Weed Control Strategies for Your
Christmas Tree Plantation
Ronald Lemin
Vegetation Management Sales Consultant
CPS – Timberland
Bangor, Maine
INTEGRATED PEST MANAGEMENT
(IPM)
A decision making process that integrates
into a management system, a combination
of practical pest management strategies to
prevent or control pests in ways to reduce
health, environmental and economic
risks.
IPM as Defined by Maine Statute
(Title 7, Chapter 423)
The selection, integration and
implementation of pest damage prevention
and control based on predicted
socioeconomic and ecological consequences,
including:
IPM

Understanding the system in which the pest exists.

Establishing dynamic economic or aesthetic
thresholds to determine whether the pest warrants
control.

Monitor pests and natural enemies.

When needed selecting the appropriate system of
cultural, mechanical, genetic, biological or chemical
prevention techniques for desired suppression.

Systematically evaluating the pest management
approaches utilized.
IPM Council Mission
To define, promote and enhance
implementation of IPM practices that reduce
or minimize harmful environmental and
human impacts of pesticides and other
management practices. The Council will
promote the education of the public
regarding the need, benefit, and practices of
IPM.
Current IPM Council Activities
Raising awareness, appreciation, and understanding
of IPM (consumers and public audiences)
 WWW.GotPests.org is our website which was
developed in collaboration with MBPC
 Recognized by EPA as an Environmental
Stewardship Partner
 Meet 2-4 times per year in Augusta (open to the
public)
 For more information contact Kathy Murray
Kathy.murray@maine.gov 287-7616

What is a Herbicide?

They are one type of “pesticide” such as:
insecticide, fungicide, bactericide, etc.

Relatively low in toxicity

Work on enzymes only found in plants, not in
humans, animals, and insects
Herbicide Modes of Action

Selective or non-selective

Residual or non-residual

Foliar absorbed, Root absorbed, or Both

Post-Emergent, Pre-Emergent, or Both

Contact or systemic
Application Methods
Aerial – Helicopter or Fixed-wing
 Ground – Skidder, Tractor, ATV
 Backpack Foliar - Mistblower, Manual
 Backpack - Basal Bark
 Stump Treatments
 Tree Injection
 Granular

Small Droplets – Be Careful of Inversions!
SURFACTANTS
 Added
to the solution to alter the dispersing,
spreading, or wetting properties of the spray
droplet.
 Reduces the surface tension of the water
droplet.
 Increases the contact surface area of the
droplet, better efficacy.
 Soaps
Foliar Absorption
Barriers to foliar absorption:
High surface
tension – no
surfactant
Low surface
tension – with
surfactant
Leaf cuticle – waxy covering on leaf
epidermal cells, herbicide moves
through by diffusion, also enter
through cracks in the cuticle,
surface tension of spray droplet
critical
Source: Anderson 1996
Questions?
2011 NEW ENGLAND GUIDE TO CHEMICAL
WEED AND BRUSH CONTROL
IN CHRISTMAS TREES
 Coordinated
and edited by: J.F. Ahrens,
Connecticut Agricultural Experiment Station,
Windsor CT
 Copies can be downloaded from the University of
New Hampshire Cooperative Extension website:
http://ceinfo.unh.edu/nrnpubs.htm
Link To Obtain a Copy Online
http://extension.unh.edu/resources/files/resource000845_rep2560.pdf
A BASIC WEED MANAGEMENT PROGRAM
 Identify
the problem weeds, evaluate control
strategies. Monitor weeds before bud break in the
spring and in July and August to help make decisions.
 Calibrate
application equipment or plan on spot
treatments. Select proper rates using this guide, read
the labels, and follow label directions.
 Consider
 Apply
site preparation before planting.
pre-emergence herbicides in the early spring.
Combine herbicides to control your problem weeds
A BASIC WEED MANAGEMENT PROGRAM
 Following
a June evaluation, consider whether
additional treatments are needed for problem
weeds; for example: Vetch, or other uncontrolled
weeds.
 Plan
on a fall treatment with Roundup or Garlon
to control perennial weeds, ferns and brush.
 Keep
good records of equipment calibration,
products used and dosages and dates applied.
GENERAL CONSIDERATIONS

Treat perennial weeds with Glyphosate (Roundup)
one or more times the year before planting. Organic
mulches such as wood chips, or pine needles conserve
moisture and control many weeds alone, or can be
used in addition to pre-emergence herbicides.

Certain herbicides are safely sprayed directly over the
trees (Princep, Goal, Devrinol, Surflan), whereas
others must be applied as directed sprays, where
contact with conifer foliage is minimized or avoided
entirely (Roundup, Garlon, etc.).
GENERAL CONSIDERATIONS
Field planting in pre-killed sod is faster and
herbicides applied after planting are used at lower
rates. Band treatments require less herbicide per
acre of trees, save money, and also prevent soil
erosion on slopes. Bands 24 to 30 inches wide are
satisfactory for two years, but as the trees grow, the
treated bands should be widened. Spring-applied
herbicides are usually required each year until the
trees are large, but dosages may be reduced after
the second or third year.
GENERAL CONSIDERATIONS
Spraying of brush or resistant weeds is done
only as needed. Soils higher in organic matter
require higher rates of pre-emergence herbicide
than sandy or gravelly soils low in organic
matter.
Fully and Semi-Directed Sprays
 Semi-Directed
Sprays are applied so that only the
basal 8 - 12 inches of the conifers are contacted.
Application is usually with the use of off-center
nozzles or wide-angle nozzles mounted low.
 Fully-Directed
Sprays are applied in ways that avoid
contact with conifer foliage such as the attachment of
an 8 inch funnel to the nozzle of knapsack sprayers, or
using shields on tractor mounted sprayers.
BARRICADE, DEVRINOL, PENNANT,
PENDULUM, SURFLAN, and TREFLAN
All control some broadleaf weeds, but are
primarily effective in controlling annual grasses.
For broad spectrum pre-emergence control these
herbicides are often combined with broadleaf
herbicides such as Princep, Gallery, or Goal.
BARRICADE (Prodiamine)
A long-residual preemergence herbicide for
field grown conifers. It is similar to Surflan
in chemistry and spectrum of weed control.
Barricade should not be used in seed beds or
transplant beds.
BASAGRAN T/O (bentazon)
A contact postemergence herbicide that
controls yellow nutsedge, Canada thistle,
musk thistle and certain broadleaf weeds
like ragweed, velvetleaf, dayflower, etc. A
rate of 1.5-2 pts per acre with 1 quart of crop
oil concentrate. White pine is tolerant
sprayed over-the-top but fully directed
sprays are needed to prevent foliar injury to
most other conifers.
SURFLAN AS OR ORYZALIN AS (oryzalin)
A long-residual pre-emergence herbicide
for field-grown conifers. It controls annual
grasses and some broadleaf weeds, but does
not control sedges or perennial broadleaf
and grass weeds. Douglas fir and Fraser fir
seedlings in transplant beds have been
injured, but 3- or 4-year-old plants have
been tolerant. It should not be used in
seedbeds or transplant beds!
TREFLAN 5G or 4E (trifluralin)
Related to SURFLAN but is volatile and
requires incorporation by tillage or
irrigation. It can be incorporated into the
soil ahead of transplanting. It is not safely
used in conifer seedbeds.
STINGER (clopyralid)
Systemic herbicide used to control vetch,
legumes, thistles, horseweed and other
broadleaf weeds. It has no effect on grasses,
sedges, or most woody brush and can be
safely sprayed over established conifers.
Can be used alone or combined with other
herbicides such as Goal in early summer or
Glyphosate in fall as a semi-directed spray.
Can cause damage to newly planted conifers
in transplant beds.
SUREGUARD 51 WDG (flumioxazin)
Broad spectrum preemergence herbicide
with some postemergence activity on some
weeds. Controls several triazine-resistant
weeds. Apply prior to bud break, and do not
apply to seedbeds. Combines well with
Glyphosate when weeds are emerged, but
alone has little effect on perennial grasses
and nutsedge. 12 oz per acre provides equal
or better results than combinations of
Simazine and Oryzalin
PENDULUM 60% WDG, 3.3EC, 3.8
AQUACAP, HURDLE 3.8 ACS
(pendimenthalin)
Chemically related to Surflan. The AQUA CAP
and HURDLE formulations are
microencapsulated, sprayable forms. While
these are registered for several Christmas tree
species, their may be risk to young seedlings.
The water dispersible granule (WDG)
formulation is preferred after conifer bud break.
GLYPHOSATE Products (Roundup Original,
Glyfos, Glystar, Credit 41, Mirage, Roundup
Original Max, ect)
More than 40 different types of Glyphosate
products are on the market, not all registered for
Christmas Trees. They vary in concentration and
many contain surfactants that can injure conifers.
All these products are safe to use if you can prevent
contact with the foliage. Ask your supplier for the
41% product that is similar to the Roundup
Original.
GLYPHOSATE Products (Continued)
Glyphosate is a foliar-absorbed systemic herbicide
that is rapidly inactivated in soil and controls most
weed and brush species with the right doses and
timing. Quackgrass must be actively growing and
over 6 inches tall, and perennial weeds should be in
flower bud or later stages at treatment. Woody
brush, poison ivy and brambles are best controlled
in August or September, before frost.
GLYPHOSATE Products (Continued)
 To
provide residual control of weeds from seed,
glyphosate must be followed or combined with a
pre-emergence herbicide.
 Weeds
not usually controlled with glyphosate
include perennial vetch and Asiatic dayflower.
GLYPHOSATE Products (Continued)
Glyphosate sprays will injure the foliage of conifers.
Conifers are most resistant to semi-directed basal
sprays (where only the basal branches of conifers are
sprayed) with Roundup Original or Credit late in the
season (late August, September) and most susceptible
during active growth. Douglas fir and white pine are
more susceptible to injury than spruces or true firs
(Abies spp.) Adding surfactants or emulsifiable
formulations of herbicides such as Goal or Pennant to
Roundup Original or Credit increases injury potential
on conifer foliage.
GLYPHOSATE Products (Continued)

Roundup PRO and Roundup ULTRA are 41% glyphosate
formulations that contain surfactants which make them
faster acting on weeds and more injurious to conifers than
Roundup Original or Credit. Sprays of these products
should not contact conifer foliage. Roundup ULTRA
MAX (50.2% glyphosate) should be considered for preplant and fully directed spray only.

Glyphosate is applied in the fall and pre-emergence
herbicides are applied in the early spring. To prevent
winter annuals from invading in the fall it is common to
add simazine (Princep, Simtrol) at 1 to 1.5 lbs. active
ingredients per acre to the fall glyphosate sprays
FUSILADE(fluazifop-P), ENVOY (clethodim)
Systemic postemergence grass herbicides that
control or suppress grasses with no effect on
broadleaf plants and sedges, and have little or no
residual activity in soil. Immature grasses are
more susceptible. Can be sprayed over conifers
and combined with or followed with simazine.
Summer tank mixes with Goal are also effective.
PENNANT MAGNUM (s-metolachlor)
A pre-emergence herbicide that is applied in
early spring before bud break. It controls yellow
nutsedge and annual grasses in transplant beds
or field-grown conifers. Comines well with
Simazine or Goal for broad-spectrum control,
but not safely used in seedbeds. Second
applications may be needed for season-long
control of nutsedge.
TOWER 6E (dimethenamid-P)
A pre-emergence herbicide similar to Pennant
that controls yellow nutsedge and annual
grasses, but differs in that it will control ragweed
and lambsquarter. It does injury white pine and
other conifers during active growth and should
be applied before bud break. It fails to control
perennial grasses and weeds and should be
applied after a glyphosate treatment.
WESTAR (sulfometuron methyl, hexazinon)
A combination of two active ingredients for a broader
control of annual and perennial weeds including quack
grass, ragweed, lambsquaters, yellow nutsedge,
horseweed and many others. It is safely applied on
dormant trees before bud break but applications after
bud break will injure conifers. Trail use in Christmas
trees is suggested at 6-10 oz per acre. Lower rate on
newly planted trees. Adding glyphosate to the mix
improves control of other weeds. Do not use in seed
beds or transplant beds.
GALLERY 75DF (isoxaben)
A pre-emergence herbicide that controls most
annual broadleaf weeds and suppresses annual
grasses. It controls weeds for 3 to 4 months or
longer by root activity and can be sprayed overthe-top of labeled conifers. It does not control
emerged weeds. For broad spectrum control of
annual weeds it can be combined with
preemergence grass herbicides such as Surflan,
Devrinol, or Pennant and the post-emergence
herbicides Goal or Stinger.
GALLERY 75DF (isoxaben)
 Use
in plantations but not in seedbeds or
transplant beds.
 It
is a potential alternative to Simazine on
freshly tilled sites or on sites where glyphosate
is used to kill established weeds. Gallery could
substitute for Simazine for reduced leaching
potential in aquifers.
GOAL 2XL (oxyfluorfen)
A
pre-emergence and post-emergence herbicide
useful for annual weed control in seedbeds,
transplant beds, and Christmas trees. Dosages
vary with the size of the conifers and the length of
control desired.
 Pre-emergence
control of broadleaf weeds lasts
longer than control of grasses.
GOAL 2XL (oxyfluorfen)
 Goal
causes contact injury on spruces and true firs
during rapid growth. Avoid applications on those
conifers during the 5 to 6 week period following
bud break. Emerged chickweeds, spurge and
annual grasses are tolerant of Goal, but seedlings
of purslane, carpetweed, pigweeds and several
other weeds are controlled.
 Goal
could substitute for simazine for reduced
leaching potential in aquifers.
SIMAZINE products (Princep 4L , Princep
Caliber 90, Simtrol)
 Broad-spectrum
 At
pre-emergence herbicides.
low rates they fail to control annual grasses,
but at high rates they control certain established
perennial grasses when applied before growth
starts in the spring. Both sprays and granules are
safely applied over the tops of tolerant plants.
SIMAZINE products (Princep 4L , Princep
Caliber 90, Simtrol)
 Simazine
combines well with pre-emergence
"grass herbicides" such as oryzalin, metolachlor
or pendimethalin to provide broad-spectrum preemergence control.
 Conifer
tolerance varies with the species and
age. Therefore, lower rates are used in transplant
beds and on field-grown spruce than on firs or
pines.
TRICLOPYR products (Crossbow, Garlon 3A,
Garlon 4 Ultra, AquaSweep)
 Systemic
weed and brush herbicides, useful in site
preparation or around conifers in late August or
September, before leaf drop of target weeds (Garlon
3A).
 They can be applied in water during the growing
season or in oil for basal applications on brush
during the dormant season (Garlon 4). Garlon 4 can
produce vapors that injure actively growing conifers
during hot summer weather.
 Triclopyr controls vetch, other legumes, goldenrod,
bedstraw, brambles, many other broadleaf weeds and
TRICLOPYR products (Continued)
 It
is especially useful to control susceptible broadleaf
weeds in row middles where grass cover is desirable.
It also is more effective than Roundup in controlling
oriental bittersweet in early fall.
 Conifers
established for three full years tolerate
semidirected basal sprays of triclopyr in September.
 Crossbow
is a combination of 2,4-D and triclopyr,
useful in spot treatments (fully directed sprays) for
woody vines and brush. AquaSweep is a 2,4-D.
Garlon 3A combination that can be used for brush
control outside the plantation.
Product Availability
 Round
Up Original is no longer being produced
by Monsanto
 Mirage, Honcho, Ranger are other identical
products produced by Monsanto.
 Key component is a 4lb product with the 7.5%
surfactant load.
 Credit 41 is a 4lb product with the 7.5%
surfactant load provided by CPS.
QUESTIONS?
What is WPS?
WPS is the Worker Protection Standard set by the
Federal EPA to protect farm, forest, greenhouse,
nursery workers and pesticide handlers from pesticide
exposure.
 WPS applies to anyone who uses pesticides in the
production of agricultural plants on farms, forests,
nurseries or in greenhouses.
 Whether or not you employ agricultural workers and
pesticide handlers, all applicators of agricultural
pesticides are required to comply with PPE and REI
statements on the labels.

What is Required Under WPS?
INFORMATION – employees will be informed through
training, posters, access to labeling, and REI notification
for treatments.
 PROTECTION – ensure that your employees will be
protected from exposure to pesticides, during
application and within REI intervals.
 MITIGATION – decontamination sites, wash stations,
emergency assistance, labels and MSDS for medical
personnel.

Contact the Board of Pesticides
Control for More Information to Help
You Comply With the WPS Standards
Common Herbicides use in Small
Woodlot Management

ARSENAL (Imazapyr)

RODEO, ROUNDUP (Glyphosate)

GARLON 4 ULTRA AND GARLON 3A (Triclopyr)

PATHFINDER II (Triclopyr and basal oil)
ARSENAL










Imazapyr, 4 LBS ACTIVE PER GALLON
ORIGINALLY DEVELOPED AS A POSSIBLE DRUG
WATER SOLUBLE SALT
NON VOLATILE
AMINO ACID INHIBITOR
MERISTEMATIC GROWTH INHIBITOR
BOTH ROOT AND FOLIAR ACTIVE
POOR LEGUME, RUBUS, AND FORB CONTROL
USED IN TANK MIX FOR MAPLE CONTROL
NONIONIC SURFACTANT TO INCREASE EFFICACY
IMAZAPYR - SOIL BEHAVIOR
WEAKLY BINDS TO SOIL PARTICLES
 ADSORPTION INCREASES WITH OM AND CLAY
 DEGRADATION WITH SOIL MICROBES
 SOIL HALF-LIFE FROM 19 TO 34 DAYS
 WEED CONTROL UP TO 2 YRS DEPENDING ON
RATE
 REMAINS IN THE TOP 30 CM OF THE SOIL
 LATERAL SOIL MOVEMENT IS LIMITED

RODEO (Concentrate)-ROUNDUP
Glyphosate, 40 or 54% ACTIVE PER GALLON
 NON VOLATILE,WATER SOLUBLE SALT
 AMINO ACID INHIBITOR
 DEPLETION OF 3 ESSENTIAL AMINO ACIDS
 FOLIAR ACTIVE ONLY
 LOCKS UP TIGHTLY TO SOIL MOLECULES
 ACCORD USED FOR CONIFER RELEASE
 NONIONIC SURFACTANT TO INCREASE
EFFICACY

RODEO (Concentrate)-ROUNDUP
ROUNDUP CONTAINS NONIONIC SURFACTANT
 GLYPHOSATE IS A NON-SELECTIVE HERBICIDE
 NO SOIL RESIDUAL ACTIVITY
 COVERAGE IS ESSENTIAL
 EPA CLASSIFIES GLYPHOSATE IN CATERGORY
“E” (EVIDENCE OF NON-CARCINOGENICITY
FOR HUMANS), “E” BEING THE MOST
FAVORABLE

GLYPHOSATE - SOIL BEHAVIOR
 RAPIDLY
ADSORBED TO SOIL
 SOIL AND ORGANIC MATTER ARE
GLYPHOSATE’S WORST ENEMY.
 REQUIRES CLEAN WATER FOR MIXING
 PLANTING CAN OCCUR IMMEDIATELY
AFTER APPLICATION
 MICROBIAL DEGRADATION
 SOIL HALF LIFE OF 47 DAYS
GARLON 4

Triclopyr

44% ACTIVE INGREDIENT PER GALLON

ESTER FORMULATION WITH MSO CARRIER

VOLATILE AT HIGH TEMPS AND LOW REL.
HUMIDITY

NO GRASS CONTROL - SELECTIVE

TYPICAL AUXIN-TYPE PLANT RESPONSE

ABSORBED THROUGH THE FOLIAGE, BUT ALSO
ROOTS, BARK, AND STEM
GARLON 4

INDUCES CELL ELONGATION,
UNCONTROLLED CELL DIVISION AND
GROWTH.

ADD TO WATER FOR FOLIAR TREATMENT

CREATES AN E.C. WITH OIL (20%,80%) FOR
BASAL APPLICATIONS

OIL CARRIES THE TRICLOPYR THROUGH
BARK

FOLIAR EFFICACY IS BETTER IN EARLY-MID
SUMMER DURING ACTIVE PLANT GROWTH
GARLON 3A

Triclopyr

3 LB ACTIVE INGREDIENT PER GALLON

AMINE FORMULATION WITH 1% ETHANOL

ADD A NON-IONIC SURFACTANT FOR BETTER
EFFICACY IN FOLIAR TREATMENTS

BEST FOLIAR EFFICACY IN EARLY-MID
SUMMER DURING ACTIVE PLANT GROWTH
PATHFINDER II

Triclopyr 14% and basal oil 86% mix

READY TO USE FORMULATION FOR BASAL
BARK AND STUMP TREATMENTS

BEST BASAL CONTROL ON STEMS LESS THAN 6
IN.

YEAR ROUND APPLICATION EXCEPT WHEN
SNOW PREVENTS APPLICATION TO THE
GROUND

TRICLOPYR IS TRANSPORTED THROUGH THE
BARK BY THE BASAL OIL
GARLON 4, GARLON 3A, AND
PATHFINDER II- SOIL BEHAVIOR

BINDS TIGHTLY TO SOIL OM AND CLAY
PARTICLES

BROKEN DOWN BY SOIL MICROBES AND
SUNLIGHT

SOIL HALF LIFE RANGES FROM 10 TO 46 DAYS
FOR GARLON 4 AND PATHFINDER II, AND 30-45
DAYS FOR GARLON 3A

MOST OF ACTIVE INGREDIENTS ARE FOUND IN
UPPER 12 INCHES OF THE SOIL.
Cut Stump Treatment with
glyphosate or Garlon 3A
Cut Stump Treatment with
Garlon 4 and oil
Applying Herbicide to a
Girdled Tree
Spaced Axe Frill Prepared for
Herbicide Injection
Basal Bark Application
To Lower 12-18 Inches
Aquatic Use Labels for Common
Brush Control Herbicides
Rodeo– Has the aquatic and terrestrial use labeling for
several years. Glyphosate products with surfactant are
not aquatic labeled.
 Imazapyr –BASF received labeling for 2 lb/gal
imazapyr for aquatic use (Habitat marketed by SEPRO,
Polaris by NuFarm).
 Triclopyr – DowAgrosciences relabeled Garlon 3A for
aquatic use (Both on the Garlon 3A label and the
SEPRO label as Renovate)
 All are pseudo Restricted Use under Maine’s Pesticide
Regulations.

Glyphosate versus Triclopyr
 Triclopyr
(Garlon 4 and 3A work better
early in the season before woody plants
begin to shut down.
 Glyphosate
works better later in the season
as plants begin to produce sugars to store in
the roots.
 Christmas
trees can be more susceptible to
Garlon 4 than Garlon 3A.
Some Herbicides to be Cautious
Milestone and Capstone – contain aminopyralid
which is soil active and will move through the soil
and damage softwoods. A good product to use in
headland areas to control volunteer softwood
brush
 Method, Viewpoint and Streamline – contain
aminocyclopyrachlor (Imprelis) which can also
cause severe softwood damage as it moves
through the soil.

Ronald C. Lemin, Jr.
CPS Timberland
Bangor, Maine
207-944-6160
ronald.lemin@cpsagu.com
http://extension.unh.edu/resources/files/resource000845_rep2560.pdf