Montana Pesticide Education Program Residential Weed Management

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

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

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 Montana Category 3

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 Soil disturbance We plant them!

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 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

Weed Biology/Life Cycles Exploit Weed Weaknesses

Monocots: parallel leaf veins, growth points at/below soil level Grasses –Grass family Cheatgrass, quackgrass –Sedge family Nutsedge –Lily family Wild onion, death camas

F Dicots: net-like leaf veins, diverse growing 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 Characteristics Persistent Non Persistent

Herbicide Characteristics Selective Non 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 Characteristics F Leaf hairs F Deactivation F Life cycle stage

Herbicide Effectiveness

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 seedlings apply 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 Backpack Hand Held Spot Treatment < 1/10 th acre Up to 1 acre > 1 acre depending on tank size & GPA

General Precautions Prevent Drift Calibrate Your Sprayer Add the right amount

Use Common Sense Sense

1.30% Dicamba 3.05% 2,4-D 10.6% 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