Noxious Weeds and Management Strategies Presented By: Dale Whaley Washington State University Extension

A weed in one place could be a benefit in another Lots of weedy plants are used by birds, animals, insects and people It depends on the threat to resources or ecosystems A honey bee visits bull thistle flowers Are all weeds bad all the time? F. & K. Starr, Starr Environmental, Bugwood.org

What is an invasive weed? Introduced / non-native Out-compete native plants Change local ecology Reproduce and spread rapidly D. Whaley, WSU Extension Diffuse knapweed Infestation

Invasive plants like English Ivy transform forests and natural areas Invasive plants harm native habitats and species. J.M. Swearingen, USDI National Park Service, Bugwood.org

Increased Risk of Fire D. Whaley, WSU Extension D. Powell, USDA Forest Service, Bugwood.org

Invasive plants impact wildlife. Humming bird stuck to Burdock burs eventually dying on the spot. D. Whaley, WSU Extension

Understanding Washington’s Noxious Weed Law and List

Washington’s noxious weed law involves both public and private landowners. King County NWCP

What is a noxious weed? Non-native plant that impacts agriculture, wildlife, human health, land values or natural resources Defined and regulated by state law (RCW 17.10) Visit the Washington State Noxious Weed Control Board websiteWashington State Noxious Weed Control Board website

Noxious Weed List (WAC ) –Weeds that are beginning to invade but not yet widespread –Regulated by county noxious weed boards –Property owner required to prevent plants from seeding State Quarantine List (WAC ) –To prevent spread of new introductions (does not include already naturalized plants) –Regulated by WSDA Nursery Inspection Program –Businesses are prohibited from selling plants or seeds Different lists regulate nurseries and landowners.

Class A Weeds – new invaders, control required statewide, still a chance to eradicate Class B and C Regulated Weeds – control required only in particular counties or regions, still have a chance to stop them from getting established Non-Regulated Class B and C Noxious Weeds and Weeds of Concern – control not required but definitely a good idea whenever possible Noxious weeds are ranked by how widespread they are.

Class A: Common Crupina Class B Regulated: Scotch broom Class C Non-Regulated: Old man’s beard Here are a few examples of weed classes. J. Andreas, WSU Extension King County USDA APHIS PPQ Archive, Bugwood.org

Strategies for Managing Invasive Weeds S. Shaw, King County NWCP

Ecology-based weed management is a long- term approach to weed management Prevent Control Restore Weed Population Growth Time If less than 15% cover is desirable plants, then need to restore as well as control weeds

Get to know the type of weed in order to control it better. Annual Biennial Perennial Woody plant Vine Annual: Common Groundsel Perennial: Spotted Knapweed Biennial: Tansy Ragwort Shrub: Scotch Broom Utah State Univ. Archive, Bugwood.org S. Dewey, Utah State Univ., Bugwood.org L.L. Berry, Bugwood.org King County NWCP

Getting to know your roots is especially important. K.W. Zobrist WSU Extension

Practice integrated pest management. Prevention Land management Manual controls Mechanical controls Chemical controls Biological controls

Prevention is the cheapest weed control method. King County NWCP D. Whaley, WSU Extension

Manual control is targeted and effective, but also lots of work. Pulling and bagging garlic mustard Pulling gorse with a weed wrench Digging giant hogweed C. Gray, GA EPPC, Bugwood.org S. Shaw, King County NWCP

Make sure you have a disposal plan for the weeds you dig up. Noxious weeds that are regulated should go in the garbage. Commercial yard waste composting is good for widespread weeds Make sure the weeds are dead when you leave them King County NWCP

Mechanical control reduces the weed’s vigor without disturbing the soil. Be careful not to move weed seeds on equipment.

Sheet mulching is another way to starve the weeds without disturbing the soil. Bark or woodchips over cardboard or layered newspaper - best for soil building Geotextile fabric - good for weed control Black plastic - cheapest, not good for soil King County NWCP T. Neuffer, WSU Extension

Biological Weed Control The intentional use of one living organism to control/suppress another organism, such as WEEDS Caesar, USDA ARS; bugwood.org Nematodes Piper, WSU; bugwood.org Pathogens Healing Hooves Mammals WSU Extension Insects

How Does It Work?

Solution – “Classical Biocontrol” Degree Latitude Belt

Classic Noxious Weed Infestation Diffuse Knapweed

Solution – “Classical Biocontrol” Degree Latitude Belt

Host-specific ~ only attacks target weed High searching capacity ~ capable of dispersing and finding host High reproductive potential ~ produces many offspring Long-lived adults ~ increase searching, egg distribution, compensates for asynchronies in phenology Multi-voltinism ~ more than one generation a year Ideal Biocontrol Agent Characteristics

Advantages Safe – USDA APHIS approves biological control agents before introduction into U.S. Ecologically desirable – herbicide alternative Insects are mobile Long-term solution Cost effective Leafy Spurge Biocontrol

Limitations Long time to make impact Subject to predators May not establish at some sites Very slow approval of new agents No eradication Predatory mite Predatory insect

When To Use Biocontrol? Established weed infestations Remote, inaccessible, less disturbed areas Areas not controlled by other means Environmentally sensitive sites such as near water Kittitas CNWCB WSU Extension

When NOT To Use Biocontrol? Small or new infestations Highly disturbed areas Roads or traveled paths Areas unfavorable for insect On weeds with no approved agents Mazerolle, Air

Weeds with Biocontrol Agents Scotch broom tansy ragwort meadow, diffuse, & spotted knapweed Canada & bull thistle purple loosestrife St. Johnswort yellow starthistle puncturevine rush skeletonweed bindweed Russian knapweed Dalmatian & yellow toadflax leafy spurge

Contact central Washington State’s biocontrol program for assistance and information. Site assessments to determine if biocontrol is an option Contact: –Dale Whaley, WSU Extension office –Jennifer Andreas, WSU Extension office

Chemical control can be highly effective but requires special care and knowledge. Know your site Know your weed Know your product Follow label instructions Always be cautious and selective in your application King County NWCP

There are a few special considerations when using herbicides in forestry. Read the Forestry section in the PNW Weed Management Handbook:

Here are a few useful websites for herbicide information. WSDA Pesticide Licensing and Education – PNW Weed Management Handbook – (see especially the chapters on Control of Problem Weeds) Crop Data Management Systems, Inc. – labels and MSDS for most herbicides –

A Complete Integrated Vegetation Management Approach Small Weed Infestations –Preventative measures such as; weed free mulches or utilizing certified weed-free seed –Control or Eradication of the population Hand-pulling (physical control) Mowing (mechanical control) Spot spray (chemical control) –Once completed; utilize preventative measures in order to minimize future weed invasions

A Complete Integrated Vegetation Management Approach cont… Large Established Weed Infestations –Large scale mowing or tillage operations to stop seed production (mechanical control) not recommended for perennial type weeds –Herbicide applications to the weed perimeter (chemical control) –Incorporation of weed eating insects or goats/sheep (biological control) –Once completed; utilize preventative measures in order to minimize future weed invasions

Helping You Put Knowledge to Work! Dale Whaley Regional Extension Specialist 203 S. Rainier St., PO Box 550 Waterville, WA