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COMMERCIAL
PESTICIDE APPLICATORS
MANUAL
AGRICULTURE PLANT
UL.ARY
ST. C'SX CAUMS
C~lll jjj; THE V.1,
IVE EXTENSION
SERVICE
OF THE VIRGIN ISLANDS
COLEC BON
SVYCV 48.8:
S4/8
SAg-P
OCT 182
COMMERCIAL PESTICIDES APPLICATOR MANUAL:
AGRICULTURE: PLANT
This manual was adapted for Virgin Island needs from materials
furnished by the Training Branch, Operations Division, Office of
Pesticide Programs, U.S. Environmental Protection Agency, Washington,
D.C. It supplements the EPA/USDA publication: "APPLY PESTICIDES
CORRECTLY - A GUIDE FOR COMMERCIAL APPLICATORS." That publication
should be read first.
The information herein provides a base to use in preparing for
the certification examination in the category of AGRICULTURAL PLANT
PEST CONTROL.
Refe'ence to commeAcMit products ot trade names i6 made with the
understanding no dicaimination z in-tended and no endoAhement L6, implied
by the Cottege of the ViAgin Island6 Coopetative Extension SeAvice.
William D. Fitz 'wateA
Pesticides Training Officer, CVI Cooperative Extension Service
DaAuhan S. Padda, PhV
Director, CVI Cooperative Extension Service
Oscar E. Henty
Commissioner, Virgin Islands Department of Agriculture
December, 1975
COOPERATIVE EXTENSION
(Acts of
Agricultural Extension
and the United States
D.
WORK IN AGRICULTURE AND HOME ECONOMICS
May 8 and June 30, 1914)
Service, College of the Virgin Islands
Department of Agriculture, Cooperating
S. Padda, Director
V. 012979
TABLE OF CONTENTS
Standards for Certification ......................... 1
Problems with Pesticide use ......................... 1
Eyes ........................................... 3
Lungs ......................... .................. 3
Respirators & Gas Masks ......................... 3
Reentry into Treated Fields ..................... 3
Days to Harvest Intervals ....................... 4
Hazards to crops ................................ 4
Hazards to bees ................................. 5
Drift .. ............... .......... .......... .. 5
Contamination ................................... 6
Specific use Problems ........................... 6
Herbicides .................................. 6
Growth Regulators ........................... 7
Desiccants & Defoliants ..................... 7
Soil fumigants .............................. 8
Non-volatile Soil Pesticides ................ 8
Combinations/Mixtures of Pesticides ......... 8
Mixtures of Pesticides & Fertilizers ........ 9
Serial Application of Pesticides ............ 9
Adjuvants or Spray Additives ................ 9
Pests ...................... .... .... ............ . 11
Identification & Diagnosis ..................... 11
Insects ........................................ 11
Ways Insects Can Injure Plants ............ 11
Diseases ....................................... 12
Ways Parasitic Diseases Injure Plants ..... 12
Nematodes ...................................... 12
Ways Nematodes Can Injure Plants or Crops 12
Weeds .......................................... 12
Ways Weeds Injure Plants or Crops ......... 13
Vertebrate Animals ............................. 13
Economic Controls .............................. 13
Life Cycles ... ................................ 14
Other Methods of Control ....................... 14
Crops & Pests ...................................... 16
Fruit & Nut Crops .............................. 16
Corn & Sorghum ................................. 16
Grain Legumes .................................. 17
Tropical Root Crops ............................ 17
Vegetables ..................................... 17
Pests .......................................... 19
Nematodes ................................. 19
Diseases ... (Tables pgs. 20-24) .......... 19
Insects ... (Tables pgs. 25-29) ........... 19
Pesticide Application Equipment ................... 30
Boom Sprayers .................................. 30
Granular Applicators .......................... 30
Soil Fumigation Applicators ................... 30
Appendix: Suggested References .................... 32
COMMERCIAL
APPLICATOR
PESTICIDES
MANUAL
AGRICULTURE PLANT
W. D. Fitz water, 0. S. Padda, and 0. E. Henytt
STANDARDS FOR CERTIFICATION
The U.S. Environmental Protection
Agency has set these specific
standards:
"Applicators must demonstrate pract-
ical knowledge of crops on which they
may be using restricted use pesticides.
The importance of such competency is
amplified by the extensive areas in-
volved, the quantities of pesticides
needed, and the ultimate use of many
commodities for food and feed.
Practical knowledge is required con-
cerning soil and water problems, pre-
harvest intervals, reentry intervals,
phytotoxicity, and potential for
environmental contamination, non-target
injury and community problems result-
ing from the use of restricted use
pesticides in agricultural areas.
Applicators must demonstrate a
practical knowledge of crops grown and
the specific pests of these crops on
which they may be using restricted
use pesticides. You must:
- accurately identify the pests
- select the correct registered
pesticides
- apply the most effective, efficient
and least environmentally disrupt-
ing control measures.
In order to minimize environmental
problems you must recognize:
- Soil and water problems, such as,
leaching, residues, erosion, etc.
- preharvest and reentry intervals
- phytotoxicity and potential for
environmental contamination
- non-target injury
- community problems, such is,
nearby housing, schoolgrounds,
waterways, etc. resulting from
the use of restricted pesticides
in agriculture.
Careless habits resulting in
misuse and contamination of the
environment are not only prohibited
by law but may affect you, your
family, your neighbors, and your
Islands.
PROBLEMS WITH PESTICIDES USE
As a commercial. applicator you
are daily exposed to many pesticides
ranging from low to high toxicity.
You must consider their total effect
on yourself. Your health and your
business depends upon your knowledge
and care in application to avoid the
side effects of phytotoxicity, bee
toxicity, drift damage, reentry,
residues, tolerances, etc.. See
Table 1 for relative hazards:
TABLE I. RELATIVE HAZARD OF SPRAY CHEMICALS TO SPRAYMEN
MOST DANGEROUS1
DANGEROUS
LESS DANGEROUS
LEAST DANGEROUS
carbofuran
(Furadan) (C)
Di-Syston (OP) 2
methomyl
(Lannate) (C)
parathion (OP)
Phosdrin (OP)
Schradan (OMPA) (OP)
strychnine (M)
demeton (Systox) (OP)
TEPP (OP)
thimet (Phorate) (OP)
Zinophos (OP)
aldrin (CO)
Carzol (C)
dioxathion
(Delnav) (OP)
dieldrin (CO)
dinoseb (DNBP) (N)
endrin (CO)
Methyl Parathion (OP)
nicotine (M)
paraquat (M)
Phosphamidon (OP)
carbophenothion
(Trithion) OP)
Zectran (C)
zinc phosphide (M)
naled (Dibrom) (OP)
chlordane (CO)
dimethoate (Cygon) (OP)
De-Fend (OP)
Diazinon (OP)
ethion (OP)
Fundal (M)
Galecron (M)
Guthion (OP)
Imidan (OP)
Lead arsenate (M)
Lindane (CO)
Meta-Systox-R (OP)
binapacryl
(Morocide) (N)
Plictran (M)
endosulfan
(Thiodan) (CO)
toxaphene (CO)
Zolone (OP)
Alar (M)
aminotriazole
(Amitrole) (M)
calcium nitrate (M)
captain (M)
dichlobenil
(Casoron) (M)
copper sprays (M)
dodine (Cyprex) (M)
dalapon (M)
dichlone (M)
diuron (Karmex)(M)
ethephon (Ethrel) (I
ferbam (D)
Gardona (OP)
Glyodin (M)
iron chelate (M)
Karathane (N)
Kelthane (CO)
lime-sulfur (M)
malathion (OP)
maneb (D)
methoxychlor (C))
Moreston (M)
napthaleneacetic acid
(NAA) (M)
oil (M)
Omite (M)
Perthane (CP)
rotenone (M)
carbaryl (Sevin) (C)
simazine (M)
terbacil (Sinbar) (M)
sodium polysulfide (M)
Solubor (M)
sulfur (M)
tetradifon (Tedion) (CO)
2,4-D (CO)
2,4,5-T (CO)
2,4,5-TP (CC)
urea (M)
zinc sulfate (M)
zineb (D)
ziram (D)
1These estimates are based on use experience as well as on observed acute dermal and oral toxicity of the com-
pounds to experimental animals. The classification into hazard groups is both approximate and relative.
2The chemical class to which the pesticide belongs is designated as follows: C, carbamate; CO, chlorinated organic;
D, dithiocarbamate; M, miscellaneous; N, nitro; and OP, organic phosphorus.
Your greatest hazard from pest-
cides is from absorption through the
skin as is the case of 80% of agri-
cultural poisoning cases. This
hazard is increased by cuts, abrasions,
scratches, scuffs, or other damage to
the skin. However, absorption can occur
even through healthy skin. Absorption
is high and rapid in such sensitive
areas as the:
- scrotum
- arm pit
- ear canal
- forehead
- scalp
It is lower and slower in less sensi-
tive areas as the
- palm of the hand
- ball of the foot
But even in these lower absorp-
tive areas, penetration can be great
and the rate will vary from material
to material. Whether highly toxic
or relatively safe, any pesticide
spilled on the skin should be washed
off immediately as pesticides can be
absorbed within a few minutes.
Waiting until a job is done before
washing may be too late! Wash by
rubbing the hands together or with
a piece of cloth using detergent and
water. Do not scrub with a brush
as this may abrade the skin permit-
ting more rapid absorption. Wear
gloves when working spray machinery.
Eyes
The eyes are particularly sensi-
tive to harm and should be protected
with goggles or face shield. If a
pesticide is splashed into the eye,
immediately wash it with a gentle
stream of clean running water while
holding the eyelid open. Large amounts
of water should be used and continued
for 15 minutes or more. Do not use
chemicals or drugs in wash water. A
convenient plastic eye wash bottle
and holder is now available and would
be useful to carry in the field.
Lungs
Inhalation of pesticide droplets or
dust is of next importance to skin
contact as a cause of agricultural
accidents. Vapors and extremely fine
particles, 10 microns or less, are
particularly hazardous because of the
large absorptive surface in the lungs.
Repirators should be worn as indicat-
ed on the label or under conditions
you think protection is desirable.
Daily use of even moderate pesticides
greatly increase exposure dangers. It
is also wise to wear a respirator when
using moderately toxic pesticides like
malathion during the same day you are
using more highly toxic pesticides of
the same group.
Respirators And Gas Masks
All respirators must be approved by
the Mining Enforcement and Safety Adminis-
tration (MESA) and the National Institute
for Occupational Safety and Health (NIOSH)
An approval number must appear on the box
in which the respirator is packed and on
the boxes in which replacement filters
and cartridges are packed. These appro-
val numbers will start with the letters
"TC". Those bearing the letters "BM"
should be discarded. A listing of appro-
ved respirators as of'the date of this
publication will be found in the Appendix.
Please check for the latest information.
Reentry into Treated Fields
These standards were established
in 1974 and apply particularly to
agricultural uses. You must follow
these rules:
- no unprotected person may be in
the field you are treating with
any pesticide.
- no pesticide application shall be
made that will expose any person
to pesticides, directly or in-
directly, through drift other
than those involved in the ap-
plication and wearing protective
clothing.
- the label restriction and direc-
tions must be followed.
Those pesticides presently re-
stricted (you must keep aware of any
changes) and requiring workers to
wear protective clothing when enter-
ing treated fields wi-thin the following
time periods are as follows:
24 hours
EPN
ethion
Guthion
phosalone
48 hours
Azodrin
Bidrin
carbophenothion
demeton
endrin
ethyl parathion
Meta-Systox-R
methyl parathion
It is recommended that you notify
your client any time you apply one of
the above materials to avoid misunder-
standing, poor public relations, and
possible litigation. Tell him the name
of the material, time of application,
and required reentry interval. If
workers must enter the field prior to
the expiration of the required interval,
growers are obligated to notify the
workers of the necessary reentry infor-
mation and furnish them with protective
clothing.
Fields treated with pesticides
other than those listed above may be
reentered without protected clothing
after the spray has dried or the dust
settled. New labels will indicate
the necessary reentry information;
old ones may not.
Days To Harvest Intervals
Don't confuse with reentry inter,
vals. This is the time period that
must pass between pesticide applica-
tion and crop harvest to allow the
pesticide residues in the crop to
fall to the tolerance levels or below
to protect the consumer. The same
pesticide may have different interval'
for different crops and conditions.
Hazards To Crops
The greatest hazard is usually
an adverse reaction by the crop to
the chemical. This "phytotoxicity"
may be the result of direct applica-
tion or drift on to the plant, runoff
from a treated field, or from per-
sistent soil residues. Injury to the
plant may appear as poor germination,
dead, burned or scorched spots on
leaves, stunting, delayed development
russeting or misshapen fruit, or deatl
of the plant. Unfortunately, these
signs usually do not appear until
several days after application and
then they may be confused with other
problems. These clues will help you
determine if the injury is due to
chemicals:
- location of injured plants or
areas on a plant
- nature of the injury
- lack of signs of other causes of
injury, such as, ooze or fungus
- weather records
- cropping history
- location in relation to highways,
industrial sites, cities, etc.
- sharply defined injured areas
- uniform color of injured area
The likelihood of plant injury
resulting from the use of pesticides
varies with the chemical, the formula-
tion used, the concentration, method
of application, growing conditions,
and the stage or conditions of the
plant.
- Desicants, defoliants, and herbi-
cides are particularly hazardous
through drift to sensitive plants.
- Organophophates, carbamates, and
oils are more likely to cause
injury when drying conditions are
poor.
- Chlorinated hydrocarbons are more
injurious in hot, dry weather.
- Emulsifiable concentrations are
more hazardous than wettable
powders because solvents may dis-
solve waxy protective covering on
plant leaves.
- Mixtures of pesticides are more
likely to cause damage than mat-
erials applied individually.
- Applications at high pressures may
cause more damage than at lower
pressures.
- Row ends and field edges are more
apt to be damaged because of ma-
neuvering of spray rigs.
- Growing conditions (shallow soils,
wet spots, etc.) may make plants
more susceptible to injury.
- Differences in the sensitivity of
varieties are not uncommon.
- While these are all possible even
following recommendations, severe
injury is unlikely and is usually
a sign of other problems.
Hazards to Bees
Honey and wild bees are necessary
for pollination, thus potential loss
of these insects must be reduced by:
- not applying pesticides toxic to
bees to crops that are in bloom
- selecting pesticides least harm-
ful to bees (see Table II)
- using least harmful formulations
(dusts more hazardous than
sprays; ECs less residual than
WPs; granular formulations have
lowest hazards)
- timing applications to reduce
contact with bees (evening is
better than morning but both
are safer than daytime appli-
cations)
- avoid treating near hives to
reduce the possibility of drift
- contact beekeeper before spraying
and request he move his bees
- mowing a cover crop in bloom
just before treatment
Drift
Pesticides are not pollutants as
long as they stay on target.
Drift of pesticides from target areas
is probably the most important and
costly problem to commercial applica-
tors because:
- possible lawsuits resulting from
off-tarqet iniurv or unsalable
crops
- local public relations may pre-
vent an effective program from
continuing
- loss of working time because of
unfavorable conditions
Almost any application will result in
some drift, but it can be minimized by:
- working when there is little or no
wind, if necessary in early morn-
ing or evening
- when downwind crop calls for the
same pesticides as the target crop
- locating areas away from houses,
streams, or similar situations
- using good judgment to stop treat-
ment when conditions are poor
- selection of application equipment
- selection of chemical and formu-
lation
- adding adjuvants as thickeners or
foaming agents to increase the
particle size
In addition to actual Dhvsical
drift, certain materials vapori7z
producing rumes wnicn may cause damage
for long distances downwind. Volatile
compounds include esters of 2,4-D,
2,4,5-T and other phenoxy compounds,
dinitros, and some carbamate herbicides
Spraying in the coolest part of the
day decreases vaporization potential.
Contamination
Keep contamination of areas where
pesticides are not wanted to a minimum
by:
- confining applications to the
target area
- considering drift, runoff, soil
erosion, volatility of pesticide,
persistence of pesticide, plant
absorption, use of minimum
dosages, etc.
- choosing the best pesticide that
will give effective control, per-
sistent enough to do the job, and
yet break down when no longer
needed
- check on grazing or feeding by
livestock on treated areas
- tying pesticides down in the back
of the truck when transporting
to prevent spills while carrying
broom, shovel, and neutralizers
(Clorox, lime, etc.) to take
care of spills
using a separate pump with check
valves to prevent back siponage
when filling from a well
proper disposal of "empty" pesti-
cide containers
- wearing protective clothing when
mixing and applying pesticides
and cleaning equipment after
application
- keeping spray equipment in good
repair to stop leaks and mal-
functioning
- keeping alert to the dangers and
using good judgment is the best
preventative of all
Specific Use Problems
Some categories of pesticides
have special problems requiring your
attention over and above the usual
awareness.
Herbicides
The use of herbicides -as grown so
fast they now represent the largest
single group of pesticides used in
agriculture. Although as a group
they are relatively not toxic to
humans and wildlife, they are not
without danger and some are highly
toxic. Biggest problem is their
phytotoxic effect on non-target plants
through misapplication. This can
occur as:
- drift of spray, particles or
vapor
- soil contamination
- excessive soil persistence
- sprayer contamination
All must be avoided. While they
produce readily seen effects, it is
too late to remedy the cause by the
time they are visible. The follow-
ing herbicides, in particular,
present a hazard to non-target plants
through drift:
2,4-D
2,4-DB
dicamba
dichlorprop
dinoseb
fenac
mecoprop
MCPA
MCPB
paraguat
picloram
propanil
2,3,6-TBA
silvex
2,4,5-T
The above pesticides are also
most likely to cause sprayer conta-
mination. Decontamination is a pro-
blem as repeated flushings with
water may not be a dependable method.
Emulsifiable formulations are more
difficult to remove than water
soluble,.metallic and amine salts.
Attempt to decontaminate by adding
1 quart of household detergent to
25 gallons of warm water. Circu-
late through all parts of the
sprayer, Let stand for several
hours, drain, and flush with more
water. Test on sensitive plants,
such as, bean or tomato seedlings.
Injury will usually appear in 2-7
days if the sprayer is still conta-
minated.
Soil persistence of herbicides
is an important factor. You must
consider the crops that are to fol-
low. Soil persistence is dependent
upon manyfactors including:
- rate
- formulation
- type of application
- soil type
- microbial populations
- soil temperature
- moisture
- tillage
In general herbicide breakdown is
most rapid in warm moist soils with
good microbial growth.
Growth Regulators
These pesticides are used to im-
prove crops by stimulating more growth
flowering, fruiting or the opposite.
They may upset the physiology of the
flower or fruit when applied during or
after bloom causing reduction in fruit
and seed production. Or they may im-
prove fruit set, prevent excessive fruit
drop or control fruit maturity. Because
of the sensitivity of plants to these
chemicals, extra precautions must be
made to insure that the right amounts
are applied at the precise time.
Calibration of equipment is vital.
Application is usually made as a foliar
spray, soil drench or bark injection.
Sprout inhibition is another form
of growth regulation to prevent sprout-
ing in storage. These should not be
applied to onions intended for use as
seed. Others break up dormancy of
plants or parts. Fertilizers and
olant nutrients are not included in
this rnOUD.
Desiccants and Defoliants
Defoliant chemicals cause leaves
to drop from a crop, such as, tomatoes,
to make harvest easier without killing
the plants. Desiccants speed up the
drying of plant parts to aid in harvest-
ing of some seed crops and nursery
stock by killing the foliage. Frequent-
ly the terms are used interchangeably
Their advantages include:
- reduce disease or insect populations
- kill weeds interfering with harvest
- aid and simplify mechanical harvest-
ing
- improvement of quality
- reduce moisture content of seed
- reduce disease of stored crops
- increase yields
Their disadvantages may be:
- reduction in yield and quality
- presence of toxic residues
Complications can result from the
use of these materials due to various
side effects and because treated crops
cannot be generally used for grazing
and many do not permit use of seed for
food, feed or oil purposes.
Soil Fumigants
The soil is the most complex
medium you will treat for the con-
trol of pests. You must know the
characteristics of the pesticide,
the soil and the pest and their
interrelationships to effectively
use soil pesticides. The volatile
pesticides or fumigantss" vary
considerably in action and appli-
cation. Dosage depends upon the
concentration in the soil and
the time the organism is exposed
which in turn is influenced by soil
conditions, such as, soil type,
moisture level, etc. Recommended
rates are selected to perform satis-
factorily over a wide range of soil
conditions. Dosage is also affected
by temperature and stage of deve-
lopment of the organism. Soil
structure and conditions also influ-
ence the effectiveness of fumigants.
.Aeration time (the time needed to
allow the fumigant to leave the soil)
is important to avoid injury to the
crop. This will vary with the:
- chemical
- soil temperature
- moisture
- texture
- crop to be planted
Non-Volatile Soil Pesticides
These vary from high to low wa-
ter solubility, from non-systemic to
systemic activity, and from short to
long residual effectiveness. Sys-
temics may translocate in the plant
tissues. Other pesticides usually
rely on movement to the organism
through direct application, mixing
with soil and/or water or depend up-
on the organism to seek it out usual-
ly in the root zone. Non-fumigant
soil pesticides are usually more
dependent upon soil moisture than
the fumigants. Moisture is often
needed to:
- activate or release the pesticide
- move or distribute it into or
through the soil
- aid absorption into the plants.
However, this need is quite va-
riable as those with low water solu-
bility, high evaporation rates, sen-
sitivity to breakdown by sunlight, or
high absorption rates on soil parti-
cles, usually require mechanical mix-
ing into the soil regardless of rain-
fall or irrigation.
Combinations/Mixtures of Pesticides
The mixture of different pesti-
cides to accomplish two or more objec-
tives at the same time thus reducing
labor costs in application is an old
and widely used-method. Under present
federal regulations, uses of pesticides
inconsistent with (or not mentioned on)
the labeling are a misuse and unlawful.
The legislative history shows, however,
that it was the intent of Congress that
EPA be reasonable in interpreting and
enforcing misuse provisions. Accord-
ingly, EPA has set the policy until
modified by further regulations that
tank mixtures and serial applications
are consistent with the label if:
- the label specifies such uses,
- there is state registration for
such uses, or
- such uses are recommended by state
agencies or are common agricul-
tural practice.
Even when pesticides are approved
for use in a mixture, problems may
still result. Formulations of a
pesticide vary from product to product
due to the different additives. Incom-
patibilities are expressed in many
different ways, including:
- crystalline precipitate or gela-
tinous masses are commonly formed
- breaking the emulsion so that
different ingredients separate
out
- lessened activity of the combi-
nation
Incompatability may be minimized by:
- using formulation produced by
same manufacturer
- keeping equipment clean and well-
drained
- partially filling a tank before
adding any pesticides
- diluting concentrates before
combining them
- mixing wettable powders with
water to form a slurry before
they are added to the tank un-
less you have an inductor sys-
tem
- making certain that agitation is
adequate to maintain the sus'-
pension
- adding wettable powders to the
tank before the emulsifiable
concentrates.
Mixtures of Pesticides and Fertilizers
Many of the principles for using
tank mixtures of pesticides also apply
to fertilizer-pesticide mixtures. The
most important thing to remember Is
that the resultant mixture is to be
treated as a pesticide not a fertili-
zer. The total quantity of pesti-
cide in the tank may be less than the
accepted variation in fertilizer appli-
cation. Timing, placement and dis-
tribution are frequently different for
pesticides and fertilizers.
Serial Applications of Pesticides
These are applications in which
the pesticides are applied individually
but following one after another.
Although the time is generally limited
to a few days, it can be longer. Pro-
blems arising from incompatible serial
applications may include:
- plant injury
- loss of effectiveness of one or
both pesticides
- excessive residues
Adjuvants or Spray Additives
Pesticides are formulated for
general performance purposes under
average conditions. For many jobs
they perform satisfactorily but
there are also many situations where
they fall far short. The substan-
ces added to a spray mixture to aid
or improve the performance of the
main ingredient are called adjuvants.
They may be added to a spray mixture to:
- improve the wetting of the foliage
or the pest
- change the evaporation rate of the
spray
- improve the weathering ability of
the spray deposit
- improve the penetration absorp-
tion and translocation of the
pesticide
- adjust or buffer the pH of the
spray solution increasing the
effectiveness and longevity of
the alkalaine sensitive particles
- improve the uniformity and the
amount of the deposit
- improve the ease of mixing or
compatibility of the spray mix-
ture
- increase the safety from spray
injury to the crop
- reduce the drift hazard to neigh-
boring crops
- improve physical properties of the
mixture, such as, anti-foaming
agents.
Depending upon their intended use,
adjuvants are called emulsifiers,
wetting agents, stickers, spread-
ers, deposit builders, film form-
ers, buffering agents, thickeners,
penetrants, foaming agents, anti-
foaming agents, etc.
These are highly active materials.
In most cases, a very small quantity
will have great effect so use only the
amount recommended. Regulations require
spray adjuvants, for use with pest-
cides, to be exempt from the requirement
of a tolerance or to have a tolerance
established. Also they must be regis-
tered and carry an EPA number.
PESTS
Accurate diagnosis of the pest
and its damage is essential in
deciding how to solve a pest
problem.
IDENTIFICATION AND DIAGNOSIS
While identification of the pest
and the damage it causes is essential,
a knowledge of the crop and its growth
characteristics is important in re-
cognizing the damage.
INSECTS
Most insects injurious to agri-
cultural crops have a life cycle in
which either (1) the newly hatched
insect looks like the adult except
for size and possibly wing develop-
ment and feeds in the same places or
(2) the adults and young are not
alike going through several different
life forms generally from egg to
larvae to pupa to adult with differ-
ent habits for each stage. See Fig. 1
,* %
I p
I /
Nymphal stages
Ai
Adult
Adult
Larvae
Pura
GRADUAL METAMORPHOSIS
(stink bug)
Adult
fir !-
COMPLETE METAMORPHOSIS
(House fly)
Fig. 1
Careful observation often reveals
the cause. An insect may be eating
plant roots but the first signs appear
on the leaves. So until the roots are
examined, the cause may not be correct-
ly identified. With careful observa-
tion, knowledge of the plant's history,
and a general knowledge of possible
causes within the geographical area,
plant ills can frequently be diagnosed.
The following are some elementary
aids to assist you in this diagnosis:
Ways Insects Can Injure Plants
- chewing usually leave obvious
feeding wounds, such as, ragged
leaves, holes in wood, wilted
or dead plants, etc.
- sucking no obvious wounds as
they suck out juices causing off-
color scorch or hopper burn,
wilted or misshapen foliage/fruit
01
- oviposition scars- scars formed
on woody part of plants or fruit
caused by egg-laying
- vectors carry diseases on their
bodies or inject them with their
mouthparts while feeding from
plant to plant resulting in wilt,
dwarfing, off-color foliage, etc.
- excretions honey dew deposits
secreted by some insects encour-
age growth of sooty mold inter-
fering with plant functions
- gall formation irregular growths
of scar tissue may form on leaves,
twigs, buds, and roots to dis-
figure plants
Diseases
Unlike insects, you cannot see
the organisms causing disease. Only
the signs and symptoms of their pre-
sence and these are often difficult to
identify in the early stages. Some
diseases are caused by non-living agents,
such as, air pollution, drought, etc.
As there is no pesticide control need-
ed here we are not concerned with these
except to differentiate them from
the damage caused by living organisms
known as pathogens or parasitic plant
diseases. Prevention or prevention of
spread is the primary concern in dis-
ease control.
Ways Parasitic Diseases Injure Plants
- Damage water-conducting cells-
these plug the vascular system
which carries food and water
throughout the plant and results
in wilting and dead branches.
- Damage cells of leaves or fruit-
these leave splotches or spots
on the surface lowering market-
ability of fruit.
- Damage roots and root hairs -
these interfere with the plant's
intake of nutrients and water
causing wilting, yellowing, and
stunting.
- Damage to cells by overgrowths -
these irregular growths occur on
various parts of the plant inter-
fering with normal growth
processes.
- Damage to flowers, fruit and seeds -
rot and molds destroy the via-
bility of these plant parts.
- Damage or death of plant tissues
from production of toxins.
Nematodes
Nematodes are small, worm-like
animals. Some cause no harm but
others feed on or in the roots of
stems of plants. Symptoms are usually
spotty and except for the galls of
root knot, are not distinctive
enough for definite diagnosis.
Ways Nematode Can Injure Plants
- Mechanically disrupt water-
conducting cells this inter-
feres with translocation of
nutrients and water, causing
wilt, loss of color, roots with
dead spots, or dead and stunted
roots.
- Damage roots and root hairs -
this interferes with absorptive
capability of the plant causing
the same symptoms as above.
- Gall informations these cause
growths on the roots that may
be confused with nitrogen-fixing
nodules on legumes, bacterial,
or fungal infections.
Weeds
Of our common pests, weeds are
generally the easiest to see and re-
cognize since a weed is a plant out
of place. The effects of weeds are
generally shown in reduced yields and
small size or through contamination
of the crop.
There are two major types of weeds:
narrowleaf and broadleaf. The narrow-
leaf weeds are the grasses and sedges.
These are parallel veined. The broad-
leaf weeds include purslane, field
bindweed and many others. The veins
in this group are netlike.
Ways Weeds Injure Plants Or Crops
- Reduce yields compete for moist-
ure, light and nutrients
- Reduce crop quality weed seeds,
dockage, weeds in hay, etc.
- Increase production costs require
additional labor and equipment
expense in tillage, cultivation,
harvesting, etc.
- Lower land values.
- Carriers or hosts for insects and
diseases encourage these other
pests
- Poisonous or irritating to animals
or people poison ivy hay fever,.
Manchioneel etc.
Vertebrate Animals
These can become pests under local
conditions. In general they attack the
whoJe plant as in the case of the forage
or the fruit and seed as in the case
of sorghum. In the Virgin Islands,
rats and mice cause the biggest loss
to stored materials. There is some
loss to field crops by birds. As
deer numbers are low, most damage to
forage is done by domestic browsing
animals not under control.
ECONOMIC CONTROLS
Economic injury levels depend on
the amount of damage that can be tolera-
ted rather than on pest population
levels. In some instances the presence
of even small numbers may result in too
much damage, while other cases,
heavy populations may not cause signi-
ficant injury. Sometimes the pest is
very conspicuous but may not af-
fect crop yields or quality. The
number of pests that can be tolerated
varies widely even for the same species
in different areas on the same crop
and at different stages of crop
maturity. In most agricultural situa-
tions, complete control or eradication
of an insect is not practical or
necessary.
When damage to quality or yield
is threatened and other factor such
as parasites, predators, pathogens,
weather, etc. will not prevent it,
pesticides will be needed. This is
often referred to as economic or
damage threshold. The decision to
apply a pesticide or not is usually
based on the experience and knowledge
of the costs or risks versus benefits
related to control. In making this
decision, one must consider the
following questions:
- Is the population-approaching
levels to cause economic thres-
hold damage? Are natural con-
trols (parasites, predators,
weather, etc.) present and likely
to reduce the population before
economic damage results?
- Will costs of the pesticide and
labor needed to apply it be less
than the gains to be made?
- What effect will the pesticides have
on the environment and the bene-
ficial forms including non-target
species?
- Can the crop be harvested before
damage is serious?
The dollar return from control
should be greater than the cost of the
control. These figures change from
season to season and within a season,
as the market price of the crop changes.
There is no single or simple answer.
LIFE CYCLE
Thorough knowledge of the life
cycle of the pest is important in mak-
ing the decision as to whether or not
to take control measures, and if so,
when?
Most if not all pests, are most
readily controlled at one particular
stage in their development. The treat-
ment for many must be applied before
their damage is noticed. Most fungi-
cides are protectants and must be on
the leaves, stemsbranches and/or
fruit as a protective coating before
the disease spore arrives. Most in-
fection occurs under moist conditions.
So, it is important to spray before
the rain comes, not afterwards.
Identification of the casual agent and
a knowledge of the disease cycle is
the key to proper application of pre-
ventative fungicides.
The procedure you follow may be
influenced by the biology of the insect,
disease, or weed. If the insect is
held partially in check by parasites,
you may use less pesticide for a lower
degree of control to give the parasites
a better chance of survival.
An understanding of the growth
habits of weeds is also a requirement
for making judgments of chemically
treating with herbicides versus culti-
vation, rotation, or other such prac-
tices. The weed population in a given
field may be controlled by ordinary
cultivation or it may be one, such as,
bindweed, that is sheltered within the
rows and will later emerge to affect
the crop.
OTHER METHODS OF CONTROL
You should not ignore supplemental
cultural practices which you can sug-
gest to your growers. One such prac-
tice is crop rotation. When a success-
ful rotation program is followed, a
pest specific to one crop will not
carry over to the following crops.
Sanitation practices, such as,
cleaning up cull piles and plowing
down old stubble, are a definite help
in eliminating off-season sources of
some pests. The use of resistant
varieties of food and feed crops
should be encouraged to minimize the
dependence on chemical controls.
Biological control is the prac-
tice of reducing the numbers of a
pest by the use of natural agencies
such as parasites, predators and dis-
eases. The fundamental basis of
such control is the fact that life
in nature exist in a state of balance
which is maintained by the competi-
tive interaction of various forces.
Cottony-Cushion scale is a serious
pest of citrus and lady-bird beetle
known as the vedalia is most effec-
tive in controlling the scale. The
successful solution of the scale pro-
blem by the use of natural enemies
has given biological methods of con-
trol great prominence. The other agri-
cultural pests that bhve been brought
under control by biological methods
include sugarcane leaf hopper, sugar
cane borer, cocoanut moth, cocoanut
scale, black scale and more recently
oriental fruit fly. The use of re-
sistant varieties of food and feed
crops should be encouraged to mini-
mize the dependence on chemical con-
trols.
Integrated pest management (the
use of cultural practices, biological
controls, resistant varieties, release
of sterile pests, and other non-chemi-
cal methods along with chemical pesti-
cides) is the direction agriculture
must go in the future. Economics and
control effectiveness are going to de-
pend on flexible approaches to
individual problems.
CROPS AND PESTS
It is not possible in a manual
such as this to provide detailed in-
formation on all agricultural crops
and pests associated with them.
For more specific information and
literature, you should contact the
CVI Cooperative Extension Service.
On the Virgin Islands we are con-
cerned with the following commodities:
Fruit and nut trees
Corn and sorghum
Grain legumes
Tropical root crops
Vegetables
FRUIT AND NUT CROPS
While the primary type of pesti-
cide application equipment used in
horticulture on the mainland is the
air-blast sprayer, this type is not
practical on the Islands. Application
equipment consists solely of high
(over 100 psi) or low (under 100 psi)
pressure sprayers. Consequently the
problem of. drift and hazards to thM \
applicator are not quite as extreme
as with the air-blast sprayer. But as
the material must be put up in the air
these problems are still present to
more of a degree than on ground crops.
Do not apply when strong winds
are blowing. Be particularly careful
on planting borders with other crops
that may be more sensitive or have
residue problems because of food or
feed involvement. Avoid drifting
pesticides on yourself as the applica-
tor. Wear adequate clean protective
clothing as needed. Put protective
glove cuffs outside your sleeves when
spraying directly upwards. Do not
mix oil with hiqhlv toxic pesticides be-
cause oils evaoorate slowly thus increas-
ina the problem of drift and applicator
exDosure. Start vour sDrav Dattpmns so
the aoolicator will be working unwind at
all times.
Phytotoxicitv or sorav injury is
also a problem needing vour continuous
attention. There is a areat difference
in response between varieties as well as
between different fruits. Poor fruit
finish is often the result of chemical
iniurv. To avoid iniurv do not sDrav
at temperatures of 90F. or above and
some materials, such as sulfur should
not be aoolied above 850F..
Avoid spraying trees in early bloom
with insecticities whenever possible
because of toxicity to 3ees and other
pollinating insects. Avoid leaving
puddles of spray material or contamina-
ted water as this can be highly toxic to
bees foraging for water.
If you apply any of the insecti-
cides calling for either a 24 or 48
hour reentry period (see oaae 4) be
sure your client knows the situation
and is aware of the oroDer reentry
intervals as well as the davs to
harvest limitations.
CORN AND SORGHUM
One of the most widely used pesticides
is the herbicide atrazine. This is of
little hazard to the applicator and is
generally not considered a hazard to
wildlife. However, it is persistent
and may injure sensitive crops plant-
ed too soon on the same area after corn
or sorghum is harvested. Read the label
before planting a different crop. Be
careful not to leave puddles or permit
drift to hay or pasture land. If live-
stock gets sick for any reason, atra-
zine will be suspected so your applica-
tion technique must not be faulty.
Atrazine plus oil is recommended in
post-emergence treatments to provide
a quicker kill of weeds. However,
it is possible to cause severe damage
to corn or sorghum if unsuitable oil
or contaminated sprayers are used.
Read the label.
Some of the newer carbamate insect-
icides used on corn are highly texic
and you should use care in their
handling and application to protect
yourself against toxic splashes or
drift. In some areas runoff from
cultivated fields is a problem. This
can be reduced by leaving a sodded
buffer strip between the corn or
sorghum field and water. Also your
client may wish to consider planting
crops using safer pesticides near
sensitive areas.
GRAIN LEGUMES
Runoff can be substantially de-
creased by keeping sod between the
cultivated area and water. This, of
course, is your client's responsibi-
lity, but you can suggest it to him.
You can also suggest planting crops
that do not require hazardous materials
where runoff is a problem.
Operating your sprayer at ex-
cessive speeds will contribute to
both drift and slopping of spray from
the tank. If your client's fields
are rough you may be able to get him
to do a better job of leveling in the
future. Excessive pump pressures
also cause more drift because more
fine droplets are formed as pressures
are increased. Use tha lowest pressure
to still give good coverage and
satisfactory control.
Bee kill is a problem. Bees are
necessary pollinators as well as honey
producers and should be protected.
Spraying while bees are working on bloom
in the fields should be avoided whenever
possible. Spraying in early morning
or evening will help and choosing
pesticides of low residual activity
(see Table II,) is desirable.
Some of the herbicides used on soy-
beans can result in phytotoxicity. When
applied as preemergence treatments,
chloramben (Amiben) may stunt soybeans
if heavy rains concentrate the chemical
near the seeds. Randox, Ramrod, and
Lasso may cause leaf crinkling on seedlings.
Other herbicides used on soybeans can
cause post-emergence phytotoxicity.
Soybeans are treated with several
insecticides including toxaphene which is
deadly to fish in small quantities and
is persistent in the bottom silt of
ponds, lakes and streams. Avoid drift
and runoff. Other insecticides include
Lannate and methyl parathion. When
using these highly toxic materials you
must wear adequate protective clothing
and equipment both when mixing and
applying.
TROPICAL ROOT CROPS
Root crops commonly cultivated in
the Virgin Islands include yam, sweet
potato, cassava, and tannia. Root
rot and leaf spots are most common
fungus diseases. Black rot is a root
disease caused by fungus, Rosellina
spp.. No chemical soil treatment has
so far been effective in controlling
this condition. Rotation of crops and
sanitation are the only control measures
available.
VEGETABLES
As vegetables involve many different
crops and pests, you will be working with
TABLE 2. POISONING HAZARD TO HONEY BEES OF INSECTICIDES AND MITICIDES ON BLOOMING CROPS
Use Rating Residual Toxicity Material
Hazardous to honey bees at High, 1 day to 2 weeks arsenicals, Azodrin, Baygon, Bidrin, carbaryl (Sevin), car-
any time bofuran (Furadan), chlorpyrifos (Dursban), Dasanit,
dichlorvos (Vapona), dimethoate (Cygon), dinoseb, endothall,
EPN, fention (Baytex), Guthion, heptachlor, Imidan,
lindane and benzene hexachloride, malathion D, malathion
ULV, Matacil, Methyl Parathion, Methyl Trithion, naled
(Dibrom) D, parathion, Phosdrin, phosphamidon.
Not hazardous if applied Moderate, 3 hours to Abate, carbophenothion (Trithion), Carzol, chlordane, demeton
in either evening or 1 day (Systox), dioxathion (Delnav), Di-Syston EC, endosulfan
early morning when (Thiodan), endrin, ethion, heptachlor G, malathion EC,
honey bees are not methomyl (Lannate SP), methoxychlor, Meta-Systox-R,
foraging, except dur- Morocide, naled (Dibrom) EC, VC-13 Nemacide, Orthene,
ing periods of high Perthane, phorate (Thimet) EC, G, Phostex, Phosvel, TEPPs
temperature in these Thanite, Torak, toxaphene, trichlorfon (Dylox), Zolone.
times
Not hazardous to bees at Low, 1 hour to 1 day Acaraben (chlorobenzilate), Acaralate (chloropropylate),
any time allethrin, Baygon G, carbaryl (Sevin) G, carbofuran
Furadan) G, Dasanit G, Dikar, Di-Syston G, Galecron and
Fundal SP, Karathane, Kelthane, lime-sulfur, malathion G,
Morestan, oil sprays (Superior), propargite (Omite),
Pentac, Plictran, pyrethrum, rotenone, sulfur, Temik G,
tetradifon (Tedion). Most herbicides and fungicides.
Abbreviations: EC emulsifiable concentrate; D dust; ULV ultra low volume; WP wettable powder;
G granular; SP soluble powder
a variety of pesticides, several of
which are highly toxic. Adequate
clean protective clothing and equip-
ment is necessary. High pressure
equipment makes fine drift and in-
creases your problem as does the use
of dusts. As you turn the end of
the row you frequently move back
through the drift so protect your-
self accordingly.
Many vegetable fields border
sensitive areas backyards with veq-
etable gardens, ornamentals, children
and toys, pastures, other crops, barn-
yards, roads, etc.. Be sure not to
drift hazardous pesticides onto them.
Use equipment that is less likely to
cause drift in sensitive situations or
adjust it to minimize drift by lower
pressures, larger droplets, etc..
You must be careful not to drift re-
gistered pesticides from one crop onto
another for which it may not be re-
gistered. Similarly, the herbicide
you use safely and legally on one
vegetable crop may be deadly to a
nearby vegetable. Check to be sure
the crop following can be planted
with no risk of damage from herbicide
contaminated soil.
While it is the grower's respon-
sibility to notify his workers, make
him aware of the use of any pesti-
cide having the special reentry period
of 24 to 48 hours (see page 4). Be
sure your client is familiar with the
days to harvest limitations.
PESTS
It cannot be repeated too often
that effective pest control is based
on accurate recognition of the pest
causing the damage so that the appli-
cator can determine the most effective
and selective means of controlling the
damage. The following is a brief sum-
mary of nematode, insect and disease.pests
found in the Virgin Islands.
Nematodes
Nematodes are microscopic round
worms that require special diagnostic
examination to determine the species
present. Symptoms of their injury are
stunted or sickly-looking plants with
no visible aboveground damage. The roots
may show numerous knots or galls or
may be distinctly enlarged or swollen.
Nearly all common vegetable crops
are susceptible to nematodes and they
may become a production problem in gar-
dens planted in the same place each
year, particularly on light, sandy soil.
Problems can be extreme in soils low in
organic matter, soil nutrients and
moisture.
The most practical control measure
is rotating crops with non-susceptible
crops or converting to other uses for
a year or two. However, grass rotations
are needed to suppress weed growth as
the latter are excellent alternate
hosts to the nematodes. Turning over
the soil several times at monthly inter-
vals during the dry season will aid in
reducing nematode populations. If they
become excessively damaging, it may be
necessary to treat the soil with a
chemical nematicide before planting.
Diseases
A discussion of common, diseases
will be found on pages 20-24.
Insects
A discussion of injurious insects
will be found on pages 25-29.
DISEASES OF PLANTS IN THE VIRGIN ISLANDS 1
Name of Disease
Anthracnose
Black leg
Black rot
(bacterial)
Black rot
(fungal)
Black scurf
(sooty mold)
Bliqht. Early
Plants Attacked
Types Parts
Banana
Cucurbits
Legumes
Mango
Papaya
Tomatoes
Cole crops
Cole crops
Sweetpotato
Sweetpotato
Citrus
Celery
Eggplants
Tomatoes
Fruits
Stems
Leaves
Stems
Leaves
Leaves
Roots
Tubers
Leaves
Leaves
Stalks
Fruits
Injury Diagnosis
Round sunken spots with
pinkish-tan centers that
later darken into elongated
tan spots on stems. Whitish
spots on onion leaves.
Grayish spots speckled with
tiny black dots on stems
near ground; stem girdling;
wilted foliage
Black leaf veins; black
ring near outside edge on
crosscut stem.
Round black sunken spots on
tubers; black cancers on
underground parts of stems.
Dark Velvety growth that
interferes with photosyn-
thesis thus weakening plant.
Small, circular yellow-brown
spots becoming larger and
qraver as they spread.
Cankers sometimes qirdle
stems. Dark leathery spots
on fruit stem end.
Control Measures
Chemical: Spray with fungicides
Cultural: Rotate crops every
3 years; plant clean seed
Chemical: Treat seeds with
fungicides.
Cultural: Rotate crops; plant
resistant varieties.
Cultural: Rotate crops; plant
resistant varieties.
Cultural: Destroy diseased
plants; rotate crops; plant
clean seed pieces.
Chemical: Control of insects
whose honeydew secretions
encourage the mold.
Chemical: Apply fungicide every
7-10 days.
DISEASES OF PLANTS IN THE VIRGIN ISLANDS 2
Name of Disease
Blight, Late
Blossom end rot
Damping-off
Fruit rot
Fusarium wilt
Plants Attacked
Types Parts
Celery
Tomatoes
Eggplants
Tomatoes
Watermelons
Many plants
particularly
those raised
from slips.
Eggplants
Peppers
Tomatoes
Eggplants
Okra
Pepper
Tomatoes
Leaves
Stems
Fruits
Fruits
Seeds
Seedlings
Stems
Leaves
Fruits
Leaves
Stems
Internal cork Sweetpotato
Injury Diagnosis
Gray, water soaked spots at
leaf margins. Hard, corky
brown rot below surface of
fruit.
Large, dark, sunken corky
spots at blossom end. Pre-
valent where soil dried
rapidly while plants were
making vigorous growth.
Seed decayed; blackening of
roots and stem at ground;
water-soaked constriction
of stem at ground line.
Brown sunken stems at soil
line: brown or arav leaf
soots: larae. rinaed circular
brownish soots on fruit.
Yellowina and wiltina of
foliage beainnina with lower
leaves: browning of wood
tissue under qreen Dart of
stem.
Touah. corkv tubers.
Control Measures
Chemical: Apply fungicide every
7-10 days, midseason to harvest.
Cultural: Physiological disorder.
Provide calcium.especially during
drought.
Chemical: Treatment of seed bed
with funaicides or heat.
Cultural: Plant resistant
varieties.
Cultural: Rotate crops but do
not use other crops that are
susceptible. Plant resistant
varieties.
Cultural: Plant cork-free seed
stock.
Tubers
DISEASES OF PLANTS IN THE VIRGIN ISLANDS 3
Leaf spot
(bacterial)
Name of Disease
Leaf soot
(fungal)
Mildew, Downy
Plants Attacked
Types Parts
Many plants
Celery
Many plants
Cabbage
Cucurbits
Many plants
Leaves
Stems
Fruits
Leaves
Leaves
Roots
Injury Diagnosis
Variable leaf spotting with
brown to yellow circular
spots that spread. Found on
older leaf margins and
oroqress inward.
Spots vary from small to C
large, circular to irregular, C
light tan with darker v
borders but can also be black,
gray, or brown. Followed by
drying and defoliation.
Difficult to tell from
bacterial leaf spot.
High humidity-temperature C
conditions. Underleaf sur- a
faces have white to purple- s
black mold. Upper leaf
surfaces turn yellow and curl.
Brown, necrotic areas on roots.
Control Measures
Che,'i cal :
Cultural :
resistant
and clean
Spray with fungicides.
Crop rotation;
varieties; good drainage;
seed.
chemical: Spray with fungicides.
cultural: plant resistant
varieties; crop rotation with
unrelated plants.
chemical: Treat with fungicides
s soon as svmotoms appear as it
reads rapidly.
Mildew, Powdery
Many plants
Leaves
Stems
White powdery growth on upper Chemical: Spray with fungicides.
leaf surfaces. Later infect-
ed areas become brown and dry.
Appears in dry seasons.
Many plants
Leaves
Stems
Fruits
Mottling of leaf surfaces;
distorting of leaves; stems
streaked or necrotic. Fruits
develop knobbv soots, loss
of color, and spotting.
Chemical: Control of nearby weed
reservoirs and insect vectors.
Cultural: Resistant-varieties.
Mosiac
DISEASES OF PLANTS IN THE VIRGIN ISLANDS 4
Name of Disease
Panama Disease
Plants Attacked
Types Parts
Banana
Leaves
Stems
Injury Diagnosis
Control Measures
Reddish discoloration and Cultural:
streaking in leaves, resulting ieties.
in wilting and yellow dis-
coloration starting at tips
and along margins.
Plant Resistant var-
Purple blotch
Rhizoctonia
canker
Root rot
(bacterial)
Root rot
(fungal)
Onions
Eggplants
Tomatoes
Avocado
Carrots
Legumes
Leaves
Leaves
Stems
Fruits
Roots
Roots
Roots
Stems
Large purple spots intermixed
with white spots on leaves.
Hardy, shiny black bodies on
roots; white water-soaked
spots on fruits; brown cankers
on sprouts and stolons; sprouts
dying or developing numerous
off-shoots. Lower leaves
drooping but not dripping.
Decayed or soft roots.
Chemical:
fungicides,
Spray with
Cultural: Plant disease-
free pieces in clean soil.
Cultural: Good drainage,
release plants; rotate
crops.
Decayed roots and plant base. Chemical: Treat seeds with
fungicides.
Cultural: Plow cover crops
under 8 weeks before planting.
Rust pustules on all parts, Chemical:
but most common on underleaf Cultural:
surfaces. Dirty white when varieties.
young, but reddish brown with
age. Eventually kills foliage.
Use of fungicides.
Rust resistant
Rust
Legumes
Above
DISEASES OF PLANTS IN THE VIRGIN ISLANDS 5
Name of Disease
Scab
Plants Attacked
Types Parts
Avocados
Citrus
Cucurbits
Soft rot
Smut
Onions
Corn
Sorghum
Wilt (bacterial)
Wilt (fungal)
Wilt (virus)
Corn
Eggplants
Peppers
Tomatoes
Cole crops
Carrots
Leaves
Stems
Fruits
Bulbs
Stalks
Ears
Leaves
Leaves
Leaves
Roots
Injury Diagnosis
Sunken brown spots disfigure
stem, twist leaves, dis-
color fruit. Gummy ooze
exudes from spots.
Rotting of bulbs.
Large irregular galls that
release black spores.
Stunted, wilted plants;
yellow substance oozes from
cut parts.
Yellowish-green leaves
starting on one side of
plant, followed bv leaf drop.
Yellow-green leaves in center
spreading to roots or on
side of plant followed by
leaf drop.
Control Measures
Chemical: Spray with fungicides.
Cultural: Destroy diseased fruit;
rotate every 3 years.
Cultural: Harvest bulbs promptly
and store in dry, airy place.
Plant resistant varieties.
Cultural: Remove and destroy galls.
Rotate crop.
Cultural: Rotate crop; plant
resistant varieties.
Cultural: Plant resistant-
varieties.
Chemical: Control leafhopper
Cultural: Plant resistant
Varieties.
INSECT I'FSTS OF PLANTS IN THE VIRGIN ISLANDS 1
Name of Insect
Plants Attacked
Types Parts
Pest Recognition
Injury Diagnosis
Beans
Cole Lc'ois
Cucurbits
Papaya
Sorghum
Most plants
Leaves
Tiny, slow-moving, soft-
bodied insects found densely
congested on curled leaves.
Plant vitality weakened.
Molds form on honeydew.
Armyworms
Bean leaf
beetles
Cabbage looper
Corn earworm
Beans
Corn
Sorghum
Most vegetables
Beans
Cole crops
Soybeans
Beans
Corn
Cowpeas
Okra
Tomatoes
Leaves
Leaves
Leaves
Pods
Fruits
Black to greenish
caterpillars with light
stripes up to 40mm long.
Larvae are oval, green to
yellow, six-spined cater-
pillars. Adults are green,
yellow or red beetles with
black markings.
Pale-green caterpillars with
white stripe down both sides.
Up to 40mm long. Crawls with
a looping motion.
Light green to nearly black
caterpillars with light and
dark stripes. Red brown
head.
Holes eaten in leaves or
entire leaves eaten.
Regular-shaped holes
eaten in leaves.
Skeletonize undersurface.
Ragged holes eaten in
leaves.
Caterpillars bore into
pods, fruits and stems.
Eat kernels of corn down
to cob particularly
near tip. Brown, moist
castings.
Aphids
INSECT PESTS OF PLANTS IN THE VIRGIN ISLANDS 2
Name of Insect
Cornstalk borer
Lesser
Crickets, Field
Crickets, Mole
Cutworms
Diamondback moth
Flea beetles
Fruit fly
Plants Attacked
Types Parts
Corn
Sorghum
Beans
Cucurbits
Tomatoes, etc.
Cole crops
Onions
Peppers
Cole crops
Cucurbits
Okra
Many plants
Cole crops
Beans
Cole crops
Cucurbits
Tomatoes
Many plants
Mango
Young
plants
Seedlings
Fruit
Pods
Seedlings
Leaves
Stems
Roots
Leaves
Buds
Leaves
Roots
Fruit
Pest Recognition
Small, greenish, soil
inhabiting caterpillars.
Short, dark-brown, jumping
insects. Nocturnal.
Dark-brown, burrowing
insects.
Medium sized (up to 50mm)
caterpillars. Colpr varies
with species.
Small, green caterpillar.
Small moth lays yellow eggs.
Tiny, metallic hopping
beetles. Slender, whitish
worms up to 8mm long.
White maggots, pointed at
anterior end. 10mm long.
Small fly with two white
bands on yellowish abdomen.
Injury Diagnosis
Young plants tunneled
and killed
Seedlings and fruit
eaten.
Seedlings uprooted by
burrowing activities.
Leaves or small plants
cut off near ground by
soil-inhabiting cater-
pillars. Leaves ragged.
Stands spotty.
Small holes eaten in
underside of leaves and
buds. I
Small round holes eaten
in foliage by adults.
Larvae tunnel in roots
and eat small rootlets.
Eggs and larvae in fruit
pulp.
INSECT PESTS OF PLANTS IN THE VIRGIN ISLANDS 3
Name of Insect
Grasshoppers
Hornworms
Leafhoppers
Leaf miners
Lima bean pod
borer
Melonworm
Midges
Plants Attacked
Types Parts
Beans
Cucurbits
Tomatoes
Peppers
Tomatoes
Beans
Carrots
Lettuce
Okra
Beans
Cowpeas
Cucurbits
Okra
Tomatoes
Many plants
Beans
Cucurbits
Sorghum
Other grasses
Leaves
Leaves
Fruit
Leaves
Stems
Leaves
Pods
Leaves
Seeds
Pest Recognition
Gray to green, large, hopping
insects.
Large caterpillar, green to
brown. Horn-like projection
on posterior.
Small (3mm) wedge-shaped,
hopping insects
Tiny worm burrowing between
leaf surfaces.
Small, pink caterpillars.
Pale-green, white-striped
caterpillar.
Pink to orange larvae.
Adults are orange fragile,
gnat-like insects.
Injury Diagnosis
Leaf feeding.
Large caterpillar feeding
on leaves or fruit.
Leaves yellowed or bronzed
then wilting especially
at tips. May transmit
diseases also.
Foliage tunneled by tiny
maggots leaving lace-like
appearance.
Bores into bean pods.
Worms feeding on under-
side of leaves.
Eggs deposited during
pollination and larvae
develop in seeds.
INSECT PESTS OF PLANTS IN THE VIRGIN ISLANDS 4
Name of Insect
Millipedes
Mites, Spider
rl
Scale
Stink bugs
Slugs and
snails
Striped cucumber
beetle
Plants Attacked
Types Parts
Tomatoes
Beans
Corn
Eggplant
Lettuce
Tomatoes
Many plants
Cucurbits
Okra
Tomatoes, etc.
Lettuce
Cucurbits
Seedlings
Fruits
Leaves
Fruit
Leaves
Stems
Fruits
Leaves
Leaves
Stems
Leaves
Pest Recognition
Hardshelled, many-legged
worm-like
Microscopic, 8-legged,
spider-like insects.
1) protective coat of wax
like a blister (armored scale)
2) no coat of wax and move
about more (soft scale)
3) white, cottony appearance
mealybugss)
Green or brown, shield-
shaped sucking insects about
13mm long.
Legless, shelled or shelless
slimy animals.
Black-yellow striped beetles.
Injury Diagnosis
Cut off young shoots;
chew tender plant parts
Leaves webbed and dis-
colored by bronzing.
Calyx ends of fruit are
most susceptible to
attack.
Distinctive clusters
of these types of insects.
Give off honeydew secretions
which attact sooty mold.
Wilting of leaves or buds
Slimy tracks on vegetation.
Very large holes or com-
plete leaves eaten.
Feed on leaves and tender
shoots. Carry wilt and
mosaic diseases.
INSECT PESTS OF PLANTS IN THE VIRGIN ISLANDS 5
Name of Insects
Thrips
Webworms
Weevils
White grubs
Wireworms
Plants Attacked
Types Parts
Beans
Lettuce
Okra
Onions
Peppers
Cole crops
Cucurbits
Sorghum
Many plants
Beans
Corn
Peppers
Spinach
Sweetpotato
Corn
Lettuce
Leaves
Leaves
Heads
Pods
Fruit
Buds
Leaves
Roots
Roots
Bulbs
Pest Recognition
Tiny, elongated insects,
1-3mm long. Wingless or
4 narrow, hairy wings.
Spotted, coarsely-haired
caterpillars, 6-18mm long.
Silk-lined tunnels
White or yellow fat grubs.
Adult beetles have prominent
snouts.
Cream to pink, robust,
U-shaped grubs.
Hard, shiny larvae.
Injury Diagnosis
White, silvery blotches
on leaves
Leaves webbed together
and eaten.
Bore into pods.
Feed on foliage, buds
or fruit.
Large grubs feeding on
roots.
Roots and bulbs tunneled by
larvae.
PESTICIDE APPLICATION EQUIPMENT
The equipment used in applying
agricultural pesticides varies with
the crop, the type of application,
the pest to be controlled, and the
formulation used. There are several
types - granule spreaders, boom
sprayers, soil fumigation machinery,
dust pumps, etc. - but they all have
one requirement in common. They must
apply the right amount of pesticide
equally over the target area at the
recommended rate.
Too little, uneven, or too much
deposit are all inefficient uses of
material resulting in insufficient
control, spotty control, or excessive
residue, respectively. Proper adjust-
ment and calibration of the sprayer
prevents needless waste of pesticides.
The total deposit laid down on
a crop depends on:
- the concentration of pesticide in
the tank
- the rate of discharge through
the nozzles
- the speed at which the sprayer
travels
All of these factors must be controlled
if the correct amount is to be applied.
BOOM SPRAYERS
Your core manual tells you about
low pressure and high pressure field
sprayers. While they differ somewhat
in performance characteristics, both
are used as agricultural boom sprayers.
The methods of calibration apply to
both types as well as boomless sprayers
which have a central nozzle or nozzles
that produce a wide swath similar to
the others.
There are four variables that you
can adjust to govern the amount of
spray delivered by boom sprayers:
- nozzle spacing on the boom
- nozzle tip orifice size
- pressure
- ground speed of sprayer
Routine checks should be made to
be sure the nozzles are not badly worn,
have uniform output and spray pattern,
and equal fan angle.
GRANULAR APPLICATORS
Granular pesticides must be ap-
plied with precision. Application
of less than 90% of the rate may re-
sult in ineffective control. Applica-
tions greater than recommended are
costly and may injure the crop. The
amount of the granules applied depends
on the size of the metered opening,
speed of travel, field roughness, and
the flow rate of the granules. Granules
flow at different rates, depending upon
size, density and type of granule, tem-
perature and humidity. Therefore, it
is necessary to recalibrate for each
different formulation.
SOIL FUMIGATION APPLICATORS
Some of the principle methods
used for soil treatment are:
1. Injection system fumigantss and
other liquid soil pesticides)
a. Chisel cultivators, bT des,
or shanks with non-volatiles.
b. Sweep-type cultivator
shovels
c. Planter shoe
d. Plow
e. Transplant water
2. Surface treatment soil incorpo-
ration. Use mostly for low
and non-volatile materials.
Mixing is usually shallow, 5
inches or less. The simplest
method is to spray soil, turn
it in with disks and compact
with a drag, float, or culti-
Packer. Rotary hoes or weeders
are also used.
3. Drenching and flooding. Usual-
ly used prior to planting.
May also be applied by ir-
rigation water.
In all calibration measurements the
pesticide amounts applied should be
within 5 percent of the recommended
dosages or you must recalibrate
until they are.
APPENDIX: Suggested References
Maxwell, Lewis S.
1974. Florida Insects. Their Habits and Control. 119p
Maxwell Publ. Co., Tampa, Florida
Metcalf, C.L. and W. P. Flint
1962. Destructive and Useful Insects. 1087p McGraw-Hill
Book Co. New York
Naylor, A. G.
1974. Diseases of Plants in Jamaica. 129p Ministry of
Agriculture, Kingston, Jamaica.
Winters, Harold F. & George W. Miskimen
1967. Vegetable Gardening in the Caribbean Area. 114p
U.S. Dept. of Agriculture, Agricultural Handbook No. 323
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