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
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
Budget available Available manpower Time commitment
– Chemical/biocontrol Joint agreements
– Neighbors Re-vegetation Evaluate list & determine
plan of action
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,
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