Transcript Using Herbicides to Manage Noxious Weeds

Using Herbicides to Manage
Invasive Weeds
Herbicide Development
Stimulus:
• realized chemical environment of plant
easier to manipulate than climatic, edaphic,
or biotic environments in which they grow
Herbicide Classification
Many Schemes
Degree of response among plants:
• selective
 controls some species in presence of others
• non-selective
 controls all species
Herbicide Classification
Method of application:
• foliar applied
• soil applied
• broadcast
 entire area
• spot
 restricted area
• band
Herbicide Classification
Length of soil persistence:
• persistent
 injure follow crop normal rotation
• residual
 injure/kill germinating weeds short time
o 1 growing season or less
• long residual
 control several growing seasons
Herbicide Classification
Chemistry/herbicide family:
• inorganics
• organics
Herbicide Classification
Organics:
• phenoxy-, benzoic-, pyridine-, quinolinecarboxylic
acids
• sulfonylureas, imidazolinones, triazolopyrimidine
• triazines, substituted ureas, uracils
• thiocarbamates, halogenated acids
• dinitroanilines, carbamates, phosphoric amides
• aryloxyphenoxypropionates, cyclohexanediones
• nitrodiphenyl ethers
• those with no particular family
Herbicide Classification
Plant related characteristics:
• systemic
 translocates throughout plant
• contact
 no translocation
• mode/mechanism of action
Herbicide Classification
Mode/mechanism of action:
• amino acid biosynthesis inhibitors
 Escort, Amber, Plateau, Roundup
• auxin-like
 Tordon, Curtail, 2,4-D, Vanquish/Clarity
• photosynthetic inhibitors
 Velpar, Karmex, Krovar, Spike
• cell division inhibitors
 Treflan, Prowl
• lipid biosynthesis inhibitors
 Poast, Fusilade
Herbicide Formulations
Form solutions:
• soluble liquids
 Tordon, Plateau, 2,4-D amine
Form emulsions:
• emulsifiable concentrates
 2,4-D ester, Treflan
Herbicide Formulations
Form suspensions (need agitation):
• water dispersible granules
 Escort, Amber
• flowables
 Sencor
• wettable powders
 Karmex, Krovar
Dry solids:
• pellets
 Spike
Methods of Application
Broadcast:
• aerial or ground
 low volume liquid
 granules or pellets
Spot treatment:
• typically by ground
 high or low volume liquid
 granules or pellets
Band:
Herbicide Application
Rule Number 1:
• Read and follow the label directions!!
Rule Number 2:
• see Rule Number 1
Factors Influencing
Herbicide Performance
Plant factors:
• Weed ID
• Weed phenology/physiological status
 life cycle
 monocot v dicot
o location of meristems
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growth stage
cuticle
leaf number, shape, orientation, & pubescence
metabolism
• Competition from desirable plants
Factors Influencing
Herbicide Performance
Herbicide factors:
• formulation
 volatility
 absorption
• dose
• placement
• retention
 use of adjuvant
Factors Influencing
Herbicide Performance
Climate:
•
•
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precipitation & relative humidity
temperature
wind
light
Factors Influencing
Herbicide Performance
Edaphic (soil) factors:
• adsorption, degradation, leaching, volatility,
availability for absorption
 texture
 organic matter
 pH
 moisture
 temperature
Factors Influencing
Herbicide Performance
 Other factors:
• topography
 application efficiency
• sprayer calibration
• knowledge of operator
• Water
 Use clean water
Commonly Used Herbicides
Rangeland & Non-crop
2,4-D - Many Trade Names
 Auxin-like, systemic, selective
• ester and amine formulations
 Short residual in soil
• average half-life 10 days
 Broadleaf herbicide
• many annual broadleaf weeds
 notably weak on kochia
• often tank-mixed
 High volatility
Dicamba -
Vanquish/Clarity/Overdrive
 Auxin-like, systemic, selective
 Relatively short soil residual
• < 14 days good conditions metabolism
• low to medium leaching potential, weakly adsorbed
 Broadleaf herbicide
• many annuals, biennials, perennials
 thistles and knapweeds
 weak on toadflaxes & Russian knapweed
 Don’t use near water or trees/shrubs
• buffalograss sensitive to injury
Picloram Tordon 22K, Picloram 22K
 Auxin-like, systemic, selective
 Residual herbicide
• average half-life 90 days
• high leach potential, weakly adsorbed
 Broadleaf herbicide
• thistles, knapweeds, leafy spurge, houndstongue, toadflaxes,
bindweed, locoweed, larkspur, lupines …
 Grazon P+D is picloram + 2,4-D
• very weak kochia & some mustards
 Don’t use near water, trees/shrubs
• smoothbrome sensitive to injury
Aminopyralid
Milestone, Milestone VM,
Forefront R&P
 Auxin-like, systemic, selective
 Short residual
• average half-life 34.5 days in North America
• Lab studies show potential movement; limited movement in
field
 Broadleaf herbicide - odd spectrum
• thistles, knapweeds, hawkweeds, oxeye daisy, dandelion,
absinth wormwood …
 Forefront R&P is aminopyralid + 2,4-D
 Can spray to water’s edge
• Half-life in water 0.6 days
• Safe around some trees/shrubs
Clopyralid
Transline, Clopyralid 3
 Auxin-like, systemic, selective
 Short residual
• average half-life 40 days
• moderate leaching, weakly adsorbed
 Broadleaf herbicide - odd spectrum
• thistles, knapweeds, hawkweeds, oxeye daisy, dandelion,
locoweeds …
 Curtail is clopyralid + 2,4-D
• only control emerged weeds
 Don’t use around water
• Safe around trees/shrubs
Metsulfuron –
Escort/MSM 60/Cimarron Plus;
 Amino acid biosynthesis inhibitor
• systemic, selective
 Moderate residual
• typical half-life 30 days
 persistence increases with soil pH
 Broadleaf herbicide
• perennial mustards, biennial thistles, arrowgrass, locoweed,
halogeton, houndstongue, camelthorn, African rue …
• weak on toadflaxes, Canada thistle, diffuse knapweed
• must use a surfactant!!
Chlorsulfuron –
Telar/Chlorsulfuron 75
Cimarron Plus
 Amino acid biosynthesis inhibitor
• systemic, selective
 Residual
• average half-life 40 days
 persistence increases with soil pH
 Broadleaf herbicide
• perennial mustards, Russian knapweed, Canada thistle
 RK, CT high rates and fall best
• must use surfactant!!
• Fall applications more injurious to some grass species
Imazapic
Plateau, Panoramic
 Amino acid biosynthesis inhibitor
• systemic, selective
 Residual
• most “imis” persistent
 e.g. imazapyr 1-4 months
 Broadleaf and grass
• leafy spurge, bindweed, houndstongue, cheatgrass, foxtail
barley …
• must use methylated seed oil!!
 Cool-season grass injury
• fall applications for leafy spurge
Glyphosate -
Roundup, Campaign, Rodeo, Aquamaster
Amino acid biosynthesis inhibitor
• systemic, non-selective
 Campaign is glyphosate + 2,4-D
 Rodeo is aquatic formulation
Moderate persistence
• average half-life 47 days
• strongly adsorbed, no soil activity
Broadleaf and grass
• many annuals, biennials, perennials
 Campaign good control perennial pepperweed
Aminocyclopyrachlor
Perspective, Method
 Perspective - noncrop
• Telar + aminocylopyrachlor
 Method - noncrop
• aminocyclpyrachlor
 Amino-acid biosynthesis inhibitor + Auxin-like;
systemic, selective
 Short to long residual
• Aminocylcopyrachlor half-life range 5-164 days in North
America
• Lab studies show potential movement; limited movement in
field
 Broadleaf herbicide - odd spectrum
• thistles, knapweeds, leafy spurge, mustards (Telar) …