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Meddlesome milfoils: Parrotfeather & Eurasian watermilfoil Vanessa Morgan Center for Lakes and Reservoirs Aquatic Weed Workshop Salem, Oregon April 24,

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Presentation on theme: "Meddlesome milfoils: Parrotfeather & Eurasian watermilfoil Vanessa Morgan Center for Lakes and Reservoirs Aquatic Weed Workshop Salem, Oregon April 24,"— Presentation transcript:

1 Meddlesome milfoils: Parrotfeather & Eurasian watermilfoil Vanessa Morgan Center for Lakes and Reservoirs Aquatic Weed Workshop Salem, Oregon April 24, 2014

2 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

3 Overview Identification Impacts Habitats & growth habits Reproduction and dispersal Control options –Non-chemical –Chemical

4 Parrot feather (M. aquaticum) Eurasian watermilfoil (M. spicatum)

5 Northern watermilfoil (M. sibiricum) Whorled watermilfoil (M. verticillatum) Andean watermilfoil (M. quitense) J. Parsons, WA DOE A. Hipp, U of WI-Stevens Point V. Morgan, PSU-CLR ©2012 Vernon Smith

6 Variable-leaf watermilfoil (M. heterophyllum) Hybrid watermilfoil (M. spicatum × sibiricum) L.J. Mehrhoff, U of CT, Bugwood.org © 2014 Donald Cameron michiganlakeinfo.com V. Morgan, PSU-CLR

7 Milfoil Character Comparison submerged leaves Status in PNW# leaflet pairsleaf sizeleaves/whorlemergent leaves (bracts)winter buds (turions) Northern watermilfoil (Myriophyllum sibiricum) NATIVE<14 (5-14)< 4 cm long3 to 5 reduced (1-3 mm long); smaller than flowers yes whorled watermilfoil (Myriophyllum verticillatum) NATIVE<14 (5-14)< 5 cm long4 to mm long; deeply pinnately lobed yes Andean watermilfoil (Myriophyllum quitense) NATIVE cm long 2 to cm long; partially toothed yes Parrot feather (M. aquaticum) INVASIVE cm long 3 to cm long; leaflet pairs stiff, waxy, bright green no Eurasian watermilfoil (M. spicatum) INVASIVE> 14 (12-24) cm long 3 to 6 reduced (1-3 mm long); smaller than flowers no Variable-leaf watermilfoil (M. heterophyllum) INVASIVE cm long 4 to cm long; larger than flowers; serrated/lobed yes Hybrid watermilfoil (M. spicatum × sibiricum) INVASIVE cm long ???

8 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

9 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).

10 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

11 Reproduction & dispersal Fragments –Autofragmentation –Allofragmentation (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

12 Non-Chemical Control Options MethodDescriptionProsConsUsed in Dredgingmechanical sediment removal long-term controlexpense, non-selective shallow small ponds Drawdowndewatering 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 selectivelabor intensive, expensive localized area, rapid response to new infestations Harvestingmechanical cutting & collection removes biomassexpensive, 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, slowlocalized area, rapid response to new/recent infestations Rotovationaquatic cultivator, tills sediments intermediate results sediment disturbance, spread of fragments heavy infestations with little/no natives Biocontrolinsects, fish, etc..selective, long- term expensive, variable results heavy infestations

13 Non-Chemical Control Options MethodEst. cost Parrotfeather (M. aquaticum) Eurasian watermilfoil (M. spicatum) Dredgingvariable Drawdownvariable ?? Benthic barriers$ /sq. ft. ? Hand cutting/pullingvariable ? 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. ?

14 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

15 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

16 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 University of Florida, IFAS Extention Clean Lakes, Inc. Vassios et al. 2014

17 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

18 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 – lbs/acre Liquid - dimethylamine salt –DMA*4IVM; – 4 ppm (2.84 gal/acre foot)

19 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 to 2.5 ppm a.e.; sinking agent > 6 –Granular – 0.5 to 2.5 ppm a.e.

20 Chemical - recent developments Flumioxazin (Clipper) –Non-selective, liquid contact herbicide – ppb submersed –Quick kill – potential dissolved oxygen problems Bispyribac-sodium (Tradewind) –Non-selective; slow acting, wetable powder –20-45 ppb, maintained for days Use patterns still developing

21 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)

22 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

23 EWM Chemical cont… Contact herbicides –Diquat dibromide (Reward, Weedtrine) nonselective, liquid contact herbicide Not for use in turbid waters gal/surface acre –Endothall (dipotassium salt-Aquathol, Cascade) nonselective, liquid or granular spot treatments ppm Control is temporary – root crowns not killed Quick kill – potential dissolved oxygen problems

24 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

25 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

26 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 days –Fair canopy suppression –1-2 pints/acre Wersal & Madsen 2007

27 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: ppm ( gal/ac.ft. liquid; lbs/ac.ft granular) –Spot treatments: ppm ( gal/ac.ft. liquid; lbs/ac.ft granular)

28 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

29 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)

30 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), 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), 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), 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, 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), 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,


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