Developed by Pringle Developed by Pringle Creek Watershed CouncilCreek Watershed Council

Salem, OregonSalem, Oregon

Urban Weed ManagementUrban Weed Management

Presentation overview

• Definition of “weeds”

• Weed impacts

• Ways to identify and control common invasive plants

• How to tackle weeds in your yard

• Resources for additional help

What is considered a weed?

• Any plant growing where it is not wanted.

• Invasive and noxious weeds are the most troublesome.– Rapidly dominate the site– Very difficult to control

Noxious Weeds in Oregon• Landowners are responsible for controlling

the spread of noxious weeds on their property

• Class A – worst; Class B – not as bad

Class “A” Weeds Class “B” Weeds

Weed impacts• Out-compete other plants for water, nutrients, and sun• Costly and difficult to control• Loss of wildlife and fish habitat; yard space• Some are toxic to people

and animals• Decrease property value• Increase erosion• Can take over

recreational areas• Minimize land uses• Spread rapidly

How do weeds spread?

• Humans• Pets• Wildlife• Water• Wind• Vehicles• Machinery• “Wildflower” mixes• We plant them• Soil disturbance

Weed Management

• Buy clean seed for wildflowers or lawns; don’t plant weeds!

• Clean yard equipment before using it in another area

• Control weeds along streams

• Use mulch materials or weed mats

• Pull weeds early – before they go to seed!

Prevention is the most effective practice of all!

Control MethodsMechanical• Mowing, hand pulling, burning, solarizing

Cultural• Shading, site preparation, plant

appropriate competitive vegetation

Biological• Parasites, predators, and pathogens;

typically a slow process

Chemical• Often requires repeated application; can

be sprayed, wiped or painted onto leaves or stumps; usually most effective in fall; USE ACCORDING TO LABEL

Perennial

Woody evergreen vine

Reproduces by seed and roots

Can kill trees!

Berries are poisonous to most wildlife. Starlings love them!

Control methods: hand pull or roll up vinescut stems on vines in trees & pull away lower vines from trunkapply herbicides (requires repeated application due to waxy leaves)

English Ivy (Hedera helix)

Perennial

Deciduous to partially evergreen

Reproduces by seed and roots

Doesn’t grow as well in shade

Control:

mow (at ground level) repeatedly

dig or pull up root crowns

deep shade from larger trees

apply herbicides in the fall to leaves or cut stumps

Himalayan Blackberry (Rubus discolor)

Biennial

2-5 feet tall

Flowers purple July-September

Reproduces by seed

Seed can be viable for 10 years

Bull Thistle (Cirsium vulgare)

Control:

hand pull

cut or mow before going to seed

apply herbicides in late fall or early spring

Perennial

Flowers light pink-purple

Grows 1-4 feet tall

Has deep horizontal roots

Reproduces through creeping roots, some seed

Canada Thistle (Cirsium arvense)

Control:

pull by hand (small plants)

apply herbicides; spot-spraying young plants is very effective

PerennialCan grow up to 12 feet tallHollow, bamboo-like stemsLong creeping roots Dies back in winter

Control: Cut close to ground regularly (every 2 weeks during growing season)* dig (small plants and surface roots)apply herbicides to leaves & stems in the summer or early fall*be sure to properly dispose of all plant material

Japanese Knotweed (Polygonum cuspidatum)

Control:

hand pull or dig* (small plants)

apply herbicides in early spring or late fall*be sure to wear gloves & properly dispose of all plant material

Biennial

Grows to 10 feet tall

Tiny white flowers & purple-mottled stems

All parts of plant are highly poisonous (if eaten)

Reproduces by seed

Poison Hemlock (Conium maculatum)

Control:pull with weed wrenching toolmow or cut (prior to seed ripening)apply herbicides to foliage while actively growing or bark anytime

Perennial

Woody shrub with dark green branches, 3-10 feet tall

Reproduces by seed; seeds are protected by a flat pod

Soil disturbance results in a new crop of seedlings 

Scotch Broom (Cytisus scoparius)

Perennial grass

Leaves ¼ - ¾ inches wide

Stems 2-7 feet tall, covered by waxy coating

Forms thick mat of roots and rhizomes

Reed Canarygrass (Phalaris arundinacea)

Control:hand pull or mowsolarize shade out the plantapply herbicides in early spring or fall

Control: cut, dig, or hand pull (small plants) cut and remove the flowering spikes to prevent new seedlingsapply herbicides when actively growing at full to late flowering

Perennial

Flowers purple on spikes

Stems are square; plant can be 6-8 feet in height

Reproduces by seed and roots

Purple Loosestrife (Lythrum salicaria)

Perennial

Grows up to 6 feet tall

White, pink, violet or blue flowers

Brought to the U.S. as an ornamental; widely planted

Control:

hand pull (seedlings)

apply herbicide to cut stumps

Note: cutting the plant encourages growth and applying herbicides to leaves is generally ineffective.

Butterfly Bush (Buddleia davidii)

Weed treatment in riparian areas

• Select the most effective treatment methods for the site

• If herbicides are used, be sure the label allows application adjacent to or in the water

• Consider wipe application or hand removal

Now what?• Inventory the plants on

your property

• Identify invasive plants and weeds

• Do you have a weed problem? Why?

• What can you change about the way you manage your property to decrease the weed population?

ENGLISH IVYENGLISH IVY

Proper disposal of weeds

• Put fresh noxious and perennial weed material in your garbage

• Don’t add it to your compost bin or yard debris cart; especially seeds or root material

• Don’t leave any root parts or seeds in wet areas; they will sprout!

Then...• Determine appropriate

controls and your plans for the site and start working

• Monitor for invasive plants

• Plant native plants in your yard after the weeds are under control

• Marion & Polk SWCDs have annual native plant sales in February

• Share this information with others

Helpful Resources

Pringle Creek Watershed Council…………....503-566-4034web: www.open.org/pcwc

Marion Soil & Water Conservation District….503-391-9927web: www.open.org/mariswcd

Oregon Department of Agriculture…………...503-986-4621web: www.oregon.gov/ODA

OSU Extension - Marion County Office……...503-588-5301web: extension.oregonstate.edu/marion

Pacific NW Weed Control Handbookweb: weeds.ippc.orst.edu/pnw/weeds

Helpful BooksWeeds of the West Western US Cooperative Extension ServicesTom Whitson, Editor; 2001

Northwest WeedsRonald J. Taylor; 2003

Plants of the Pacific Northwest CoastJim Pojar and Andy Mackinnon; 1994

Handbook of Northwestern PlantsHelen Gilkey and LaRea J. Dennis; 2001

Gardening with Native Plants of the Pacific NorthwestArthur Kruckeberg; 2003

Trees and Shrubs for Pacific Northwest GardensJohn Grant, et. al.; 2003