APPLY PESTICIDES CORRECTLY
A GUIDE FOR COMMERCIAL APPLICATORS
FOREST PEST CONTROL
..VIRONMENTAL PROTECTION AGENCY
OFFICE OF PESTICIDE PROGRAMS
WASHINGTON, D.C. 20460
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TABLE OF CONTENTS
Page
Acknowledgments 1
Preface 1
Introduction 2
Forest Types 3
Forest Pests—Recognition and Control 4
Weeds 4
Insects 6
Diseases 7
Vertebrates 8
Pesticide Labeling 8
Application 8
Environmental Hazards 9
Human Hazards 10
1976
i
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ACKNOWLEDGMENTS
PREFACE
This manual has been developed by Oregon State
University under U.S. Environmental Protection
Agency (EPA) contract number 68-01-2263. This
contract was issued by the Training Branch, Opera-
tions Division, Office of Pesticide Programs, EPA.
The leader of this group effort was Michael New-
ton, Oregon State University. Editors were Mary
Ann Wamsley, EPA, and Donna M. Vermeire,
North Carolina State University.
Contributors were:
Lawrence P. Abraham, U.S. Forest Service,
Joseph Capizzi, Oregon State University,
William E. Currie, U.S. Environmental Protection
Agency,
Charles H. Fitzgerald, University of Georgia,
William D. Fitzwater, U.S. Environmental
Protection Agency,
Harvey A. Holt, Purdue University,
Peter P. Laird, U.S. Forest Service,
Logan A. Norris, U.S. Forest Service, Corvallis,
Oregon,
Debby J. Sundbaum, Artist, Oregon State University,
Donald P. White, Michigan State University.
Federal regulations establish general and specific
standards that you must meet before you can use
certain pesticides. Your State will provide materials
which you may study to help you meet the general
standards. This guide contains basic information
to help you meet the specific standards for applica-
tors who are engaged in forest pest control.
Because the guide was prepared to cover the entire
nation, some information important to your State
may not be included. The State Agency in charge
of your training can provide the other materials you
should study.
This guide will give you information about:
• types of forests,
• characteristics of common forest pests,
• pest control methods,
• pesticides and application equipment used in
forestry, and
• environmental and human hazards.
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INTRODUCTION
Control of forest pests is a long-term proposition.
The goal is to keep pest populations at a level low
enough to prevent destruction of forest trees.
Chemical pest control must be combined with other
management methods to minimize recurrence of
pest problems.
FOREST REGIONS OF THE UNITED STATES
WESTERN FORESTS
ROCKY MOUNTAIN FOREST
Ponderosa pine Idaho wfiiic p«*.
western lirch Engelmjnn spruce
DougJas in lodgepole pme. tuga>
pme; wesle>n red cedar western
hemlock, white I", and othert
Surplus conilers shrubs, dwarl
mittletoes and bark beetles ire
important petls
Weslem Pine Region
Douglas fir western hemlock, red-
wood western r«d cedar. Silka
spruce sufiar pine, lodgepole
p»ne. incense cedar, whi'c lir.
Port Orford ceder and others.
Hardwoods shrubi bark beetles
Mna deer are important pesti
PACIFIC COAST FOREST
Douglas Fir and
California Redwood Region
ALASKAN COAST FOREST
Sitka ipruce western hemlock.
western red cedar Alaska cedar
Shrubi. browsing animals ant) de-
loha'or msecti are principal pesls
ALASKAN INTERIOR FOREST
White spruce while birch, and
black spruce
Shrubs and browting animals are
principal pests
CENTRAL HARDWOOD
FORESTS
NORTHERN PORTION
Oaks hickories ashes etms ma-
ples, beech black walnut, pitch.
shortleal and Virgnia pmes. col-
ton wood end others
Low-grade hardwoods, deer and
gypsy molhs are principal peits
Appalachian Hardwood Region
SOUTHERN PORTION
Oaki. red and black gums, hick-
ones ashes, black walnut, east-
em red cedar, cottonwood. yellow
poplar beech and others.
Low-grade hardwoods, deer and
heart'rotting lungi are principal
pesls.
Southern Hardwood Region
EASTERN FORESTS
NORTHERN FORESTS
Red. bitch and <*nne spruces, bat-
sam In whttt. 'ta iack and pitch
p«es eastern hemlock maples
o*k». beech, birches and aspen
Low-grade hardwoods, deer
Spruce budworm and balsam
wooty aphid are important pests
Northern Pint and Hemlock and
Northern Hardwood Rtgiont
SOUTHERN FORESTS
Longteal. shortleal. loMotty and
tUth pinct southern oaks r«d
gum: hickories southern cypress
eastern and southern red cedars.
•nd others
Low-grade hardwoods, southern
pin* beetle. Fomut tnnotut toot
rot and fusiform run are pnncipal
pests
Southern Pme and
Southern Hardwood Regions
TROPICAL FOREST
Evergreen or deciduous tropical
hardwoods
Low-value tree
secis are principal pesls
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Poor harvesting practices have left forest prob-
lems such as weed trees, brush, and weed-covered
lands without commercial stands. Fire control ef-
forts increase pest-susceptible species. Increased
travel of man helps introduce weeds, insects, dis-
ease*, and animals which may cause widespread
damage. Forests are attractive to people for the
beauty of the scenery, the abundance of wildlife,
and the quiet environment. Choose effective pest
control methods that are the least disruptive of
these values.
Tree cover affects all other forest resources (wa-
ter, wildlife, and esthetics). Methods used to im-
prove or protect the tree cover have a great
influence on the other resources. Pesticides are
not generally used except to improve the timber.
Take care to avoid injury to the other resources.
Habitat management will control many forest pests.
Good vegetation control and management will not
only control pests, but will enhance the timber
production and may permanently solve some forest
problems.
FOREST TYPES
The preceding map shows the principal natural
forest regions of the United States, and the im-
portant kinds of natural forest communities and
pests within each region.
All regions have second and third generations of
man-made forests. These usually are even-aged
stands of a single species. They often are com-
posed of:
• trees not native to the area, or
• native trees which do not normally grow in single
species stands of high density. Many of the major
insect and disease problems occur in such man-
made forests.
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8
Time to Control
Insects
Time to
Control
Weeds
Value of a
Healthy Forest
of Forest
it by Insects
$ Accumulated Costs
Value of Forest
Held Back by Weeds
100
Age of Stand (Years)
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FOREST PESTS-
RECOGNITION AND
CONTROL
WEEDS
Weeds are plants that interfere with land man-
agement objectives. Weeds cause more forest losses
than all other pests combined. Inadequate control
of forest weeds is causing a major shortage in future
supplies of high quality wood products. Weeds may
be classed as:
• weed trees,
• brush,
• vines, and
• herbaceous weeds.
Weed Trees
Weed trees often cause significant losses in forest
production. They affect both young and old com-
mercial trees within the stand. Included are:
• noncommercial hardwood and conifer species,
• deformed, defective, or undersized individuals of
commercial species (such as crooked trees or
those with heart rot), and
• offsite species (commercial species in a location
where they cannot develop well).
Some weed trees may be removed by mechanical
methods. Some of these can be sold as pulp or fuel.
Chemical control methods include:
• broadcast foliar application of herbicides,
• directed basal-cut application of herbicides to
individual trees,
• directed basal bark application of herbicides, and
• broadcast soil application of herbicides.
BROADCAST FOLIAR APPLICATIONS of herbi-
cides (usually aerial sprays) are used for:
• Site preparation—Preparation of ground for plant-
ing. Treat during early or middle part of the
growing season. Using a controlled fire afterwards
may be helpful.
• Release—Removal of hardwoods from coniferous
stands. Make the application during the season
when hardwoods will be controlled with minimum
damage to conifers. The label will tell you the
correct season for using the herbicides and the
dosage at which it is selective. Season is important.
DIRECTED BASAL-CUT APPLICATION OF
HERBICIDE TO INDIVIDUAL TREES. Aerial
sprays are ineffective on some hardwood species.
Noncommercial trees remaining after aerial applica-
tion must be treated individually. Otherwise, they
may reseed and crowd out desired species.
Release desirable hardwoods by using individual
stem treatments on competing trees. Directed basal-
cut treatment usually involves applying water-soluble
amines or various other salts of herbicides in con-
centrated form to cut surfaces. The cut surfaces are
created by:
• Girdling—removing 4-inch chips into the sap-
wood to completely encircle the tree bole. Apply-
ing herbicide spray to the girdle will hasten top-
kill and retard basal sprouting.
• Frilling—encircling the bole with a series of over-
lapping single line ax cuts which penetrate the
cambium. A herbicide must be applied to insure
kill by preventing bridging. Apply the herbicide
spray to the frill.
• Felling the tree and wetting margins of cut stump
surfaces with concentrated herbicide spray.
• Trunk injection—using special tools (such as the
tree injector or modified hatchets) that inject
herbicide concentrate.
• Putting granular herbicide (ammonium sulfamate)
into ax-cut cups spaced around the base of the
tree near the ground line.
DIRECTED BASAL BARK APPLICATION to in-
dividual trees consists of spraying a herbicide in oil
solution on the bark of the lower one foot or bole
and exposed roots to the point of runoff. The entire
root collar must be treated without gaps. Remove
debris first.
Basal Bark Treatment
BROADCAST SOIL APPLICATION OF HERBI-
CIDES can be used to kill trees. They are not
always effective. Use them with care to avoid leav-
ing residues in soil that are harmful to desirable
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trees. Spot treatments are more useful than broad-
cast applications.
Brush
Brush includes:
• woody shrubs, and
• noncommercial stump sprouts.
Dense brush keeps light from tree seedlings. It
also can deprive taller commercial species of water
and nutrients. It interferes with planting and can
create habitat for wildlife species that may damage
tree seedlings.
Broadcast applications of foliar herbicides are used
for general or selective control of susceptible brush
species. If the brush is not over 20 feet high, air
blast sprayers may be used for ground application.
Aircraft are usually used on taller vegetation.
Application of chemicals to individual stems can
be expensive if large numbers of stems per acre are
treated. Basal bark applications are effective, but
are costly in labor, chemical, and fuel oil. Systemic
brush-killing herbicides do the best job of controlling
large woody vegetation.
Vines
Greenbriar, Japanese honeysuckle, wild grapes,
kudzu, and other vines are serious pests, especially
on better forest soils. They strangle trees, drag
down branches and crowns, and compete for light
and nutrients. Poison ivy is a human health hazard.
Vines are the most difficult weeds to control. They
have vigorous sprouting habits. Systemic herbicides
kill their root systems.
Herbaceous Weeds
Herbaceous weeds compete with seedlings in new
plantations. The seedlings may develop poorly or
die, especially in time of drought. Herbaceous
weeds also create favorable cover for tree-damag-
ing animals such as mice, gophers, and moles. Con-
trol herbaceous weeds with herbicides labeled for
this forest use. Killing all ground cover for several
years can cause soil damage, especially from loss of
nutrients and from erosion. Use banded application
in areas with summer rainfall. In dry-summer cli-
mates, short-residual herbicides permit winter
ground cover to develop.
For herbaceous weed control in new plantings,
apply herbicides in the spring before growth of tree
seedlings begins. Chemicals that injure planted trees
on contact may have to be applied before planting
or be used as directed spray.
Herbaceous weeds recover rapidly after treatment
with contact herbicides. Use residual herbicides to
extend weed control through the tree seedlings' first
growing season.
Weeds of Special Importance in
Small-acreage Forest Crops
Forest nurseries, seed orchards, and Christmas tree
plantings should be completely free of weed trees,
brush, and vines. Herbaceous weed control is critical
in these high-value forest crops.
Control of herbaceous weeds in forest nurseries re-
quires continuing effort throughout the growing sea-
son. Mechanical and hand weeding are still com-
mon. Preemergence herbicides are sometimes used
for selective weed control in conifer nurseries.
Seasonal variation in herbicidal effect on tree seed-
lings is critical. Use contact herbicides when trees
are resistant and residual herbicides to carry through
sensitive period.
For control of both weeds and diseases, fumigants
can be used before seeding. Fumigants may injure
desirable fungi and should not be used for general
weed control.
Herbaceous weeds may limit seed production in
seed orchards. They may be controlled by mowing
and chemical applications. Herbaceous weeds retard
the growth of Christmas trees and may seriously
damage their shape.
Herbicides
You must understand the terms used on herbicide
labels to describe their uses in forestry. These terms
include:
• Reforestation—the process of establishing tree
seedlings.
• Site preparation—preparing an area for reforesta-
tion by clearing or other vegetation control.
• Plantation weed contol—using herbicides for se-
lective weed control to insure survival and rapid
growth of planted tree seedlings. This is one
method of animal habitat management.
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• Release—applying selective herbicides to woody
or herbaceous weeds competing with commercial
crop species.
• Desiccation—applying herbicides to vegetation in
preparation for burning as part of site preparation.
• Timber stand improvement—selective removal of
undesirable trees to improve growing conditions
for desirable trees.
• Chemical precommercial thinning—removing all
excess trees in a young forest by applying chemi-
cals to individual trees. Herbicides labeled for
basal spraying, cut-surface application, trunk in-
jection, frilling, or stump treatment may be used
for this purpose.
• Preharvest drying of softwood timber—the treat-
ment of trees with chemicals to allow timber to
season before cutting. May also loosen bark and
control insects and diseases. Herbicides registered
for conifer thinning may be used for this purpose.
• Dormant spray—applying before buds open in
the spring, or after trees go dormant in the fall.
• Early foliage spray—application while new
growth is elongating rapidly, but after first leaves
are fully expanded.
• Summer foliage spray—application to mature
foliage near midsummer.
• Fall foliage spray—application in late summer to
early fall, generally used with readily translocated
herbicides.
• Cut-surface—includes trunk injection, bore-hole,
frill, frill-girdle, girdle and stump treatment.
• High-volume ground spray—application of herbi-
cide to low brush with power sprayer delivering
enough volume to wet foliage to the drip point.
Noncrop herbicides may be used when crop
species are not present.
• Low-volume spray—broadcast application by air-
craft or ground rig, including air blast sprayers,
at the rate of 30 gallons per acre or less. Does
not soak foliage. Aircraft application must be
specified on the label. Forestry use must appear
on the label if crop species are affected.
Herbicides generally move very little in forest
soils. They are broken down in place by micro-
organisms, sunlight, and chemical reactions. A com-
pound that has an effective life of several months
will usually move less than a foot or two from the
site of application. Therefore, herbicides are not a
serious threat to water supplies or fish unless they
are placed directly (especially by spillage) into for-
est streams or on areas which will become waterways
during storm periods.
INSECTS
The major groups of insects affecting forests are:
• defoliators,
• bark beetles,
• suckling insects,
• shoot borers, and
• wood borers.
DEFOLIATORS include:
• forest tent caterpillar,
• gypsy moth,
• tussock moth,
• spruce budworm, and
• loopers.
The larvae of defoliators feed on buds, flowers,
and leaves of both hardwood and coniferous trees.
Early spring defoliation often keeps the trees from
fruiting, reducing regeneration potential.
Defoliation suppresses shoot development and
growth rates. Repeated defoliation can kill the trees.
Symptoms are the trees obviously stripped of foliage.
One or more hatches may occur each year depend-
ing on species and climate. The nonpersistent insec-
ticides are most commonly used for control. Apply
insecticides from aircraft:
• in low volumes of oil or water mixtures, or
• in ultra^low volumes of a few ounces per acre of
undiluted formulation concentrate.
Timing of the application is critical to insure that:
• the entire hatch has emerged or will be exposed
in later sprays, and
• damage has not progressed past a harmful point.
BARK BEETLES include:
• the southern pine beetle,
• the western pine beetle, and
• the European elm bark beetle.
Bark beetles normally kill some trees each year.
In epidemic years, they kill large numbers in some
regions. Their effects are most severe in unthrifty
stands and under adverse weather conditions.
Mature insects enter the tree and lay eggs in chan-
nels etched between the bark and wood of conifers
and certain hardwoods. The larvae feed on cambium
tissue. Their tunnels girdle a substantial portion of
the tree. As the tree dies, adults emerge and fly to
another tree. Trees may also be killed by the fungi
introduced by some beetles.
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Several hatches of bark beetle may occur each year,
depending on species and region. Since adults are
exposed for only a short time, beetles are seldom
a good target for insecticides.
If the pest is recognized early, organic arsenical
herbicides sometimes can be applied to the host tree
by injection, killing the insects as the tree dies.
Infested trees are sometimes felled and chemically
treated. Insecticides are seldom used to control out-
breaks except in recreational sites, seed orchards,
Christmas tree plantations, or other high-value spe-
cial-use areas.
SUCKING INSECTS include:
• the balsam woolly aphid, and
• the beech scale.
Sucking insects feed on plant fluids below the sur-
faces of bark and leaves. Mass attacks reduce vigor
and kill shoots and leaves. Entire trees or stands
may be killed. Sucking insects cause scaly, mealy, or
powdery masses on trunks, twigs, and lower surfaces
of leaves.
Contact insecticides must be used as sprays. Cov-
erage is seldom complete, especially for insects on
lower leaf surfaces. Systemic insecticides within the
tree have better control potential.
SHOOT BORERS include both moths and weevils.
Examples are:
• the pine tip moth, and
• the white pine weevil.
Eggs are laid on both terminal and lateral shoots.
Developing larvae bore down the pith, killing the
shoot. Recognition is by dead shoots and presence
of larvae in central channels. Borers seldom kill
trees, but they slow tree growth and cause malformed
seedlings.
Since some species of shoot borer have several
hatches each season, use systemic insecticides.
WOOD BORERS include:
• oak borers, and
• turpentine borers.
Wood borers channel in the tree bole and lower
the quality of the wood. Secondary damage is caused
by fungi that produce stains and mar the appearances
and utility of products. Borers leave holes in the
bark that frequently exude sap. There is no eco-
nomical control by insecticides, except for protec-
tion of cut timber.
Insecticides
Few insecticides can be used for broadcast appli-
cations in forests. Forest insecticides are used
mainly to combat widespread epidemics such as
gypsy moth and spruce budwonn, in regional con-
trol programs, and to spot treat individual plots in
nurseries, seed orchards, and Christmas tree planta-
tions.
Like herbicides, insecticides are not highly mobile
in soil. Keep insecticides away from open water by
leaving adequate buffer strips along streams and im-
poundments when applying by air.
Buffer Zone between
/ ^—(Spray and Stream
Keep Pesticides Away
from Open Water
DISEASES
In terms of losses to future forest production, the
rusts, root rots, and dwarf misteltoes are the most
important diseases.
Fungicides are not available for use in forests. Dis-
eases cause heavy losses in forest nurseries. Some
soil fumigants and fungicide sprays can be used in
nurseries. Nursery diseases can be separated into
these types:
• root and soilborne diseases, controlled by fumi-
gation,
• stem and branch diseases, and foliage diseases,
may be prevented with fungicide sprays.
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Many nurseries fumigate to control weeds, and
disease control is a secondary benefit. Where major
disease problems are known to exist, fumigation can
be used specifically for disease control. Fumigants
are nonselective.
VERTEBRATES
Animals damage trees at all stages in the develop-
ment of the forest.
• Seed-eating birds and mammals can be an impor-
tant limiting factor in natural forest regeneration.
• Browsing animals like deer and rabbits can de-
form or kill seedlings.
• Mice and mountain beaver can kill seedlings by
completely debarking them.
• Birds and rodents that feed on buds can seriously
deform trees.
• Pocket gophers, wild hogs, and mice can destroy
root systems of saplings, and occasionally larger
trees.
• Bears, porcupines, mice, wood rats, and squirrels
can kill larger trees by girdling.
• Beaver, besides felling trees, cause extensive tim-
ber losses from water impoundments.
L Sharp
Sharp 45° Cut
Top Dies
Tattered Bark
on Girdled Sapling
from Antlers
Browsed Off
Stem Blunt
Bears Strip Bark in Spring
and Scrape Fresh Sapwood
Dying Top
Porcupines feed on Bark,
Girdling, and Causing Top to Die Back
planting stock large enough to be beyond the vul-
nerable stage.
• Physical control includes fencing large tracts, in-
stalling protectors around individual trees, and
shooting or trapping.
• Chemical control includes the use of repellents
and baits. Many of the baits have low concentra-
tions of active ingredients (less than 2 percent)
because of their extreme hazard to all warm-
blooded animals.
Because of the reproductive potential and move-
ments of pest animals, baited areas are soon re-
stocked with target animals, making this method
ineffective for long-term control.
PESTICIDE LABELING
Forest lands are considered to be cropland when a
stand of commercial trees is present. This means
that "noncropland uses" listed on a pesticide label
may not apply to forests. Pesticides used in forests,
seed orchards, Christmas tree plantations, or nurser-
ies must bear directions for use on the specific crop
and pest species.
Some forestry uses are included on labels princi-
pally devoted to other uses. For example, pesticides
may be applied to Christmas trees, seed orchards, or
nurseries if the label gives directions for use:
• on ornamentals or shade trees, including conifers,
and
• for the pest you need to control.
Herbicides registered for other crops, range, or
non-crop lands may be used before crop trees are
planted. Some pesticides registered for use in for-.
estry may be tank mixed. In mixtures of two or more
products, the rate of each component may not ex-
ceed the rate prescribed on its label. Check labels
or recognized authority for details.
APPLICATION
Control of vertebrates usually is not feasible ex-
cept in intensively managed forests or in nurseries.
• Cultural methods include the use of tree species
on which the pest will not feed, and the use of
Aircraft are used for most forest pesticides appli-
cations. Other techniques include the use of:
• air blast sprayers—Air blast sprayers are used
most often for applying herbicides to brush under
conifer stands, or for selective brush control in
regenerating stands. In these cases, the standing
trees restrict air movement. This provides some
drift control.
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When using an air blast sprayer in forests:
Work on a calm day (less than 5 mph wind).
Apply herbicides only in timber production areas.
Follow local regulations regarding distance from
crops.
Use operating pressure less than 20 psi.
Use the largest practical nozzle openings.
Do not spray under stands of sensitive desirable
trees.
Do not spray near recreation areas.
tree injectors—Tree injectors are used to control
Injectors Apply Herbicides in Continuous
Frills or Space Cuts at the Base of the
Tree or at Waist Height
Basal Tree Injection
with Tree Injector
Spaced Cuts
Hatchet Injector
Used at Waist Level
Frill Cut
woody species that have passed the "brush" stage.
A tree injector makes a wound through tree bark
and places herbicide in the wound. It may be a
pipe with a chisel-like bit on the lower end, or
a hatchet with built-in calibrated pump. Chisel
types are directed at the base of the tree. Hatchet
types are used at any convenient level. Injections
are usually spaced 1 to 4 inches apart, depending
on species and chemical.
Herbicides used in injectors should be water-soluble
salts. They are usually used full-strength but can be
used diluted in unmetered injectors. Esters are less
effective.
• directed sprayers—Some herbicides that control
weeds can also damage trees. Hand sprayers
equipped with shields or with directional nozzles
can prevent damage to seedlings. Such equipment
also can be mounted on tree planting machines
so that weeds can be treated while seedlings are
being planted if label requirements are met.
ENVIRONMENTAL
HAZARDS
The most serious adverse effects of misuse of forest
pesticides are:
• Damage to desirable trees.
• Injury to desirable soil organisms.
• Elimination of desirable predator and pollinator
insects.
• Unwanted changes in wildlife habitat.
• Drift damage to adjacent crops.
• Direct poisoning of nontarget birds and mammals.
• Injury to fish from application to open water.
• Soil erosion from prolonged devegetation by re-
peated use of residual herbicides.
Some adverse effects are likely even with correct
use practices. Pest control decisions must minimize
the adverse effects and weigh them against the
benefits.
Every part of a forest changes somewhat when
another part is removed. Since pesticides act by re-
moving living things, the entire forest responds when
a pesticide is used. Although the target could be
the only organism affected directly, other organisms
may be affected indirectly if they depend on the
one(s) removed.
GPO 906-282
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Removing any kind of plants, for example, helps
the ones that remain to grow better, whether they
are wanted or unwanted.
Weigh the environmental consequences of pes-
ticide used against those of nonuse. The adverse
effects of not using a pesticide may last for many
decades in a forest. These effects may include:
• continuing weed problems which may keep de-
sirable trees from growing,
• insect epidemics which may totally destroy the
forest or change the species composition,
loss of seedlings in nurseries, and
an increase in the time needed for reforestation.
HUMAN HAZARDS
Pesticides used in forests seldom come in con-
tact with humans at exposure rates high enough to
cause injury. The risk is greatest for applicators,
ground personnel, flagmen, or forest workers. Ob-
serve all necessary safety precautions during and
after pesticide application.
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