Japanese Knotweed Polygonum cuspidatum by pengtt

VIEWS: 146 PAGES: 45

									Japanese Knotweed--
Biology, Impacts, and
       Control

   Brock Woods, Wisconsin Dept. of
  Natural Resources and Univ. of Wis.
 Extension—with help from Oneida Co.
                LWCD
“The Worst Invasive Plant in the
           World”?
Polygonum cuspidatum (Fallopia
 japonica; Reynoutria Japonica)
P. cuspidatum
internationally
recognized
F. japonica most used
in Europe
R. japonica being
used less recently
 Mexican Bamboo, Japanese
Fleeceflower, Crimson Beauty
     Distribution and Spread
From Japan, Chinas &
Korea where it invades
newly exposed soils
Into Europe in 1840s
US East coast in 1869?
Wisconsin ~1960
In at least 42 states
Plant sales
  Description: An exotic, semi-woody
               perennial
              fruit
                                     leaf
   Stalk


              Node




                 Rhizome



                           flowers
Roots
                   Leaves

Simple, alternate
Oval to triangular, 3-4”
wide, 4-6” long
Flat base, narrows to a
point
Upper dark green,
under light green
Petioles long
Stems
6– 12 feet tall
Thick, erect, smooth,
hollow, round, swollen
nodes
Green and reddish brown
Bamboo-like, arching
Killed by frost but stems
stay upright through the
winter
Dead stems can be a fire
hazard
Stems turn rusty in fall making winter a
       great time to note plants
               Root System




Tap root often 2-3 meters deep
Horizontal rhizomes to 20 meters
Rhizomes and fibrous roots become large & massive
Will grow under roads, break brick walls & pavement
                  Flowers
Small, cream to light
green, plume-like
clusters
Upper part of leaf axils
near ends of stems
Functionally dioecious
Male flower stems erect,
female flower stems
droop?
Blooms Aug-Sept
Fruit and Seeds
  3-winged fruit
  Seeds small, shiny
  black, triangular
  Up to 130,000 per stem
  7 million seeds per
  plant of 10 stems
  Easily transported by
  wind and water
  Seeds live 1 to 4 years?
Reproduction—still evolving
Asexual through root, rhizome, and stem fragments in or on
moist soil
Sexual through both intra-species fertilization and inter-specific
fertilization with P. sachalinense (giant knotweed) to produce
hybrid P. x bohemicum (Bohemian knotweed)
Hybrid vigorous and common, with introgression back to
parent plant
Suggests enhanced reproduction over time, making targeting
hybrids for elimination wise
Some research suggests both male and female plants in most
patches making functional seed common
Unclear if this is true in the Midwest
     So-called Sterile Hybrids
Male garden
varieties such
as Variegated
Knotweed
can pollinate
wild female
plants, thus
producing
seed
Bann them?
Polygonum sachalinense Leaves &
           Flowers
Leaves are larger, with
distinct, long, multicellular
hairs on underside midrib
(bumps on P. cuspidatum)
Leaf bases are deeply
cordate
Inflorescences are smaller,
shorter
P. x bohemicum traits are
intermediate
P. sachalinense (AKA Giant or
     Sakhalin Knotweed)
      P. cuspidatum Seedlings
Research on germination is
mixed
May have no germination
requirements at all
May need cold period
Requires light and moist
soil
Few to 10,000s/ sq. m
Seedlings found in
Madison, Wisconsin
Vegetative dispersal mechanisms
Moving contaminated soil
Flooding carries broken
pieces of rhizomes/stems
downstream
Mowing without collecting
plant parts
Buying it as an ornamental
Trades
     Plant Growth and Form
1 to 3.3 inches/ day
Documented patches
up to 16 acres
Patches often round
mound shaped
Along water and roads
patches often linear—
10 meters wide and
hundreds of meters
long
            Typical Patch Forms

                                JK clone in Oneida Co., Wis.




JK on Hwy 51, Vilas Co., Wis.
                 Habitats
Upland, wetland,
shoreline, hillsides,
roadsides, yards,
woodland edges
Prefers sun, but
tolerates shade
Moist soil to germinate
or grow roots
Many types of soils
Variety of Habitats
    Impact--Why Worry?
Threat to native plant and animal communities
Reduces light
Allelopathic; possible other soil changes
Eliminates native plants and reduces biodiversity
Very little wildlife habitat value: cover
Web: “Life on the Japanese Knotweed”
Poor erosion control; ground cover absent and poor
surface root system
Increases siltation
Suspect trout populations impacted
Japanese Knotweed in the UK Causes
Ecological and Infrastructure Damages
      Effects on Infrastructure
Costs UK $2 to 10 million per
year
“One of the worst IS along UK’s
2200 miles of canals and rivers”
Mortgages refused
“Capable of pushing through
concrete, posing a risk to the
structure and fabric of the
building” (typical loss $10,000)
Safety compromised: signs
obscured and guard rails covered
Will these problems occur here?
    Control / Management
Very difficult if not impossible to eradicate once
established
Large stands are difficult to manage & keep under
control
Crucial to start control as soon as it appears
Typically takes multiple treatments over several
years, depending on size & control methods – don’t
expect immediate results!
Landscape scale strategy best for long-term control
  Typical types of Control
Manual/Mechanical
  Pulling, digging, cutting,
  mowing
Covering
Chemical
  Foliar
  Stems
Biological
  Goats
Combinations
          Control in the UK
Landowners increasingly required by law to be
responsible for removing their JK
Herbicides
Bury contaminated fill on site (at least 2 meters)
Fill dump—pay to put their fill elsewhere
“Spoil to Soil”—removing all contaminated soil,
treating with heat or other means and returning it
10 year guarantees typical
 Choice of Treatment Method
Herbicide or
Manual/mechanical:
  Cut
  mow
  Pull
  Dig
  Cover
           Control
      Manual – Mechanical
Small stands, new       Not generally
plants                  recommended but may be
Mowed and/or cut        effective on very small
  Needs to be done      plants
  regular, short-term   Beware root fragments
  basis
                        Difficult to remove the
  Nearby stand?         entire root
  Years of cutting to
  weaken rhizomes       Heavy machinery for
  enough to kill it     massive roots?
  Collect all pieces:
                  Covering
Heavy duty black plastic or geo textile fabric
Better in open areas, on smaller patches
Often 3 or more growing seasons
Cut old stems, cover a minimum of 7 ft beyond existing stand
Leave cover loose but anchor with rocks or cement blocks
Watch for holes from new growth or other objects
Eliminate new growth every few weeks by stomping and
clean debris
Best if done in spring before growth takes place
Later in the year should be cut several times during the
season beforehand
     Chemical Application
The most effective control
method for now
Several methods to choose
from
   Pre-emergence
   Foliar spray or wipe
   Stem: pour
         inject
Follow label directions
Acquire permits
  Foliar Spray Treatment
Late summer application (before a killing
frost)
  Sugars to the rhizomes for storage will take the
  herbicide along
  Combine with cutting in June
  If done carefully: less contact with the soil & less
  risk of injury/kill of non targeted plants thru root
  systems
  Non-selective herbicides; take care
Stem Injection | Cut & Pour
 Only glyphosate is labeled   Glyphosate is used for the
 for stem injection           cut & pour
 Highly effective             Cut stems between the
 Use injection gun            lowest two nodes
 Labor intensive especially   Pour measured amount in
 large dense stands           each hollow stem
 Stems >1/2 inch              Labor intensive
 Prevents drift               Follow directions on label
 Needs to be repeated         for application rate
                              Best in late summer, early
                              fall
                              Prevents drift
Choice of Chemical, Timing & Rate
  See handouts for suggested herbicides and
  application rates
  Follow directions!! Read the labels!! Use
  caution!! Keep children and pets away from
  the site!!
  Timing depends on methods, but herbicides
  almost always best used late in the season
   Dispose of all Plant Parts
           Properly
Do not compost stems, rhizomes and/or roots;
discard with trash or burn
Care with seeds
Keep all parts of JK out of waterways,
wetlands, or other wet sites!
          Biological Control
Goats will eat foliage
   Not always feasible
   Control on a lands with
   acreage
   Graze several times a season
   over many years
Other biocontrol is still
being researched and not
yet available
Two possible biocontrol
organisms: an insect and a
fungus
Aphalara itadori (psyllid)
What can we expect from biocontrol?
  Long term approach to weed control; major results likely to
  take years.
  Control, not eradication, is the end point
  Target weed reduced to an acceptable level should reduce
  costs
  Anticipate attacked knotweed plants will have reduced vigor,
  allowing neighboring plants to re-establish thanks to reduced
  competition.
  What we should not expect is the complete abandonment of
  current treatments
  Natural enemies should be seen as part of an integrated
  control programm, not the complete solution.
Testing Potential BC Organisms
                                             Goldenrod

 Restoration
Critical; often neglected
Fast growing, possibly aggressive,
native species
Needs research
   Some examples: willow (Salex sp),
   aspen (Populus sp), red maple (Acer
   rubrum), dogwood (Cornus sp),
   goldenrod (Solidago sp), hyssop
   (Agastache sp), native grasses, etc.                  Dogwood
   Nurse crop of annual rye, buckwheat,
   or other annual cover crop
   waterways and other erodible areas


                                          Poplar
           Into the Future?
Research needed
Testing being done on soil steaming, injecting
steam in the contaminated soil to kill plant
parts
Support Biological control research now
Eradication is not a likely option in the future
Education & management may be the key to
minimize this plant
 Resources for this presentation
Invasive Knotweed BMP, January 2008, King County DNR, www.kingcounty.gov/weeds
Invasive Plants of the Upper Midwest, An Illustrated Guide to Their Identification and Control. Elizbeth
J. Czarapata
Japanese Knotweed: Facts, Discussion Forum, and Encyclopedia Article.
www.absoluteastronomy.com/topics/Japanese_Knotweed
2010 Pacific Northwest (PNW) Weed Management Handbook. Control of Problem Weeds. Bob Parker.
Revised October 24, 2008. Page 475, 494
Ohio Perennial & Biennial Weed Guide. Japanese Knotweed Polygonum cuspidatum. www.oardc.ohio-
stateedu/weedguide/singlerecord.asp?id=230
PennState Vegetation Management USDA. Conservation Reserve Enhancement Program (CREP).
Technical Assistance Series. Factsheet 4. www.pgc.state.pa.us/crep
PennState College of Agricultural Sciences, Cooperative Extension – Centre County. Fact Sheet:
Invasive Weeds. Prepared by David R. Jackson, Forest Resources Extension Educator
Robert W. Freckman Herbarium. University of Wisconsin – Stevens Point.
wisplants.uwsp.edu/scripts/detail.asp?SpCode=POLCUS
http://www.fs.fed.us/database/feis/plants/forb/polspp/all.html#LIFE%20FORM
Some photos from http://images.search.yahoo.com/search/images?_adv_prop=images&fr=my-
myy&va=japanese+knotweed+photos
Photo credit: Linda M. Wilson & Tom Heutte

								
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