Christmas Tree Weed ControlChristmas Tree Weed ControlTREE SCHOOL 2012TREE SCHOOL 2012
Paul BorgenAgronomy Manager
Pratum Co-opSalem, OR
ResourcesResources
PNW Weed Control HandbookPNW Weed Control Handbook
Weeds of the WestWeeds of the West
Extension PublicationsExtension Publications http://eesc.oregonstate.eduhttp://eesc.oregonstate.edu
Why control weeds?Why control weeds?
Ease of harvest Ease of harvest
Weed cover harbors pestsWeed cover harbors pests
Compete for water and Compete for water and nutrientsnutrients
Why control weeds?Why control weeds?
Remember that control does not Remember that control does not mean eliminationmean elimination
Benefits of leaving some vegetationBenefits of leaving some vegetation
Keys to successKeys to success
Know your weedsKnow your weeds
Properly calibrated equipmentProperly calibrated equipment
Know the proper rateKnow the proper rate
Keys to successKeys to success
Start cleanStart clean
Keep good recordsKeep good records
Expect to do more than spray once Expect to do more than spray once and forget itand forget it
Weed ShiftsWeed Shifts
Weed infestations change depending on Weed infestations change depending on cultural practicescultural practices
Cultivation promotes deep rooted plantsCultivation promotes deep rooted plants Mowing promotes prostrate weedsMowing promotes prostrate weeds Use of the same chemicals promote tolerant Use of the same chemicals promote tolerant
weed species (e.g. false dandelion, field weed species (e.g. false dandelion, field bindweed, rattail fescue)bindweed, rattail fescue)
Preventing Weed ShiftsPreventing Weed Shifts
Combine a variety of cultural practices and Combine a variety of cultural practices and chemical treatmentschemical treatments
Understand the effect each practice or Understand the effect each practice or product has on your particular weed product has on your particular weed populationpopulation
Alternate or combine chemicals effectivelyAlternate or combine chemicals effectively Use different modes of action or chemical Use different modes of action or chemical
familiesfamilies Target specific weeds or get broad spectrumTarget specific weeds or get broad spectrum
Preventing Weed ShiftsPreventing Weed Shifts
Keep records of how your practices Keep records of how your practices affect weedsaffect weeds
Note how each herbicide affects each Note how each herbicide affects each weed then tank-mix or alternate to weed then tank-mix or alternate to achieve desired resultsachieve desired results
Reduce chance of promoting resistant Reduce chance of promoting resistant speciesspecies
Preventing Weed ShiftsPreventing Weed Shifts Combine or rotate practices;Combine or rotate practices;
mechanicalmechanical hand removalhand removal spot treatmentspot treatment Band sprayBand spray broadcast spraybroadcast spray wiperswipers
Provide cost effective, year-round controlProvide cost effective, year-round control
Ground CoversGround Covers
Remove unwanted weedsRemove unwanted weeds
Plant sub-clover or dwarf plant varietiesPlant sub-clover or dwarf plant varieties
Regulate vegetation height with with sub-Regulate vegetation height with with sub-
lethal rates of chemicals (chemical mowing)lethal rates of chemicals (chemical mowing)
Spot spray is necessary to keep unwanted Spot spray is necessary to keep unwanted
weeds in checkweeds in check
Ground CoversGround CoversBBenefitsenefits
Reduces soil erosionReduces soil erosion
Improve traffic conditions in wet weatherImprove traffic conditions in wet weather
Aids in harvestAids in harvest
Reduces mud on trees at harvestReduces mud on trees at harvest
Ground CoversGround CoversDrawbacksDrawbacks
Monitoring and management is necessary Monitoring and management is necessary during much of growing seasonduring much of growing season
Frequent mowing is necessary to regulate Frequent mowing is necessary to regulate height if chemicals are not an optionheight if chemicals are not an option
Still provides competition for tree and harbors Still provides competition for tree and harbors pestspests
Difficult to maintain around tree basesDifficult to maintain around tree bases
Soil Active HerbicidesSoil Active Herbicides
Residual weed controlResidual weed control Pre-emergent activity, Post-emergent Pre-emergent activity, Post-emergent
activity or bothactivity or both Apply late Winter/early SpringApply late Winter/early Spring Most need rain to activate chemical in soilMost need rain to activate chemical in soil Can combine with contact herbicidesCan combine with contact herbicides Apply March through AprilApply March through April
Foliar Active HerbicidesFoliar Active Herbicides
Leaf or stem contact control onlyLeaf or stem contact control only Little or no soil residual qualitiesLittle or no soil residual qualities Apply to actively growing plantsApply to actively growing plants 2 days to several weeks needed to show results2 days to several weeks needed to show results May be tank-mixed with some soil residual May be tank-mixed with some soil residual
productsproducts
Product ReviewProduct Review
AlwaysAlways read and follow label directions read and follow label directions Obtain specific directions for rates, Obtain specific directions for rates,
timing, and application timing, and application
The label is the law!The label is the law!
AtrazineAtrazine
Root absorbedRoot absorbed
Water solubility 33 ppm (Simazine Water solubility 33 ppm (Simazine 3.5ppm)3.5ppm)
Inhibits photosynthesisInhibits photosynthesis
OK on newly transplanted conifersOK on newly transplanted conifers
VelparVelpar
Also inhibits photosynthesisAlso inhibits photosynthesis
Water solubility 33,000 ppmWater solubility 33,000 ppm
Not restricted useNot restricted use…except in WA…except in WA
Better on perennial grassesBetter on perennial grasses
Post-emergent Grass KillersPost-emergent Grass Killers
ArrowArrow
Poast / VantagePoast / Vantage
Envoy PlusEnvoy Plus
Post-emergent Grass KillersPost-emergent Grass Killers
Inhibit the growing pointInhibit the growing point
Very slow to show symptomsVery slow to show symptoms
Surfactants a mustSurfactants a must
Summer annual grassesSummer annual grasses