objectives for using herbicides - university of tennesseefwf.ag.utk.edu/sites/silviculture/herbicide...
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Objectives for Using Herbicides
Site PreparationWoody ReleaseHerbaceous ReleaseMid-Rotation ReleaseRight-of-Way Maintenance
How they Control the Vegetation
Kills top and roots --- translocation to reduce sprouting
Kill on contactApplied to soilHormone-type herbicides
Mechanism
AdsorptionTranslocation
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Timing of Application
Stage of Plant DevelopmentCondition of LeavesGrowth StageSoil Moisture
SelectivityWhy some species are affected or Not
Differential WettingBiochemical DifferencesPhenological DifferencesTiming
Chemical Techniques
Foliar SprayBasal SprayStump SpraySoil AppliedGirdling & Injection
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History
2,4,5 – T (2,4,5 – trichlorophenoxyaceticacid)
Registered in about all crops and usesCheapAgent OrangeDioxinBanned about 1980The best thing to happen was to ban it for forestry.
Effectiveness
TechniqueTimingResult
BiologicalEconomic
Crop Safety
Acceptable DamageMechanical Methods Do Damage Trees!
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On-Site Impacts
Non-Target OrganismsSoil HealthEcosystem Recovery
Off-Site Impacts
DriftLeachingRunoffLandscape Impacts
Measuring and Evaluation
When to apply?Was the treatment applied correctly?Was the treatment a success?What were the other impacts?
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Use of Chemicals
“Most problem with pesticides arise from two categories of ignorance about their chemistry and biological effects. Oneform is hysteria on the part of the public, and the other isheedlessness or stupidity of complacent users. Education isthe best solution to both problems. The public is not required to educate itself, but users are.”
Smith, Larson, Kelty, and Ashton. 1997. The Practice of Silviculture Applied Forest Ecology, Ninth Edition.
How to Apply HerbicidesHelicopterGround Equipment
TractorSkidder
BackpackDirected sprayBands or circlesBark application
Basal spray and thinlineOil based
Spot gun
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Helicopter Nozzles
TVB – Thru the Valve BoomMicrofoil Boom (hay rake)Conventional Boom (not for herbicides)Rain Drop (not for herbicides)
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What do we put in the tank?
Carrier (water or oil)Aqueous spraysOil spraysInvert emulsions
HerbicideAdjuvant (increases the effectiveness)
SurfactantsSpreader-StickersCuticle penetration
BuffersAmmonium salts
Herbicides for Silviculture
Aqueous spraysOil spraysInvert emulsions
Making PrescriptionsDefine goals Know your crop and siteIdentify weedsKnow research resultsRead the label and re-read the labelRead and heed the MSDSUse correct volume and applicationUse correct adjuvantsFollow up on efficacy
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Herbicides for Pine Silviculture
ImazapyrChopper - BASF – Ester formulationArsenal AC -BASF – Amine formulationImidazolinone familyInhibits branched amino acid synthesis
ALS (or AHAS)– Acetolactase synthetase
Isoleucine, leucine, valine
Herbicides for Pine Silviculture
GlyphosateRoundup (not registered for forestry) - MonsantoAccord – DowAgroRodeo – Monsanto (aquatic label)Various genericsFamily of its ownInhibits aromatic amino acid synthesis
EPSP– 5-enolpyruvylshikimate-3-phosphate synthase
tryptophan, tyrosine, phenylanaline
Herbicides for Pine SilvicultureTriclopyr - DowAgro
Garlon 4 – DowAgro – EsterGarlon 3A – DowAgro – AminePyridinecarboxylic acid family
PhenoxysBehaves like auxin (IAA)
Over stimulates cell metabolism
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Herbicides for Pine SilvicultureHexazinone - DuPont
Velpar L - LiquidVelpar ULW - GranuleOustar (+ sulfometuron) – Soluble granulesTriazine familyInhibits photosynthesis by blocking electron transport which leads to lipid peroxidation and cellular disintegration
Herbicides for Pine SilvicultureSulfometuron - DuPont
Oust XPSulfonylurea familyInhibits branched amino acid synthesis
ALS (or AHAS)– Acetolactase synthetase
Isoleucine, leucine, valine
Herbicides for Pine SilvicultureMetsulfuron - DuPont
Escort XPSulfonylurea familyInhibits branched amino acid synthesis
ALS (or AHAS)– Acetolactate synthetase
Isoleucine, leucine, valine
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Herbicides for Pine SilvicultureClopyralid
Transline – DowAgroPyridinecarboxylic acid familyBehaves like auxin (IAA)
Over stimulates cell metabolismEffective only on composites and legumes
Herbicides for Pine Silviculture2,4-D
Various brands (read the label)Phenoxyacetic acid familyBehaves like auxin (IAA)
Over stimulates cell metabolism
Herbicides for Pine SilviculturePicloram
Tordon - Dow-AgroVarious formulations
Pyridinecarboxylic acid familyBehaves like auxin (IAA)
Over stimulates cell metabolismLong Residual
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Herbicides for Pine SilvicultureSurfactants
Entry II (ethoxylated tallow amine)– Original Surfactant in Roundup– Excellent safety on pine
• Cannot penetrate the cuticle of pine but can hardwood
– Used for Release
Timbersurf 90NU-FILM-IRSun-it II (methoxylated sunflower oil)
Herbicides for Pine Silviculture
Tank mixesSynergies
Less of bothComplementary controlRule rather than the Exception
Herbicides for Hardwood Silviculture
Same as herbicides for pineCrop herbicides for plantationsInjection and basal sprays for natural stands
Flashback
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Certification
Sustainable Forest InitiativeUse registered pesticidesFollow label
Forest Stewardship CouncilHerbicides are ok but their “dependence”should be reduced.No transgenics
Transgenics
Hysteria Without Substance. (If you don’t like herbicides then you will hate GMO’s!)The Need for Sterility. Resurrection of a Species (American Chestnut)EvaluationEconomicsEthicsHazard Potential
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