Download Slide 1

Meddlesome milfoils:
Parrotfeather & Eurasian watermilfoil
Vanessa Morgan
Center for Lakes and Reservoirs
Aquatic Weed Workshop
Salem, Oregon
April 24, 2014
Overview
•
•
•
•
•
•
Haloragaceae (water-milfoil family)
Eight genera;±100 species
Dicot
Annual & perennial herbs
Generally monoecious & aquatic
Myriophyllum spp.
– 30 species worldwide
– 14 in North America
– 3 non-natives + hybrid(s) in PNW
– Some commonly cultivated
Overview
•
•
•
•
•
Identification
Impacts
Habitats & growth habits
Reproduction and dispersal
Control options
– Non-chemical
– Chemical
Parrot feather
(M. aquaticum)
Eurasian watermilfoil
(M. spicatum)
Whorled watermilfoil
(M. verticillatum)
Andean watermilfoil
(M. quitense)
V. Morgan, PSU-CLR
V. Morgan, PSU-CLR
Northern watermilfoil
(M. sibiricum)
A. Hipp, U of WI-Stevens Point
©2012 Vernon Smith
J. Parsons, WA DOE
Hybrid watermilfoil
(M. spicatum × sibiricum)
michiganlakeinfo.com
Variable-leaf watermilfoil
(M. heterophyllum)
V. Morgan, PSU-CLR
L.J. Mehrhoff, U of CT, Bugwood.org
© 2014 Donald Cameron
L.J. Mehrhoff, U of CT, Bugwood.org
Milfoil Character Comparison
submerged leaves
Status in PNW # leaflet pairs
leaf size
leaves/whorl
emergent leaves (bracts)
winter buds (turions)
Northern watermilfoil
(Myriophyllum sibiricum)
NATIVE
<14 (5-14) < 4 cm long
3 to 5
reduced (1-3 mm long);
smaller than flowers
yes
whorled watermilfoil
(Myriophyllum
verticillatum)
NATIVE
<14 (5-14)
< 5 cm long
4 to 5
2-10 mm long;
deeply pinnately lobed
yes
Andean watermilfoil
(Myriophyllum quitense)
NATIVE
5-10
1.5 - 4 cm
long
2 to 5
0.5-1 cm long;
partially toothed
yes
10-15
1.5 - 3.5 cm
long
3 to 6
2-5 cm long; 16-18 leaflet
pairs
stiff, waxy, bright green
no
> 14 (12-24) 2 - 4 cm long
3 to 6
reduced (1-3 mm long);
smaller than flowers
no
yes
?
Parrot feather
(M. aquaticum)
INVASIVE
Eurasian watermilfoil
(M. spicatum)
INVASIVE
Variable-leaf watermilfoil
(M. heterophyllum)
INVASIVE
5-12
2-4 cm long
4 to 6
0.5 - 3 cm long;
larger than flowers;
serrated/lobed
Hybrid watermilfoil
(M. spicatum × sibiricum)
INVASIVE
8-19
1.5-4.2 cm
long
?
?
ID Verification
• Multiple samples should be taken prior to any treatment
• Morphological samples:
CLR, PSU
• Genetic verification:
Annis Water Resources
Institute, Grand Valley
State University, MI
(Moody & Les 2007)
Impacts
• Altered habitats
– Outcompetes native plants
– Hybridization with native milfoil species
– Loss of fish spawning areas
– Predator-prey relationships
• Altered food web dynamics
– Loss of native food sources for waterfowl
– Reduced phytoplankton
• Water quality (temperature, oxygen, pH)
• Irrigation – clogging pumps & intakes
• Increased mosquito breeding ground
• Recreational uses (boating, swimming, fishing) – 1% decrease in
recreation = $500K loss in recreation) (Eiswerth et al. 2000).
EWM Habitats & Growth
•
•
•
•
•
•
•
•
•
Lakes, reservoirs, ponds, rivers, and streams
Fresh to brackish water (up to 15 ppt)
Depth: (0.5) 1-5 (10) meters
pH range: 5.4 to 11
Fine-textured, inorganic sediment
Early & rapid spring growth (water temp >15 ͦ C )
Tops out in water < 5 m
Autofragmentation in fall/early winter
Overwintering root crowns
• Fragments
– Autofragmentation
– Allofragmentation
www.brantlakemilfoil.org
Reproduction & dispersal
(boats, swimmers, control efforts)
• Seed (EWM & Hybrids)
• Water movement &
Waterfowl
• Aquaria dumps,
boats/trailering, bait buckets
Osceola County, Hydrilla Dem. Proj.
Rich Miller, PSU-CLR
Non-Chemical Control Options
Method
Description
Pros
Cons
Used in
Dredging
mechanical
sediment removal
long-term control
expense,
non-selective
shallow small ponds
Drawdown
dewatering
4-8 wks
effective on certain
species
environ. impacts,
non-selective
Small, man-made
lakes/ponds
Benthic
barriers
material covers
plants
effective, long
lasting
non-selective, small
scale, maintenance
near docks, launches, small
areas
Hand
cutting/pulling
tools or hand
pulling
selective
labor intensive,
expensive
localized area, rapid
response to new infestations
Harvesting
mechanical
cutting &
collection
removes biomass
expensive, sediment
disturbance, short
term, non-selective
heavy infestations with
little/no natives
Diver
dredging
vacuum removal
of whole plants
selective, longerterm, reduced
sediment disturb.
expensive, slow
localized area, rapid
response to new/recent
infestations
Rotovation
aquatic cultivator,
tills sediments
intermediate
results
sediment
disturbance, spread
of fragments
heavy infestations with
little/no natives
Biocontrol
insects, fish, etc..
selective, longterm
expensive, variable
results
heavy infestations
Non-Chemical Control Options
Method
Est. cost
Dredging
variable
Drawdown
variable
Benthic barriers
Hand cutting/pulling
Harvesting
$0.40-0.50/sq. ft.
variable
$2,500-3,000/day
$500-1,000/acre
Diver dredging
$1,500-2,000/day
(1/4 to 1 acre/day)
Rotovation
$1,500-2,000/day
Biocontrol
Carp - $5-20/fish
Milfoil weevils - $1.20/ind.
Parrotfeather
(M. aquaticum)
Eurasian watermilfoil
(M. spicatum)

?
?
?


?



?



?
?
EWM Chemical Control Options
• Whole lake/pond treatments
– Goal: eradication of heavy infestations
– Systemics (fluridone, 2,4-D, triclopyr) offer
excellent control
• Partial or spot treatments
– Goal: suppress EWM growth, allow native plant
recovery
– Contact herbicides (endothall, diquat) offer good
control
Prerequisites for Efficacy
• Adequate concentration & contact time
– Water exchange & plant biovolume
• Proper placement (proximity for uptake)
• Optimal season and phenological stage
• Appropriate water quality
– Turbidity interferes with diquat
Application methods
• Liquids
Clean Lakes, Inc.
• Boat-mounted hose for subsurface injections
• Foliar sprays
Vassios et al. 2014
• Pelletized & granular
formulations (slow & quick release)
• Boat mounted
hopper/spreader to ensure
even application
* boat speed; rate of delivery from the
spreader; swath width
University of Florida, IFAS Extention
EWM Control cont…
• Fluridone (Sonar, Avast!)
– Systemic, slow acting (45-90 days)
– Selective at low doses, non-selective at higher rates
• 8-10 ppb maintained for 10 wks (16-75 ppm
recommended label rates)
• FasTEST (SePRO) determines concentration &
any needed bump treatments
Reference to specific tradenames is not intended as an endorsement
EWM Control cont…
• 2,4-D
– Systemic, fast acting; selective treats dicots
– Formulations
• Granular – butoxy-ethyl-ester
– Navigate and Aqua-Kleen; toxic to fish/aquatic inverts
– 100-200 lbs/acre
• Liquid - dimethylamine salt
– DMA*4IVM;
– 4 ppm (2.84 gal/acre foot)
EWM Control cont…
• Triclopyr (Renovate 3 – liquid; Renovate OTF – granular)
– Systemic, fast acting
– Selective treats dicots; native pondweed species
and coontail, rushes and cattails unaffected
– Liquid - 0.75 to 2.5 ppm a.e.; sinking agent > 6’
– Granular – 0.5 to 2.5 ppm a.e.
Chemical - recent developments
• Flumioxazin (Clipper)
– Non-selective, liquid contact herbicide
– 200-400 ppb submersed
– Quick kill – potential dissolved oxygen problems
• Bispyribac-sodium (Tradewind)
– Non-selective; slow acting, wetable powder
– 20-45 ppb, maintained for 60-90 days
• Use patterns still developing
(EWM)
Chemical - recent
developments
• Long-term exposure, low rates of
2,4-D or triclopyr may provide
control for EWM & hybrids (Glomski
et al. 2010, Poovey et al. 2007)
– Individual hybrid population
responses
– Impacts to native plants
(hybrid milfoil)
(Glomski et al. 2010)
EWM Chemical Control Options
• Whole lake/pond treatments
– Goal: eradication of heavy infestations
– Systemics (fluridone, 2,4-D, triclopyr) offer
excellent control
• Partial or spot treatments
– Goal: suppress EWM growth, allow native plant
recovery
– Contact herbicides (endothall, diquat) offer good
control
EWM Chemical cont…
• Contact herbicides
– Diquat dibromide (Reward, Weedtrine)
• nonselective, liquid contact herbicide
• Not for use in turbid waters
• 0.5-2.0 gal/surface acre
– Endothall (dipotassium salt-Aquathol, Cascade)
• nonselective, liquid or granular
• spot treatments 3.0-5.0 ppm
• Control is temporary – root crowns not killed
• Quick kill – potential dissolved oxygen problems
Parrotfeather Habitats & Growth Habits
• Lakes, ponds, canals, and
other slow moving waters
• High nutrient inputs
• Depth: wet banks to 2 m
• pH range: 6.8 to 8
• Temperature:16 to 23 ͦ C
• Emergent growth ~ 1’ above water; lateral, branching
stolons
• Flowers form in spring, no seed production
• Submersed leaves senesce in early summer
Wersal and Madsen 2011
Parrotfeather Control
• Robust rhizomes
• Waxy cuticle on emergent leaves,
requires wetting agent
• Use of contact herbicides (diquat &
endothall) of limited use
• No single treatment effective
– Imazapyr & triclopyr most
promising for long-term control
Parrot feather – foliar applications
• Imazapyr (Habitat, Arsenal)
– Inhibits plant-specific enzyme (ALS-inhibitor)
– Slow-acting, moderate residual soil activity
– 2-4 pints/acre to actively growing emergent foliage
• Triclopyr (Renovate 3)
– 1.0 to 2.5 ppm a.e/acre
– Good to fair canopy knockdown, rapid regrowth
•
Imazamox (Clearcast)
– Slow-acting, impacts 60-120 days
– Fair canopy suppression
– 1-2 pints/acre
Wersal & Madsen 2007
Parrot feather – subsurface
• Triclopyr (Renovate Max G, Navitrol DPF)
– 1.0 to 2.5 ppm a.e./acre
– repeat treatments needed
• Endothall (Aquathol K, Aquathol Super K, Cascade)
– Whole pond/large area: 2.0-3.0 ppm (1.3-1.9 gal/ac.ft.
liquid; 8.8-13.2 lbs/ac.ft granular)
– Spot treatments: 3.0-5.0 ppm (1.9-3.2 gal/ac.ft. liquid; 13.222 lbs/ac.ft granular)
Considerations
• Proper identification & verification
• Repeat treatments & continued monitoring
• Timing – target plants actively growing and, when
possible, when non-target plants are dormant
• Consider IPM approach
• Upstream/nearby propagule source
• Secondary invasion (replacing EWM with curly pondweed?)
• Chemical treatments:
– Partial treatments – 1/3 to 1/2 of total area
– Use restrictions (drinking, livestock, irrigation, swimming)
– “The label is the law”
Resources
• Biology and Control of Aquatic Plants: A Best
Management Practices Handbook
(http://www.aquatics.org/aerf_handbook.pdf)
• PNW Weed Management Handbook
(http://pnwhandbooks.org/weed/)
• WA Dept. of Ecology, Aquatic Plant Management
(http://www.ecy.wa.gov/programs/wq/plants/plantmgmt.html)
• Information Center Online (PICOL) Databases
(http://picol.cahe.wsu.edu/LabelTolerance.html)
References
•
•
•
•
•
•
•
•
Eiswerth, M. E., Donaldson, S. G., & Johnson, W. S. (2000). Potential Environmental Impacts and
Economic Damages of Eurasian Watermilfoil (Myriophyllum spicatum) in Western Nevada and
Northeastern California 1.Weed Technology, 14(3), 511-518.
Glomski, L. M., & Netherland, M. D. (2010). Response of Eurasian and hybrid watermilfoil to low
use rates and extended exposures of 2, 4-D and Triclopyr.Journal of Aquatic Plant Management
(JAPM), 48, 12.
Hofstra, D. E., Champion, P. D., & Dugdale, T. M. (2006). Herbicide trials for the control of
parrotsfeather. Journal of Aquatic Plant Management, 44(1), 13-18.
Moody, M. L., & Les, D. H. (2007). Geographic distribution and genotypic composition of invasive
hybrid watermilfoil (Myriophyllum spicatum× M. sibiricum) populations in North
America. Biological invasions, 9(5), 559-570.
Patten, K. (2007). Parrotfeather milfoil (Myriophyllum aquaticum) – Assessment of management
alternatives. Final Progress report to WA Dept. of Ecology.
Poovey, A. G., Slade, J. G., & Netherland, M. D. (2007). Susceptibility of Eurasian watermilfoil
(Myriophyllum spicatum) and a milfoil hybrid (M. spicatum x M. sibiricum) to triclopyr and 2, 4-D
amine. J. Aquat. Plant Manage, 45, 111-115.
Vassios, J. D., Nissen, S. J., Koschnick, T. J., & Heilman, M. A. (2014). Triclopyr Absorption and
Translocation by Eurasian Watermilfoil (Myriophyllum spicatum) Following Liquid and Granular
Applications. Weed Science, 62(1), 22-28.
Wersal, R. M., & Madsen, J. D. (2007). Comparison of imazapyr and imazamox for control of
parrotfeather (Myriophyllum aquaticum (Vell.) Verdc.). J. Aquat. Plant Manage, 45, 132-136