War on Weeds !

Cindy A. Kinder

University of Idaho, Camas County Extension, Fairfield, Idaho

Definition of WeedsA plant that is growing were it is not

desired.

Noxious weeds are harmful/injurious to the land, livestock and/or people by state law.

Weedy Conditions Disturb the soil or ground cover

Leave an opening for weeds to germinate

Once established, prolific seed producers

Seeds can lie dormant for many decades

Long term commitment to weed management

Affect everyone–Aesthetic & visual values–Decrease functions of natural

ecosystem –Displace native vegetation–Decrease wildlife habitat–Increase erosion & stream

sedimentation–Reduce recreational value

Weeds

The War

Land managers –Forest service,

–BLM,

–Parks & recreation

–Private

Wildlife habitat, range production, recreation, timber

Weed Identification/education Is it a weed ?

Know Plant Life Cycles Annuals- grow, flower, seed then die in one

growing season ( ex. Downy brome).

Biennials- 1st season- rosette & taproot.2nd season- flowers, produces seed & dies. (Ex. Bull thistle).

Perennials – live for more than 2 years.Reproduce by roots, rhizomes, seeds etc.(Most noxious weeds).

Controlling Weeds

Prevention.– Cheapest,– Watch roadways, fence lines, clean machinery,

buy clean seed,– Composting manure – gets most not all.

Mechanical.– Hand-pulling, mowing, burning, cultivation,

plowing.– Disrupts root system & plants dry out before re-

root.

Cultural.– Land & water management.– Crop rotation – peas, winter wheat, spring

barley.– Crop competition - nurse crop.– Optimum soil fertility.

Chemical.– Timing critical.– Select best chemical for situation.– Don’t over dose, need to kill the root also.

Controlling Weeds

Biological.– “Natural enemy.”

– Insects, goats, sheep.

Integrated approach.– Works best.

– Most effective.

Controlling Weeds

Controlling Annuals

Mechanical – Mowing, no!

– Burning, may not kill seeds

– Tillage, yes!

Chemical– Only need to kill shoots

– Easiest at seedling stage

Controlling Biennials Mechanical

– Tillage Chemical

– Only need to kill shoots (post emergence)

– Easiest at seedling stage

– Apply at rosette stage, before bolting

Controlling Perennials Mechanical

– Mowing, yes! (For many) Can stimulate new shoot growth, field bindweed.

– Tillage, no! (For many) Can be effective for leafy spurge.

Chemical– Apply

Seedling stage When food reserves depleted (after rapid growth) NOT at mature stage Choose chemical that moves to the roots

Management Plan

List of problem weed (s)

– Know the life-cycle and how

they spread

Methods of controlling

Management Plan

Map location and

number of acres

Morning Glory

Diffuse Knapweed

Management Plan

Budget available Available manpower Time commitment

– Chemical/biocontrol Joint agreements

– Neighbors Re-vegetation Evaluate list & determine

plan of action

Knapweed Identification

Spotted

Diffuse

Russian

Knapweed IdentificationSpotted Diffuse Russian

Diffuse Knapweed Perennial/biennial Reproduce-seeds Treatment

– Yearly tillage may work– Biocontrols

Moth Root weevils Seed head weevils Seed head flies

– Chemical Tordon at rosette

stage in fall Tordon, 2,4-D stop

flower production Curtail, stinger,

Transline, Banvel

Spotted KnapweedPerennialReproduce-seedsTreatment

–CulturalTillage – NOMowing – reduce seedsHand pulling – some regrowth

–BiocontrolsSeed head mothroot weevils

-ChemicalTordon- rosette – prebud & in fallStinger, Banvel – early budBroadleaf control – not after flowering

Russian KnapweedPerennialReproduce- seeds & rhizomesTreatment

–CulturalTillage – NOMowing – reduce seedsHand pulling – some regrowth

–BiocontrolsSeed head mothroot weevils

-ChemicalTordon- rosette – prebud & in fallStinger, Banvel – early budBroadleaf control – not after flowering

Leafy Spurge Perennial Reproduce: seeds and spreads

with shoots Extensive root system

– Recover from physical/chemical treatment

Milky latex in plants Treatment

– Mechanical - not really– Biocontrol

Sheep/goats Flea beetles

– Chemical 2,4D or Picloram plus 2,4-D Tordon with 2,4-D at full bloom Plateau in the fall

Rush Skeletonweed Perennial Reproduces by seeds and re-

growth from roots When broken exude a milky latex

substance Treatment

– Cultivation Ineffective, may cause more

spread– Biocontrol

Rust, mite, and midge– Chemical

Difficult to control– Tordon,2,4-d, – Stinger, Banvel,

Hoary Cress (White Top)

Perennial Reproduces by

seeds and rhizomes

Treatment– Chemical

Early growth stages 2,4-D amine, LV

ester Escort, Telar

Canada Thistle

Perennial Reproduces by seed but

spreads by rhizomes The flower heads are either

male or female Treatment

– Cultivation No!! Cause to spread

more– Biocontrol

Weevils– Chemical

Stinger- rosette stage Curtail – before bud stage 2,4-d

Summary War on weeds Weed identification Plant life cycles

– Annuals, biennials, perennials Control methods

– Prevention mechanical, cultural, chemical, biological, integrated

Management plan– List of priority weeds, mapping, budget, time

commitment Knapweed, leafy spurge, rush skeletonweed white

top, Canada thistle,

Your Plan of Action

Identify & map problem weeds List ways to control problem plants List budget limits List people availability Set short and long term goals

Just do it