Managing Woodland Invasive Plants

John ExoFeb. 18, 2012

john.exo@ces.uwex.edu

Today’s Outcomes

• Know why species are invasive• Determine management goals• Understand range of management methods• Know integrated strategies

From John T. Curtis,

Vegetation of Wisconsin, 1959

Early Vegetation

Early Invasives?

“Our waters filled with fish, and the air with game birds, and the rock ledges with rattlesnakes, and the woods with large game…We have no Canada thistles or mean men.”

Wm. H Canfield, 1842Sauk County Surveyor

Invasive Beginnings

Wisconsin Historical Society

Invasives Follow Us

Definitions

“Invasive” definitions differ depending on the goal.

“…causes economic harm to….” “interferes with land management goals…” “kills or displaces populations of native species…”

What makes a plant invasive?

• Tolerate wide range of soil, light, other conditions

• Enjoy longer growing period• Ability to alter soil chemistry• Prolific seed production• Have few or no natural controls

What do we do?

Learn to ID and know plants’ biology Take inventory, map Create a plan Learn & use control methods Monitor & adapt

Know thy enemy

Learn to identify the plants Seedling Adult Dormancy

Learn plants’ biology Annual Biennial Perennial

Know thy enemy

AnnualsLive one growing seasonSurvive through seedRagweed, foxtails

Know Thy Enemy: biennials

Live TWO growing seasonsSurvive through, and produce a lot of, seed

Garlic mustard*Wild parsnipBull, musk, plumeless thistleSweet cloverSpotted knapweed

Biennial biology

• Seedling/rosette yr 1• Flower, then die yr 2• Spread by seed only

– Vehicles– Shoes– Animals – Water

Garlic Mustard Effects

• Release soil toxins.• Disrupt soil-fungi

associations.• Reduce/prevent tree

regeneration.

Biennials: Bull, musk, plumeless thistle

Know Thy Enemy: Perennials

Greater threat to woodland goalsLive many growing seasonsSurvive through stored root energyReproduce via seeds, suckers, rootsImportant to know if:

Simple roots (honeysuckle)Creeping or clonal roots (Canada thistle)

Perennial: Multiflora Rose

Identifying characteristic:

bristles at base of petiole

Perennial: Multiflora Rose

Perennial: Common buckthorn

• Male & female plants.• Visible late into fall.• Use these features to

your advantage.

Unfair competition. . .

Perennials: Bush Honeysuckles

Habitat: upland, especially under roost treesBlooms: May to June; white, yellow, orange or pinkBerries: orange or redEarly leaf-out, late leaf drop

Perennials: Autumn olive

Habitat: dry uplandBlooms: May to JuneFlowers white and fragrantReproduces mostly by root suckering

Autumn olive

Perennial vine: Oriental bittersweet

• Woody vine that climbs other vegetation

• Thrives in a wide range of conditions

• Grows to 60+’ in length• Introduced as an

ornamental

Urtica/Flickr creative commons

Human vectored dispersal

Highly invasive and damaging

Vines strangle trees, reduce available light; added vine weight can break trees

Distinguishing bittersweets

American Oriental

Fruit capsule color

Fruit position

Problem Ornamental Species

• Japanese knotweed• Japanese barberry• buckthorns• Asian honeysuckles• Amur maple• Common tansy• Oriental, or Round-

leaved bittersweet

Take inventory

Aerial photo or scaled lot layout Estimate species present & density Identify land use – past, present & future Look beyond your property lines

Take Inventory

Prioritize!

Importance of habitat? Size of population? Rate of spread? Interfere with land use? Resources available? Other priorities?

General Management Strategies• Monitor, especially

along trails, roads• Look beyond property

lines• Prioritize species; areas• Timing is critical• Attack outer edges first

Management methods• Ounce of prevention…• Pull• Cut/Mow • Girdle• Cut stem• Graze• Prescribed fire• Herbicide (foliar, basal bark)• Integrated methods

Prevention

• Encourage competition• Early detection & removal of new species• Consider steps to prevent introduction during

timber management

Pull• Good for young people,

small infestations, small plants.

• *Flowers can still set seed after pulling.

Mow/Cut• Goal: weaken plant; prevent seed set.• Timing is critical—best when in flower.• Repeated mowing often needed• Weakens, but may not kill plants.• Can be combined with herbicide methods.

Mowing/Cutting Equipment

Grazing

Principles similar to mowingGoats can be “trained” to some speciesRepeated treatments necessaryContractors available

Girdle

• Goal: starve roots• Good for clonal tree

species.• Labor intensive.• Very effective if done

correctly.• Timing: June-July best.• 1 or 2 step method.

Photo courtesy of Tom Brock

Photo courtesy: Tom Brock

Girdling – Step 1 Girdling – Step 2

Cut-Stem Treatment• Goal: kill plant• Good winter option• Very targeted use

of herbicides

Photo: Savanna Oaks Foundation, Inc

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Cut-stem Control Method

Target: • Shrubs/trees• buckthorn, honeysuckle, autumn olive, prickly ash,

multi-flora rose, undesirable trees, etc.

Herbicides: • Systemic• Active ingredients glyphosate (Roundup/generic) or

triclopyr (Garlon 4/Element 4)

Cut-stem Control Method

Timing: • Summer, Fall or Winter preferred• Avoid early spring and deep snow periods• Above-freezing temps with glyphosate• Triclopyr (Garlon) at any temperature• Apply glyphosate within minutes of cutting.

Cut-stem Control Method

Technique: • Cut stems at no higher than 6”.• Work in pairs, if possible, to

avoid “escapes”.• Work in a pattern.• Treat only outer edge of larger

stumps.

Photo courtesy: Tom Brock

Prescribed Fire

Photo courtesy of Tom Brock

Requires training, experience

Specialized equipment Good public relations Good neighbor relations Timing! Effective when integrated

with other methods

Foliar herbicide

• Safety first• Better for larger infestations• Selective vs. non-selective

herbicides• Pre- vs. post-emergence

application

Foliar herbicide

Timing• Rosette stage best for

biennials.• Before flowering, in

general.• Combine with fire/mow.

Basal bark herbicide

• Small; smooth bark• Generally, single-stem

shrubs & trees• Treat all clone stems• Oil-based chemicals

(triclopyr: Garlon 4 or Element 4)

Photos courtesy of Tom Brock

Integrated Methods

• Successful control efforts include:– Integrated approach– monitoring – early detection.

Photos courtesy Tom Brock

Other Precautions

• Clean boots to prevent seed spread (wheeled vehicles, too?).

• Minimize soil disturbance.• Consider spread by wildlife & water.• Monitor imported materials (gravel, topsoil,

mulch, etc).

Develop a management plan•Garlic mustard detected•Goal is to …

Road

Develop a management plan

Road

Garlic mustard control1. Develop a map2. Satellite plants--goal to eradicate.3. Extensive patch along road--goal

to prevent further spread.

Example Plan

• Satellite populations:– Pull 2nd year plants before flowering– Spray 1st year plants in fall or very early spring

Example Plan

• Large patch along road/trail:– Mow, pull, spray along road before seed set.– Work perimeter inward

• Spray rosettes fall/early spring• Pull escapes in between

• Repeat, monitor, re-map subsequent years.

Volunteer Opportunities

Learn while doing• Kickapoo Valley Woods Cooperative• The Prairie Enthusiasts• The Nature Conservancy

Other Resources

• County Extension office– fyi.uwex.edu/weedsci

• County DNR foresters– dnr.wi.gov/topic/ForestHealth/

• Oaksavannas.org• www.ipaw.org

Summary

• Early detection & prevention are critical• New species introduction & spread mostly

dependent on our behavior• Set realistic goals• Make a plan, then adapt, using…• Integrated methods

Questions?

john.exo@ces.uwex.edu(608) 355-3554