Hoh River Knotweed Project - Clallam County, Washington · Lower Hoh 1 731 ns ns ns 394 337 ns 46600 9622 18585 8463 2911 6557 2468 ns = not surveyed _____ 10,000 Years Institute

Hoh River Knotweed Project:…will it never end?

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10,000 Years Institute

Jill SilverExecutive Director

10,000 Years Institute

jsilver@10000yearsinstitute.org

360.385.0715

Allison FawcettField Coordinator

afawcett@hotmail.com

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10,000 Years Institute

Project Partners

Local Landowners

Hoh Indian Tribe

Hoh River Trust

Olympic National Park

Olympic National Forest

Clallam County Noxious Weed Program

Jefferson County Noxious Weed Program

Washington State Department of Corrections

Olympic Region Department of Natural Resources

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10,000 Years Institute

Project Funding and Support

Washington Department of Agriculture

National Fish and Wildlife Foundation:

Community Salmon Fund

Clallam County Noxious Weed Program

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10,000 Years Institute

1998

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10,000 Years Institute

What’s the Problem with Knotweed?

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10,000 Years Institute

• Large Downed Wood – Pools, Dens, New

Trees

• Litterfall – Bugs, Food Web

• Nutrient Cycling – Nitrogen Fixation

• Bank Stability and Erosion Control

• Shade - Microclimate, Humidity

• Nesting and Roosting Sites

• Food for Wildlife, Insects, Fish

Ecological ‘Services’ of Native Forests…

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10,000 Years Institute

Knotweed Harms Native Forests…

• Interrupts the

succession

of native plants

•Replaces native

plants completely

•Has no habitat

benefits of natives

•Steals nutrients

•Acidifies soils

•Alters sediment

transport

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10,000 Years Institute

Hoh Knotweed Control Project History

• 1998– one clump on right bank floodplain at RM 29.5

• 2001– float trip observations

– infrequent knotweed clumps spread along gravel bars

• 2002– inventory only

– 9,622 canes to RM 9.5

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10,000 Years Institute

Hoh Knotweed Control Project History

• 2003

– Inventory and treatment to RM 9.5

– 18,585 canes

• 2004

– Inventory and treatment to RM 0.5

– 7155 canes to RM 9.5

– 1308 canes to RM 0.5

– 8463 total canes

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10,000 Years Institute

Hoh Knotweed Control Project History

• 2005 – 2006

– Inventory and treatment of entire river

– Assistance from the Hoh Tribe and

Clallam County crew

– 4551 total canes

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10,000 Years Institute

Hoh Knotweed Control Project History

• 2007

– Inventory and treatment of upper river, RM 27 to

RM 17

– 916 acres

– 2468 total canes

– Most plants single-stemmed and smaller than 3

feet

– Used only 1.23 gallons of Aquamaster!

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10,000 Years Institute

Treatment Appropriate to the Site and Plant

• 2003

– Inject each cane with 5 cc RoundUp UltraMax™

using a hypodermic syringe

– Spray small plants and canes too small to inject

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10,000 Years Institute

Treatment Methods Evolve…

• 2004 onward…

– Inject each large cane with 3 - 5 cc Aquamaster™using JK International injection gun

– Spray small plants and canes too small to inject with a mix of 6% Aquamaster,1.5%Agridex, and 0.5% Blaze-on-Blue marker dye

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10,000 Years Institute

Most Effective Treatment

• Time of Year

– Plant Size

– Plant Physiology

– Type of Plant

• Location

• Substrate

• Proximity to Water

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10,000 Years Institute

2003

Injection vs. Spray – Change Over Time…

2004

2005

Inject

Inject + Spray

Spray

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Treatment Success Rate…. > 98%

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We’ve gone from THIS ….

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….to THIS:

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From THIS … …to THIS:

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10,000 Years Institute

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10,000 Years Institute

Grid-Style Surveys

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10,000 Years Institute

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10,000 Years Institute

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10,000 Years Institute

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10,000 Years Institute

Treatment Uncertainties…

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10,000 Years Institute

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10,000 Years Institute

Number of Canes by Year, River Bar, and River Mile

River Bar River Mile # Canes 2002 2003 2004 2005 2006 2007

Brandeberry 29.75 5019 ns 4108 707 69 135 ns

Canyon Creek 28 2479 932 1046 357 31 21 92

Lewis Channel 28 1154 ns 505 509 36 104 ns

Owl Creek 27 6794 869 4517 1053 238 117 ns

Fletcher Island 27 158 ns ns ns ns 158 ns

Spruce Creek 27 1644 49 ns 1078 58 239 220

Spruce Canyon 26 681 133 336 162 39 8 3

Spruce Canyon LB 26 374 326 ns ns 48 ns ns

Coontz' Bar 25 30 7 ns ns ns 23 ns

Coontz' LB 25 2155 1925 136 47 ns 47 ns

Morgans 24 503 ns 15 215 67 15 191

Clear Creek 23 1388 ns 729 556 36 15 52

Lindner 23 9668 3299 3717 1227 303 819 303

Peterson's Bar 21.5 1405 ns 559 206 387 62 191

Peterson's Bar West 21 1908 ns ns 821 ns 35 1052

Schmidt Bar 20 3661 1437 1798 217 35 94 80

Elk Creek 19.5 1089 ns ns ns 639 384 66

Alder 19 544 ns ns ns ns 326 218

Allen's Bar 15 25 ns ns ns ns 25 ns

Allen's Bar II 15 60 ns ns ns ns 60 ns

Hell's Roaring 15.5 572 ns ns ns ns 572 ns

Old Joe's Slough 14 238 ns 181 ns 14 43 ns

Baker 13 1524 319 ns 857 224 124 ns

Dengate Island 12 217 ns 125 31 50 11 ns

Cottonwood 10.5 1611 326 813 318 119 35 ns

Nolan Creek 8 11 ns ns ns 11 ns ns

Nolan Bar 8 286 ns ns ns ns 286 ns

Rayonier Bar 7 275 ns ns ns ns 275 ns

G & L 6 113 ns ns ns 113 ns

Lower G&L 5.5 132 ns ns ns ns 132 ns

Fletcher Creek 2.5 151 ns ns 102 ns 49 ns

Lower Hoh 1 731 ns ns ns 394 337 ns

46600 9622 18585 8463 2911 6557 2468

ns = not surveyed

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10,000 Years Institute

Results

• ~98% success rate was observed on treated

plants 3 – 5 weeks after treatment.

• Some “killed” plants had new shoots near the

parent plant in the following spring.

• A surprisingly high number of very small plants

were found from 2004 to 2007 – either

developed after treatment or sprouted from

plant material deposited by winter storms.

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10,000 Years Institute

Conclusions

• A single plant can start the entire infestation

over again.

• A decade may be a reasonable amount of time

to determine whether knotweed has been

successfully eradicated on the Hoh River.

• Applied research is needed to assist with

developing effective control methods and to

inform herbicide application.

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10,000 Years Institute