Montana Pesticide Education Program http:mtpesticides.org

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Montana Pesticide Education Programhttp//mtpesti
cides.org
Residential Weed Management
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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

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Change the location and any plant can become a
weed. For example, bluegrass invading a flower
bed is a weed.
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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

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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 2
Category 1
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Noxious Weeds in Montana
Category 3
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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

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How do weeds spread?

• Humans
• Pets
• Wildlife
• Water
• Wind
• Vehicles
• Machinery
• Wildflower mixes
• Soil disturbance

We plant them!
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Weed Management
Prevention is the most effective practice of all!

• Buy clean seed for wildflowers or lawns dont
  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!

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Control Methods

• Mechanical
• 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

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Chemical Control
Weed Biology/Life Cycles Exploit Weed Weaknesses
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• Monocots parallel leaf veins, growth points
  at/below soil level

Grasses

• Grass family
• Cheatgrass, quackgrass
• Sedge family
• Nutsedge
• Lily family
• Wild onion, death camas

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• Dicots net-like leaf veins, diverse growing
  points

Broadleaf

• Composite family
• Dandelions, thistles, knapweed
• Mustard family
• Shepherd's purse, lambsquarter, whitetop
• Carrot family
• Hemlock

Many others
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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

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• 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

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

Houndstongue, mullein, burdock, bull thistle
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• Perennial weeds live 3 or more years
• most persistent
• difficult to control
• propagules
• rhizomes, stolons, bulbs, tubers
• wide range of dicots and monocots

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Managing Landscape Weeds

• Maintain competition grazing management
• Prevent seed production
• Prevent seed germination
• Limit emerged weeds early
• Limit susceptible stages of mature weeds.

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

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Herbicide Characteristics
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Herbicide Characteristics
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Herbicide Characteristics
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Herbicide Characteristics

• Application in relation to plant development
• Pre-plant
• Before crop is planted
• Pre-emergent
• Before weeds emerge
• Post emergent
• After weeds emerge

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Herbicides and Plant Characteristics

• Growing points
• Leaf shape and orientation
• Wax and cuticle

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Herbicides and Plant Characteristics

• Leaf hairs
• Deactivation
• Life cycle stage

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Herbicide Effectiveness
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Climatic Factors

• Relative humidity
• Light
• Precipitation
• Temperature

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Bull Thistle (Cirsium vulgare)

• Biennial
• 2-5 feet tall
• Flowers purple July-September
• Reproduces by seed
• Seed can be viable for 10 years

• Control
• hand pull
• cut or mow before going to seed
• herbicides?

When?
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Canada Thistle (Cirsium arvense)

• Perennial
• Flowers light pink-purple
• Grows 1-4 feet tall
• Has deep horizontal roots
• Reproduces through creeping roots, some seed

• Control
• pull by hand (small plants)
• apply herbicides spot-spraying young plants is
  very effective

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Poison Hemlock (Conium maculatum)

• Biennial
• Grows to 10 feet tall
• Tiny white flowers purple-mottled stems
• All parts of plant are highly poisonous (if
  eaten)
• Reproduces by seed

• 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

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Purple Loosestrife (Lythrum salicaria)

• Perennial
• Flowers purple on spikes
• Stems are square plant can be 6-8 feet in height
• Reproduces by seed and roots

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

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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

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Herbicides in a Residential Setting
Where is this water going?
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Sprayers For Urban/Residential Use
Up to 1 acre
gt 1 acre depending on tank size GPA
Spot Treatment lt 1/10th acre
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General Precautions
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What To Use
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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?

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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
  

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