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

    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


   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.

  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.


  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-
   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
    • 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,
    • 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  Grains  and Small  Grains

 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.

  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.
  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
       Low Pressure Field Sprayer
  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.

   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 an 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-

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
  Many of these crops are perennial and may remain
in 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 most often  used on these crops in-
     • air  blast  sprayers  with  fixed  or movable
     • high-pressure sprayers with fixed or movable
     • dusters,
     • hand-held  booms, and
     • aircraft.
            High Pressure Field Sprayer

 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.

   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
 grains 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.

   Pesticide application equipment  most often used
 on these crops is low-pressure  boom sprayers and
 aircraft-mounted sprayers.


    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.

Insects  and  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.
                Wings and Mouthparts
                 Insect Damage
                 Two Wings
   Four Wings
   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 fob'age. Thrips  may  attack every type of
agricultural  crop. Common species are:
     • bean thrips on legumes,
     • citrus thrips,
     • flower thrips  on  grasses,  vegetables,  and
     • onion thrips on  onion and other vegetables,
     • tobacco thrips.
                          Root Feeding
                          White Grub
             GLADIOLUS  THRIPS

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
   Injury to plants is characterized by mottled grey
spots on foliage, deformed buds  or fruit (carfacing),
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

   Common aphid species include:
     •  grape phylloxera,
     •  the greenbug—grains,
     •  green peach aphid—tobacco, peaches, pota-
        toes, spinach,
     •  melon aphid—melons, cotton, fruits, vegeta-
     •  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 Vz  inch long), soft-bodied insects
with hind legs adapted for jumping. The adults have
two pairs of transparent wings held in a rooflike posi-
tion  when at rest. During the life cycle they change
gradually  hi  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 curlytop.
   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)

  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
     • Mexican   mealybug—cotton,   greenhouse
     • red scales—citrus fruits, other tree fruits,
     • San Jose scale—tree fruits,
     • brown soft scale—tree fruits, ornamentals,
     • black scale—citrus.
   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
  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 plan's is  characterized by tears, tunnels,
and ragged holes in the affected plant part.


  Budworms are medium-sized caterpillars that feed
in or on opening buds. Common species include:
     • pecan budworm,
     • tobacco budworm—tobacco, cotton.

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."


  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 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 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-
       common stalk borer-
       other stem plants,
       European corn borer-
       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 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 cottoiLbqllworm, 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-
       oriental  fruit moth—tree fruits,
       codling moth—tree fruits,
       green fruitworm—tree fruits,
       pickleworm—crucif ers,
       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.

  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-
  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
     • fall  and  spring  cankerworms—tree  fruits,
     • cabbage  looper—cole crops,  lettuce, other
     • currant spanworm—currants, gooseberries.
   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,
     • leajminers mine in and feed between the sur-
       faces of leaves  of many fruit and vegetable

       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 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.

 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.

    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
  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.

   Other beetles with root^feeding 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

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.
    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.

Flies,  Gnats,  and  Midges
  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.
   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-
                 HESSIAN FLY
   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 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,

      clover mite—grasses, cereal grains,
      red mites—tree fruits, citrus,  nuts.
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

   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.

  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.
    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.

   The common names of leaf spot diseases may be
 general (peanut leaf spot), descriptive  (zonate leaf
 spot), or  named after  the fungus (Septoria leaf
   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

   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
    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

   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

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  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,
    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.
                           AND TO OTHER 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

 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 leafhoppers), 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 leafhoppers. 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
    • 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-
     •  rugose—leaves are crinkled and deformed.
   Every type of agricultural crop may be affected by
virus and mycoplasma diseases.


   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
 Actual Length Equals 1/50 to 1/25 Inch

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.
   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.

   Knowledge of the characteristics and life cycles of
 the  weed species  and the agricultural crops to be

protected is necessary for a successful weed control
program. Weeds harm desirable plants by:
     • competing for  water,  nutrients, light,  and
     • contaminating the product at harvest,
     • harboring pest insects,  mites, vertebrates, or
       plant disease agents, or
     • releasing toxins in the soil which inhibit crop
 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
     • 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 coqkle-
                               MATURITY  (ANNUALS)
   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)

  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
(Johnson Grass)
 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,

and broadlea'
nial, and per

                contain species with annual, bien-
                '  ';fp cycles.
tact herbicide sprays.
  Grass see   u        nly 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
           Grasses and Broadleaf Plants

   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

 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-
                                                                SEEDLING   ANNUAL
                                                            SEEDLING     ANNUAL
                                                            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.

  Size and Age—Young, rapidly growing plants are
more susceptible to herbicides than larger, more ma-
ture plants.
  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
                                                           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

reaching  seedling  weeds,  thus  preventing  weed
growth  between  crop  row.s or  around  trees  and

  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


   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
                   Stomach 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
   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-
   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-


   Miticides are chemicals used to control mites. Us-
ually these are contact poisons  (such  as acarol,

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

   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.

   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


  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
     • Using  plants or seeds  resistant to  specific
       virus or mycoplasma diseases.
     • Eliminating alternate plant hosts.
     • Using cultural practices such as crop rota-


   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

 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  herbieides.
 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.


  Pesticides  used to control snails and  slugs  are

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-
  Both the use of a herbicide and the way it is ap-
plied depend upon these characteristics of the active
    • foliage-absorbed or root-absorbed,
    • contact or translocated,
    • selective or nonselective,
    • persistent or  nonpersistent.

          Selective vs Nonselective Herbicide
          Preemergence and Postemergence
  Preemergence lo the
    Crop and Weeds
Postemerged Crop
Preemerged Weeds
Postemergence to the
 Crop and Weeds

  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.

                        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.

                        These herbicides are absorbed by the foliage and
                      translocated throughout  the  plant.  Since they are
                      nonselective, they cannot be applied when a crop is

present, but they can be used before planting  or
after harvesting. Examples: TBA, glyphosate.
chloropicrin, methyl bromide, calcium cyanamide.
                                                                                         2 DAYS

  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.

  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,

  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.

                              6-8 WEEKS

  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

simazine and atrazine at high rates.
                    MORE THAN 1 YEAR

   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.

                   MORE THAN I  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 rfiay 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
    • 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

  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.

 Soil  and  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

  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
     • Low-volume concentrates are more likely to
       drift than high-volume  dilutes.

     • 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
     • 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

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
                                A1 or Below  \
                               Tolerance, ihe Crop
                           Can be Sold lor
                          cuod jnd Feed
Deposit           Residue           Residue
       (Shading Denotes Pesticide Residue)

              Days to Slaughter

                        At Application


                           5 Days
                        After Application


                         Slaughter Day
                      At or Below Tolerance
          (Shading Denotes Pesticide Residue)
                                                        The worker reentry period is the minimum time
                                                      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

                                                                         Reentry Sign
                                                                      DANGER • POISON

                                                                         Do Not Enter

                                                                        This Area Until
                                                                      Wednesday, June 2
                                                                         Treated With
                                                                           De Pesto

                                                             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,

     • 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.
                                                                      * U. S. GOVERNMENT PRINTING OFFICE : 1978 720-335/6142