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Injections of Herbicide into Rhizomes of Knotweeds and Other Invasive Plant Species
The document discusses the issue of knotweed, recognized as one of the world's worst invasive species, and outlines various control methods including rhizome injection of herbicides. It provides detailed identification characteristics of different knotweed species, the ecological impacts of knotweed invasions, and evaluates current chemical control techniques. The proposed rhizome injection method aims to enhance herbicide efficacy by delivering it directly to the rhizome, potentially improving control outcomes and reducing herbicide usage.
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Injections of Herbicide into Rhizomes of Knotweeds and Other Invasive Plant Species
- 1. Subterranean Rhizome Injectionof Herbicides for Knotweeds and Other Invasive Species Midwest-Great Lakes Chapter, Society for Ecological Restoration Fourth Annual Chapter Meeting University of Michigan John Lampe Green Shoots, LLC Saint Paul, Minnesota May 5, 2012 1
- 3. Knotweed – WhyControl? • It is listed by the World Conservation Union as one of the world's 100 worst invasive species. • This is not precise ranking but does show recognition of how problematic species is.
- 4. Outline of Talk •Knotweed Background • Current Control Methods • Rhizome Injection
- 6. Knotweed Background Pioneer speciesin native habitat – for example, Mt. Fuji
- 7. Common Species ofKnotweed • Japanese knotweed (Polygonum cuspidatum) • Giant knotweed (Polygonum sachalinense) • Bohemian knotweed (Polygonum x bohemicum) – hybrid
- 8. Knotweed Colony Photo Credit:Randy Westbrooks, U.S. Geological Survey. Bugwood.com
- 9. Knotweed Leaves • Dark green leaves • Un-toothed • alternate Photo Credit: Steve Manning, Invasive Plant Control, Bugwood.com
- 10. Knotweed Stem -Dry • Hollow internodes • Septum separating • Up to 2 in. dia. Photo Credit: James H. Miller, USDA Forest Service, Bugwood.com
- 11. Knotweed Stems -Young
- 12. Winter Dry Stems Photo Credit: Justin Knabe, Minnesota DOT
- 13. Common Features ofKnotweed (con.) Rhizome • Rhizome can extend 6 to 8 feet in year • Rhizomes can lay dormant for up to 20 years
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- 15. Rhizome – Vertical Cross- Section
- 16. Common Features ofKnotweed (con.) • Spread by: – Rhizome extension – Distribution of plant parts • Rhizome pieces – as small as 0.7 g (Brock & Wade 1992) • Node pieces – Seeds – not major source in WA. (Miller 2005)
- 17. Key Distinctions AmongSpecies • Giant knotweed – Leaf blades up to 18 inches long and half as wide – Cordate (heart-shaped) at base – Straight stem • Japanese knotweed – Leaf blade is 8 inches long and almost as wide – Flat across base – Zig-zag stem • Bohemian – blend of two
- 18. Identification Good source: PratherTS, Miller TW, Robins SS, Knotweed shrubs: identification, biology, and management, Pacific Northwest Extension Publication 2009
- 19. Knotweed Badness • Riparianareas especially vulnerable • Out-compete other plants => monoculture • Tree Absence leads to: – Loss of shade – Loss of woody debris • Changes in soil fertility • Erosion along streambeds and stream banks
- 20. Knotweed Monoculture Photo Credit: Justin Knabe, Minnesota DOT
- 21. Current Control Methods •Cutting or Removal • Coverage or Burial • Chemical
- 22. Cutting, Removal, Coverage,Burial • Cutting or removal – probably not practical except on small scale; high risk of spread. • Coverage or burial – probably not practical except on small scale.
- 23. Coverage is ReallyTough Photo Credit: Popplewell Associates, York, UK
- 24. Control – Chemical • Foliar • Cut stem • Stem injection • Stem wipe
- 25. Knotweed Rhizome Toughto Kill! Key Problem: older parts of rhizome and dormant buds are weak sinks. (Bashtanova et al. 2009.)
- 26. Foliar • Best totreat after July 1 • Backpack sprayer • Typical chemicals used are: glyphosate, triclopyr, and imazapyr
- 27. Foliar • Advantages – Fastest – Treat small-stemmed plants – Good control: 81%. (Miller 2005) • Disadvantages – Off-target harm: Avg. injury: 68%. (Miller 2005) – Hard to treat large plants
- 28. Cut Stem • Cutstem 5 to 10 inches off ground • Immediately pour up to 5 ml into hollow of stem
- 29. Pouring Herbicide intoCut Stem
- 30. Cut Stem • Advantages – Low cost equipment – Good control • Disadvantages – Time-consuming – Disposal of green aerial shoots – Amount of herbicide used
- 31. Stem Injection • Usehypodermic or special injector • Inject up to 5 ml into stem • Between 1st and 2nd node above ground
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- 33. Stem Injection • Advantages – Precision – No stem disposal – Efficacy; Avg control: 88% (Miller 2005) • Disadvantages – Time-consuming – Id of treated stems – Amount of herbicide used – Cost of equipment – Non-target injury: 26% (Miller 2005)
- 34. Stem Wipe • Eithercut stem or leave stem whole • Abrade stem in some manner near base • Wipe onto exposed inner tissue
- 35. Stem Wipe withFoam
- 36. Stem Wipe • Advantages – Low cost equipment – Efficacy is good; control: 89%. (Miller 2005) • Disadvantages – Time-consuming – Off-target injury: avg = 13% (Miller 2005)
- 37. Follow-Up Applications • Itseems that all methods of application currently used require follow-ups for many years • According to Washington State Dept Agriculture: “The trend of this data shows a significant decrease in knotweed following six years of annual treatments. Despite these dramatic reductions, knotweed is still present at each monitoring site.” (Statewide Knotweed Control Program; 2010 Progress Report)
- 38. Can We Doa Better Job of Killing the Knotweed Rhizome?
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- 40. Rhizome Injector • 6in. blunt tipped needle • Metered dosing • 250 ml capacity (treatment for approximately 125 plants)
- 41. Rhizome Injection –the Concept First Premise: Efficacy of any method depends on herbicide reaching rhizome and roots.
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- 43. Rhizome Injection –the Concept Second Premise: Efficacy decreases as trans- location distance increases.
- 44. Efficacy and Translocation 100% Efficacy Decreases meters Translocation Distance Increases
- 45. Translocation Distance Foliar Application – 3 meters Stem Injection or Wipe – 20 cm Rhizome Injection – 5 cm
- 46. Rhizome Injection –1st Step • Access inside hollow stem near ground level – Cut stem at ground level – dead or living stem; or – Bend stem at ground level and create opening into the stem hollow
- 47. Rhizome Injection –2nd Step • Insert needle of injector through septum in hollow of stem • Probe down into rhizome hollow as far as possible
- 48. Rhizome Injection –3rd Step • Inject Herbicide • I set dose at 2ml • AquaMaster label, for example, forbids injection in excess of 5 ml into stem
- 49. Rhizome Injection Needle reaches to below-ground Internode
- 50. Inserting Needle intoCut, Dead Stem
- 51. Injecting into Rhizome through Cut Stem
- 52. Inserting Needle intoBent Live Stem
- 53. Inserting Needle intoBent Live Stem
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- 62. Potential Advantages –Rhizome Injection 1. Injection directly into rhizome – the part of plant that herbicide must reach 2. Amount of herbicide can potentially be less 3. Eliminate disposal problems – leave live aerial shoots attached or treat when aerial shoots are dead
- 63. Potential Advantages –Rhizome Injection 4. Extend application season: – Summer – after July 1 or so – Fall – Late fall – after stems have died – winter 5. Treat fewer stems? – Depends on amount of translocation
- 64. Green Shoots John Lampe– contact: • john@greenshootsonline.com • 651-245-4682 (cell) Website: www.greenshootsonline.com • Email or call for copy of presentation 64