Japanese Knotweed Control:It Takes a Community

Leslie KuhnField Projects Coordinator

Mid-Michigan Stewardship Initiativewww.stewardshipnetwork.org/midmich

KuhnL@msu.edu

Mid-Michigan Stewardship Initiative (MMSI)• The Mid-Michigan chapter of the Stewardship

Network• Brings together volunteers, professionals,

landowners, and public agencies to restore natural areas

• We focus on invasive species control and community outreach on invasive species• We also create native plant demonstration gardens

MMSI Planning Committee meeting at Ingham County Parks

Knotweed Team: Laurie Kaufman, Jim Hewitt, Billy Hartill, Pat Witte, Leslie Kuhn, and volunteers

Japanese Knotweed (Fallopia japonica)

• Introduced from Asia as an ornamental in mid-1800’s

• Flowers in late summer• Known invasive in US by 1900• Reddish reeds, alternate leaves• Also called Mexican bamboo

https://en.wikipedia.org/wiki/Fallopia_japonicaLeslie Kuhn

Partner in Crime: Giant Knotweed (Fallopia sachalinensis)

• From Russia• Less common in Michigan than JK• A cross between Japanese and giant

(Fallopia X bohemica) generates fertile seeds – has created a major problem in UK

Photos: Leslie KuhnFallopia X bohemicaGiant knotweed

Knotweed Leaf Differences

≤ 6”

≤ 12”

inte

rmed

iate Above: michiganinvasives.org

Left: Bailey et al. (1996) Watsonia 21, 187

For learning to identify invasive species, see very useful fact sheets & training modules at: http://www.michiganinvasives.org/resources

Plants Sometimes Confused with Japanese Knotweed

Redbud (Cercis canadensis)

Differences: has truly heart-shaped, soft leaves (equally wide and long), and branching woody stems (not reeds).

Photo by B.S. Walters from michiganflora.net

Pokeweed (Phytolacca americana) Differences: has brilliant solid pink-red stems (not reeds with joints); leaves are narrower; and has pink flowers and white berries.

Photo by Leslie Kuhn

What’s so Bad about Knotweed?

• Roots grow up to 9’ deep and plants up to 15’ tall; can penetrate cement

• < 1 gram of rhizome (size of a fingernail) can start a new plant • Stalk fragments can grow new roots and shoots from leaf nodes• There are no significant herbivores, insects or pathogens of Japanese

or giant knotweed in the western world

Fallopia japonica var. compacta growing on lava in Japan Photo from J. Bailey, Univ. of Leicester,http://www2.le.ac.uk/departments/genetics/people/bailey/res/hab

Japanese knotweed rhizomes & rootsPhoto by John Cardina, The Ohio State University, Bugwood.org, from http://www.fs.fed.us/database/feis/plants/forb/polspp/all.html

Knotweed Up-close and Friendly with Foundations and Pavement at Apartments in East Lansing

• The spread is coming from roots or stalk fragments, not from airborne seeds

• Can be very hard to control once it establishes under/within infrastructure

Photos: Monica Day, Grand-Raisin Cluster of the Stewardship Network

An Ecological Nightmare: Rivers on the Olympic Peninsula of Washington

One clump of JK on banks of the Hoh River (UNESCO World Heritage Site) within 5 years had spawned 18,585 canes downriver

Excerpt from http://www.10000yearsinstitute.org/10k_pdf/Hoh%20Knotweed%20Project%20Report%202005.pdf

etc…Knotweed infestation and knotweed beaver dam on the Big River, Olympic Peninsula http://www.clallam.net/weed/images/Knotweedbeaverdam.jpg

Michigan Law on Invasive Knotweed

Prohibited Plant Species (Natural Resources and Environmental Protection Act (Act 451 of 1994, as amended): Prohibited species identified under this Act cannot be sold or grown in the state. Any of the following plants, fragments [e.g, by cutting/mowing], seeds or a hybrid or genetically engineered variant thereof are specifically prohibited…

Photo of variegated Japanese knotweed cultivar from Washington State University Clark County Extension

What is the Japanese Knotweed Situation in Michigan and the Midwest? Ask misin.msu.edu

Homing in on Mid-Michigan Japanese Knotweed

Site #1, first treated in 2010

(Lansing urban sites not shown)

What patterns do you see??

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Wmston

DeWitt

Holt

Mid-Michigan Stewardship Knotweed Treated Sites:

How to Prioritize? Depends on the Speciesand Site Characteristics

• For invasive knotweed, rapid spread along rivers and trails and roadsides is caused by cutting/mowing and stalk/rhizome breakage

• Outliers of a main population (satellites) are like burning embers!• Highest priority: colonies or spread in/near high-quality habitats• We aim to control all the observed sites in our area, one by one

Talman Rd. Bridge over the Looking Glass River in Eagle, MI; photo by Nick Babcock, MSU Vets to Ag

Most Important Habitats to Protect from JK InvasionLooking Glass River and Vermillion Creek

Red Cedar RiverSycamore Creek

Contacting landowner to:•inform them about invasive species•describe why treatment is important•gain multi-year permission to treat plus liability waiver

Most landowners are keen to treat, but find specialty herbicides intimidating

In the field: It’s fun! A great workout and you meet lots of interesting people and habitats!

Daily Summary Sheet for Each Treatment Site

Tracking Annual Permissions/Treatments/Monitoring

DEQ Aquatic Nuisance Treatment Permit: needed for any site with standing water at the time of treatment: http://www.michigan.gov/deq/0,4561,7-135-3313_3681_3710---,00.html

Right-of-way (ROW) Permit: needed from road commission or municipality if site is within a given distance of centerline of road (e.g.,33’ for a two-lane road in our area)

Pesticide Applicator Certification: needed if doing herbicide/pesticide application for your job; see pested.msu.edu and MDARD Pesticide Applicator Certification

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*Residual soil activity for ~18 mo. Do not spray under redbud, locusts, cedar, juniper, grape, mimosa, mulberry, rose, spruce, caragana, pinyon pine. See Milestone link on Helpful Resources page at end of this document. Info via Katie Grzesiak, IPN.

Our Experience with Herbicides for Foliar Spray on Japanese Knotweed

Our wetland choice:

Our upland choice:

Imazapyr

0.5% Imazapyr at Maguire Park: Full Japanese knotweed control with no harm to neighboring trees

Japanese knotweed colony East Lake Drive in Haslett

Progress in Japanese Knotweed Control

Year 1, post-mowing (mowing is no longer recommended)

Year 3

2015 Control of Canada Thistle Succession by Using Aminopyralid for a JK Site Previously Treated with Imazapyr

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An Important Component! Collaborate with Parks, Road Commissions, Utilities and Homeowners to Stop Mowing/Cutting/Spreading Knotweed Along Roads and in Yard Waste

Meeting with local parks & city staff to brainstorm on how to change mowing practices to reduce spread of Japanese knotweed

How Long Does it Take to Win the Battle?

• Imazamox: 30-95% of invasive knotweed remained after 2 years (problematic at more established sites; ceased using it)

• Imazapyr: 5-15% JK remaining after 2-3 years; important to use lower 0.5% concentration to not hurt nearby trees

• Aminopyralid: our first year of treatment, but it’s looking good, and has worked well at MDNR treated sites

• Expect to keep monitoring for 4+ years after apparent control. Can rebound in wet years.

• Stem injection or cutting-and-filling may be more effective but is much more labor intensive; trade-off between # sites to treat and rate of control

Stem injector kit; can be connected to herbicide reservoir (lower right) or hose to herbicide container

Stem methods contacts:Carolyn Henne (NW MI CWMA; Emily DuThinh, Oakland County CISMA)

The Future: Japanese Knotweed Biocontrol“In 2004, the psyllid [a type of louse], Aphalara itadori, was selected for release in the UK and first releases made in the spring 2010 and again in 2011 and 2012. In 2003-2005, release and control sites were identified in OR and WA and data collected concerning knotweed growth patterns. In 2012, similar release and control sites were identified in MA, VT, and NH. In 2013, the TAG recommended release of A. itadori in the US.”From http://www.fs.fed.us/foresthealth/technology

Aphalara itadori, a natural enemy and specialized feeder on Japanese knotweed; photo from The Independent

Community Flyer on Identifying/Controlling Invasive Knotweed

New Community-wide Efforts to Control Japanese Knotweed in Western MichiganKathy & Bill Hanley, The St. Joseph Knotweed Eradication Group, Randy Counterman (Native Landscapes), and City of St. Joseph 2015

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The Kalamazoo Bamboo Summit, 2015;City of Kalamazoo and many stakeholders, organized by Hannah Hudson

https://www.facebook.com/kzoobamboocrew

Some Helpful Resources• See Japanese knotweed training module and fact sheet under “Learn” and best control

practices document under “How to” at: michiganinvasives.org

• This presentation will soon be posted at www.stewardshipnetwork.org/midmich under “Resources”

• Maps and spreadsheets of known invasive knotweed locations under “Browse data” at misin.msu.edu Upload your own data there individually or in bulk; see

http://www.misin.msu.edu/train/MISIN/Protocols/MISIN%20data%20submissions%20(Email_Bulk).pdf

• List of trees sensitive or not sensitive to aminopyralid/Milestone: http://www.cwc-chemical.com/download/dow/Milestone%20-%20Around%20Woody%20Plants%20InfoSheet.pdf

• Fascinating article on the history of Japanese knotweed and control efforts in the UK in Harper's Magazine, May 2015: http://harpers.org/archive/2015/05/the-day-of-the-knotweed/

• MIPN Invasive Plant Symposium, Dec. 9-10, 2015 (Indianapolis, IN): http://www.inpaws.org/wp-content/uploads/2015-MIPN-symposium-with-NCWSS-agenda.pdf

• Stewardship Network Conference Jan. 15-16, 2016 (East Lansing, MI) on the Science, Practice, and Art of Restoring Native Ecosystems:

https://www.stewardshipnetwork.org/2016-stewardship-network-conference

• Mid-Michigan Stewardship Initiative free community-oriented hands-on workshop on Herbicide selection, safety, dilution, and application: Saturday, June 4, 2016; see

http://www.stewardshipnetwork.org for details in 2016 or contact midmich@stewardshipnetwork.org

Thanks to Lisa!

Any questions?