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Definitions

Definitions . Control – prevention of spread by removing fruits and limiting vegetative spread Eradicate – to completely remove a species from a location. Topics. Approaches to control Methods of control Mechanical Chemical (types of herbicides, application methods Selected PNW species.

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Definitions

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  1. Definitions • Control – prevention of spread by removing fruits and limiting vegetative spread • Eradicate – to completely remove a species from a location

  2. Topics • Approaches to control • Methods of control • Mechanical • Chemical (types of herbicides, application methods • Selected PNW species

  3. Assessing Invasive Species Threats At the landscape scale it is necessary to take two approaches simultaneously and iteratively: By invasive species (Scary species) By spatial distribution of invaders and conservation goals (Superlative sites)

  4. Two Assessment Approaches • Species Based • Site Based

  5. Weed Increase Over Time and Control Potential Local control and management only Eradication feasible Eradication unlikely, intense effort required Eradication simple Public awareness typically begins Acres Infested Control Costs Introduction Detection Scattered locations Numerous locations At or near biological potential Plant absent Time

  6. A = Alhagi H = Hydrilla P = Peganum From: Rejmanek,M. and M. Pitcairn (2002)

  7. Study Conclusions • Eradication possible if under 1 hectare • 1/3 of infestations between 1 and 100 hectares eradicated • ¼ of those between 101 and 1000 eradicated • Cost goes up greatly with size • SO early detection and rapid response is essential!!!!! Rejmanek and Pitcairn 2002

  8. Bradley Method • Work in the least invaded areas first, working towards invaded areas • Make minimal disturbance – mulch if you must disturb the soil • Let native plant regeneration and your maintenance ability dictate the rate of weed removal – never overclear

  9. Manual and Mechanical • Hand pulling -can use volunteers -good for small infestations -can have low ecological impact -need to keep equipment clean -minimize disturbance! Mulch! -best for annuals or shallow rooted perennials

  10. Weed Wrench

  11. Manual and Mechanical • Tillage/hoeing • Mowing, brush cutting • Best for species that don’t coppice • “controls” – does not eradicate except through repeated use • Girdling – remove cambium (do not use on coppicing species, beware creating a hazard tree!) • May need to remove stem fragments

  12. Mechanical • Mulching – bark, hay, cardboard carpet, etc. • Flooding/drawdowns • Fire

  13. Manual or MechanicalSoil solarization - kills tissue if around 113-131 degrees F clear plastic more likely to heat to this - soil should be moist - not as good for rhizomatous species - may alter soil biology and chemistry

  14. Steam or Hot Water • Hot water breaks down the epidermis, the plant becomes dehydrated • Waipuna now promoting foam – coconut syrup and water

  15. Infrared Technology • Heats to 1000oC • Bursts cells – stops photosynthesis • Not good for deeply rooted species

  16. Grazing • Can eliminate or encourage invasive plants • Can use cattle, goats, sheep, geese, chickens, ducks, etc. • Goats eat broadest list of weeds • 500 sheep = 4/5 acres/day • Need to fence or pen them in • May disturb soil, may pass seeds

  17. Mechanisms - Herbicides • Inhibit respiration • Arsenic compounds • Metallo-organics (also based on arsenics) • Phenols • Can be very toxic to mammals

  18. Mechanisms - Herbicides • Auxins – 2,4,D – causes excess cell division and overgrowth, good on broadleaf weeds, non-persisting, low mammalian toxicity 2,4,5,T – better for woody plants >> has dioxin = Agent Orange, causes cancer • Common now: Clopyralid (persists in compost), picloram, triclopyr (Garlon, Brush B Gone)

  19. Mechanisms - Herbicides • Inhibitors of biosynthetic processes • Cell division – “pre-emergent” • Nucleic acid or protein synthesis inhibitors – “pre-emergent” • Glyphosate – non-selective contact herbicide, interrupts an amino acid production pathway not found in animals – “post-emergent,” Rodeo® used for aquatics

  20. Adjuvants • Added to facilitate mixing, effectiveness, or application of herbicide • “Surfactants,” “spreader-sticker” • Usually chemically active, but may be termed “inert” • Sometimes included, if not, research to find recommended one for what you use

  21. Considerations using Herbicides • Non-target species • Use best management practices for handling concentrates • Follow ALL laws • Must post treated areas • Carefully assess site conditions, including weather • Likely cannot use volunteers

  22. Methods of Application • Foliar – spot, boom • More herbicide delivered to non-targets • May need a surfactant

  23. Methods of Application • Basal bark • 6” band 1’ up stem • Must mix with low ester oil • Best for smaller shrubs

  24. Methods of Application • “Hack and squirt” • Cut every 2 in or so of stem • Good for small trees 4-5” dia • Creates hazard trees!

  25. Methods of Application • Cut stump “Cut and dab” • Only need to treat the cambium • Apply immediately after cutting • Paintsticks handy • May need to reapply • Not as good in early spring

  26. Methods of Application • Injected into cambium • Can be good for some herbaceous as well as woody • Little human contact with herbicide • Buy appropriate injectors

  27. Reed Canary GrassPhalaris arundinacea • Rhizomatous grass • Mow 5X +/yr • Mulches (+ cardboard) • Glyphosate (2%) • Shading with plantings

  28. Atlantic/English Ivies H. helix ‘Pittsburg’ Hedera hibernica ‘Hibernica H. helix ‘Star’ H. helix ‘Baltica’

  29. Ivies • Fast-growing ground cover • Remove vertical vines first • Pull and wad vines on ground • Can use string trimmer followed by glyphosate or triclopyr

  30. Japanese KnotweedFallopia japonica • Strongly rhizomatous shrub • Very hard to kill • 2X/month mowing for 3 years • Injection – 5 ml of 100% glyphosate • Triclopyr or glyphosate

  31. Himalayan blackberryRubus armeniacus • Repeated mowing • Digging • Cut stump, treat with triclopyr or triclopyr + 2,4 - D

  32. Iris pseudacorusYellow flag iris • Freshwater aquatic but drought resistant • Seeds and rhizomes • Dense thickets along shore • Dig by hand or machine • Cutting + glyphosate

  33. Scotch broom Cytisus scoparius • Prairies, grasslands • Nitrogen-fixer • Pull or cut stump • Seeds long lived

  34. herb robert, stinky bob Geranium robertianum • Herbaceous annual • Spreads by explosive seeds • May be allelopathic • Easy to pull • Seeds live 5+ yrs

  35. hedge bindweed Calystegium sepium • Older name Convolvulus sepium • Fleshy rhizomes 1-2 ft deep • Blankets shrubs • Likes wetter soils • Responds to triclopyr – pull as much as possible, mulch, then spray as vines grow

  36. Resources • TNC Weed Control Handbook http://tncweeds.ucdavis.edu/handbook.html • TNC “Stewardship Abstracts” http://tncweeds.ucdavis.edu/esadocs.html

  37. Conclusions • Start with smallest infestations first • There are a variety of mechanical and chemical control methods –combinations may provide the best control • For PNW invaders there are a number of strategies for control that must be tailored to the biology of the species

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