Montana Pesticide Education Program Residential Weed Management

Montana Pesticide Education Montana Pesticide Education ProgramProgram

http://mtpesticides.orghttp://mtpesticides.org

Residential Weed Residential Weed ManagementManagement

Residential Weed Residential Weed ManagementManagement

What is considered a weed?

• Any plant growing where it is not wanted.

• Obnoxious Weeds– Toxic Weeds– Invasive and Noxious weeds are the most

troublesome.• Rapidly dominate the site• Very difficult to control

Weeds are Indicators of Site Conditions

• Salty Soils– Shepherds Purse, Russian Thistle

• Acid soils – Very Acid Soils– Horsetail – Hawkweed & Knapweed

• Badly drained soils– Horsetail

• Deep shade– Ground ivy, chickweed

Noxious Weeds in Montana• Landowners are responsible for controlling the spread noxious

weeds on their property

• Cat 1 = established & widespread

• Cat 2 = recently introduced and rapidly spreading

• Cat 3 = Not yet detected or in few locations

Category 1 Category 2

Noxious Weeds in MontanaCategory 3

Weed Management

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

• Clean yard equipment before using it in another area

• Get weeds along streams under control

• 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 – not for urban

Chemical• Repeated application

• Plants must be growing

• USE ACCORDING TO LABEL

Weed Biology/Life Cycles

Exploit Weed Weaknesses

• Monocots: parallel leaf veins, growth points at/below soil levelGrasses

–Grass family

•Cheatgrass, quackgrass

–Sedge family

•Nutsedge

–Lily family

•Wild onion, death camas

Dicots: net-like leaf veins, diverse Dicots: net-like leaf veins, diverse growing pointsgrowing points

Many others

Broadleaf–Composite family

•Dandelions, thistles, knapweed

–Mustard family

•Shepherd's purse, lambsquarter, whitetop

–Carrot family

•Hemlock

Stages of Weed Development

• 1. Seedling

– Tender, vulnerable

• 2. Vegetative

– Great uptake of water and nutrients

• 3. Seed production

– Reduced uptake, energy directed to flowers, fruit

• 4. Maturity

– Little uptake or energy production

• Annual weeds: live one year – Summer annuals: seed & die by winter.

• Pigweed, lambsquarter, black medic

– Winter annuals: germinate in late summer, overwinter, produce seed, die the next season.

• Chickweed, curly dock, cheatgrass, black medic

Biennial weeds: broadleaf plants with a 2-year life cycle

Houndstongue, mullein, burdock, bull thistle

– mature, seed and die in second year

– vegetative growth first year (Rosette)

• Perennial weeds: live 3 or more years– most persistent

– difficult to control

– propagules• rhizomes, stolons, bulbs, tubers

– wide range of dicots and monocots

Managing Landscape Weeds

• Maintain competition – grazing management

• Prevent seed production

• Prevent seed germination

• Limit emerged weeds early

• Limit susceptible stages of mature weeds.

Chemical designed to control weeds. Plant, soil and weather conditions influence herbicidal activity.

Herbicide Characteristics

Contact Systemic

Herbicide Herbicide CharacteristicsCharacteristics

PersistentNon

Persistent

Herbicide Herbicide CharacteristicsCharacteristics

SelectiveNon

Selective

Herbicide Characteristics

• Application in relation to plant development

– Pre-plant• Before crop is planted

– Pre-emergent• Before weeds emerge

– Post emergent• After weeds emerge

Herbicides and Plant Characteristics

• Growing points

• Leaf shape and orientation

• Wax and cuticle

Herbicides and Plant Herbicides and Plant CharacteristicsCharacteristics

Leaf hairsLeaf hairs

DeactivationDeactivation

Life cycle stageLife cycle stage

Herbicide Effectiveness

0

20

40

60

80

100

seedling vegetative flowering mature

% control

Climatic Factors

• Relative humidity

• Light

• Precipitation

• Temperature

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

herbicides? When?

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

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: 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)

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

Sensitive areas

Where is this water going?

Non-target vegetation

Herbicides in a Residential Setting

Drift

Animals & kids

Concerns over chemical use

Movement of contaminated soil and vegetation

Hose End

Sprayers For Urban/Residential Use

Skid Mount

ATV & Lawn Tractor

BackpackHand Held

Spot Treatment < 1/10th acre

Up to 1 acre> 1 acre depending on tank size & GPA

General Precautions

Prevent Drift

Calibrate Your Sprayer Add the right amount

UseCommon

Sense

1.30% Dicamba 3.05% 2,4-D10.6% MCPP

8.0% Triclopyr

What To Use

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?

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

• Share this information with others