meddlesome milfoils: parrotfeather & eurasian watermilfoil vanessa morgan center for lakes and...
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Meddlesome milfoils: Parrotfeather & Eurasian watermilfoil
Vanessa MorganCenter for Lakes and Reservoirs
Aquatic Weed WorkshopSalem, 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)
Northern watermilfoil (M. sibiricum)
Whorled watermilfoil (M. verticillatum)
Andean watermilfoil (M. quitense)
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Variable-leaf watermilfoil (M. heterophyllum)
Hybrid watermilfoil (M. spicatum × sibiricum)
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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 5reduced (1-3 mm long);
smaller than flowersyes
whorled watermilfoil(Myriophyllum verticillatum)
NATIVE <14 (5-14) < 5 cm long 4 to 5 2-10 mm long;
deeply pinnately lobedyes
Andean watermilfoil (Myriophyllum quitense)
NATIVE 5-10 1.5 - 4 cm long 2 to 5
0.5-1 cm long; partially toothed
yes
Parrot feather (M. aquaticum)
INVASIVE 10-15 1.5 - 3.5 cm long 3 to 6
2-5 cm long; 16-18 leaflet pairs
stiff, waxy, bright green no
Eurasian watermilfoil (M. spicatum)
INVASIVE > 14 (12-24) 2 - 4 cm long 3 to 6 reduced (1-3 mm long);
smaller than flowersno
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
yes
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
(Moody & Les 2007)
• Morphological samples: CLR, PSU
• Genetic verification: Annis Water Resources Institute, Grand Valley State University, MI
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
Reproduction & dispersal
• Fragments– Autofragmentation– Allofragmentation
(boats, swimmers, control efforts)
• Seed (EWM & Hybrids) • Water movement &
Waterfowl• Aquaria dumps,
boats/trailering, bait buckets
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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, longer-term, 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, long-term
expensive, variable results
heavy infestations
Non-Chemical Control Options
Method Est. costParrotfeather
(M. aquaticum) Eurasian watermilfoil
(M. spicatum)
Dredging variable Drawdown variable ? ?Benthic barriers $0.40-0.50/sq. ft. ? Hand cutting/pulling variable ? Harvesting $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. ?
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• Boat-mounted hose for sub-
surface injections• Foliar sprays
• Pelletized & granular formulations (slow & quick release)• Boat mounted
hopper/spreader to ensure even application* boat speed; rate of delivery from the spreader; swath width
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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
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
(Glomski et al. 2010)
(hybrid milfoil)
(EWM)
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; 13.2-
22 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