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!

TriazinesTriazines

AtrazineAtrazine

SimazineSimazine

VelparVelpar

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

DNA’sDNA’s

SurflanSurflan

BarricadeBarricade

PendulumPendulum