT)
Con
cent
ratio
n (µ
g/L
ae)
C-1C-2C-3C-4Irrigation Standard
Connors Lake, Sawyer Co.
2,4-D Herbicide Concentrations 2010
Area vs. Concentration 24 HAT
Connors Lake, Sawyer Co. 2,4-D Herbicide Residuals 2010
0
500
1000
1500
2000
2500
3000
3500
0 24 48 72
Hours After Treatment (HAT)
Con
cent
ratio
n (µ
g/L
ae)
Mean Bay Sites (A,D,E)
Mean Exposed Sites (F, G, H, I)
100 µg/L ae
Connors – 2,4-D ConcentrationConnors Lake, Sawyer Co.
2,4-D Herbicide Concentrations 2010
Treatment Site LocationProtected vs. Exposed Sites
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 5 10 15 20 25 30 35 40 45
Area (acres)
Mea
n [2
.4-D
] 0-2
4 H
AT
ProtectedExposed
Connors Lake, Sawyer Co. 2,4-D Herbicide Residuals 2010
0
100
200
300
400
500
600
700
0 6 12 18 24
Hours After Treatment (HAT)
Con
cent
ratio
n (µ
g/L
ae)
Mean BottomMean SurfaceIrrigation Standard
Connors – 2,4-D ConcentrationConnors Lake, Sawyer Co.
2,4-D Herbicide Concentrations 2010
Endothall Treated Area: 35 acPercent treated area: 4% Target Conc. = 1.05 ppm
2,4-D Treated Area: 29.3 ac Percent treated area: 3%Target Conc. = 2.23-2.43 ppm
Little St. Germain, Vilas Co.
Little St Germain Endothall Concentrations, 2011Site CLP B-11(E)
0
200
400
600
800
1000
1200
1400
1600
1800
0 6 12 18 24 30
Hours After Treatment
Endo
thal
l Con
cent
ratio
n, u
g/L
ae
Surface Mean Bottom Mean
Target Concentration Detection Limit
Little St. Germain, Vilas Co. Endothall
Little St Germain 2,4-D Residual Concentrations, 2011Site H-11 (D)
0
50
100
150
200
250
300
0 6 12 18 24 30Hours After Treatment
2,4-
D C
once
ntra
tion,
ug/
L ae
Surface Mean Bottom Mean
Irrigation Std
Little St. Germain, Vilas Co. 2,4-D
2,4-D Concentration/Exposure Time
Green & Westerdahl, 1990JAPM 28:27-32
Recommended label rate: 2.0 – 4.0 ppm
mg/
L ae
2.0
0.5
1.5
1.0
(Hours) 1.0 mg/L = 1.0ppm = 1000 ppb
Small scale treatments
Preliminary Findings• Actual CET in the field is more difficult to predict
and maintain in smaller scale treatments• Aquatic plant data is more difficult to collect and
analyze in smaller scale treatments• Rapid dissipation occurred and concentrations
were < 100 ppb (0.1 ppm) by 24 HAT in many treatment sites
• Mean concentrations in the protected sites were greater than those from the more exposed sites
• Granular formulation did result in a vertical gradient from top to bottom, however horizontal dissipation through the water column was rapid and similar to liquid formulations
Wild Rice Selectivity Literature• Nelson, Owens & Getsinger (2003). ACOE ERDC Tech Report.
• Invasion of exotic plants may contribute to the decline and displacement of wild rice
• Controlled tank study examining four herbicides at varying application rates and wild rice growth stages
• Wild rice treated at earlier growth stages (early tillering or seedling) was more sensitive to chemical treatment
• Wild rice treated at the mature growth stage (late tillering and flowering) was not affected
• Endothall, diquat and fluridone reduced dry weight but not seedhead or tiller production
• 2,4-D rates of 1.0 ppm sustained for 7 DAT inhibited production in young wild rice
Wild Rice Selectivity Literature• Madsen et al. (2009). J. Aquatic Plant Mgmt.
• Controlled tank study examining the herbicide triclopyr at
varying application rates and wild rice growth stages
• Wild rice exposed to 0.75 ppm for 72 hours did not reduce
height, biomass, seed density or tiller production
• Wild rice exposed to 2.5 ppm for 72 hours reduced height and
biomass
• Wild rice seedlings exhibited the greatest sensitivity to triclopyr,
while young and mature plants were more tolerant
Next Steps• The WDNR and Army Corps of Engineers have compiled
a draft summary report of the herbicide monitoring project case studies, and will continue with a final synthesis
• Continue evaluation of the longevity of whole lake and large scale treatment impacts as well as native plant and water quality responses
• Continue evaluation and monitoring of the efficacy of small scale treatments utilizing different application techniques and formulations
• Further exploration of hybrid water milfoils and effectiveness of herbicide treatments
• Further exploration of potential direct and indirect impacts on other organisms
Deciding on the best management approach:
1) Quantify the problem – collect data!
2) Set reasonable expectations and goals (ecological and economical)
3) Weigh the benefits with the risks
4) Recognize that managing invasives is a long-term commitment with any tool (action based on data)
DISCUSSION
michelle.nault@wisconsin.gov608-221-6359