Invasive plants in wetlands and their control

1. Invasive plants in wetlandsand their control Neil Anderson University of Minnesota ander044@umn.edu

2. Early detection & rapid response • Early Detection: • Surveillance • Monitoring • Control: • Rapid response • Goal: Prevent new introductions

3. Early detection:Assessment—vegetation surveys • Used for: • Monitoring for potential invasives • Assess effectiveness of vegetation management techniques used • Document rare/endangered species • Methods: • Garmin hand-held units (above-water) • Under-water technologies (Trimble units) • Cameras, • Geographic positioning system or GPS mapping with ESRI ArcGIS software • Positive plant identification http://www.aquaticcontroltech.com/index.html

4. Water quality surveys • One-time vs. scheduled monitoring • Types: in-lake, storm water, tributary sampling • On-site measurements: temperature, dissolved oxygen, water quality • Analysis laboratory: pH, total alkalinity, N/P series, turbidity, color, bacteria http://www.aquaticcontroltech.com/index.html

5. Bathymetric surveys • Map of water depths • Necessary for determining type(s) of control methods • e.g. for a drawdown – bathymetry map will calculate water volume and exposed area during drawdown • For chemical treatment: accurate water depths, volumetric data to calculate herbicide application amounts http://www.aquaticcontroltech.com/index.html

6. Wildlife habitat surveys • May be needed for permitting compliance • Regulatory agencies

7. Control Methods • Mechanical • Physical • Biological • Chemical • Site Modification • Disturbance Regime • Ecological Controls • Prevention • Education Risky Business: Invasive species management on National Forests A review and summary of needed changes in current plans, policies and programs (www.kettlerange.org/weeds/)

8. Mechanical methods • Hand-pulling • Special tools may be required, e.g. Weed Wrench (New Tribe, 5517 Riverbanks Rd., Grants Pass, OR 97527) • Use the best tool(s) for the species

9. Lythrum salicaria removal in the 1930s

10. Hand pulling by divers • Used when plant density is low or intermixed invasive and desirable species • May be used with mechanical harvesting, if water edges are not deep enough for diving

11. Effectiveness of hand pullingMyriophyllum • 3-year study • While numbers of plants pulled were 3x greater each year, milfoil reproduction was exponential (10x greater/yr) (http://www.dudleypond.org/Milfoil_Report_for_2006_for_ConCom.pdf)

12. Mechanicalcutting, harvesting • Effective for "area selective" control of invasive aquatics: clearing or cutting through large populations • May enhance access for boating, fishing, swimming • Works for all plant species, but best for those with a dense surface canopy or those annuals with high seed production (Trapa, water chestnut). • Disadvantages?

13. Mechanical raking,Hydro raking • A floating barge with a ‘backhoe’, rake • Effective technique for selective removal of rooted vegetation • Can clear debris, e.g. muck, peat, decaying leaves • Hydraulic paddle wheel for propulsion • Can operate in water 0.3 m to ~4 m depths • Duration of control ranges for 1 season (Myriophyllum) to 2+ yrs or longer for deep rooted plants (Typha, Nelumbo)

14. Dredging(sediment excavation) • May provide years of benefit, if done correctly • Costly! • Significant ecosystem disturbances • Requires careful articulation of purpose • Sufficient deepening of area needed to preclude light requirements of rooted plants • Excavation should not expose inorganic substrates that prevent plant recolonization

15. Physical methods • Hot water / steam treatment (“wet infra-red”)* • Removes waxy cuticles, causing quick death • Not plant specific • Enhanced with a surfactant • Temporary decrease for ~1 month *Waipuna Int’l., Carrboro, N. Carolina, USA

16. Fountains and Aeration systems • Aeration, circulation of stagnant water • Suppresses algae • Enhance oxygen levels for fisheries

17. Weed barriers • Permeable or ‘Benthic’ barriers secured to lake bottom • Eliminates rooted plant growth • Effective, ~low cost weed control strategy for small beachfront areas

18. Drawdown • Lowering water levels • Requires water control structures to drop water levels for extended time periods • In winter, lowering the water level exposes the sediment to freezing, water loss • Best for species with no overwintering structures • Negative consequences?

19. Chemical methods • Herbicides • Broadleaf, grass • Selective, non-selective • Modes of action: inhibition of electron transport, growth regulation (auxin, cytokinin mimicry), amino acid synthesis inhibition, lipid synthesis inhibition, seedling growth inhibition, photosynthesis inhibition, cell membrane disruption, and pigment inhibition (Anderson, 1994) • General in specificity, side effects, application issues • Hazards

20. Registered Aquatic herbicides, USA

21. Surfactants, Wetting Agents • Primarily used as adjuvants with herbicides • Increase effectiveness of hot water treatments • May control weeds directly • (Havey, 1999).

22. Biological controls • Seed bank control (Quarles, 1999, Luken, 1990, Luken, 1997) • Invasives often dominate seed banks • Factors affecting seed bank quantity, viability, quality: • (1) Local vegetation sources • (2) Seed germination rates • (3) Seed decay rate, physical destruction of seeds • (4) Seed predation • (5) Reseeding efforts

23. Invertebrate biological controls • Research and release of agents carries the risk that unintended hosts will be attacked and decimated • Not every native plant and growing environment can be tested.  Examples: • Natural insect enemies (Hobbs and Humphries, 1995) • Introduced invertebrate control species • Flea beetles (Aphthona spp.) reduces leafy spurge (Euphorbia esula) • Galerucella beetles control some populations of purple loosestrife (Lythrum salicaria) • Musk thistle (Carduus nutans) control with the head weevil, Rhinocyllus conicus • Genetically altered (transgenic or designer) insects may eventually be introduced for weed control

24. Herbaceous fish, insects • Herbaceous fish: control of nuisance plants, algae • Triploid (sterile) grass carp (nonselective) • Require permitting • Limited to ponds, small lakes where outflow can be blocked • Herbaceous insects: control invasive, submerged or emergent aquatic plants • Milfoil weevil (Euhrychiopsis lecontei) • Purple loosestrife beetle (Galerucella sp) • Mixed success

25. Biocontrol disadvantages • Not risk-free, e.g., unanticipated host switching • Won’t establish or control target pest • Establishes but does not increase or spread on its own • Successful only 16-26% of the time

26. Pond dyes • Blue, black dyes • Alter sunlight penetration into a lake or pond • Reduces photosynthetic capacity of plants, algae • Not recommended for “natural” ponds • More suitable for contained, man-made ponds with little or no outflow (storm water detention ponds, reflecting pond, golf course pond, etc) • Break down over time • Periodic reapplication

27. Allelopathy • Production of plant growth, germination inhibitors by plants (Aldrich, 1987; Harrison and Peterson, 1991) • Multiple benefits (Schmidt, 1980; Jarvis et. al., 1985) • Controlled allelopathy: possible through planting of allelopathic plants, application of allelopathic chemcals or genetically modifying a plant to produce allelopathic substances

28. Genetic methods • Hybridization - Invading species may evolve or adapt to a less (or more) pathogenic form over time • Well-adapted invading species are less lethal to their host ecosystem, e.g., a parasite that kills its host ecosystem is not likely to be successful • This effect represents an interaction between the newly invaded ecosystem as well as within the invading organism • Biologically engineered hybrids - Genetic engineering has the potential to change the fitness of invading species: lethal mutations, sterility

29. Soil chemistry • Nutrient availability and cycling to manage invasives: tend to be less dependent on specific soil nutrients • Soil pH - high or low soil pH depending on species, e.g., blueberries and other Ericaceous species are acid-loving, whereas species such as some bluegrasses, junipers, etc. favor basic soils • Soil amendments can favor desirable species, affecting vegetation dominance • Timing of fertilization encourages certain species (Deal, 1966)

30. Shading • Amount, timing of shade • Duration • Impact • Effective vegetation management tool (Elmore, 1993b).

31. Mulching • Straw mulch (6-8cm): 98% control of yellow star-thistle (Centaurea solstitialis) (Dremann 1996) • Other types: • Greenwaste materials, cover crops (Elmore, 1996; Weston, 1996) • Allelopathic mulching (Putnam and Weston, 1986; Altieri and Doll. 1978; Quarles, 1999).

32. Prevention—the most important tool • Prioritize new invaders • Use signage along infested areas to avoid public transport • Seed transport: a primary cause of the spread of invaders. Prevented by • 1. Contaminated seeding mixtures (Quarles 1999); use only 100% noxious-weed free seed • 2. Avoid contaminated mulch • 3. Avoid contaminated topsoil (Quarles, 1999) • 4. Use quarantines and vehicle washing, e.g., of tractors, cattle and logging trucks that may have just passed through a weed-infested site and are planning to go to a new site • Eliminate the cause, not the symptoms, of the spread of invaders

33. Education • A. Make a list of targeted user groups • B. Provide weed identification information distribution at central locations • C. Post public relations / media / local displays at central locations • D. Establish a weed sighting report form • E. Sponsor research projects that study invasive species (Morrison, 1997). Projects should include a set of study goals; replicate sampling; randomization; controls; preliminary sampling; and sampling authentication. Projects might include setting thresholds for measurement; coherent problem questions; area division; appropriate sample sizes; data distribution tests.

34. Can invasive species be 100% controlled (eliminated)? • ~Yes! Early detection / rapid response • Mechanical control, e.g. hand-picking of snails and hand-pulling of weeds • Chemical control, e.g. using toxic baits against vertebrates and spraying insecticides against insect pests • Biopesticides, e.g. Bacillus thuringiensis (BT) sprayed against insect pests;sterile male releases, usually combined with chemical control • Habitat management, e.g. grazing and prescribed burning;hunting of invasive vertebrates. • No! Phalaris arundinacea—virtually impossible

35. References Aldrich. R.J. 1987. Interference between crops and weeds. In: Waller, Allelochemicals: Role in Agriculture and Forestry. ACS Symposium Series No. 330. American Chemical Society, Washington, DC., pp. 300 312. Altieri, MA. and J.D. Doll. 1978. The potential of allelopathy as a tool for weed management in crop fields. PANS 24(4):495 - 502. Anderson, Sharon D., Director. 1994. [Title Unknown] A web publication of North Dakota State University Extension Service, Fargo, ND (701/231-7881). Biesboer, D., B. Darveaux, W.L. Koukkari. 1994. Controlling leafy spurge and Canada thistle by competitive species. Final report. Submitted to the Minnesota Dept. of Transportation. Office of Research Administration. St. Paul, MN; June. Daily et al. 1998. Ecosystem services: Benefits supplied to human societies by natural ecosystems. Issues in Ecology, Ecological Society of America (http://esa.sdsc.edu/daily.htm). Deal, EE. 1966. Grasses as lawn weeds. Plants and Gardens 22(3):23 - 25. Dremann, C.C. 1996. Grasses and mulch control yellow-star thistle (California). Restoration and Management Notes 14(1):79. Dunham. R.S. 1973. The Weed Story. Institute of Agriculture, University of Minnesota, St. Paul. 86 pp. Elmore, C.L. 1993a. Alternate methods for weed management in an urban environment. Preceedings of the 45th Annual California Weed Conference, pp. 26-30. Elmore, C.L. 1993b. Perennial weeds respond to control by soil solarization. California Agriculture 47(l):19 - 22. Elmore, C.L. 1996. The potential for the use of "greenwaste" and mulches in trees and vines for weed control. Proceedings of the 48th California Weed Conference, pp. 63 - 66. Elmore, C.L. and S.M. Tafoya. 1993. Water savings and weed control with mulches and plastics. Proceedings of the 45th Annual Weed Conference, pp. 147 - 154. Friedman, J. 1987. Allelopathy in desert ecosystems. In: Waller, Allelochemicals: Role in Agriculture and Forestry. ACS Symposium Series No. 330. American Chemical Society, Washington, DC., pp. 53 - 68. Grossman, J. and W. Quarles. 1992. Strip Intercropping for biological control. IPM Practitioner 15(2): 1 - 11. Grossman, Joel. 1999. Conference notes - ESA and APS Joint Meeting - Part 2. IPM Practitioner, 21(3) March 1999, Berkeley, CA. Hanawalt, R. B. 1971. Inhibition of animal plants by Arctostaphylos. In: National Research Council, Biochemical Interactions Among Plants. National Academy Press, Washington, DC., pp. 33 - 38. Harris, P. 1991. Classical spurge biological control  with insects and pathogens. In Proc. Leafy Spurge Control Coordination / Planning Meeting, April 23-25, 1991. USDA Agricultural Research Service, Minneapolis, MN Harrison. H.F. and J.K. Peterson. 1991. Evidence that sweet potato (Ipomoea batatas) is allelopathic to yellow nutsedge (Cyperus esculentus). Weed Sci. 39:308 - 312. Hartmann, K.M., W. Nezadal. 1990. Photocontrol of weeds without herbicides. Naturwissenschaften 77:158 - 163. Havey, William J. 1999. The Havey proposal for leafy spurge eradication Submitted to District Ranger Bruce C. Greco, Flagstaff, AZ, by Wm. Havey, Ed.-In-Chief, Sierra Magazine, San Francisco, CA. Hiebert, Ronald D. 1993. Handbook for Ranking Exotic Plants for Management and Control. Natural Resources Report NPS/NRMWRO/NRR-93/08, USDI-NPS, Natural Resources Publication Office, Denver, CO. Hobbs, Richard J., and Stella E. Humphries. 1995. An integrated approach to the ecology and management of plant invasions. Conservation Biology, 4:761-770. Jarvis. B,B., N.B. Pena, M.M. Rao. N.S. Comezoglu. T.F. Comezoglu and N.H. Mandava. 1985. AlIelopathic agents from Parthenium hysterophorus and Baccharis megapotamica. In: Thompson, A.C., The Chemistry of Allelopathy: Biochemical Interactions Among Plants. ACS Symposium No. 268, American Chemical Society, Washington, DC., pp. 149 - 159. Johnston, A., R.W. Peake. 1960. Effect of selective grazing by sheep on the control of leafy spurge (Euphorbia esula) L. J. Range Mgt. 13(4):192-195. Kempen. H.M. 1992. Non herbicidal techniques for IWM programs. In: Proceedings of the 44th California Weed Conference, pp. 147 - 155. Luken, James O., and J. W. Thieret, eds. 1997. Assessment and Management of Plant Invasions. ISBN 0-387-94809-0 Springer-Verlag Ney York. Miller, G.R. 1975. Weeds and their control. Plants and Gardens 31:4-11. Muller, C , H. 1971. Phytotoxins as plant habitat variables. In: National Research Council, Biochemical Interactions Among Plants. National Academy Press, Washington, DC., pp. 64 - 71. Neal, J.C. 1993. Turfgrass weed management an IPM approach. Weed Facts August: 1 - 8 [Weed Management Series No. 8. Cornell Cooperative Extension, Ithaca, NY]. Noss, Reed. 1999. A Citizen's Guide to Ecosystem Management. Biodiversity Legal Foundation, Boulder, CO. Olivarez, James P. 1995. Hay and grain pellets: Weed free or not? PNW-EPPC Newsletter, 1995.  weed prevention Pimentel, David. 1999 Principles dealing with invading exotic-weeds, control and environmental sustainability. Boulder Weekly Newspaper, Boulder, CO, April, 1999 Putnam, A R. and L.A. Weston. 1986. Adverse impacts of allelopathy in agricultural systems. In: A.R. Putnam and C. S. Tang, The Science of Allelopathy. John Wiley & Sons, New York. 1986, pp. 43 - 56. Quarles, William. 1999. Non toxic weed control in the lawn and garden. Common Sense Pest Control 15:4-17 Box 7414, Berkeley, CA 94707. Rice. E.L. 1987. Allelopathy; an overview. in: G.R. Waller, ed., Allelochemicals: Role in Agriculture and Forestry. ACS Symposium Series No. 330. American Chemical Society, Washington, DC., pp. 8 – 22. Saggese. E.J.. T.A. Foglia, G. Leather. M.P. Thompson, D.D. Bills and P.D. Hoagland. 1985. Fractionation of allelochemicals from oilseed sunflowers and Jerusalem artichokes. In: Thompson, A.C., The Chemistry of Allelopathy: Biochemical Interactions Among Plants. ACS Symposium No. 268, American Chemical Society, Washington, DC., pp. 99 - 112. Sedivic, K.K., R.P. Maine.1993. Angora goat grazing as a biological control for leafy spurge; A three-year summary. Proc. of the 1993 Great Plains Agricultural Council Leafy Spurge Task Force Symposium; July 26-28, 1993, Silvercreek, CO. Avail USDA ARS, 1995. Purge spurge; Leafy spurge database. Vandenberg, John, Moderator, USDA/ARS, 1996. Evaluating Risks of New Associations Resulting from Biocontrol, Cornell Community Conference on Biological Control, April 11-13, 1996, Cornell Univ., NY. Walker, C. and T.S. Prather. 1996. Weed species controlled with fabric mulches, Proceedings of the 48th California Weed Conference. pp. 59 - 62. Weston, L.A. 1996. Utilization of allelopathy for weed management in agroecosystems. Agron. J. 88:860 - 866.