Invasive Plants and Noxious Weeds: Identification and Management

1. Invasive Plants and Noxious Weeds:Identification and Management Sasha Shaw King County Noxious Weed Control Program www.kingcounty.gov/weeds Courtesy of Sasha Shaw, King County Noxious Weed Control Program

2. Agenda • Brief review of definitions, lists and impacts • Biology and control of common invasive plants and noxious weeds • Early detection training for less common noxious weeds • IPM for managing noxious weeds in natural areas • Methods for staff and volunteers • Field trip to Kiwanis Ravine (two stops) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

3. What is an Invasive Plant? • Successful invader • Introduced from elsewhere, non-native • Escapes into natural areas • Persists and spreads • Generally lacks predators and natural controls • Causes harm • Disrupts ecosystems • Out-grows, out-spreads and out-competes native plants Invasive plants such as English ivy displace native plants and wildlife and can transform entire ecosystems Courtesy of Sasha Shaw, King County Noxious Weed Control Program

4. 11% 20% 9% 25% 18% 17% In 47% of Seattle’s forests, the majority of the plant cover consists of invasive species How bad is the problem in our cities? • Seattle has ~8,000 acres of public land • Invasive non-native plant species are present in 94% of these urban natural areas • 20% of the city’s forested areas are highly invaded by a suite of invasive species Courtesy of Sasha Shaw, King County Noxious Weed Control Program

5. Sources of Introduction • Intentional (accidentally on purpose) • Ornamental planting • Crops • Erosion control • Accidental • Ballast material • Contaminant • Seeds • Hay • Live plants Ornamental escapee Ship ballast and ornamental escapee Seed and hay contaminant Erosion control Courtesy of Sasha Shaw, King County Noxious Weed Control Program

6. Dispersal Methods • Natural Processes • Wind • Water/flooding • Birds and other animals • Human Causes • Hitchhiking on vehicles, boots, boats, etc • Construction/Grading • Mowing/Equipment • Yard waste dumping • Being planted Courtesy of Sasha Shaw, King County Noxious Weed Control Program

7. What is a Noxious Weed? • Legal term, defined and regulated by Washington State law (RCW 17.10) • Non-native plant that impactsagriculture, wildlife, human health, land values or natural resources • Private and public property owners are required to control selected weeds • Goal of law is to prevent spread of new invaders to un-infested areas • Weeds are regulated only where they are not widespread • Regulated at the county level; lists and priorities vary by county • Not all invasive weeds are on the noxious weed list and not all noxious weeds impact natural areas Courtesy of Sasha Shaw, King County Noxious Weed Control Program

8. Ecologically-based concept Legal, policy-based concept Courtesy of Sasha Shaw, King County Noxious Weed Control Program

9. One Law, Two Lists(both covered under RCW 17.10) • Noxious Weed List (WAC 16-750) • Dictates which weeds need to be controlled statewide or in particular counties or regions • Weeds are regulated where they are beginning to invade but not yet widespread or according to county priorities • Updated annually by the State Weed Board, administered by county noxious weed boards • Each county has its own weed list set by the county weed board • County lists can include more but not fewer noxious weeds than required by the state • State Prohibited Plants List (WAC 16-752) • Determines what can’t be sold (quarantine list) • Administered by WSDA Nursery Inspection Program • Goal is to prevent introduction of new weeds Courtesy of Sasha Shaw, King County Noxious Weed Control Program

10. What are the Categories on the King County Weed List? • Class A Weeds– new invaders, control required statewide, still a chance to eradicate • Examples: garlic mustard, giant hogweed • Class B and C Regulated Weeds– control required in King County, still have a chance to stop them from getting established • Examples: garden loosestrife, policeman’s helmet • Non-Regulated Class B and C Noxious Weeds and Weeds of Concern– widespread noxious and invasive weeds in King County, control not required but definitely a good idea whenever possible! • Examples: English ivy, holly, butterfly bush, Scotch broom, etc. Courtesy of Sasha Shaw, King County Noxious Weed Control Program

11. Most Abundant Regulated Noxious Weeds in King County Purple Loosestrife Spotted Knapweed Giant Hogweed Garlic Mustard Tansy Ragwort Orange Hawkweed Policeman’s Helmet Garden Loosestrife Sulfur Cinquefoil Dalmatian Toadflax Courtesy of Sasha Shaw, King County Noxious Weed Control Program

12. Examples of Non-Regulated Weeds www.mobot.org English Holly Butterfly Bush Canada Thistle Yellow Archangel Bittersweet Nightshade Blackberry English Ivy Yellow Flag Iris Scotch Broom Poison-hemlock Knotweed Bull Thistle Courtesy of Sasha Shaw, King County Noxious Weed Control Program

13. Some Local Invaders and How to Control Them Courtesy of Sasha Shaw, King County Noxious Weed Control Program

14. Himalayan Blackberry (Rubusarmeniacus) Evergreen Blackberry (Rubuslaciniatus) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

15. Blackberry Control • Base control plan on ability to maintain • Least infested areas first, then more heavily infested areas • Preserve native vegetation • Clear mature blackberry with loppers, brush mowers, machetes, or goats before seed set • Dig up root crowns or spot spray re-sprouting canes at about 2 ft tall in late summer or fall (foliar spray or wiped onto fresh cut stems) • Or cut several times a year for several years to exhaust the roots • Mulch and re-vegetate as needed to reduce soil erosion and weed seedlings Courtesy of Sasha Shaw, King County Noxious Weed Control Program

16. Chemical Control of Blackberry • Triclopyr amine (2-3% solution) apply anytime during active growth period – spring to fall • e.g. Garlon 3A, Brush B Gon, Lilly/Miller Blackberry and Brush Killer • Or triclopyr ester (4% solution) is effective in the winter, when many native plants are dormant(leave 60 foot buffer from water) • e.g. Garlon 4, Crossbow • Or glyphosate (2-3%) fall application • e.g. Roundup, Aquamaster • Cut stem – apply any of above per label to fresh cut stems, need to apply to both sides if rooted at nodes Courtesy of Sasha Shaw, King County Noxious Weed Control Program

17. English Holly (Ilex aquifolium) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

18. English Holly Control • Prevent further spread by removing berries or berry-producing trees • Re-sprouts from cut stumps and root crowns so digging is best non-chemical method • Cut stump or girdling with herbicide (glyphosate or triclopyr) is more effective than foliar spray http://web.reed.edu/canyon/natu/invasives Courtesy of Sasha Shaw, King County Noxious Weed Control Program

19. Scotch Broom (Cytisus scoparius) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

20. Scotch Broom Control • Plants under 3 feet can be hand pulled when soil is moist • Remove larger plants with weed wrenches • Can cut older plants near ground level in the dry season (July-September) • Spray plants spring to early summer (before leaves fall) • For less dense sites, use selective treatment – cut stump (late spring), stem injection, basal/stem spray (in fall) • Monitor site for at least ten years for new seedlings Broom removal with weed wrenches Courtesy of Sasha Shaw, King County Noxious Weed Control Program

21. English Ivy (Hedera helix, H. hibernica) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

22. Ivy Control: “Lifesaver Method” Kill upper growth by cutting the vines all around the tree at about shoulder height and clearing the trunk. Pull up ivy about 6 ft from base of tree and maintain ivy-free area. Use a hand saw or clippers to cut vines and then pull vines off trunk Courtesy of Sasha Shaw, King County Noxious Weed Control Program

23. Ivy Control: Hand Pulling/Digging Hand-pulling ivy is hard work but very effective – and gets done quickly with large groups of young volunteers! Pulled ivy can be rolled up like a carpet – easiest to do from the top of the hill down! Courtesy of Sasha Shaw, King County Noxious Weed Control Program

24. English Ivy Control with Chemicals • Waxy coating on leaves reduces herbicide uptake, especially during the summer and fall growing season • Young ivy leaves absorb more herbicide than older leaves • In the early spring or regrowth from being mowed • Applying pelargonic acid before or with herbicide may increase absorption • Or can create “wounds” with a weed trimmer before spraying • Either glyphosate or triclopyr (2-5% solution) sprayed on a sunny winter or early spring dayis more effective than summer or fall • Can also cut stems and apply 25% solution glyphosate to freshly cut surfaces • Ivy may respond slowly to herbicide, so wait to follow up for at least a few months • Can combine methods: pulling where roots are accessible and chemical control for rocky areas or steep slopes Courtesy of Sasha Shaw, King County Noxious Weed Control Program

25. Old Man’s Beard (Clematis vitalba) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

26. Old Man’s Beard Control • Combination of cutting and chemical treatment • Cut climbing vines in the winter at waist height (leave the top stems to wither) • Spray the foliage in the spring to summer with triclopyr or glyphosate, avoid natives • Mature plants – use cut stump method • Stem and root fragments should be collected and burned or disposed of; do not compost Courtesy of Sasha Shaw, King County Noxious Weed Control Program

27. Bittersweet Nightshade (Solanum dulcamara) This aggressive woody vine can form dense patches and blanket trees and shrubs along creeks Courtesy of Sasha Shaw, King County Noxious Weed Control Program

28. Bittersweet Nightshade Control • Manual removal of roots can be effective • Hand pull the stem close to the ground and pull or dig up the roots, taking care not to break the slender roots • This method is most effective with young plants and new infestations • Be thorough because stem and root fragments can re-sprout • Along streams, need to prevent erosion, contain sediment • Cutting may improve access to roots but won’t control plants • Chemical treatment: use care to avoid drift, spot spray or wipe on herbicides Courtesy of Sasha Shaw, King County Noxious Weed Control Program

29. Invasive Knotweed (Polygonum spp.) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

30. Knotweed has hollow, upright, bamboo like stems, often reddish Courtesy of Sasha Shaw, King County Noxious Weed Control Program

31. Knotweed Control – Non-Chemical • Dig up individual plants growing in soft soil • Dispose of roots and rhizomes in the garbage • Cut down twice a month between April and August, once a month after that until the first frost • Don’t let stems exceed 6 inches • Cut stems can be dried, crushed and composted • Cover with heavy-duty erosion control fabric or sturdy plastic • Weigh down with rocks or cement blocks (no stakes) • Monitor and maintain (stomp down re-growth, pull or spray re-sprouts along edges, fix holes) • Leave in place for five years Seattle Public Utilities Loose fabric allows growth without breaking through; rocks hold it down without creating holes. Courtesy of Sasha Shaw, King County Noxious Weed Control Program

32. Chemical Control – Spraying or Injecting • Spray the leaves and stems • Imazapyr (most effective) or glyphosate (next best) • Usually mid-June to September • Continue to monitor sites for at least three years after knotweed appears to be gone • Stem injection with concentrated glyphosate • Need to inject every stem • July to September • Highly effective and reduces drift • Some limitations • Labor-intensive and uses more herbicide • Limited to about 2500 canes per acre per year per glyphosate label • Some stems will be too small to inject • Will need to spray re-growth the next year Spraying knotweed re-growth Injecting knotweed Courtesy of Sasha Shaw, King County Noxious Weed Control Program

33. Yellow ArchangelLamiastrumgaleobdolon(a.k.a.Lamium) Small yellow mint-type flowers in leaf axils Silvery markings on leaves of this popular garden plant make it easy to spot invading into shady forests Courtesy of Sasha Shaw, King County Noxious Weed Control Program

34. Yellow Archangel Infestation Courtesy of Sasha Shaw, King County Noxious Weed Control Program

35. Yellow Archangel Control – Persistence Required! • Hand pulling – collect all roots and stems or they will regrow • Covering – needs to be very well-covered, no holes and extending beyond plants • Spraying – combinations and repeat treatment • Glyphosate (Roundup) mixed with either triclopyr (Garlon), imazapyr (Habitat) or aminopyralid (Milestone) • Add surfactant for best results • Concentrated vinegar products – short term control is good, need to re-apply regularly Regrowth after spraying Seedlings emerging in treated area Courtesy of Sasha Shaw, King County Noxious Weed Control Program

36. Herb Robert (a.k.a. Stinky Bob)(Geranium robertianum) Weak roots make this plant easy to pull but plants seed prolifically and germinates multiple times in a season so repeat visits to the same location are needed for complete control. Courtesy of Sasha Shaw, King County Noxious Weed Control Program

37. Some Threatening Noxious Weeds • Prevention of spread in the county and state is highest priority • Call your County Noxious Weed Program if you find these or any other regulated noxious weeds • King County 206-296-0290 • Pierce County 253-798-7263 • Snohomish County 360-435-7830 Courtesy of Sasha Shaw, King County Noxious Weed Control Program

38. Class A Noxious Weed Garlic Mustard(Alliariapetiolata) Infestation along Longfellow Creek Courtesy of Sasha Shaw, King County Noxious Weed Control Program

39. Class A Noxious Weed Garlic Mustard(Alliariapetiolata) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

40. Class A Noxious Weed Garlic Mustard In undisturbed forests, garlic mustard spreads up to 120 feet in one year. It inhibits tree growth through negative impacts on beneficial fungi and has no natural enemies in North America. Garlic mustard covering a hillside near Carkeek Park in Seattle. Courtesy of Sasha Shaw, King County Noxious Weed Control Program

41. Garlic Mustard in King County in 2000 2000 Courtesy of Sasha Shaw, King County Noxious Weed Control Program

42. Garlic Mustard in King County 2011 Courtesy of Sasha Shaw, King County Noxious Weed Control Program

43. Lots of Look-A-Likes Garlic Mustard Nipplewort (Lapsana communis) Nettles White-Flowered Money Plant Courtesy of Sasha Shaw, King County Noxious Weed Control Program

44. Prevention of Spread • Don’t take it with you Clean your boots and equipment Don’t move mulch from infested sites Courtesy of Sasha Shaw, King County Noxious Weed Control Program

45. Class A Noxious Weed ashtabula.osu.edu Giant Hogweed (Heracleummantegazzianum) 15 feet tall with a stout, purple-blotched stem, large white umbrella-shaped flower clusters, and giant, sharply toothed leaves Courtesy of Sasha Shaw, King County Noxious Weed Control Program

46. Class A Noxious Weed Giant Hogweed – Use Caution When Handling Sap from hogweed causes painful burns Wear gloves and long sleeves when cutting off flower heads, then dig up roots Courtesy of Sasha Shaw, King County Noxious Weed Control Program

47. Giant Hogweed (Heracleummantegazzianum) Courtesy of Sasha Shaw, King County Noxious Weed Control Program

48. Purple Loosestrife Garden Loosestrife (Lythrumsalicaria) (Lysimachiavulgaris) Class B Noxious Weeds Courtesy of Sasha Shaw, King County Noxious Weed Control Program

49. Class B Noxious Weed Policeman’s Helmet (Impatiens glandulifera) Annual with fleshy, reddish stems, 3-10 ft tall, flowers resemble English policeman’s helmet, vary in color from white to dark pink-purple Courtesy of Sasha Shaw, King County Noxious Weed Control Program

50. Class B Noxious Weed Policeman’s Helmet (Impatiens glandulifera) Policeman’s helmet spreads along creeks and out-competes and crowds out other plants Can grow to 10 feet tall in one season Courtesy of Sasha Shaw, King County Noxious Weed Control Program