STICIDES CORRECTLY
A GUIDE FOR COMMERCIAL APPLICATORS
AGRICULTURAL
PEST CONTROL--
PLANT
IRONMENTAL PROTECTION AGENCY
OFFICE OF PESTICIDE PROGRAMS
WASHINGTON, D.C. 20460
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CONTENTS
Page
Acknowledgments 1
Preface 1
Introduction 2
Major Crops 2
Feed Grains and Small Grains 2
Hay and Pasture 3
Fruits and Nuts 3
Vegetables 4
Specialty Crops 4
Pests 4
Insects and Mites 5
Thrips 5
Grasshoppers and Crickets 6
True Bugs 6
Aphids and Psyllids 6
Leafhoppers, Spittlebugs (Froghoppers) and Treehoppers .... 7
Scales and Mealybugs 7
Whiteflies 8
Moths and Butterflies 8
Beetles 10
Flies, Gnats, and Midges 13
Sawflies 13
Mites 13
Plant Disease Agents 14
Fungi 14
Leaf Diseases 14
Wilts, Root Rots, and Crown Rots 15
Stem Cankers 15
Fruit Rots 16
Seed and Seedling Diseases 16
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Page
Bacteria 16
Bacterial Wilts 16
Bacterial Blights, Leaf Spots, and Rots 16
Bacterial Galls and Overgrowth 17
Viruses and Mycoplasmas 17
Nematodes 17
Parasitic Seed Plants 18
Snails and Slugs 18
Weeds 18
Development Stages 19
Weed Classification 19
Grasses 20
Broadleaves 20
Factors Affecting Control 20
Determining the Weed Problem 21
Weed Control Methods 21
Vertebrate Pests 22
Pesticides 22
Insecticides 22
Miticides 22
Fungicides 23
Bactericides 23
Controlling Viruses and Mycoplasmas • 23
Nematicides 23
Controlling Parasitic Seed Plants 23
Molluscicides 23
Herbicides 24
Controlling Vertebrate Pests 26
Environmental Protection 27
Soil and Water 27
Drift ' 27
Reentry and Preharvest Intervals 28
Phytotoxicity 28
Community Problems 29
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ACKNOWLEDGMENTS
This guide has been developed by the Program
Support Branch, Operations Division, Office of Pes-
ticide Programs, Environmental Protection Agency.
Much of the information was drawn from materials
published by the Cooperative Extension Services in
several States; the U.S. Department of Agriculture;
and other sources. The Agency extends its apprecia-
tion to these sources and also to the many persons
throughout the country who reviewed the manual at
various stages and whose valuable comments con-
tributed greatly to its preparation.
PREFACE
Federal regulations establish general and specific
standards that you must meet before you can legally
use certain pesticides. Your State will provide mate-
rial which you may study to help you meet the
general standards. This guide contains basic informa-
tion to help you meet the specific standards for ap-
plicators who are engaged in agricultural plant 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 mate-
rials you should study.
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INTRODUCTION
Pesticides are a valuable tool for profitably pro-
ducing a high-yield, market-acceptable crop, but they
should be used only when and where they are needed.
Usually pesticides should be used only when pest
numbers and/or the pest problem has reached the
economic threshold and other pest management
methods do not provide effective control. In some
cases, preventive use is a necessary, cost-effective way
to protect crops. Protectants should be used only
when knowledge of the pest indicates it is necessary.
You should be familiar with alternatives to the use
of pesticides and inform your customers about them.
Be sure they know the possible consequences of both
pesticide use and the use of alternative control meth-
ods.
Sometimes a producer asks you to apply a specific
pesticide on a crop. At other times you are asked to
both diagnose a pest problem and to provide control.
Accurate detection, identification, or diagnosis is a
science. Experience is important. This manual is not
intended to make anyone an expert in identifying
pests on crops or in selecting the proper control
technique. However, you should be able to identify
the more common pests that attack agricultural
crops. When you find a pest or pest problem you
cannot identify, ask an expert to help you.
Integrated Control
This manual discusses some of the general produc-
tion practices that may increase or lessen pesticide
problems. You will be a better applicator if you un-
derstand these basic principles.
You as an applicator should:
• understand crop production and cropping
practices,
• be able to identify common pests and signs
and/or symptoms of the damage they cause,
• have basic knowledge of the chemical charac-
teristics and the mode of action of pesticides,
• understand application techniques and equip-
ment use,
• recognize pesticides' potential for injury to
people, pets, livestock, and the environment,
and
• know and follow the safety practices essential
for protecting yourself and your employees,
the producer and his employees, the con-
sumer, and the environment.
MAJOR CROPS
Feed Groins end Small Groins
Crop Characteristics
These widely grown crops are summer or winter
annual grasses. In the past, seedbed preparation us-
ually included complete removal or incorporation of
the previous year's crop residue. This practice con-
tributes to wind and water erosion of soil particles
and the attached pesticides. No-till seeding is becom-
ing more common. It minimizes erosion and may
simplify weed control, but its impact on disease,
rodent, and insect control is not known.
These crops have a relatively low unit value. As a
result, per acre pest control costs must be kept low.
Resistance to several common diseases and insect
pests is good in some of the more popular crop varie-
ties. Certain cultural control practices may reduce
the need for pesticides. These include:
• no-till seeding,
• moldboard plowing,
• cultivation,
• crop rotation,
• planting date and harvest date timing, and
• special harvest and storage methods.
These methods may be used alone or in combination.
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Many producers use pesticides preventively to con-
trol some soil-infesting insects such as wireworms,
plant disease agents such as nematodes, and weeds
such as pigweed and foxtail.
Machines are widely used in the production and
harvest of these crops. This lessens worker exposure
to pesticide residues. However, these crops are used
as food or feed, so be sure to inform your customer
of the limitations on the time between pesticide ap-
plication and harvest, slaughter, or grazing.
Equipment
Many types of low-pressure field sprayers are used,
ranging in capacity from 50 gallons to more than
1,000 gallons. They can do many highly specialized
jobs.
Low Pressure Field Sprayer
Granular Applicator
Dry formulation application equipment also comes
in a wide variety of sizes and capabilities.
Aircraft can be specially adapted for the different
applications of pesticides to these crops.
Hay and Pasture
Crop Characteristics
These widely grown crops include:
• intensively cultivated alfalfa, clover, and
grasses introduced in most parts of the coun-
try, and
• native grasses and broadleaved plants grown
with a minimum of cultivation.
Resistant varieties, harvest timing, and other non-
chemical control practices such as burning are espe-
cially useful in pest control in hay crops. Hay
producers often use fall seeding, or plant with spring-
seeded small grains as a nurse crop to control weeds.
Without insect- and disease-resistance, alfalfa could
not be grown over much of its present range in the
United States.
Since all hay and pasture crops are used for live-
stock feed, it is essential to obey time limitations be-
tween pesticide application and grazing or harvest.
Especially restrictive residue tolerances apply to milk
and dairy products.
Equipment
Pesticides are usually applied to hay and pasture
crops with low-pressure boom sprayers or aircraft
equipped to apply both liquid and dry formulations.
Fruits and Nuts
Crop Characteristics
Small fruits include such crops as grapes, bram-
bles, blueberries, strawberries, and cranberries. Tree
fruits' include such crops as apples, peaches, pears,
citrus, cherries, and plums. Nuts include such crops
as walnuts, almonds, and pecans.
Highly sophisticated pest control practices are used
on fruits grown for human consumption. In some
situations, the crops are closely monitored for pests.
If pests are found, pesticides may be recommended.
The surface appearance of fruits grown for fresh
market has long been critical to the producer. To
produce blemish-free fruit, the producer sometimes
must use pesticides preventively on a schedule modi-
fied only to adapt for variable weather.
Many fruit crops must be harvested by hand labor.
Hand labor is also required to prune fruit trees and
to thin some crops selectively during the growing sea-
son. Pesticide labels specify time, intervals between
pesticide application and reentry or harvest. These
directions are critical and must be obeyed. The law
requires applicators to inform their customers and
employees of these intervals.
Two or more pesticides often are applied in com-
bination. Pesticides may also be combined with fer-
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tilizers. The applicator must pay strict attention to
their physical and chemical compatibility. The label-
ing on chemical products sometimes identifies prob-
lems of incompatibility. Follow label instructions
exactly.
Many of these crops are perennial and may remain
hi place for decades. Pesticides may persist on or-
chard or vineyard soil from repeated use. Local ex-
perts are aware of potential residue problems. They
can help you.
Equipment
Equipment most often used on these crops in-
cludes:
• air blast sprayers with fixed or movable
heads,
• high-pressure sprayers with fixed or movable
booms,
• dusters,
• hand-held booms, and
• aircraft.
High Pressure Field Sprayer
Air Blast Sprayer
or Mist Blower
Vegetables
Crop Characteristics
In general, these are intensively cultivated annual
plants, the fruits, stems, leaves, or roots of which are
used as human or livestock food. Vegetables, like
tree fruits, are expected by the consumer to have a
blemish-free appearance. Since the edible portions
of most of these crops are produced under an inten-
sive schedule of pesticide application, worker reentry
and pre-harvest intervals are critical to protect field
workers, harvesters, and consumers.
Resistant varieties and cultural control methods,
including selective planting and harvesting dates and
destruction or removal of cultivated crop residue, are
an important part of pest control on vegetables.
Equipment
Pesticide application equipment most often used
on vegetables includes:
fixed- and movable-head air blast sprayers,
high- and low-pressure boom sprayers,
dusters,
granular applicators, and
aircraft.
Specialty Crops
Crop Characteristics
Specialty crops include cotton, soybeans, tobacco,
sugar beets, sugar cane, and peanuts. Most are row
seeded and managed much the same as the feed
grams and small grains. Some of these crops, such
as cotton and soybeans, require extensive use of
pesticides for successful production. Other specialty
crops, such as sugar beets and sugar cane, can be
produced almost without the use of pesticides.
Equipment
Pesticide application equipment most often used
on these crops is low-pressure boom sprayers and
aircraft-mounted sprayers.
PESTS
The first step in solving any problem is to under-
stand what is causing it. So the first step in your job
is to recognize the pests you need to control.
We favor certain plants and animals that provide
us food and fiber. But we also provide good growing
conditions for other plants and animals that harm
them. These living things that compete with us for
food and fiber, or attack us directly, are pests. The
living plant or animal a pest depends on for survival
is called the host.
Pests can be put into five main groups:
• insects (plus mites, ticks, and spiders),
• plant disease agents,
• snails and slugs,
• weeds, and
• vertebrates.
Most applicators know most of the pests they see
on the job. But sometimes unfamiliar pests may ap-
pear. You can get identification aids, publications,
and pictures to help find out what they are. But the
best thing to do is to contact local experts. Ask the
Cooperative Extension Service or a competent con-
sultant to help you.
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Insects ond Mites
The large number of insects, mites, and related
animals can be divided into three categories accord-
ing to their importance to man:
• species which are of only minor importance
—About 99 percent of all species are in this
category. They simply "take up space" and
supply food for birds, fish, mammals, reptiles,
amphibians, and other insects. Some have es-
thetic value.
• beneficial insects and mites—In this small but
important group are the predators and para-
sites that feed on destructive insects, mites,
and weeds. Examples are lady beetles, some
bugs, ground beetles, tachinid flies, many tiny
parasitic wasps, and predaceous mites. Also
in this category are the pollinating insects,
such as bumblebees and honeybees, some
moths, butterflies, and beetles. Without pol-
linators, many fruits, vegetables, and forage
crops could not be produced.
• destructive insects and mites—Although this
is the category which usually comes to mind
when insects are mentioned, it includes the
smallest number of species. In this category
are certain species of thrips, grasshoppers,
true bugs, aphids, leafhoppers, scales, white-
flies, moths, beetles, flies, sawflies, and mites
that feed upon food and fiber crops.
Insect Damage
Scale Insects
Wings and Mouthparts
Two Wings
Four Wings
Wings
Chewing
(Grasshopper)
Sucking
(Mosquito)
Mouthparts
Thrips
Thrips are thin, tiny insects with four narrow
fringed wings in the adult stage. During their life
cycle they change gradually in size and slightly in
form from egg through several wingless nymphal
stages to winged adults. Several generations are pro-
duced each year. Both nymphs and adults have tube-
like mouthparts and feed on plants by rasping the
surface tissue of tender buds, flowers, fruits, and
leaves, then sucking the plant juices (sap).
Injury to plants is characterized by discolored and
distorted flowers and buds or grey speckled areas on
fruit and foliage. Thrips may attack every type of
agricultural crop. Common species are:
• bean thrips on legumes,
• citrus thrips,
• flower thrips on grasses, vegetables, and
fruits,
• onion thrips on onion and other vegetables,
and
• tobacco thrips.
Root Feeding
White Grub
GLADIOLUS THRIPS
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Grasshoppers and Crickets
Grasshoppers and crickets are large-bodied insects
with hind legs adapted for jumping. During their life
cycle they change gradually in size and slightly in
form from egg through several wingless nymphal
stages to winged or wingless adults. Usually there is
only one generation produced each year. The eggs
overwinter in the soil. Both nymphs and adults have
toothed (chewing) mouthparts which they use to cut
small sections from leaves and stems of plants.
Injury is characterized by ragged holes in foliage
and stems. In large numbers, grasshoppers and
crickets may consume all of a plant or plants in an
area. Grasshoppers and crickets may attack every
type of agricultural crop. Common species include
Mormon cricket, mole cricket, field cricket, migra-
tory grasshopper, and two-striped grasshopper.
True Bugs
Pest species of true bugs in the adult form have
two pairs of wings. The first pair is leathery at the
base and nearly transparent at the tip. At rest, the
wings lie flat across the thorax and abdomen with
the transparent tips overlapping. During their life
cycle true bugs change gradually in size and slightly
in form from egg through several wingless nymphal
stages to winged adults. One to several generations
are produced each year. Both nymphs and adults
have tubelike (piercing-sucking) mouthparts and feed
on plants by puncturing seeds, stems, foliage, flowers,
or fruit and sucking the sap. Some true bugs may
inject a toxin into the plant which causes further
damage.
Injury to plants is characterized by mottled grey
spots on foliage, deformed buds or fruit (catfacing),
loss of vitality, wilting, and—in severe infestations
—death. Some plant disease agents are carried by
these insects. True bugs may attack many kinds of
fruit, vegetable and grain crops.
Common species include:
• chinch bug—corn and grain crops,
• harlequin bug—crucifers,
• stinkbug—vegetable crops,
• squash .bug—vine crops, and
• tarnished plant bug—vegetables and fruits.
HARLEQUIN BUG
ADULT AND NYMPH
Aphids and Psyllids
Aphids and psyllids, called plant lice and jumping
plant lice, are small, soft-bodied insects usually less
than 1A inch long. In the adult form they usually have
transparent wings which are held vertically over the
body when at rest. During their life cycle they change
gradually in size and slightly in form from egg
through several wingless nymphal stages to winged
and wingless adult stages. Many generations are
produced each year. Both nymphs and adults have
tubelike mouthparts and feed on plants by puncturing
tender plant parts and sucking the sap.
Injury to the plant is characterized by loss of plant
vigor, stunted and deformed buds and flowers, or
curled and puckered foliage. Plant lice and jumping
plant lice secrete honeydew which attracts ants and
upon which unsightly sooty mold grows. Aphids also
transmit some viral, bacterial, and other plant disease
agents.
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Common aphid species include:
• grape phylloxera,
• the greenbug—grains,
• green peach aphid—tobacco, peaches, pota-
toes, spinach,
• melon aphid—melons, cotton, fruits, vegeta-
bles,
• potato aphid—potato, tomato, and
• apple aphids.
Common psyllids are:
• potato psyllid—potato and tomato, and
• pear psyllid.
Leafhoppers, Spittlebugs
(Froghoppers) and Treehoppers
Leafhoppers, spittlebugs and treehoppers are small
(usually not over Vi inch long), soft-bodied insects
with hind legs adapted for jumping. The adults have
two pairs of transparent wings held in a roofiike posi-
tion when at rest. During the life cycle they change
gradually in size and slightly in form from egg
through several wingless nymphal stages to winged
adults. Many generations are produced each year.
Both nymphs and adults have tubelike mouthparts
and feed on plants by piercing leaves and stems and
sucking the sap.
Injury to the plant is characterized by mottled, dis-
colored, and curled leaves, and stunted or wilted
stems. 'Spittlebug nymphs are easily identified by the
foamy spittle mass which surrounds and protects
them during feeding. All these hoppers may transmit
plant disease agents, especially those agents causing
yellows, stunt, and curly top.
SPITTLEBUG
Some leafhoppers secrete honeydew, which at-
tracts ants and supports the growth of unsightly sooty
mold. Other leafhoppers inject a toxin into the plant
during feeding, causing a browning of leaves called
"hopper burn." Treehoppers damage plants by slit-
ting the bark or stem to deposit their eggs.
Common species include:
• buffalo treehopper—tree fruits,
• alfalfa hopper,
• meadow spittlebug—strawberries, legumes,
forage crops,
• aster leafhopper—lettuce, celery, other vege-
tables, grains,
• potato leafhopper—potato, legumes, apples.
Scales and Mealybugs
Scales and mealybugs are small, oval insects which
resemble reptile scales or tiny bits of wax or wool.
They may be mistaken for parts of the plant itself.
Mealybugs are soft-bodied scales covered with white
powder and often with cottony fibers. Scales may be
soft-bodied or armored with a crusty shell. Adult
females are wingless and usually stationary, but adult
males resemble tiny flies with a single pair of wings.
During the life cycle they change gradually in size
and slightly in form from egg through several wing-
less nymphal stages and a pupalike stage to adults.
Many generations are produced each year. Adult
males do not have mouthparts and do not feed.
Nymphs and adult females have very long, slender,
tubelike mouthparts. They feed on plants by sucking
sap from plant stems, leaves, and branches.
San Jose Scale: (A) Adult Female Scale; (B) Male Scale;
(C) Young Scales; (D) Nymph (Crawler)
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Injury is characterized by stunted, yellowed,
wilted, and often deformed growth. Scales and
mealybugs also transmit some plant disease agents
and secrete large amounts of honeydew, which at-
tracts ants and supports unsightly sooty mold. Large
quantities of sooty mold on crops usually indicates
an aphid or scale infestation. Mealybugs and scales
may attack many kinds of fruit, vegetable, and espe-
cially greenhouse crops.
Common species include:
• citrus mealybug—citrus fruits, greenhouse
crops,
• Mexican mealybug—cotton, greenhouse
crops,
• red scales—citrus fruits, other tree fruits,
• San Jose scale—tree fruits,
• brown soft scale—tree fruits, ornamentals,
• black scale—citrus.
MEALYBUGS
Whiteflies
Whiteflies are tiny, soft-bodied insects covered
with white, waxy powder. The adults have two pairs
of broad wings and resemble tiny white moths. Dur-
ing the life cycle they change gradually in size and
form from egg through several wingless, scalelike
nymphal stages and a pupalike stage to winged
adults. Several generations are produced each year.
Both nymphs and adults have long, slender tube-
like mouthparts and feed on plants by sucking plant
juices. They also secrete honeydew. Whiteflies attack
greenhouse crops in the North and a wide variety of
outdoor agricultural crops in the South.
Common species include:
• citrus whitefly,
• greenhouse whitefly.
Moths and Butterflies
Moth and butterfly adults have a dense covering
of tiny scales and hairs on their wings and bodies
which gives the body a soft, fuzzy appearance. The
adults have two pairs of fairly large wings which
are usually brightly colored in butterfly species and
dull, neutral-colored in moth species.
During their life cycle they change completely in
size and form from egg to wingless wormlike larva
to immobile pupa to winged adult. One to several
generations are produced each year. Adults have
long tubelike mouthparts and feed on plants by
sucking or siphoning plant nectar. They do not harm
plants; however, their presence around crops or in
pheromone or light traps may indicate potential pest
problems. The adults lay eggs that hatch into poten-
tially harmful larvae.
Four Stage Life Cycle
Larva
Adult
The larvae, called caterpillars, are long, fleshy,
and soft-bodied with three or more pairs of legs.
They have well-developed, toothed jaws and feed on
plants by cutting and tearing leaves, stems, and other
plant parts. Different kinds of caterpillars feed on
all parts of herbaceous and woody plants including
roots, stems, foliage, buds, flowers, fruits, and seed.
Injury to plants is characterized by tears, tunnels,
and ragged holes in the affected plant part.
Budworms
Budworms are medium-sized caterpillars that feed
in or on opening buds. Common species include:
• pecan budworm,
• tobacco budworm—tobacco, cotton.
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Several other destructive caterpillars, such as the
corn earworm, fall armyworm, and European corn
borer, may feed on or in developing buds. Although
these are not true budworms, the injury they cause
is often called "budworm injury."
Arm/worms
Armyworms occur in large numbers, and may des-
troy every plant in their path. They will eat any part
of a herbaceous plant, especially stems, leaves, and
fruits. Common species are the fall armyworm and
true armyworm, both of which attack grasses and
cereal grains.
ARMYWORM: (1) EGG MASS;
(4) LARVA; (6) ADULT
Cutworms
Cutworms usually feed near the soil surface by
cutting through succulent stems of young plants.
Some cutworms can climb up stems and trunks to
feed on buds, leaves, and fruit and are called climb-
ing cutworms. Different species of cutworms may
attack many kinds of agricultural crops. Black cut-
worm is a common surface-feeding caterpillar on
many vegetables and grain crops. Variegated cut-
worm will feed on the soil surface and also act as
a climbing cutworm attacking herbaceous and
woody tissues on fruits and vegetables.
Borers
Borers are caterpillars which bore into and feed
on stems, woody tissues, and roots. Some other insect
larvae are also borers. They may attack young fruit
and nut trees and row crops. Common species in-
clude :
common stalk borer-
other stem plants,
European corn borer
potatoes,
peach tree borer—stone fruits,
potato tuberworm—Irish potatoes,
citrus borer.
:orn, potato, tomato,
:orn, beans, peppers,
DURRA STALK BORER: ADULT
(LEFT); PUPA (TOP RIGHT);
LARVA (BOTTOM RIGHT)
Fruitworms
Fruitworms and some other caterpillars bore into
and feed on the fruits of plants. The caterpillar of
one moth species may be called the corn earworm,
tomato fruitworm, or cotton bollworm, depending on
where it is feeding. These caterpillars also bore in
and feed on beans, cabbage, peanuts, grasses, grains,
and other crop plants. Other common species in-
clude:
• oriental fruit moth—tree fruits,
• codling moth—tree fruits,
• green fruitworm—tree fruits,
• pickleworm—crucifers,
• tomato pinworm—tomato, potato.
Foliage Feeders
Foliage feeders are by far the largest group of cat-
erpillars. They may feed on the leaves of every type
of agricultural crop.
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Webworms and Tent Caterpillars are caterpillars
that build a nest or "tent" of silk. Webworms feed
entirely within the web, which is built around the foli-
age and is extended as the enclosed leaves are con-
sumed. Tent caterpillars build tentlike nests in the
crotch of a tree and leave the nest to feed on the
foliage. Common species include:
• eastern tent caterpillar—apples,
• fall webworm—tree fruits, nuts,
• garden webworm—grass, cereal grains, vege-
tables.
Hornworms are very large, foliage-feeding cater-
pillars with a hornlike projection at the end of the
body. Two common species are tobacco and tomato
hornworms, both of which attack tobacco, tomatoes,
potatoes, and peppers.
Loopers, Cankerworms, and Spanworms are foli-
age-feeding caterpillars which move by drawing the
abdomen to thorax to form a loop and then extend-
ing again. They often drop down and dangle on a
long silken thread when disturbed. Common species
include:
• fall and spring cankerworms—tree fruits,
nuts,
• cabbage looper—cole crops, lettuce, other
vegetables,
• currant spanworm—currants, gooseberries.
CABBAGE LOOPER MOTH
Other Foliage-Feeding Caterpillars include such
species as:
• redhumped caterpillar—fruits, nuts,
• imported cabbageworm—cole crops,
• parsley worm—many vegetables.
In addition, there are several pest species with
common names that describe how they attack and in-
jure leaves. For example:
• leaf crumplers crumple new leaves together
with a silken thread and feed on new leaves
and buds of some fruit crops,
• leaffolders feed inside folded leaves of some
small fruit crops,
• leafminers mine in and feed between the sur-
faces of leaves of many fruit and vegetable
crops,
RED-BANDED LEAF ROLLER
leajrollers feed within the rolled up leaves
of many fruit and vegetable crops,
leaf skeletonizers skeletonize leaves of some
fruits, vegetables, and specialty crops by eat-
ing everything but the veins and outer layer.
leaftiers tie together and feed on the leaves
of some small fruit crops.
Beetles
Beetles are the largest group of insects. They make
up about 40 percent of known insect species. Adults
are easily identified by the pair of hardened, opaque
wings that meet in a straight line down the thorax
and abdomen and the folded second pair of trans-
parent wings.
During their life cycle, beetles change completely
in size and form from egg to wingless, wormlike larva
to immobile pupa to winged adult. One generation
may be produced every 2 to 5 years or several gen-
erations may be produced each year. Both the larvae,
some of which are called grubs, and the adults have
distinct, hard, capsulelike heads with toothed jaws.
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They feed on plants by biting and tearing the food.
Many adult beetles feed on plant foliage or fleshy
stems. Larvae may feed on roots, stems, foliage,
buds, seeds, fruits, or woody tissue. Injury to the
plant is characterized by tears and ragged holes in
the affected plant part. In some species both the adult
and the larva are pests. In other species only one
stage causes damage.
JUNE I JULY AUG. SEPT.
BEETLES FEED ON FOLIAGE AND FRUIT
LIFE CYCLE OF THE JAPANESE BEETLE
Rootfeeding Larvae
These include wireworms, rootworms, and other
beetles. The root-eating larvae feed on and burrow
in roots and underground stems. Wireworms also at-
tack seeds.
Wireworms are shiny, slender, hard-bodied, wire-
like, yellow to dark brown larvae. They may be
found at all times of the year in almost any soil. The
adults, which are not important pests, are called click
beetles because they right themselves with a sharp
click if held or disturbed. Many species are pests.
They may attack all agricultural crops, especially
corn, grasses, tobacco, cotton, and root vegetable
crops.
Rootworms are small, curved, white, soft-bodied,
wormlike grubs. The adult beetles are leaf-feeders
and may attack the foliage of entirely different plant
species than the crops injured by the grubs. For ex-
ample, the clover rootworm, which feeds on pasture,
hay, and grain crops, becomes the grape colapsis
beetle, which feeds on small fruit and vegetable
crops. The southern corn rootworm, which feeds on
corn and beans, becomes the spotted cucumber
beetle, which feeds on legumes and cucurbits. Other
common species include:
• northern corn rootworm,
• strawberry rootworm—small fruits, tree
fruits, nuts.
COMMON WIREWORM: (A) ADULT; (B) LARVA;
(C) LAST SEGMENTS OF LARVA; (D) PUPA
SOUTHERN CORN ROOTWORM
LARVA (LEFT); ADULT (CENTER);
DAMAGE CAUSED (RIGHT)
Other beetles with rootnfeeding larvae also include
species in which the adults feed on different hosts
than the grubs do. Japanese beetle adults feed on all
fruits and on corn and soybean foliage, but the grubs
feed on grass roots. May and June beetle adults feed
on foliage of ornamental trees and shrubs, but the
grubs feed on roots of hay, pasture, grain, and vege-
table crops. The striped cucumber beetle adults feed
on foliage of cucurbits, legumes, and corn, but the
larvae feed only on cucurbit roots.
Stem-Eating Larvae or Borers
Stem-eating larvae tunnel in and feed on stems
and woody tissues. The adult beetles often cause
11
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damage by carving holes in stems and bark to insert
eggs, as well as by eating foliage. Borers are partic-
ularly destructive to newly set or weakened fruit and
nut trees and young herbaceous crops. Common
species are:
• potato stalk borer—potatoes, tomatoes,
• cane borers—small fruits,
• shot hole borer—fruits, nuts,
• round headed and flat headed borers—tree
fruits, nuts.
Fruit- and Foliage-Eating Larvae
This group includes snout beetles and other
beetles. In many species of beetles, both larvae and
adults feed on foliage and fruit.
Snout Beetles (Curculios, Billbugs, and Weevils)—
The head of the adult snout beetle is shaped in a
long, curved snout with toothed mouthparts at the
tip. The larvae are white, thick, soft-bodied, legless
grubs. The grubs commonly feed within the plant;
the adults feed from the outside. The snout of the
adult beetle is used to cut a hole in stems, nuts, buds,
fruits, or vegetables into which the eggs are depos-
ited. The hatching grubs eat and bore their way fur-
ther into or along the stem or fruit.
Snout beetles which feed on hay, pasture, grain,
and soybean crops are commonly called billbugs.
Common species are:
• southern corn billbug—corn, rice, peanuts,
• maize billbug.
BILLBUG
Snout beetles which feed on fruits and nuts may
be called curculios. Common species include:
• apple curculios—tree fruits,
• plum curculios—stone fruits, apples.
Snout beetles which attack vegetables and specialty
and ornamental crops are often called weevils. Com-
mon species are:
• alfalfa weevil,
• cotton boll weevil,
• bean weevil—bean seeds,
• pea weevil—pea seeds.
ALFALFA WEEVIL
Other Fruit- and Foliage-Feeding Larvae are not
snout beetles. The larvae of these beetles usually feed
on the outside of the plant along with the adult
beetles. The adults usually deposit the eggs on the
leaf or stem surface rather than into the plant. Com-
mon species include:
• flea beetles—vegetables,
• Colorado potato beetle—potatoes, tomatoes,
• Mexican bean beetle.
FLEA BEETLE
Non-Plant-Eating Larvae
The larvae of some pest beetles do not eat plants
but prey on insects, mites, and other animals. The
adults are called blister beetles because they contain
a chemical which may blister human skin. The adult
blister beetles chew on foliage and fruits and may be
very destructive to agricultural crops. The larvae of
blister beetles are parasitic on grasshopper eggs.
Numerous species feed on vegetables, flowers, young
trees, and vines.
MARGINED BLISTER BEETLE
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Flies, Gnats, and Midges
Sawflies
Flies, gnats, and midges are the major types of
insects with only one pair of wings. During their life
cycle they change completely from egg to wingless,
wormlike larva to immobile pupa to winged adult.
The pupal stage of most pest flies is buried in the
soil and adults emerge from the soil to feed. Several
generations are produced each year.
Adults have piercing-sucking or sponging mouth-
parts. Many adults feed upon nectar and pollen of
flowers. Others feed upon liquid organic matter from
decomposing plant or animal bodies. Others dissolve
solid substances in their saliva and sponge up the
solution. A number of adults suck juices from other
insects and animals, including man.
FEMALE
Sawflies belong to the group of insects that in-
cludes bees, wasps, and ants. Sawfly larvae resemble
caterpillars. The adults have two pair of transparent
wings hooked together. During their life cycle they
change completely from egg to wingless wormlike
larva to immobile pupa to winged adult. One to a
few generations are produced each year.
Larvae and adults have toothed jaws and feed on
plants by tearing soft stems and foliage. The adults
damage plants mainly by sawing into leaves to de-
posit eggs. The larvae are the most destructive stage.
They bore into and feed on stems and leaves, often
by burrowing between the surfaces of a leaf as leaf-
miners do.
Injury to plants is characterized by slits in leaves;
lumpy, wilted foliage; and stunted growth.
Common species include:
• stem sawflies—grasses, cereal grains,
• cherry fruit sawfly—tree fruits,
• imported currantworm—currants, gooseber-
ries.
HESSIAN FLY
WESTERN GRASS STEM
SAWFLY
The larvae, called maggots, are usually soft, thick,
white, and legless with a head which is not well de-
nned. Maggots have well-developed, parallel hooked
jaws. They feed on plants by burrowing in and feed-
ing on roots, stems, and fruit. The maggots are us-
ually the most destructive stage.
Injury to plants is characterized by wormy or de-
cayed seeds, stems, fruits, and roots; wilted foliage;
stunted growth; or death of the plant. These insects
may also transmit some plant disease agents, espe-
cially those causing soft rot.
Common species include:
• apple, cabbage, pepper, and onion maggots,
• seed corn maggot—vegetable seeds,
• melon fly—cucurbits,
• Hessian fly—wheat,
• sorghum midge—grasses, cereal grains,
• fruit flies.
Mites
Mites are minute, soft-bodied, wingless pests which
closely resemble insects but have eight legs. Nymphs
and adults have sucking mouthparts. They usually
are so tiny that they are discovered only after the
damage to the plant appears. The life cycle includes
both larval and nymphal stages. The larvae have
three pairs of legs; the nymphs and adults have four
pairs. Several generations are produced each year.
Foliage, buds, stems, and fruit of infested plants
may become red, bronze, rust, yellow, white, or
brown or may wither and fall off. Spider mites spin
light, delicate webs over buds and between leaves
where mites are feeding. Mites attack almost all types
of agricultural crops.
Common species include:
• spider mites—fruit trees, citrus, small fruits,
legumes, greenhouse crops,
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clover mite—grasses, cereal grains,
red mites—tree fruits, citrus, nuts.
MITE
Fungi
Fungi are plants that lack chlorophyll and cannot
make their own food. They get food by living on
other organisms. Most fungi reproduce by spores,
which function about the same way seeds do. Locat-
ing and recognizing the spores may be a key to iden-
tifying a fungus as the cause of a plant disease. Fungi
may attack crops both above and below the soil
surface. Fungal disease agents may be spread from
plant to plant and crop to crop by such things as
wind, rain, insects, birds, machinery, soil, and con-
taminated seed stock.
Plant Disease Agents
Both living organisms and nonliving agents often
cause diseases or other undesirable effects on plants.
• Living organisms include fungi, bacteria, vir-
uses and mycoplasmas, nematodes, and para-
sitic seed plants.
• Nonliving agents include unbalanced soil fer-
tility, toxic chemicals, air pollution, frost,
drought, sunburn, wind, and hail.
Disorders caused by nonliving agents often resemble
the symptoms of injury caused by living organisms.
For example, certain types of chemical injury can
look like some of the leafspots caused by fungi or
bacteria.
Symptoms and signs are the keys to identifying
plant disease. A symptom of a disease is the reaction
of the host plant to the living organism or to the
nonliving agent. Symptoms include such things as
spots on the leaves, wilting, and galls on the roots.
A sign is physical evidence of the presence of a dis-
ease agent. Signs include, for example, the visible
growth of fungi (mold) or fungal spores, or bacterial
ooze issuing from a wound.
Some living organisms cause entirely different
symptoms on different kinds of plants. Cedar apple
rust on cedar appears as gall-like swellings on twigs,
but on apple it appears as small, rustlike spots. Dis-
eases caused, by nematodes may have no visible
above-ground symptoms if soil moisture is adequate.
Root knot nematode injury on peanuts is an example.
A plant may be infected by two or more disease
agents at the same time.
Leaf Diseases
Although the fungi causing these diseases occur
primarily on leaves, some may also occur on stems,
roots, or fruits. Fungi that cause leaf diseases pro-
duce several types of symptoms. Other plant disease
agents may produce similar symptoms.
Leaf Spots—Leaf spots (other names—anthrac-
nose, scab, leaf blotch, shot hole) are usually def-
inite spots of varying sizes, shapes, and colors. Each
spot usually has a distinct margin, sometimes sur-
rounded by a yellow halo. Usually there is a fungal
growth such as tiny, black, pimplelike structures or a
moldy growth. It is often necessary to use a hand
lens to see these signs. If the spots are numerous or
close together, affected areas may join together to
form irregular areas,
often called "blotches".
Leaf spots are common on
fruits, vegetables, and some
hay and pasture crops.
FUNGI
(Smut)
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The common names of leaf spot diseases may be
general (peanut leaf spot), descriptive (zonate leaf
spot), or named after the fungus (Septoria leaf
spot).
Leaf Blights—Leaf blights look somewhat like leaf
spots but generally cause larger and more irregularly
shaped diseased areas. Blights are common on al-
most all food and feed crops. The common name
usually includes the word "blight" (southern leaf
blight, early blight).
Rusts—Rust fungi often produce "pustules,"
which look like leaf spots. Rust pustules are masses
of bright yellow, orange-red, reddish brown, or black
spores being pushed through the leaf surface. With
severe infections, the leaf withers and dies rapidly.
Some types of rust also occur on stems.
Rusts are most common on grains, pasture grasses,
and tree fruit crops. The common name usually in-
cludes the name of the crop affected and the word
"rust" (stem rust of grains and grasses, leaf and cane
rust of raspberry).
Powdery Mildew—Powdery mildew is a white to
light gray, powdery or dusty growth on leaves. It
may also occur on stems, fruits, and flowers. Affected
leaves usually turn yellow, wither, and die. Powdery
mildew is common on curcurbits, small grains, and
fruits.
Downy Mildew—Downy mildew is a light gray,
moldy growth on the underside of the leaf. It causes
a pale green to yellow area on the upper leaf sur-
face. Downy mildew fungi are important disease
agents on some vegetables such as pepper, cabbage
and soybeans.
Symptoms of Diseases
Knot!
Wilts, Root Rots, and Crown Rots
These three distinct groups of fungal disease
agents are usually soilborne. The fungi can survive
for long periods of time in the soil. These organisms
produce similar general symptoms (wilting and death
of the plant). Close examination of a wilting plant
will nearly always allow you to determine if it is
caused by wilt, root rot, or a crown rot.
Wilts—Most wilt diseases are caused by fungi
(Fusarium and Verticillium), although bacteria may
produce similar symptoms. These parasites cause
wilts on a wide range of crops. Wilt disease agents
usually enter the plant through the roots. Some of
the roots may be black and rot in the early stages of
the disease. Extensive root rotting does not occur
until after the plant is dead. A light- to dark-brown
streaking can usually be seen in the stem of an in-
fected plant.
Crown Rots—These disease agents usually attack
the plant at or near the soil line. Affected plants are
generally unthrifty with leaves smaller or lighter
green than normal. Leaves usually turn yellow. In
advanced stages of disease, the plant wilts and dies.
The crown or base of the stem will be water-soaked,
discolored, or decayed. A moldy growth with var-
ious colored fruiting bodies often forms in the dis-
eased area. Crown rot can be important on some
vegetable crops. Common names may include the
words crown rot, collar rot, stem blight, stalk rot,
or southern blight.
Root Rots—Some plants may wilt and die rapidly;
others may be slow-growing, yellow, or stunted and
may not die for some time after the symptoms ap-
pear. Roots are generally shortened, soft, and light
brown to black. The outer portion of the root may
slough off, leaving a stringlike center core. Every
type of agricultural crop may be affected by root
rots.
Stem Cankers
Stem cankers occur as well-defined, discolored
areas on main stems or branches. These areas may
be irregular or oval; they may be sunken or swollen.
Some cankers crack open and expose the wood un-
derneath. The foliage on stems with cankers is us-
ually slow-growing, light green to yellow, and re-
duced in size. Infected stems often start growth later
in the spring. The tips of infected stems may die
back. Infected branches and plants may not die for
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several months or even years after the disease first
develops. Stem cankers are very important on tree
fruit and nut crops.
Fruit Rots
Fruit rots are caused by many different kinds of
fungi. All types of fruit are susceptible to rots. The
symptoms vary from a superficial fungal growth on
the external surface to a mushy, soft, watery rot. Rot
may occur while the fruit is on the plant or after
harvest. Some rots begin as a small spot sunken be-
low the surface, containing spores or other fruiting
bodies of the fungi. Some rots may cause a shriveling
or a "dry rotting" of the fruit. Many rot-causing
fungi occur only on one type of fruit; others may
occur on different fruits.
Seed and Seedling Diseases
Seedling diseases are caused by soilborne fungi.
They usually occur during the period from germina-
tion until shortly after emergence. If infection oc-
curs before emergence, the seedling may never
emerge. After emergence, seedling stems may be
attacked at or slightly below the soil line.
Symptoms include brown to reddish-brown or
black cankers at the soil line which may girdle the
stem. A second type of symptom is a soft, watery,
rotted spot at the soil line. Seedling and seed diseases
are most common in cool, wet soils. Any agricultural
crop grown from seeds or seedlings may be affected.
Among the common names for these fungal diseases
are damping-off and seed rot.
Bacteria
Bacteria are microscopic, one-celled organisms.
They usually reproduce by dividing in half. Bacterial
numbers can build up fast under ideal conditions
such as warm, humid weather. Bacterial disease
agents can be identified by the symptoms they pro-
duce in plants or by signs of the bacteria's presence.
Bacteria may attack any part of a-plant both above
and below the soil surface. Bacterial disease agents
are spread from plant to plant and crop to crop by
infected seed, man, insects, and other animal life
including birds, snails, slugs, and worms, and by con-
taminated rain, irrigation water, equipment, tools,
etc.
Bacterial Wilts
Bacteria which attack the water-conducting vessels
of plants generally cause the same plant disease
symptom—wilting. The water-conducting tissues
may become so filled with bacteria that water can
no longer be supplied to the foliage and the plant
wilts. Often if the stems of infected plants are cut, a
whitish bacterial ooze may form at the ends of the
water-conducting vessels. Often the stem of the in-
vaded plant is stained brown or black. Bacterial wilt
may affect many types of agricultural plants, espe-
cially cucumbers, tomatoes, and cabbage.
BACTERIAL WILT OF CUCUMBER
BACTERIA DEPOSITED WITH BEETLE FECES
SPREAD THROUGH VESSELS OF LEAF, VINE
AND TO OTHER VINES
BACTERIA OVERWINTER IN STRIPED
AND SPOTTED CUCUMBER BEETLES
WHICH HAVE FED ON INFECTED VINES
Bacterial Blights, Leaf Spots, and Rots
Bacteria may attack the soft or succulent plant tis-
sues and cause death of the affected areas. On leaves
the symptoms are very similar to leaf spot and blights
caused by fungal agents. Typically, the first symptom
on the leaves appears as water-soaked spots, which
finally turn to brown or "dead" areas. The rot of
many fleshy roots, stems, rhizomes, and fruits is a
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rapid, soft, wet, bacterial rot.
• Bacterial blights, leaf spots, and rots may be dis-
tinguished from similar fungal diseases by presence
or absence of spores (indicating fungus), or by the
host which is affected. Often a microscopic examina-
tion is needed. Common diseases in this category in-
clude fire blight of apple and pear, angular leaf spot
on cucurbits and tobacco, and soft rot of vegetables
such as potatoes and onion.
Bacterial Galls and Overgrowth
Bacteria may cause abnormal cell division in a
portion of a plant, causing tumors, galls, or witches-
brooms. Often the symptoms are easily seen with the
naked eye. These diseases may attack a wide variety
of agricultural crops and are especially important on
tree fruits and nut crops. Two common diseases in
this group are crown gall and hairy root of apple.
Viruses and Mycoplasmas
Viruses and mycoplasmas are so small that they
cannot be seen with an ordinary microscope. They
are generally recognized by their effects on plants.
Viruses depend on other living organisms for food
and to reproduce. They cannot complete their life
cycle independently. They are transmitted by insects
(usually aphids or leaf hoppers), by infected plants,
pollen, fungi, nematodes, or contaminated machinery
and men.
Mycoplasmas are the smallest known independ-
ently living organisms. They can reproduce and exist
apart from other living organisms. They obtain their
food from plants. Most known mycoplasma diseases
are transmitted by leaf hoppers. Yellows diseases and
some stunts are caused by mycoplasmas. Often it is
difficult to distinguish between diseases caused by
viruses and mycoplasmas and those caused by other
plant disease agents.
Common symptoms of both virus-caused and my-
coplasma-caused diseases include:
• mosaic—light green to yellow areas of the
leaf, usually accompanied by abnormal leaf
growth.
• vein banding—a light green to yellow band
along leaf veins, which may later turn dark.
• ring spot—alternating rings of light green or
yellow and normal green of the leaf.
• yellows—the entire plant or some parts are
uniformly yellow.
• stunting—some or all parts of the plant are
abnormally small. Stunting may occur in
combination with all of the previous symp-
toms.
• rugose—leaves are crinkled and deformed.
Every type of agricultural crop may be affected by
virus and mycoplasma diseases.
Nematodes
Nematodes are small, usually microscopic, round-
worms. All nematodes that are parasitic on plants
have a hollow feeding spear (stylet). They use it to
puncture plant cells and feed on the cell contents.
Their life cycle includes an egg, four larval stages,
and an adult. In adverse conditions, some nematodes
can assume an inactive form called a cyst which is
difficult to penetrate or kill.
Nematodes may feed on plant roots, stems, leaves,
and flowers. The most damaging root-feeding nema-
todes directly interfere with water and nutrient up-
take. Nematode damage often goes unrecognized or
is blamed on something else. Typical above-ground
symptoms include stunting, yellowing, loss of vigor,
and general decline.
Nematode injury in the field is rarely uniform.
Damage often occurs in scattered areas of a field.
Symptoms of injury become more obvious when soil
moisture .and fertility are low. Injury to the plant by
nematodes may appear as galls, knots, stubby roots,
and damage to or loss of feeder roots. Nematode in-
festations may be determined by having the still-
living plant roots and surrounding soil examined in
a diagnostic laboratory. There are many different
species of nematodes which attack every type of ag-
ricultural crop.
Nematode Damage
Nematode
Actual Length Equals 1/50 to 1/25 Inch
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Parasitic Seed Plants
Dodders, broomrape, and witchweed are parasitic
seed plants which are important disease agents on
agricultural crops.
Dodders are leafless, orange to yellow twining
vines. They do not have chlorophyll and must obtain
their food from other living plants. Dodder germi-
nates in the soil and produces a slender, yellowish
thread. When it touches the host, it twines around its
stem and puts out little suckers. As soon as the
suckers are established on the host plant, the roots
of the dodder shrivel and the connection to the soil
dries up. Successful dodder parasites twine and
spread from one plant to the next. They often appear
as a tangle of matted orange hairs. Dodders parasit-
ize clover, alfalfa, and flax and are becoming more
important on some vegetables.
Broomrape -is a leafless herb which appears above
ground as a clump of whitish, yellowish, brownish,
or purplish stems. It germinates from seed in the soil
and produces a slender stem. The slender stem grows
downward into the ground and penetrates the crown
or root of the host plant. Upon contacting the host,
the broomrape forms a tuberous enlargement and
draws its food from the host. The flowering shoots
appear above ground and a new generation of seeds
are formed. Broomrape attacks tomatoes, lettuce,
and other vegetables and may live on weeds between
crop plantings.
Witchweed, as it appears above ground, has
bright-green fuzzy stems and leaves and small,
brightly colored flowers in red, yellow, or white. It
germinates from seed only when a favorable host
plant is present. The witchweed rootlet grows down-
ward to the root of the host plant, penetrates the host
root and feeds on the juices, plant foods, and min-
erals from the host. The flowers are produced above
ground. Seeds mature and lie dormant in the soil
until chemicals given off by a suitable host plant
stimulate germination. Witchweed attacks grasses
and sedges including corn, sorghum, wheat, oats,
and barley.
Snails and Slugs
Upland snails and slugs are members of a large
group of animals including oysters, clams, and other
shellfish called mollusks. All mollusks have soft, un-
segmented bodies and are often protected by a hard
shell. Snails and slugs have two pair of antennae
or feelers. Their bodies are smooth and elongate with
a slimelike mucous coating.
Snails have a spiral-shaped shell into which they
can completely withdraw when disturbed or when
weather conditions are unfavorable. They are usually
grey, but their shells vary from nearly white through
brown to black and are often decorated with stripes
or spots of contrasting colors.
SIM AIL
Slugs do not have a true shell and must seek pro-
tection in damp places during daylight hours. Like
snails, they emerge at night to feed. They range in
length from 1A inch to 8 to 10 inches, and may be
whitish-yellow to black, usually with mottled spots
or stripes.
Snails and slugs feed on plants by tearing holes in
foliage, fruits, and soft stems, using a rasplike tongue.
They may eat entire seedlings. Injury to plants is
characterized by jagged holes in foliage, stems, and
fruit. Snails and slugs also leave a trail of mucus on
the surfaces which dries into silvery streaks. These
silvery streaks may be undesirable on floral and or-
namental crops and on those portions of crops to be
sold for human food.
Snails and slugs deposit eggs in moist, dark places.
The young mature in a year or more, depending on
the species. Adults may live for several years. They
overwinter in sheltered areas in colder regions of the
United States. They are active year-round in warm
regions and in greenhouses. They may attack many
different agricultural crops. Common species in-
clude:
• spotted garden slug (8 inches),
• tawny garden slug (4 inches),
• grey or true garden slug (1 inch),
• brown garden snail,
• banded wood snail,
• white garden snail,
• subulina snail.
Weeds
Knowledge of the characteristics and life cycles of
the weed species and the agricultural crops to be
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protected is necessary for a successful weed control
program. Weeds harm desirable plants by:
• competing for water, nutrients, light, and
space,
• contaminating the product at harvest,
• harboring pest insects, mites, vertebrates, or
plant disease agents, or
• releasing toxins in the soil which inhibit crop
growth.
Development Stages
All plants have four stages of development:
• seedling—small, vulnerable plantlets;
• vegetative—rapid growth and production of
stems, roots, and foliage. Uptake and move-
ment of water and nutrients is rapid and
thorough;
• seed production—energy directed toward
production of seed. Uptake and movement of
water and nutrients slow and directed mainly
to flower, fruit, and seed structures;
• maturity—little or no energy production or
movement of water and nutrients in plant.
Annual plants complete all four stages of growth
in one year. Common annual weeds include: foxtail,
pigweed, lambsquarters, cheat, henbit, and cockle-
bur.
FLOWERING (ANNUALS)
GRASS
MATURITY (ANNUALS)
BROADLEAF
GRASS
BROADLEAF
Biennial plants complete the seedling and vegeta-
tive stages of growth in the first year and the seed
production and maturity stages in the second year.
Common biennial weeds include: mullein, burdock,
bull thistle, and wild carrot.
FLOWERING (PERENNIALS)
MATURITY (PERENNIALS)
GRASS
BROADLEAF
Perennial plants may complete all four stages in
the first year and then repeat the vegetative, seed
production, and maturity stages for several following
years. Or the seed production and maturity stages
may be delayed for several years. Some perennial
plants die back in the maturity stage each winter;
others, such as trees, may lose their leaves but do
not die back to the ground. Common perennial
weeds include: Johnson grass, field bindweed, wild
garlic, dandelion, and sumac.
Annuals, Biennials, and Perennials
Winter Annual
(Henbii)
Perennial
(Johnson Grass)
VEGETATIVE (PERENNIALS)
.A// 'S,
GRASS
BROADLEAF
Weed Classification
Most pest plants are either grasses or broadleaves.
The sedges, such as the nutsedges, are not classified
as either grasses or broadleaves. However, they have
similar characteristics to grasses and are often listed
under grasses on the pesticide label. Grasses, sedges,
19
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and broadleaves contain species with annual, bien-
nial, and perennial life cycles.
Grasses
Grass seedlings have only one leaf as they emerge
from the seed. Their leaves are generally narrow and
upright with parallel veins. Most grasses have fibrous
root systems. The growing point on seedling grasses
is sheathed and located below the soil surface. Ex-
amples of grass weed species are: foxtail, Johnson
grass.
Grasses and Broadleaf Plants
tact herbicide sprays.
Grass
Broadleaf
Plant
Broadleaves
Broadleaf seedlings have two leaves as they
emerge from the seed. Their leaves are generally
broad with netted veins. Broadleaves usually have a
taproot and a relatively coarse root system. All ac-
tively growing broadleaf plants have exposed grow-
ing points at the end of each stem and in each leaf
axil. Perennial broadleaf plants may also have grow-
ing points on roots and stems below the surface of
the soil. Examples of broadleaf weed species include:
pigweed, mullein, dandelion, plantain, sumac, poison
ivy.
Factors Affecting Control
In planning a weed control program, differences
between weeds and the crop species, such as life
cycles, foliar characteristics, and herbicide suscep-
tibility must be exploited. Generally the more simi-
lar the crop and weed species are to one another, the
more difficult weed control becomes. Plants differ
in susceptibility due to:
Growing Points—Those that are sheathed or lo-
cated below the soil surface are not reached by con-
GRASS
SEEDLING ANNUAL
PERENNIAL
SEEDLING ANNUAL
V1
PERENNIAL
Leaf Shape—Herbicides tend to bounce or run off
narrow upright leaves. Broad, flat leaves tend to hold
the herbicide longer.
Wax and Cuticle—Foliar sprays may be prevented
from entering the leaf by a thick wax and cuticle
layer. The waxy surface also tends to cause a spray
solution to form droplets and run off the leaves.
SURFACE THICKNESS
AND WAX
Dense Layer of Leaf Hairs—This holds the her-
bicide droplets away from the leaf surface.
Thin Layer of Leaf Hairs—-This causes the chemi-
cal to stay on the leaf surface longer than normal.
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Size and Age—Young, rapidly growing plants are
more susceptible to herbicides than larger, more ma-
ture plants.
SEEDLING ESTABLISHED
Deactivation—Certain plants can deactivate herbi-
cides and are less susceptible to injury from these
chemicals. Such plants may dominate over a period
of time if similar herbicides are used repeatedly.
Stage in Life Cycle—Seedlings are very susceptible
to herbicides and to most other weed control prac-
tices. Plants in the vegetative and early bud stages
are very susceptible to translocated herbicides.
Plants with seeds or in the maturity stage are the
least susceptible to weed control practices.
Timing of Stages in the Life Cycle—Plants that
germinate and develop at different times than the
crop species may be susceptible to carefully timed
herbicide applications.
Determining the Weed Problem
In cultivated crops, the weeds that are favored by
crop production practices do best. The crop produc-
tion method, especially the use or nonuse of cultiva-
tion, is often more important in determining the size
and kind of weed problem than is the crop species
involved.
Weeds with physical characteristics; growth habits;
soil, water, nutrient, and light requirements; and life
cycles that closely resemble crop habits and require-
ments are usually the most serious competitors to
crop species. Broadleaf weeds are often difficult to
control in broadleaved crops, and grass weeds are
often difficult to control in grass crops, because of the
close physical resemblance and growth requirements.
There are exceptions, however. Broadleaf weeds may
be serious in grass crops and vice versa.
Weed Control Methods
Choose the weed control method which takes into
account the differences between the crop and weed
species. Be sure that the crop you are trying to pro-
tect is not susceptible to the weed control method
that you choose. Read the herbicide label.
Cultivation—-This is a traditional and often-used
method to kill or control weeds in row crops. How-
ever, cultivation may bring buried seeds to the sur-
face where they can either germinate and compete
with the newly-planted crop or be spread to nearby
fields. Cultivation may also increase soil erosion and
may help to spread established plant diseases to un-
infected areas of the field.
Planting Timing—Fall-planted crops compete well
against summer annual weeds. Spring-planted crops
compete well against winter annual weeds. Some-
times the crop planting date can be delayed until
after weeds have sprouted and have been removed
by cultivation or by herbicides.
Nurse Crops—-Plant species (usually annuals)
which germinate quickly and grow rapidly are some-
times planted with a perennial crop to compete with
weeds and allow the major crop to become estab-
lished. The nurse crop is then removed or harvested
to allow the perennial crop to take over. For ex-
ample, oats are sometimes used as a nurse crop to
aid in establishing a crop of alfalfa or red clover.
Fire—Fire may be used to control limited infesta-
tions of annual or biennial weeds. Fire usually des-
troys only the tops of weeds and is not effective
against perennial weeds.
Mulching—Mulching is used to prevent light from
21
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reaching seedling weeds, thus preventing weed
growth between crop row,s or around trees and
shrubs.
Mowing—Mowing may be used to reduce com-
petition and prevent flowering and seeding of annual
or biennial weeds. Mowing is often used in orchards
to control weeds and prevent soil erosion.
Flooding—Flooding has long been used for weed
control in certain crops such as rice. The water
covers the entire weed, killing it by suffocation.
Vertebrate Pests
Vertebrate animals may damage or destroy agri-
cultural crops and equipment either in the field or
in storage. Some pests, such as birds, rodents, rac-
coons, deer, or coyotes, may damage crops or live-
stock in the field. Beavers may flood low-lying
cropland by building dams in creeks flowing through
the area. Birds and rodents often contaminate and
ruin more food in storage than they consume.
Barriers, trapping, repellents, and pesticides all
help to control vertebrate pests. Pesticides cannot
be used unless the specific pest can be legally con-
trolled with pesticides under State and Federal laws.
Always check with local authorities before using
pesticides to control vertebrate animals. Local and
State laws may prohibit the killing of some vertebrate
animals such as birds, coyotes, and beavers.
Vertebrate Pest Animals
PESTICIDES
Insecticides
Insecticides are chemicals used to control insects.
Insecticides such as malathion or parathion kill the
insect by touching it (contact poison). Insecticides
such as lead arsenate and Paris green have to be
swallowed to be effective (stomach poison). Insec-
ticides called systemics, such as dimethoate or aldi-
carb, are absorbed, injected, or fed into the plant
to be protected. When the insect feeds on a plant
protected by a systemic insecticide, it eats the chem-
ical and is killed. Some insecticides, such as demeton
or aldicarb, have all three properties. They can kill
either by contact or if eaten, and they are systemic.
Ways Pesticides
Attack Pests
Contact Poison
Systemic Poison
Insecticides vary in the number of different kinds
of insects that they kill. Some insecticides, such as
methoxychlor or carbaryl, are highly selective and
kill only certain kinds of insects. Sometimes you can
choose insecticides that will kill only the pest insect
and not harm beneficial insects in the area. Many
insecticides, such as parathion or pyrethrins, are non-
selective and kill most kinds of insects. Every in-
secticide is different. One that is highly effective
against one pest may not be effective against another
insect.
Insecticides also vary in how long they last as a
killing agent after they have been applied. Some
chemicals, such as chlordane, are persistent, remain-
ing active for weeks or months. These insecticides
are often used when control over an extended period
of time is needed. Other insecticides, such as carbaryl
or pyrethrins, are nonpersistent and break down
quickly (several hours to a few days) into byprod-
ucts.
Read each insecticide label carefully to determine
the insects it will control and how to use it properly.
Always choose the safest insecticide for your situa-
tion.
Miticides
Miticides are chemicals used to control mites. Us-
ually these are contact poisons (such as acarol,
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chlorobenzilate, or Plictran) or systemic poisons
(such as demeton). Thorough coverage is usually
necessary to control the pests. A few, such as Acrex,
are stomach poisons. Miticides are similar in action
to insecticides. Often the same chemical, such as car-
bofuran or parathion, kills both insects and mites. A
miticide may be selective, like Plictran or chlor-
opropylate, or nonselective, like Acrex or chlordime-
form. A miticide may also be persistent, like acarol
or chloropropylate, or nonpersistent like Acrex or
chlorobenzilate.
Fungicides
Fungicides are chemicals used to control the fungi
which cause plant diseases. All fungicides are con-
tact or systemic poisons. Most fungicides, such as
captan or maneb, must be applied to cover all plant
surfaces in order to control fungus organisms. Sys-
temic fungicides such as benomyl move in the plant
to be protected.
There are two approaches to the use of fungicides.
One is to prevent the plant from getting the disease.
Used this way, fungicides are called protectants. They
are applied before the disease gets a start. This type
of fungicide, such as zineb, thiram or Bordeaux mix-
ture, is the most commonly used. Some fungicides
control the fungi after they appear on (or in) the
plant. This use of fungicides is called "eradication."
Eradicants are much less common than protectants.
Benomyl may be used as both eradicant and
protectant in some disease control programs.
Bactericides
The word "fungicide" is often used to describe all
chemicals which are used to control plant disease
agents. The correct term for chemicals used to con-
trol bacteria-caused plant diseases is bactericide.
Some chemicals, such as fixed copper, help to con-
trol both fungi and bacteria. Others, such as strep-
tomycin, are only effective against bacteria.
Because bactericides are contact poisons, thorough
coverage is necessary to control all the bacteria. Bac-
tericides are similar in action to fungicides and are
applied either as protectants or eradicants. Some-
times the same chemical may be both a protectant
and an eradicant.
Controlling Viruses and
Mycoplasmas
No chemicals are presently used to directly con-
trol viruses or mycoplasmas that cause plant diseases.
Control of these plant disease agents may be accom-
plished by:
• Using disease-free plants—"certified" means
that plants have been inspected during the
growing season and found free of certain
diseases.
• Using plants or seeds resistant to specific
virus or mycoplasma diseases.
• Eliminating alternate plant hosts.
• Using cultural practices such as crop rota-
tion.
Nematicides
Nematicides are chemicals used to control nema-
todes. Because most nematicides are contact poisons,
thorough application is necessary to protect the plant
against nematodes in an area. Most of the early ne-
maticides were soil fumigants. These must be applied
before planting because they kill most living or-
ganisms in the soil. More recently, several contact
nematicides have been developed. They kill nema-
todes without injury to newly seeded crops or peren-
nial plants. Some of these contact nematicides are
also effective insecticides. Crop rotation and the use
of nematode-resistant plant varieties can be effective
methods of controlling nematodes. Some common
nematicides are carbofuran, aldicarb, Nemacur, and
Mocap.
Controlling Parasitic Seed Plants
Parasitic seed plants may be controlled through the
use of herbicides. Dodders, broomrape, and witch-
weed all may be controlled with certain herbicides.
Special attention must be paid to the type of crop to
be protected. The same herbicide may not be used
with every crop host. Other means of control include
avoiding seed that is infested with parasitic plants
and controlling the plants before seed is set for the
next season.
Molluscicides
Pesticides used to control snails and slugs are
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called molluscicides. They are formulated as baits,
dusts, or sprays. Baits should be placed in areas
where birds and other non-target animals cannot
reach them. Dusts and sprays are contact poisons
and should be directed at the surfaces which snails
and slugs may crawl over or feed upon. Common
molluscicides include metaldehyde, arsenic, and Bay-
luscide.
Herbicides
Both the use of a herbicide and the way it is ap-
plied depend upon these characteristics of the active
ingredients:
• foliage-absorbed or root-absorbed,
• contact or translocated,
» selective or nonselective,
• persistent or nonpersistent.
Selective vs Nonselective Herbicide
Selective
Nonselective
Preemergence and Postemergence
Preemergence to the
Crop and Weeds
Postemerged Crop
Preemerged Weeds
Postemergence to the
Crop and Weeds
Foliage-Contact-Nonselective-
Nonpersistent
These herbicides kill all foliage contacted. Because
they are nonselective, they must be applied in the
absence of a crop or as a spray directed towards
certain plants or plant parts. There is little or no
translocation to underground or shaded parts of the
weed. Grasses and perennial broadleaved weeds with
below-ground growing points will recover after treat-
ment. Seedling plants and annual and biennial broad-
leaved weeds can best be controlled with these
herbicides. Examples: dinoseb, paraquat, diquat.
HERBICIDE
Foliage-Contact-Selective-
Nonpersistent
These herbicides kill certain kinds of plants when
they contact the foliage. Differences in foliar char-
acteristics of crop and weeds determine the selectiv-
ity. These herbicides are most effective on seedling
weeds. Established grasses and biennial and peren-
nial broadleaved weeds may regrow after the foliage
is killed. These herbicides are generally not trans-
located and some may have a short effective life in
the soil. Examples: endothall, dinoseb-salts, Stod-
dard solvent.
HERBICIDE
Foliage-Translocated-
Nonselective-Nonpersistent
These herbicides are absorbed by the foliage and
translocated throughout the plant. Since they are
nonselective, they cannot be applied when a crop is
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present, but they can be used before planting or
after harvesting. Examples) TEA, glyphosate.
HERBICIDE
chloropicrin, methyl bromide, calcium cyanamide.
HERBICIDE
2 DAYS
Foliage-Translocated-Selective-
Nonpersistent
These herbicides are applied to the foliage and are
absorbed and translocated throughout the living por-
tions of the plant. Their selectivity results from the
ability of some plants to deactivate the herbicides
and therefore they can be applied over the top of
the crop. Selective translocated herbicides are most
effective when applied during the vegetative stage of
development of the weed. Examples: 2, 4-D; 2, 4,
5-T; MCPA; silvex; dalapon.
HERBICIDE
Soil-Nonpersistent-Nonselective
A small number of herbicides belong to this group.
The most widely used are fumigants, but there are
other chemicals also. Fumigants are gases at normal
air temperature and escape into the air if the treated
soil is not covered. Most fumigants are released un-
der a sheet of plastic or other gas-tight cover which
remains for about 24 hours. All weeds and other
plants, including seed, are killed. These are always
preplant applications. Examples: carbon bisulphide,
Soil-Nonpersistent-Selective
These herbicides are applied to the soil before, at,
or immediately after planting. Their active residues
last less than a year. Most herbicides used for vegeta-
ble and grain crops are in this group. Since the crop
is present at the time the herbicide is applied, or is
planted soon after application, the herbicide must be
selective. The selectivity is usually due to differences
in the internal chemistry between the crop and weed
species. These herbicides are often called preemer-
gence herbicides or preplant, soil incorporated her-
bicides. Examples: CIPC, EPTC, CDAA, substituted
ureas (diiiron, linuron, monuron), TCA, amiben,
trifluralin, atrazine at low rates.
HERBICIDE
6-8 WEEKS
Soil-Persistent-Nonselective
These herbicides are used to control all plants in
noncrop situations to maintain a bare ground. They
are used on parking lots, around warehouses, along
fences and highway guardrails, and in storage areas.
Examples: bromacil, boron, sodium, chlorate, and
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simazine and atrazine at high rates.
HERBICIDE
MORE THAN 1 YEAR
Soil-Persistent-Selective
These herbicides have a low solubility in water
and do not leach readily, so they stay near the soil
surface. The selectivity is often based on the inability
to reach deep-rooted crops. They may be applied to
the foliage of the weeds, although most of the her-
bicide is eventually absorbed through the root sys-
tem. They persist and will give weed control for
more than a year. Some can be used to control weeds
in fruit trees, nut trees, and grapes. Examples: ter-
bacil, picloram, dichlobenil, simazine at low rates.
HERBICIDE
MORE THAN 1 YEAR
Controlling Vertebrate Pests
Pesticides used to control vertebrate pests are
often named for the type of animal they control.
Common pesticide categories include:
• rodenticide—rodents,
• avicide—birds,
• piscicide—fish, and
• predacide—predatory animals.
Pesticides for control of vertebrates may be fumi-
gants, chemical repellents, reproductive inhibitors,
baits, or broadcast poisons.
Fumigants kill vertebrate pests in burrows, storage
bins, or other areas which can be easily sealed. The
pests cannot escape and are killed by inhaling the
toxic gas. Examples are cyanide and methyl bromide.
Chemical repellents may make treated areas unac-
ceptable to pests by odor or taste and thus deter
damage. In this way, the offending animal may be
forced to find a different location or new food source.
Examples are Mesurol, used as a repellent on seeds;
and napthalene, which repels by odor.
Reproductive inhibitors that control vertebrate
populations show considerable promise with some
species. Research is continuing and the future may
see birth control for pest species as an acceptable
means of combating pest problems. An example is
Ornitrol on pigeons.
Poison baits usually are in one of two categories:
• multiple-dose poisons (usually anticoagu-
lants) , which must be eaten repeatedly during
a period of several days to be effective. Ex-
amples are Warfarin and Pival for rodent
control.
• single-dose poisons, which kill quickly if
enough is consumed at one feeding. Place
baits so that they will be eaten by the target
pests but not by other animals or people.
Avoid secondary poisoning by picking up
carcasses before dogs, cats, or protected
predatory animals find them. Examples are
Avitrol for bird control, and zinc phosphide
and Vacor for rodent control.
POISONOUS BAITS
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Broadcast poisons—A few pesticides registered
for use on vertebrate pests are formulated as wettable
powders or emulsifiable concentrates. They are
sprayed on or released into the application site. The
target species present in or entering into the applica-
tion site are controlled. Piscicides are usually in this
category. The chemical is released into the pond or
stream and susceptible aquatic species are controlled.
Examples are endrin for rodent control and rotenone
for fish control.
Few pesticides are registered for use on verte-
brates. Registered pesticides have labels which name
the offending or target species, details of application,
and precautions to be taken. Poisons or repellents
may not be used on species other than those listed
on the label. Pay special attention to State and local
regulations, which may be more stringent than Fed-
eral regulations.
Pollution by Pesticides
Many combinations of these and other factors
may lead to soil and water problems. Use good
judgment and seek good professional advice. Be
aware that as the risks in a given situation arise, you
may need to consider changing time of application,
pesticides, or your normal application method.
ENVIRONMENTAL
PROTECTION
Soil ond Water
A number of factors are involved in the risk of
soil and water contamination. On crops where re-
peated pesticide applications are necessary, pesticides
(especially those that are persistent, such as lead
arsenate or copper) may build up in the soil.
On row crops where tilling is common and the
water drains into aquatic areas, runoff of contami-
nated soil particles and pesticides is likely. Do not
apply pesticides just before predicted heavy rains or
just before some types of irrigation.
Some protectant fungicide sprays should be ap-
plied before and during a rain. Some herbicides
should be applied just before rain. However, heavy
rains cause runoff and tend to wash the pesticide
away from the target area. The runoff can carry
the pesticide into sensitive areas where crop injury
may result. Runoff may also reach farm ponds,
streams, and waterways, causing contamination, fish
kills, or injury to domestic animals such as dairy
cows.
Drift
Drift is a main cause of contamination of non-
target areas. Factors affecting drift include:
* pesticide formulation,
• particle size,
* velocity and direction of wind,
• type of application equipment used,
• volatility of the pesticide, and
• temperature inversions.
A temperature inversion exists when cool air is
trapped close to the ground by a warm layer of air.
Particles released into the cool air layer at ground
level have minimum upward movement. The slightest
air movement can cause the particles to drift for
great distances before they fall.
In addition, the toxicity of the pesticide and the
sensitivity of the nontarget area will influence the
potential damage.
When other conditions are the same:
• Smaller droplets or dust particles drift farther
than larger ones.
• There is more chance of drift with air blast
sprayers than with boom sprayers.
• There is more chance of drift with high-
pressure sprayers than with low-pressure
sprayers.
• Low-volume concentrates are more likely to
drift than high-volume dilutes.
27
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« ULV sprayers have one of the greatest poten-
tials for creating drift because they produce
very small droplets.
• The chance of wind effect and drift increases
as the boom or outlet is raised above the
crop.
* Air currents which may cause drift are us-
ually greater during the middle of the day
than in early morning or late afternoon.
• High pressure and small nozzle openings
produce fine spray droplets which drift more
readily.
Reentry and Preharvest Intervals
The preharvest interval is the least number of days
allowed between the last pesticide application and
the harvest day. "Days to slaughter" and "days to
grazing" intervals apply to livestock feeding. When-
ever these intervals are applicable, they are listed on
the pesticide label. You should advise your customer
of the number of days involved for each.
Days to Harvest
Al or Below
Tolerance. Ihe Crop
Can be Sold for
food and Feed
Deposit Residue Residue
(Shading Denotes Pesticide Residue)
Days to Slaughter
Deposit
At Application
Residue
5 Days
After Application
Residue
Slaughter Day
At or Below Tolerance
(Shading Denotes Pesticide Residue)
The worker reentry period is the minimum tune
between the last pesticide application and reentry of
workers into the field without protective clothing.
The worker reentry interval will be listed in the spe-
cial "reentry" section on the new format pesticide
label. You should advise your customer of the num-
ber of days involved and the type of protective cloth-
ing that workers must wear if reentry is necessary
before the period runs out. Workers may not reenter
treated fields without proper protective clothing at
least until the sprays have dried or dusts have settled.
Proper (and legal) minimum protective clothing for
early worker reentry includes a hat or other suitable
head covering, a long-sleeved shirt and long-legged
trousers, shoes, and socks.
Inform your customer of these intervals and reg-
ulations. Misunderstanding, injury, and possible lit-
igation may result if your customer is not properly
informed.
Reentry Sign
DANGER • POISON
Do Not Enter
This Area Until
Wednesday, June 2
Treated With
De Pesto
Phytotoxicity
Phytotoxicity is injury to plants which can range
from slight burning or browning of leaves to the
death of the whole plant. Such injury to plants by
pesticides may be the result of:
• excessive dosage,
• direct application to a susceptible plant,
• drift onto the plant of spray, dust, or vapor,
* runoff from a treated field,
* persistent soil residues, or
• improper formulation.
Injury to the plant may appear as:
• dead, burned, or scorched spots on or at the
tip of leaves,
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• russeting of fruit,
• misshapen fruit, leaves, or plants,
• off-color,
• stunting,
• delayed development,
• poor germination, or
• complete death of the plant.
Unfortunately, these signs of chemical injury often
do not appear until several days after exposure to
the pesticide. If they do appear, they are not always
clear-cut and often may be confused with other prob-
lems. It may be necessary to call on experienced in-
dividuals to help identify the cause.
The likelihood of plant injury resulting from the
use of a pesticide varies with:
• the chemical,
• the formulation,
• the concentration,
• the combination of chemicals,
• method of application,
• growing conditions, or
* the growth stage or condition of the plant.
Emulsifiable concentrates, which contain solvents,
are more likely to cause injury than wettable pow-
ders. Mixtures of pesticides are more likely to cause
injury than the same materials applied individually.
High-pressure applications may cause injury when
low-pressure applications would not.
Plants growing under stress conditions, such as
those in shallow soils or wet spots, are more suscep-
tible to injury than healthy plants. Young, tender,
fast-growing plants with much new growth tend to
be more susceptible to injury. Some varieties are
more sensitive than others.
Community Problems
Agricultural land close to urban development may
have greater community problems than an all-agri-
cultural area. Drift, phytotoxicity, and other nontar-
get injury can cause problems in any community, but
the denser the human population or livestock ad-
joining treated areas, the greater the risk of injury to
humans or domestic animals.
When the crops on adjoining land are sensitive to
the pesticides you are using, be especially careful to
prevent drift.
Aquatic areas, such as ditches, ponds, or lakes,
are particularly sensitive to pesticide contamination.
Where reservoirs for community water supplies, fish-
ing, and other public uses are involved, careless
pesticide application may cause fish kills or con-
taminated water supplies.
29
*U.S. GOVERNMENT PRINTING OFFICE 197B 0-720-335/6040
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