War on Weeds !
Cindy A. Kinder
University of Idaho, Camas County Extension,
Fairfield, Idaho
Definition of Weeds
A
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
Weeds
 Affect
everyone
–Aesthetic & visual values
–Decrease functions of natural
ecosystem
–Displace native vegetation
–Decrease wildlife habitat
–Increase erosion & stream
sedimentation
–Reduce recreational value
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 reroot.
Controlling Weeds

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 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!
 Can

(For many)
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
Diffuse
Spotted
Russian
Knapweed Identification
Spotted
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 Knapweed
Perennial
Reproduce-seeds
Treatment
–Cultural
Tillage – NO
Mowing – reduce seeds
Hand pulling – some regrowth
–Biocontrols
Seed
head moth
root weevils
-Chemical
rosette – prebud & in fall
Stinger, Banvel – early bud
Broadleaf control – not after
flowering
Tordon-
Russian Knapweed
Perennial
Reproduce-
seeds & rhizomes
Treatment
–Cultural
Tillage – NO
Mowing – reduce seeds
Hand pulling – some regrowth
–Biocontrols
Seed
head moth
root weevils
-Chemical
rosette – prebud & in fall
Stinger, Banvel – early bud
Broadleaf control – not after
flowering
Tordon-
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 regrowth 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