Presentation on the invasive Japanese knotweed.

1. Japanese Knotweed
5/16/2012
Managing Aquatic Resources Since 1966

2. Invasive Species
 Japanese Knotweed
 Buckwheat family
(Lythraceae)
 Scientific Name: Fallopia
japonica
 Previously: Polygonum
cuspidatum
 Common Names: Japanese
knotweed, fleece flower,
Mexican bamboo, huzhang

3. Distribution
 Native to Asia
 Colonized the United States in Late 1800’s
 Introduced as an ornamental and for erosion control
 Presently found in a significant portion of North America

4. Description/Identification
 Herbaceous shrub 3-12 ft. tall
 Reddish, hollow, and jointed stems
 Alternate leaves are 4-6 inches, ovate with pointed tips
and flat bases

5. Flowers
 Flowers May to September
 Flowers terminal and auxiliary
 Branched sprays (racemes) 3-6 inches long
 Covered with tiny 5-petaled (sepaled) white to greenish
flowers
 3 styles and 8-10 stamens

6. Fruit
 August – November
 Dangling
 Winged
 1 triangular shiny nutlet

7. Life Cycle
 Stems and leaves survive one season
 Rhizomes survive many years
 Grows fast in spring from rhizomes and seeds
 Crowds/shades other species
 Prefers open areas such as riparian corridors, roadways,
etc.
 Does well in wetlands

8. Dispersal Mechanisms
 Ornamental trade
 Fragmentation
 Disturbance colonization
 Riparian flooding
 Roadway mowing

9. Impacts
 Alters natural ecosystem
 Crowds out native vegetation
 Dense stands provide limited wildlife habitat
 Causes structural damage to buildings, sidewalks, roads

10. Control Options
 Education/Prevention
 Physical
 Biological
 Aphalara itadori
 Chemical

11. Chemical Control Options
 Renovate 3 as 2% solution
 Glyphosate
 Foliar application with 2% solution
 Cut-stem application (label details)
 Combination of Glyphosate (2%) and Renovate (1%)
 Habitat as 1% solution
 Early treatments prevent seed production
 Late season treatments are more effective on rhizomes

12. Japanese Knotweed Sherbet
This sour rhubarb relative lends its lemony flavor and thickening
qualities to this sweet-tasting sherbet.3 cups Japanese knotweed stalks,
peeled if desired, coarsely sliced
1-1/3 cups orange juice (freshly squeezed is best)
1-1/2 cups apple juice or other fruit juice
1/2 cup lemon juice
1/4 cup canola oil
1/4 cup vegetable glycerin, honey, barley malt, or rice syrup
1 tbs. freshly grated (or 1 tsp. dried) orange rind
2 tsp. vanilla extract
1 tsp. lemon extract
1 tsp. liquid stevia (optional)
1/4 tsp. salt1.
1. Simmer the Japanese knotweed shoots in the orange juice, apple juice,
and lemon juice 10 minutes or until soft.
2. Puree in a blender with the remaining ingredients.
3. Chill.
4. Pour into an ice cream machine and run it until done.

13. Questions?
Managing Aquatic Resources Since 1966