CHRISTMAS TREE WEED IDENTIFICATION AND CONTROL

Ed Peachey and Chal Landgren, OSU

Outline for today

§  3:45-Weed biology and implications for control

§  4:00 Weed ID ú  1st step to successful control

§  4:15 Herbicides: site of action and efficacy §  4:45 Sprayer calibration §  5:00 Finding weed control info on the web

Weed Biology and Control

Weed Seedbanks (ie seeds living in the soil)

Source: vric.ucdavis.edu/issues/vegnotes-tomato/weedseed.gif

Weed seed predation videos

Weed Seed Lifespan in Soil

§  Many seeds are shorter lived if on the soil surface ú  Seed predation ú  Desiccation

§  Grass weeds 1-3 yr seed survival §  Broadleaved 3-7 yr seed survival

Depth of Emergence

§  Typically ½ to ¾ inch §  Occasionally up to 2 inches for large seeds §  Many seeds may germinate but not

emerge=fatal germination

Seed dormancy Seasonal periodicity of germination

Factors that influence germination and weed shifts §  Water §  Temperature §  Oxygen

ú  Tillage provides oxygen to seeds

§  Light ú  Light flash during tillage may cause germination ú  Weeds sense light quality changes caused by

§  Proximity to surface §  Moves seed from deep in the soil where it is preserved

§ 

Herbicides and weed seeds

§  Herbicides generally do not effect weed seeds

§  Only seeds that are germinating §  Exception is fumigant metam

Successful use of Preemergence Herbicides §  Apply before seeds germinate §  Activate §  Protect the barrier

Preemergence Herbicides

Rainfall/tillage ½ to 1

inch thick

Too much rain/ water/or

tillage

Seedbanks are a black box

What goes in, might come out

Plant Characteristics + Selection Pressure = Weed Shifts

Plant Characteristics Selection pressure or methods of control

Growth habit ú  Perennial ú  Annual ú  Biennial

Plant family Grass, broadleaf, sedge

Season of emergence or growth

Root system: tap root vs surface roots

Seed dispersal: short vs long distance

1.  Prevention 2.  Cultural 3.  Chemical 4.  Mechanical 5.  Biological

First step to effective control

Weed Identification

Dirty Dozen

Annual broadleaves

Horseweed (marestail)1

Lettuce, prickly 2

Sowthistle, annual 3

Perennial broadleaves

Northern willow herb 4

Bindweed, field5

Thistle, Canada6

Blackberry

Biennials Queen Anne’s lace 7

Annual Grasses Barnyardgrass 8

Witchgrass 9

Perennial grasses Bentgrass 10

Fescue, rattail 11

Herbicide  Effectiveness  on  Weeds  in  Christmas  TreesSOIL  ACTIVE  APPLICATIONS  THAT  PERSIST  IN  SOIL APPLIED  TO  ACTIVELY  GROWING  WEEDS

isoxaben  (Gallery)

pronamide  (Kerb)

oryzalin  (Surflan)

pendimethalin  

(Pendulum)

prodiamine  (Barricade)

flufenacet  +  metribuzin  

(Axiom)

atrazine

simazine

hexazinone  (Velpar)

hexazinone  +  

sulfometuron  (Westar)

oxyfluorfen  (Goal)

flumioxazin  (SureGuard)

dichlobenil  (Casoron)

clethodim  (Envoy)

fluazifop  (Fusilade)

sethoxydim  (Segment)

triclopyr  (Garlon  3)

2,4-­‐D

clopyralid  (Stinger)

glyphosate  (Roundup  

and  others)

glufosinate  (Finale)

asulam  (Asulox)

Herbicide  site  of  action  group 3 3 3 3 3 3  and  5 5 5 5 5  and  2 14 14 20 1 1 1 4 4 4 9 10 18

PRE=  apply  before  weed  seeds  germinatePRE/EPOST=before/  shortly  after  weeds    emerge

POST=apply  to  actively  growing  weeds

PRE PRE PRE PRE PRE PRE/EPOST

PRE/EPOST

PRE PRE/EPOST

PRE/EPOST

PRE/EPOST

PRE/EPOST

PRE POST POST POST POST POST POST POST POST POST

Potential for  runoff  (Low,  Medium,    High) L L L M L M H H H H/L M L L L L L H H H L L M

Annual  

broadleaves Horseweed (marestail)1 S R R R R R M M S M M S S R R R S S S M S* S

Lettuce, prickly 2 S R R R R R S S S S S M M R R R S S S M S* —Sowthistle, spiny/annual 3 S R R R R R S S S S S M M R R R S S S S S* —

Perennial  

broadleaves Northern willow herb 4 R R R R R M S S S S M M S R R R S S M M M* R

Bindweed, field5 R R R R R R R R R R S+ R S R R R S S R M R —Thistle, Canada6 R R R R R R M* R R R S+ R S R R R S S S S S+ RBlackberry R R R R R R R R S R R R S R R R S M R S R R

Bi-­‐

ennial

Queen Anne’s lace 7 S R R M R R M M S S M* R S R R R S R S M S* —

Grasses

Annual

Barnyardgrass 8 R M S S S S S S S S M* S* S S S S R R R S M* —

Fescue, rattail 9 S S S S R R M S S R S R R R R R R M M* RWitchgrass 10 R M S S S S S S S S S* S* S S S S R R R S M* —

Per Bentgrass 11 R S R R M M S M S S M M* S ? S S R R R S M* —

Apply  before  weed  seeds  germinate;  soil  applied;  activated  with  rainfall    

or  shallow  cultivation

Apply  before  weed  seeds  germinate;  soil  applied  in  fall  to  established  

plantings;  primarily  grass  control  including  quackgrass.  

Apply  before  weed  seeds  germinate;  soil  applied  after  soil  has  settled.  

Not  used  on  Doug  fir.

Apply  before  weed  seeds  germinate;  soil  applied  and  activated  with  

rainfall  or  cultivation.  Weak  on  sunflower  family.

Apply  before  weed  seeds  germinate.  Seldom  used  because  of  narrow  

weed  spectrum;  controls  seedling  grasses.

Apply  before  weeds  seeds  germinate  or  shortly  after  emergence.Doug  fir  

and  true  firs  only.  Not    on  first  year  seedlings.

Apply  before  weeds  seeds  germinate  or  shortly  after  emergence.  

Restricted  Use

Apply  before  weeds  germinate  in  fall  or  spring.  Do  not  broadcast  over  

trees  unless  immediately  preceding  rainfall.  Restricted  use.

Apply  in  spring  before  bud  break,  before  or  shortly  after  weed  seeds  

germinate  or  emerge;  moisture  required  to  activate.  Later  applications  in  

April  may  be  more  effective  due  to  less  loss  from  leaching.

Apply  before  or  soon  after  weeds  germinate  or  emerge.  Broadcast  on  

dormant  trees,  only;  direct  application  after  bud  break

Apply  before  or  after  weeds  emerge.  Can  be  applied  over  trees  except  

when  buds  and  new  shoot  growth  is  tender.

Can  be  applied  over  the  top  of  conifers  if  budbreak  has  not  occurred  or  

the  plants  are  hardened  off.  See  label  for  approved  conifer  species.  

Apply  midwinter  immediately  before  cold  rain  to  reduce  loss  form  

volatilization.    Controls  established  perennials.

Apply  to  emerged  grasses.  Directed  or  over  the  top  applications.

Apply  to  emerged  grasses;  results  are  often  erratic  on  grasses  stressed  

from  lack  of  vigor,  drought,  high  temperature,  or  low  fertility.

Apply  to  emerged  grasses;  results  are  often  erratic  on  grasses  stressed  

from  lack  of  vigor,  drought,  high  temperature,  or  low  fertility.

Apply  in  summer  or  early  fall  after  terminal  growth  has  hardened  off.

Controls  woody  plants  and  broadleaved  perennials.

Apply  to  growing  weeds  over  the  top  when  trees  are  dormant  using  low  

rate,  or  as  directed  spray  at  high  rates  before  budbreak  or  after  budset  

during  cool  weather

Apply  broadcast  over  tree  tops  when  weeds  are  growing  actively,  up  to  

five-­‐leaf  stage.  For  perennials  such  as  Canada  thistle,  apply  after  most  

basal  leaves  have  emerged.  Notfor  use  on  first  year  seedlings.

Prevent  crop  injury  by  directing  spray  toward  base  of  plants  or  with  

selective  applicators.  Avoid  contact  of  spray  or  mist  with  foliage  or  green  

bark  of  desirable  plants.  

Apply  to  actively  growing  weeds.    Do  not  let  spray  or  drift  contact  living  

tissue  or  green,  thin,  or  un-­‐calloused  bark,  as  injury  may  occur.  Do  not  

broadcast  over  Christmas  trees.

For  bracken  fern  control.

S  =  susceptible  to  herbicide  M  =  moderate  control  or  suppression  of  weed  competition  can  be  expected  under  normal  conditionsR  =  weeds  resist  treatments  or  competition  is  not  significantly  reduced*,  seedlings  or  volunteers  controlled  only;  

biennial  or  perennial  stages  resistant                        +,  vegetative  control  only  

12

5

7

9

8

10 11

3

64

Weed families (botanical)

§  Broadleaves (dicotyledonous) ú  Many, many families represented

§  Grass family (monocotyledonous, Poaceae)

§  Sedges (look like grass but act like broadleaf)

Horseweed (Marestail) Conzya canadensis

Sunflower (composite) family Summer annual/biennial Germinates fall through spring Rosette stage

Horseweed (Marestail) Conyza canadensis

Ø  Tap rooted Ø  Prolific seed production Ø  Glyphosate resistant

some sites Ø  Mowing may stimulate

shoots growth from base Ø  Preemerge control

needed in fall through spring (SureGuard)

Ø  Growth regulators effective and Asulam

Prickly lettuce (darn yellow composites) Sunflower family Winter annual/biennial

Prickly Lettuce

§  Common along roadsides in the Valley

§  Huge taproot ú  Early cultivation to control

seedlings §  Flowers July to September §  ALS resistant (Gr 2) §  Controlled with

ú  PS II inhibitors (Gr 5-7) ú  Growth regulators (Gr 4)

Spiny or annual sow thistle

§  Sunflower family §  Annual

Sowthistles §  Cotyledons are egg

shaped §  Milky sap (not found in true

thistles) §  Tap rooted

ú  Mowing may be ineffective

§  Germinates early spring ú  Spring peeremerge

§  PS II herbs (Gr 5-7) §  Ann/spiny sowthistle on

SureGuard label

Northern willow herb (Fireweed family)

Northern willow herb

Courtesy of Patty Skinkis, Hort, OSU

Field Bindweed

Morning glory family Deep rooted perennial

Field bindweed

§  Deep rooted ú  Growth regulator herbicides

§  Must clean up field before planting §  Cultivate biweekly for 2 summers

Field bindweed

Growth regulator herbicides suppress bindweed, multiple treatments needed

§  2,4-D works best at bud stage, can be applied

up till frost ú  Tankmixes with glyphosate

§  Garlon §  Paramount (quinclorac) registered in some

rotational crops ú  Works best if applied before frost

Bindweed Mites (Aceria malherbae)

Aceria  malherbae  400X  mag.(approx.    175µm)  

Bull thistle (biennial)

Canada thistle (perennial)

Ø Colony forming perennial

Ø Deep & spreading roots system

Ø Stinger is the herbicide of choice (Garlon, Roundup)

Ø Fall plus spring applications are dynamite

Canada thistle

Bull Thistle Cirsium vulgare Sunflower Family Biennial

Queen Anne’s Lace Wild Carrot

Daucus carota Parsley or Umbell Family

• Biennial, 2 to 4’ tall • Rosette & deep tap root first year • Pinnately compound leaves • Strong carrot odor • Native to U.S. • Mowing good option • Westar

Rat tail fescue

• Winter annual growing to 2’ tall

• Leaf blades folded and less than 1/16” wide

• Narrow flower head or panicle • Introduced from Europe

Vulpia myuros Poaceae

Grass Family

Rattail Fescue

• Axiom, Westar, glyphosate

Barnyardgrass

Weaknesses, strengths, and site of action

Commonly used herbicides

Herbicide Sites of Action

Herbicides and Resistance Management

Grp Site of action Herbicide Example Cases of resistance

1 ACCase inhibitor Segment, Envoy, Fusilade 38

2 ALS inhibitor Westar (sulfometuron part) 108

3 Microtubule assembly inhibitors Surflan, Pendulum, Kerb 10

4 Auxin herbicides Stinger, Garlon, 2,4-D 28

5-7 Photo system inhibitors Atrazine, Velpar (Westar) 68

9 Amino acid (EPSP synthase) Roundup 17

10 Amino acid (glutamine synthetase) Finale -

14 PPO inhibitors Goal, SureGuard 5

18 DHP synthase Asulox -

20 Inhibits cell wall synthesis Casoron 1

Group 1. ACCase Inhibitors

Herbicide Timing and Weeds

Tree tolerance

Comments

clethodim (Envoy Plus)

POST annual or perennial

Around or over the top of trees

Widely used but expensive

sethoxydim (Poast )

POST annual or perennial

New or established plantings.

Widely used

fluazifop (Fusilade)

POST Quackgrass

Results erratic on stressed grasses

Not widely used because of poor control on fine fescues.

Group 1 ACCase inhibitors Envoy, Fusilade

Premix: Westar

Group Herbicide Timing and Weeds

2: ALS Inhibitor Sulfometuron

5: PSII inhibitor Velpar (hexazinone)

Group 2 ALS (Aceto Lactate Synthase) Inhibitor

Sulfometuron (in Westar)

Group 3. Microtubule assembly inhibitors

Herbicide Timing and Weeds

Tree tolerance

Comments

Oryzalin (Surflan)

PRE Used in pine and true firs (but not Douglas fir)

Costly

Oryzalin + benefin (XL 2G)

PRE winter or summer annual grasses and broadleaves

Cannot be used on Douglas-fir or in new plantings of any species.

Costly

Group 3. Microtubule assembly inhibitors

Herbicide Timing and Weeds

Tree tolerance

Comments

Isoxaben (Gallery)

PRE For use on established plantings

Not widely used due to its high cost.

Isoxaben + trifluralin (Snapshot)

PRE For use on established plantings

High cost

Group 3. Microtubule assembly inhibitors

Herbicide Timing and Weeds

Tree tolerance

Comments

Pendimethalin (Pendulum)

PRE Grass and some broadleaves, not composite family

- Not widely used as a stand-alone product

Prodiamine (Barricade):

PRE Grasses

Injury possible on trees with new and actively-growing shoots.

Not widely used

Pronamide (Kerb): Restricted-use pesticide. Oregon and Washington SLNs

PRE (some POST activity) Broadleaf Ann grasses

Not recommended on trees less than 1 year old

Not widely used, very specific to certain grass weeds (such as quackgrass).

Group 3 Microtubule assembly inhibitor

Surflan, Pendulum, Barricade, Kerb

Group 4. Growth regulators Herbicide Timing and

Weeds Tree tolerance

Comments

Clopyralid (Stinger) POST, Canada thistle

Broadcast or banded

To avoid needle curling, do not apply during first year after transplanting

Triclopyr (Garlon 3A)

POST, woody species, especially blackberries.

Used with caution as a directed spray

Group 4 Auxin herbicides

2,4-D, Garlon, Stinger

Groups 5-7: Photo system inhibitors Herbicide Timing and

Weeds Tree tolerance

Comments

Atrazine PER, POST Common in new plantings

Hexazinone (Velpar)

Variable tree injury has been observed with use on new plantings.

High labeled rate is more effective on trailing blackberries.

Hexazinone + sulfometuron (Westar)

Group 5-7 Photo System (II) Inhibitors Velpar, Atrazine, Simazine

Groups 9,10: Amino acid synthesis inhibitors

Herbicide Timing and Weeds

Tree tolerance

Comments

9. Glyphosate POST Direct spray toward base of plants, or use selective applicators.

Surfactant for stressed weeds

10. Glufosinate (Finale):

POST; Suppresses horsetail

Spray must not contact living tissue or green, or thin bark; cannot be broadcast

Not widely used except by some growers to spot spray for horsetail

Group 9 Amino acid (EPSP synthase) inhibitors

Roundup

Group 14. PPO Inhibitors

Herbicide Timing and Weeds

Tree tolerance

Comments

Flumioxazin (SureGuard)

PRE, Some POST activity on very small weeds with COC.

Applied prior to spring bud break or delayed until conifers have hardened off

Do not apply to conifers within 2 years of seedling emergence

Oxyfluorfen (Goal )

PRE, POST Moderate soil residual ; Broadleaves

Over top of trees (dormant) or as a directed spray all year.

Fine fescues may be suppressed

Premix: Axiom

Group Herbicide Timing and Weeds

15: Inhibits long chain fatty-acids

flufenacet

5: Photo system II metribuzin

Groups 18: Inhibits DHP synthase Herbicide Timing and

Weeds Tree tolerance

Comments

Asulam (Asulox):

POST Used for bracken fern control. Suppresses and controls weeds of sunflower family

Groups 20: Inhibits Cell Wall Synthesis

Herbicide Timing and Weeds

Tree tolerance

Comments

dichlobenil (Casoron)

PRE, before cold rain

Perennial weeds, spot treatments

Finding weed control info

Weed Identification Resources

§ Weed Science Society of America

§ USDA PLANTS

§  Center for Invasive Plant Management

Pest Management Strategic Plans

Herbicide Uses and Labels

Future of the Handbook

Herbicide Labels

§ Registrants § CDMS § Greenbook § PICOL (Pesticide Information

Center Online)

Local Herbicide Labels

§ Special local needs (SLN) ú  OR and WA on PNN site

§ Sec 18’s on ODA site @

Misc slides

Spotted catsear

Bristly hawksbeard

Red sorrel

witchgrass