Group Title: Bulletin
Title: Plant diseases and pests and their treatment
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00088911/00001
 Material Information
Title: Plant diseases and pests and their treatment
Alternate Title: New series bulletin - Florida State Department of Agriculture ; 3
Physical Description: 280 p. : ill. ; 22 cm.
Language: English
Creator: Brooks, T. J ( Thomas Joseph ), b. 1870
Watson, J. R ( Joseph Ralph ), 1874-1946
Publisher: State of Florida, Dept. of Agriculture
Place of Publication: Tallahassee, Fla.
Publication Date: May, 1938
Copyright Date: 1938
Edition: revised
 Subjects
Subject: Plant diseases -- Florida   ( lcsh )
Plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
General Note: Includes index.
General Note: Title from cover.
General Note: Parts written by T.J. Brooks and J.R. Watson.
 Record Information
Bibliographic ID: UF00088911
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AJP8388
oclc - 41395261
alephbibnum - 001824359

Full Text





NEW SERIES


NUMBER 3


Plant Diseases and Pests
and

Their Treatment


FLORIDA BULLETIN OF THE DEPARTMENT
OF AGRICULTURE
REVISED MAY, 1938





CONTENTS

Part I-Organic Kingdoms: Life Kingdoms Outlined; Classes
of Parasites; Methods of Transmission of Plant Diseases;
Forms of Bacteria; Pathogenic Bacteria; The Struggle
Between the Higher and Lower Orders of Life.
Part II-Florida Truck and Garden Insects.
Part III-Miscellaneous.




NATHAN MAYO
Commissioner of Agriculture


\C^35>


























ALL ILLUSTRATIONS IN THIS BULLETIN
ARE BY COURTESY OF
THE FLORIDA AGRICULTURAL EXPERIMENT STATION.










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PREFACE


MAN AGAINST INSECTS
Man has many enemies in the world. During the past
Sit seems as though all the elements of nature have combined
against him-drouths, floods, earthquakes, dust-storms and
tornadoes. We have read so much of late about these destruc-
tive forces and the devastation they have left behind, that
we are apt to forget about other smaller enemies who are
no less deadly to our welfare-insects.
These creatures, so small that usually we do not even
notice them, work their insidious war against man in a thou-
sand ways. They carry disease. They ruin his crops, and
attack the animals that labor for him. They breakfast on
his books, lunch on his clothes, and dine on his furniture and
food. Their individual work is minute, but often they travel
in vast armies-like the great swarms of locusts-and leave
a blanket of barren waste behind where there were waving
fields of grain before.
The chinch bugs often spread through the grain country
of the prairie states. They travel, like an epidemic, in search
of corn and wheat for food, threatening the grain supply
from which our daily bread is made.
Well may man gird himself against the insect world. Fire
and earthquakes and tempests frighten us with their omi-
nous fury but many people believe that if mankind is ever
destroyed it will not be by these spectacular elements, but
by hordes of tiny bugs.












I















ii







Plant Diseases and Pests

Part One

BY T. J. BROOKS
Assistant Commissioner of Agriculture

LIFE KINGDOMS
The two great life kingdoms are the vegetable and the
animal. There is a point where the two kingdoms so nearly
blend that the line of demarcation eludes the scientist.
Zoology being that branch of biology that treats of ani-
mal life, has various schemes of classification adopted by
b naturalists. The following classification is standard and
will help us to locate our subject in the general scheme of
biological studies. (Many smaller divisions are omitted.)
Classification of the Animal Kingdom
Phylum I; Protozoa (One celled animals)
Class 1, Sarcodina
Class 2, Mastigophora
SClass 3, Sporozoa
Class 4, Infusoria
Phylum II; Porifera (Sponges)
Phylum III; Coelenterata (Forms possessing a coelen-
teron)
Phylum IV; Ctenophora ("Sea Walnuts")
Phylum V; Platyhelminthes (Flatworms)
Phylum VI; Nemathelminthes (Roundworms)
L Phylum VII; Annelida (Segmented worms)
Phylum VIII; Arthropoda (Joint-footed animals; lobster,
crabs, centipedes, scorpions, spiders, mites,
insects)
Phylum IX; Mollusca (Snails, clams, oysters, octopods,
nautili)
Phylum X; Echinodermata (Starfish, sea urchins, sea
lilies, etc.)
Phylum XI; Chordata
Sub-phylum 1; Enteropneusta
Sub-phylum 2; Tunicata







DEPARTMENT OF AGRICULTURE


Sub-phylum 3; Cephalochorda
Sub-phylum 4; Vertebrata
Class 1 Cyclostomata (Lampreys and Hags)
Class 2 Elasmobranchii (Sharks, Rays, etc.)
Class 3 Pisces (Fish)
Class 4 Amphibia (Frogs, Toads, Salamanders)
Class 5 Reptilia (Turtles, Lizzards, Snakes, Croco- I
diles)
Class 6 Aves (Birds)
Class 7 Mammalia (Hairy Quadrupeds, Whales,
Seals, Bats, Monkeys, and Man)

*Divisions of the Animal Kingdom
Some specialized fields of biological study are as follows:
1. Mammalology treats of mammals, a class of vertebrates
whose females have milk-secreting mammary glands to
nourish their young, embracing all warm-bodied quadru-
peds,-also bats, seals, cetaceans and sirenians.
2. Ornithology, of birds;
3. Herpetology, of reptiles;
4. Ichthyology, of fishes and lower aquatic vertebrates;
5. Ascidiology, of the tunicata-a division of metazoans;
6. Echinology, of the echinodermata-a division variously
ranked;
7. Conchology, of the molusca;
8. ENTOMOLOGY, of the INSECT;
9. ARACHNOLOGY, of the ARACHNIDA-spiders, scor-
pions, etc.;
10. Crustaceology, of the crustacea-lobsters, crawfish,
shrimp, prawns, barnacles, sow bugs, etc.;
11. HELMINTHOLOGY, of the worms;

*Those organisms that destroy, and subjects relating thereto, are
capitalized in the following outline. We are concerned about those that
are useful but for the present discussion we are more concerned about
the destructive creatures of the living world.
There are disorders of plants and animals caused by numerous things
other than parasites. Among the diseases of plants which are not caused
by organisms may be mentioned those caused by injurious sprays,
poisonous gases, malnutrition, dieback due to lack of drainage or too
much ammonia, etc. Injuries from frost, heat, flood, drouth, depreda-
tions by insects and higher animals are not really diseases.






PLANT DISEASES AND PESTS


S12. Zoophytology, of the coelentera-invertebrates as coral,
or hydroid, the sea anemones, jelly fish, etc.
13. Paleontology, of the fossil remains of plants and ani-
mals.
14. Parasitology, of parasitism.


Divisions of the Vegetable Kingdom

Botany being the science of plants is somewhat older than
zoology, but its nomenclature was long the subject of con-
troversy. The International Botanical Congress of 1905
(which met in Vienna) adopted certain rules which have done
much to bring order out of confusion. The branches of
botany of most concern here are:
1. Morphology, relating to external form;
2. Histology, relating to structure of tissues;
3. Cytology, relating to the cell;
4. Embryology, deals with the development of the egg-cell;
5. Physiology, with the functions and vital actions of or-
gans;
6. PHYTOPATHOLOGY, with PLANT DISEASES;
7. Ecology, with environment influences;
8. Phytogeography, with plant distribution;
9. Taxonomy, with the classification of plants;
10. Paleobotany, of fossil plants;
11. ECONOMIC BOTANY,-including:
(a) Agriculture
(b) Forestry
(c) Horticulture
(d) Pharmacognosy
(e) Floriculture
and cognate subjects.

Animal life is defined as "Sentient organisms, having
organs of sense; life which feed on other organisms. Ani-
mal life is usually to be distinguished by its ability to take
food into a digestive tract or cavity, and by the power of
voluntary motion."







DEPARTMENT OF AGRICULTURE


The comparative relationship of the various divisions may
be shown as follows:
11 Kingdom
21 Phylum
31 Sub-Phylum
41 Class
51 Sub-Class
61 Order
71 Sub-Order
81 Family
91 Sub-Family
101 Genus
111 Species
121 Breed
131 Strain

Vegetable life is defined as "living organisms not possessed
of animal life."
The comparative relationship of the various divisions may
be shown as follows:
11 Kingdom
21 Phylum
31 Sub-Phylum
41 Class
51 Sub-Class
f1 Order
71 Sub-Order
81 Family
91 Sub-Family
101 Genus
111 Species
121 Breed
131 Strain
21 Phyla:
31 Cryptogamia: flowerless-propagating by spores
41 Myzophyta: slime molds
42 Thallophyta: algae, fungi and lichens
43 Bryophyta: mosses and liveworts
44 Pterodophyta: ferns and their allies
45 Schezophyta: fusion plants, including bacteria
42 Phanerogamia: flowering-having stamens and pistils
51 Angiosperms
61 Dicotyledons
62 Monoctyledons
52 Spermatophyta
53 Gymnosperms

Divisions on Another Basis

On another basis we may divide animal life as follows:
A. Vivipora: Those which are born and suckle their young
a Man
b All warm-blooded quadrupeds
c Bats, seals, cetaceans and ; renians
B. Ovipora: Those that hatch from eggs and do not suckle
a Fish
b Fowls
c Insects
d Reptiles-exceptions






PLANT DISEASES AND PESTS


C. Spores: Containing no embryo
a Protozoans
b Bacteria

CLASSES OF PARASITES

The Diseases They Produce, and Remedies
Al Animal Parasites: Any form of animal life that lives in
or on and at the expense of another form.
a2 Insects: Six-legred anthropods; 300,000 species
have been named and five times as many unnamed.
a3 Kinds
a4 Chewing
a5 Curculio
b5 Codling moth
c5 Canker worm
d5 Fall web worm
e5 Tent Caterpillar
f5 Pear slug
g5 Larva of moths and butterflies
h5 Beetles and their grubs
i5 Grasshoppers
j5 Crickets
k5 Saw flies and their larva
Sprays for Chewing Insects
1. Paris green
2. Arsenate of lead
3. Arsenate of soda
S4. Arsenate of lime
5. Scheele's green
6. London purple
7. White arsenate
8. Hellebore
b4 Sucking
a5 San Jose scale
b5 Oyster shell scale
c5 Plant lice
d5 Leaf hoppers
e5 Pear psylla






10 DEPARTMENT OF AGRICULTURE


Sprays for Sucking Insects
1. Lime sulphur concentrates
2. Self-boiled lime-sulphur mixture
3. Fish-oil soap wash
4. Kerosene emulsion
5. Crude petroleum emulsion, distilled
emulsion
6. Nicotine solution
7. Pyrethrum
8. Caustic potash
9. Carbolic acid emulsion
10. Sulphur spray
11. Resin wash

Fumigants
Effective against all insects when feasible to use them:
1. Hydrocyanic-acid gas
2. Carbon disulphide
3. Sulphur dioxide

The female mosquito is carnivorous, while the male is
herbivorous. That is to say, collectively, it eats herbs and
sucks blood, therefore is both a chewing and a sucking in-
sect-chewing plants and sucking animals. It is a menace
only to the latter.
B1 Vegetable Parasites: Organisms not possessed of animal
life; 400,000 species have been described. 4
a2 Fungi: Thallophytic plants destitute of chlorophyl
a3 Obligatory parasites, with power to exist under
but one condition
b3 Faculative parasites, having power to accommo-
date themselves to different conditions
c3 Obligate saphrophytes, living on dead organic
matter
d3 Faculative saphrophytes, living without free
oxygen.






PLANT DISEASES AND PESTS


Diseases They Produce In Plants
1. Brown rot of peach
2. Bitter rot of apple
3. Rusts
4. Scabs
5. Moulds
6. Smut
7. Mildew
8. Some "blights"
9. Citrus canker

Citrus canker is caused by the fungous Macrophoma
curvispora.
Sprays for Vegetable Parasites
1. Bordeaux mixture
2. Lime sulphur
3. Sulphur dust
4. Copper sulphate-lime dust
5. Corrosive sublimate

b2 Slime Molds: Not differentiated into cells, a mass of
protoplasm propagating by spores-functioning as
seed in plants.
c2 Cuscuta:
d2 Bacteria: The unicellular variety which propagates by
fisson-splitting of the organism. No universally ac-
cepted and satisfactory classification of bacteria has
been made.

Methods of Transmission of Plant Diseases

There are a number of methods by which plant diseases
are transmitted:
1. By soil inoculation: such as the Irish potato scab, the
Irish potato rhizoctonia, and the same with beans and onions,
tomato fuscopiceous wilt, and lettuce drop.
2. By water infection: as the lemon brown rot of Cali-
fornia.






12 DEPARTMENT OF AGRICULTURE


3. By air infection: as the lemon scab, celery leaf spot,
cucumber downy mildew, tobacco peronoaper, peach brown
rot.
4. By insect transportation: such as pear fire blight,
cucumber wilt-bacterial-potato mosaic, peach brown rot.
5. By seed inoculation: as bean anthracnose, bean bac-
terial blight, sugar cane red rot, watermelon anthracnose,
cucumber angular leaf spot.
6. By dead wood: such as wither tip of citrus fruit, stem-
end rot of citrus fruits.
7. By miscellaneous methods: some diseases are spread by
more than one method.

Other Divisions of the Subject of Plant Diseases
As to effect of disease on plants:
1. Killing: blights, rusts, wilts, etc.
2. Reducing health conditions
3. Producing malformations
As to parts affected:
1. Roots
2. Stalk
3. Foliage
4. Fruit
As to kind of plants attacked:
1. Forests
2. Fruit groves
3. Field crops
4. Truck crops
5. Ornamental shrubs
6. Vines
Pathology is the study of abnormal conditions; their
causes, symptoms and characteristics-including a study
of physiology and anatomy.
Therapeutics is that department of medical science that
relates to the treatment of disease and the action of remedial
agents on the organism, both in health and disease.
A physician is one versed in or practicing the art of medi-
cine or healing bodily diseases, usually by the administration







PLANT DISEASES AND PESTS


of remedies regarded as standard by the profession-such
as are in the Pharmacopoeia.


Forms of Bacteria

A bacterium is a schizomycetes, or microscopic fusion
fungus-a non-spore former.
Spherical bacteria-cocci.
Rod-shaped bacteria-bacilli-spore former.
Spiral bacteria-spirilla.
Pathogenic bacteria: capable of doing harm directly-a
few score of them. Two general classes: those which are
strictly parasitic and those which live free in nature. A full
list of the species and of the diseases which they produce
would be too comprehensive for present purposes even were
such a list scientifically established.


NAME OF ORGANISM
Corynebacterium diphtheriae
Microbacterium leprae
Clostridium tetnai
Clostridium botulinum
Salmonella enteritidis
Ebrethella typhi 1
Ebrethella para-typhi A -
Ebrethella Dara-tynhi B I


TYPE OF DISEASE PRODUCED
Diphtheria
Leprosy
Lockjaw
Food poisoning (toxic)
Food poisoning (cellular)
Typhoid fever


Brucella abortus Contagious abortion in cattle
Brucella melatensis Relapsing fever
Neisseria gonorrhoeae Gonorrhoea
Treponema pallidium Syphilis
Pneumococcus (types 1, 2, 3, 4) Pneumonia
Staphylococci (several types) Colds and sore throats
Streptococcus scarletina Scarlet fever
Shigella dysenteriae Dysentery (Bacillary)
Endamoeba histolytica Dysentery (amoeboid)
Vibrio comma Asjatic cholera
Lactobacillus acidophilus Sours milk
Lactobacillus bulgaricus Sours milk
Bacteria nitrifyingg) Lodge in root nodules where they
fixate nitrogen.
Such diseases as smallpox, measles, mumps, yellow fever, infantile
paralysis (acute anterior poliomyelitis), "parrot fever", and many others
are caused by specific substances called filterable viruses, the nature of
which has not been agreed upon by authorities.

A plant pathologist is one versed in diagnosing and treat-
ing plant diseases.
It is an anomaly in the economy of nature that human life
is dependent upon micro-organisms and at the same time
the greatest enemies of the human race are to be found
among these micro-organisms.


0






14 DEPARTMENT OF AGRICULTURE

Some of the uses of bacteria may be mentioned-
In the arts:
1. Maceration Industries-Such as Linen, Jute, Hemp,
Sponges, Leather.
2. Fermentative Industries-Such as Vinegar, Lactic
acid, Butyric acid, Bacteria in Tobacco Curing.
In Natural Processes:
1.-As Scavengers.
2.-In Food Processes.
3.-In Soil Fertility.
4.-In Silo.
5.-In the Dairy.
The Science of microscopic life is modern in origin-in a
practical sense it is less than a hundred years old. All para-
sites are not microscopic, and such as are not received earlier
attention. Insects, fungi, and bacteria constitute a militant
army that is the most formidable enemy of the human race.
Some of these are man's friends, and it behooves him to
understand each class, that he may cope with the problems
which they present.
That branch of biology which includes a study of human
life reaches its highest and most complex themes in psychol-
ogy and sociology.
Morphology treats of form-the static form of life.
Physiology treats of function-the dynamic phase of life.
For the purpose of our present study we shall have to
confine ourselves to those branches of biology which have
to do with organisms that work an economic injury to the
human race, touching incidentally those which work a
physical injury in our treatment of bacteria.
Therefore, by process of elimination, we come to three
branches of biological study:
Entomology-the study of insect life, as it relates to plant
pathology and economic botany.
Mycology-the study of fungi, as it relates to plant pathol-
ogy and economic botany.
Bacteriology-the study of bacteria, as it relates to plant
pathology, economic botany and human pathology-patho-
genic bacteria.






PLANT DISEASES AND PESTS


The limitation of this volume will not permit a treatise
on each of these subjects. Therefore we shall devote space
only to pathogenic bacteria. The reader is concerned prin-
cipally with means and methods of destroying injurious
insects, bacteria and fungi.

PATHOGENIC BACTERIA

Destructive Organisms
(Affecting the Human Body)
Pathogenic, disease-producing bacteria constitute a rela-
tively small number of species of bacteria. The harmless
species are not parasitic and cannot grow in an animal organ-
ism. There are two general classes of bacteria which
cause disease.
1. The non-pathogenic class, which live free in nature and
are not strictly speaking parasitic.
2. The true parasitic class, which live in the bodies of
animals.
The most generally accepted theory of how bacteria cause
disease is that they produce in their growth a number of
by-products of decomposition and that some of these by-
products are poisonous. It has not been shown that all
pathogenic germs produce their effect that way, but it has
been proven that it is the method in a number of cases.
Other methods are tissue destruction and mechanical
blocking of organs.
Recognizing that bacteria may produce poisons, we read-
ily see that it is not always necessary that they should be
parasitic in order to produce trouble.
Ptomaine poison is caused by eating putrified animal mat-
ter, or of alkaloids produced by bacteria. An alkaloid is any
nitrogenous organic base, especially of vegetable origin,
having a powerful toxic effect on the animal economy-as
strychnine or morphine.
It is not always the case that a specific germ produces a
definite disease, nor that each germ disease has its specific






16 DEPARTMENT OF AGRICULTURE

bacterium. For instance, the inflammation of wounds,
formation of pus, or the different types of blood poisoning,
such as septicaemia pyaemia, gangrene, etc., all appear to
be caused by bacteria, and it is impossible to make out any
definite species associated with the different types of these
troubles. The organism which normally causes influenza
may also cause such diseases as conjunctivitis, mastoiditis,
osteomyelitis, meningitis, pneumonia, endocarditis, peri-
tonitis, bronchitis. There are three forms of so-called pus
cocci, and these are found almost indiscriminately with
various types of inflammatory troubles.
Organisms are in the air, in the ground, in the water, on
clothing, on the skin, in the mouth and the alimentary canal.
Commonly they do no harm, but they have the power of doing
injury if they get into wounds or susceptible membranes.
Some species are universal inhabitants of the alimentary
canal and are ordinarily harmless or beneficial but under
other conditions they invade the tissues and give serious
trouble.
The following diseases are among those regarded as caused
by distinct specific bacteria: Typhoid fever, whooping cough,
scarlet fever, pneumonia, syphilis.
Most pathogenic bacteria can be in some way so treated
as to suffer a diminution or complete loss of their powers of
producing a fatal disease; on the other hand conditions may
cause an increase in the virulence of a pathogenic germ.
The general course of a germ disease is divided into three
stages: (a) incubation, (b) development, (c) recovery. Dis-
ease germs enter the body through the mouth, nose, skin
and secretary ducts.
The germs of scarlet fever, tuberculosis, pneumonia, etc.,
are carried to us through the air and breathed into the cells
of the lungs, where they find lodgment and penetrate the
delicate membranes and get into the circulation. It is then
that a battle ensues between the powers of the body and the
microscopic invaders. Only a few of the thousands of
species are able to combat nature's resisting power. Those
that sometimes win out and produce disease we designate as
pathogenic.






PLANT DISEASES AND PESTS


The human body possesses extremely remarkable pro-
tective methods against the invasion of bacteria or other
foreign substances. These defense mechanisms may be
placed in three general categories, namely: (1) Humoral
antibodies- (agglutinins, precipitins, lysins, opsonins and
antitoxins). (2) Phagocytosis-(a function of the white
blood cells). (3) Complement or alexins. The last of these
three may be placed with the first as a humoral antibody, but
differs from other humoral antibodies in that it is non-specific
for all types of invasion into the blood stream, and in that it
is always present in all normal blood.
The introduction into the blood stream of any foreign sub-
stance will encite the activity of one or more of the above
protective agencies, and thus is the struggle to overcome dis-
ease begun. Recovery of the individual follows if enough
antibodies can be produced to successfully combat the in-
vading organism. On the other hand, death follows if the
invading organisms are able to overcome the above men-
tioned protective agencies.
Once they have been formed, some antibodies persist
throughout the life of the individual. This is referred to
as lasting or permanent immunity. On the other hand, some
antibodies disappear from the blood stream as soon as re-
covery from disease is brought about. Diseases, conse-
quently, which produce antibodies that are easily disasso-
ciatable may be had any number of times, and life immunity
will never result. Influenza may be cited as a disease of this
sort, since an individual may contract it any number of
times. Diphtheria may, on the other hand, be cited as an
example of a disease which produces life immunity in all
who recover from it, since no individual may have it more
than once.
Strange as it may seem, the worst disease in the world is
malaria. It has been estimated that this disease alone costs
the South $2,000,000.00 per year in loss of human efficiency.
In India it is responsible for the death of 1,000,000 persons
each year. Malaria is produced by a one celled animal para-
site of which three or four species are infectious to man.
These are Plasmodium vivax, Plasmodium falciparum, Plas-






18 DEPARTMENT OF AGRICULTURE

medium malariae, and possibly a fourth species called Plas-
modium ovale.
The malaria parasite has two separate and distinct life
cycles. One of these occurs in the blood stream of man and
a few of the higher vertebrates, and the other occurs in the
body of a mosquito. The mosquito may, therefore, be re-
ferred to as a carrier of malaria. The mosquito most often
incriminated in the transmission of this disease is Anopheles
quadrimaculatus. However, various other species of the
genus Anopheles (such as A. crucians, A. punctipenis, etc.),
are known to be carriers.
There are parasitic plants which fasten themselves in the
skin and produce irritation. Ringworm, thrush, alopecia,
and a number of other diseases are caused by plants.
The study of medicine has been mostly empirical-by ex-
perimental observation-and with very little scientific basis.
Most of the advance made in scientific medicine is the result
of the discovery of the germ theory of disease, and this dis-
covery is due to bacteriology. The science has borne its most
beneficial fruits in the line of preventative medicine and
hygiene.
In contagious diseases what is needed is a germicide that
is harmless to the human body and that can be introduced
into the circulation. Pasteur said that each contagious dis-
ease is caused by a pathogenic germ or germs which may be
identified. He predicted that a universal germicide would
be discovered, harmless to human beings, and that thereafter
no one need contract disease by infection, and that contagion
would be impossible in the presence of such an universal
germicide.
Inasmuch as a germicide that would destroy plant germs
might not destroy animal organisms, it might not be possible
to have a universal parasitic specific. But if a germicide can
be found that is harmless to animal organisms, but which
destroys all vegetable germs, it would mark the greatest
stride in remedial science. The production of such a germi-
cide is claimed for the invention of William John Knox of
Ann Arbor. It produces scientifically a germicidal vapor
which is respirable. It is a chemical product produced by a







PLANT DISEASES AND PESTS


union of ozone and vapor of pinene. Atmosphere is introduc-
ed into the machine and dried, coming in contact with elec-
tric volts guaged to rule, when ozonized and vaporized it is
expelled in the form of vapor, the formula of which is
CloH'603-a gaseous pinene ozonide.

The Struggle Between the Higher and Lower Orders of Life
Man is destined to struggle for his existence and the at-
tainment of his desires. It is by struggle that he advances.
The more complex the civilization the more strenuous the
struggle. Only the primitive barbarian has no complex prob-
lems to worry him. The absence of difficult problems indi-
cates a primitive society. The capacity of the human race
to support themselves in great numbers in a given territory
is dependent upon a complex social compact and efficiency of
efforts. The wider the circle of man's activities the stronger
the conflict between mankind and nature.
The struggle between man and the microscopic organisms
of the living world has become intensified many fold during
the last century. The intensification has been brought about
by the spread of parasites and the diseases which they pro-
duce on the animal and vegetable kingdoms. This spread
has been accentuated by the universal exchange of commodi-
ties and the migration of people from clime to clime.
But for some friendly help automatically furnished by
certain of the feathered tribe and other consumers of worms
and insects the struggle would have been vastly intensified.
He has not always appreciated these helpers in the struggle
for existence.
It is not much trouble for man to rid the community of
wild game of the larger kinds, that are a menace to him or
his crops and domestic animals, but when it comes to dealing
with the microscopic living world the struggle is shifted to
an entirely different field. Although he has among these
some which contribute to his welfare there is enough of the
injurious kind to render it necessary for him to be of grave
concern.
In the outlines which have preceded the attempt has been
made to place before the reader a comparative analysis or






20 DEPARTMENT OF AGRICULTURE


classification of living things, so as to make it easy to see the
relationship of living creatures to man's welfare. Knowing
this, it will be easier to protect plants and animals from the
inroads of their enemies. The pursuit of this task is more
interesting as we understand the characteristics and life
habits of the underworld which we must combat.
There are 300,000 species of insects already classified, and
several times as many not classified. A large percent of
these is parasitic-pestiferous as to plants or animals, or
both.
There are 400,000 species of vegetable parasites classified.
A considerable percent of these infest plants or animals,
or both.
The distribution of these enemies of life is so nearly uni-
versal and their operation is so continuous and destructive
that they constitute man's greatest economic and physiol-
ogical menace. Millions of dollars must be spent annually
to combat the enemies of vegetation and other millions to
combat the enemies of animals and of man.
Man has enough to enlist all his fighting energies if he
keeps back the armies of untold millions and billions which
are continually attacking him personally and the sources of
his means of a livelihood. Only by constant vigilance and
the help of science and the art of employing efficiently the
most destructive agencies to the myriads of creatures which
are a menace to the vegetable and animal kingdoms which
minister to the welfare of mankind can the race survive in
the struggle for existence.

INSECTS AND SPRAYS

Mistakes Often Made
1. Treatments are often made for troubles which are in-
curable; consequently no results could possibly be obtained
from any operation which might be attempted against them.
2. Treatments are often given where there are no needs
for them. When first starting to control insects many people
get the idea that they must spray even if they do not know
whether a pest is present or not.






PLANT DISEASES AND PESTS


3. Expensive methods are often used when cheaper ones
would serve the purpose equally as well. Even when a cheap
method is used, it can be so manipulated that maximum
results may be obtained with a minimum expense.
4. The wrong time is chosen to make the application for
many insects. It is necessary to understand the general
principles of the life history of a pest in order to make timely
treatments for it.
5. The improper selection of the material to use against
an insect is the most common mistake that is made. As will
be clearly shown later, it is not possible to kill sucking insects
by the use of poison.
6. Too often the grower unknowingly purchases an in-
ferior grade of spray material. The grower must insist on
a good grade of spray material, since he is paying good
money and can rightfully demand the best.
7. The use of a spray outfit not adapted for the particular
operation, and the improper use of a good outfit, are the
causes of much failure. There are accessories for use with
spray outfits that will greatly simplify the operation.
If some of these common mistakes are guarded against
there is no reason why more satisfactory results cannot be
obtained in the spraying operations against insect pests.
Local experience is really the sure gauge for successful
spraying operations.


INSECTICIDES

Materials which are used to destroy insects are called
insecticides. They may be divided into four classes:
1. Poisons-which kill by being eaten and usually contain
some form of arsenic; so are often called arsenicals.
2. Contact insecticides-which kill by clogging up the
breathing system by suffocation or by a corrosive action on
the skin.
3. Repellents-which keep the insects from attacking the
plant or animal to which they are applied.
4. Gases-which are used for fumigating.






22 DEPARTMENT OF AGRICULTURE

Poisons
Poisons are the cheapest form of an insecticide. They are
applied to the food of the insects and must be eaten to be
effective. It is evident that poisons are effective only against
biting insects, which go beneath the surface of the plant for
their food. Nearly all of the poisons are made from arsenic
and consequently are termed "arsenicals." The amount of
arsenic varies with the different poisons, but the standard
for each is set by law. Arsenicals are insoluble in water, and
it is necessary constantly to stir a liquid spray to prevent the
poison from settling. In some of the arsenicals there is a
small quantity of what is termed "water-soluble" arsenic.
Such arsenic will readily combine with water, and when such
a combination takes place heat is given off. It is in this way
that the foliage of plants is burned when such sprays are
applied. The poorer grade poisons contain more water-
soluble arsenic than the better grades. With those poisons
which contain this water-soluble arsenic it is necessary to
add lime to prevent or reduce the burning of the foliage.
Most of the arsenicals may be used either as a dry or dust
spray, or as a liquid spray.

White Arsenic

This material should never be used as a spray to put on
plants, since it severely burns all tissue that it comes in con-
tact with. The only place it can be safely used is in making
poisoned baits for grasshoppers and cutworms. It is the
cheapest form of poison that can be purchased.

London Purple

This material is so variable in composition that the results
obtained by its use have been very unsatisfactory. It should
never be sprayed on any plants since it will severely burn the
foliage. It is possible to use this material in the poisoned
bran mashes, but it is seldom recommended. The use of Lon-
don purple has been discontinued for many years in progres-
sive spraying sections of the country.






PLANT DISEASES AND PESTS


Paris Green

From the beginning of the spraying practice Paris green
has been the only material that was generally recommended.
However, it has not given entire satisfaction. When used
as a liquid spray it settles very quickly and causes an uneven
application. It does not stick well on the foliage, and as it
contains a considerable amount of water-soluble arsenic, it
may burn the foliage of the plants to which it is applied. As
a spray material Paris green has practically gone out of use.
Liquid Spray.-Never more than one-half pound of Paris
green should be used for fifty gallons of water, and when one
is spraying tender plants, such as the peach, only one-fourth
pound should be used. The Paris green should be thoroughly
mixed into a thin paste and then added to the water. This
insures a better mixing of the powder and water. To neutral-
ize the action of the water-soluble arsenic it is necessary to
add two pounds of good stone lime to every fifty gallons of
water.
Under some conditions it is advisable to use a combined
spray of a poison with a fungicide. When Paris green is used
Sin combination with Bordeaux mixture, the same amount is
required for fifty gallons of Bordeaux as for fifty gallons
of water, and it is not necessary to add the lime.
Dry Spray.-For many crops it is not advisable to use a
liquid spray. Paris green may be applied as a powder, but it
must be dusted with eight or ten times its weight of flour or
air-slaked lime, preferably the latter. As it is usually best to
apply a dry poison when there is some dew on the plants, and
since dew will combine with the water-soluble arsenic, there
is certain to be considerable burning of the leaves from the
use of this spray upon cotton. The cotton plant is partic-
ularly sensitive to burning by Paris green, and for that
reason it is not recommended now for use on cotton.
Arsenate of Lead
This material is now almost universally used as a poison
spray. It is possible to make this material at home, but the
commercial preparations are to be preferred, as the contents
of the product are guaranteed. This poison is available to






24 DEPARTMENT OF AGRICULTURE

the grower in two forms-paste and powder. The cost of the
powder is somewhat higher than that of the paste, but the
cost of the spray made from either is about the same. This
poison is far superior to Paris green, as it does not settle so
quickly in the spray tank, is much more adhesive to the
foliage, and does not burn the plants; so there is no need for
the addition of lime to the spray. The action of this poison
is somewhat slower than that of Paris green but certainly as
effective.
Liquid Spray.-For a liquid spray either the paste or
powdered form of arsenate of lead may be used; three pounds
of the paste or two pounds of the powder are required for
fifty gallons of water. Mix the required amount of paste or
powder into a thin paste before adding to the barrel of water.
It is also possible to use this poison with the Bordeaux mix-
ture, the same proportion being used as suggested for water.
Dry Spray.-When a dry spray is desired the powdered
arsenate of lead may be used without the addition of any
other material. The powdered arsenate of lead is recom-
mended for use on cotton against all chewing insects.

Zinc Arsenite
This poison is comparatively new, but the results which
have been obtained from it thus far indicate that it may be
superior to any other poison now on the market. The great-
est feature of this poison is that it is very adhesive to the
foliage.
There are two materials which are poisonous to insects but
not to higher animals unless taken in quantities. These are
hellebore and pyrethrum or Persian insect powder.

Hellebore
Hellebore is a white powder made by grinding the roots of
the hellebore plant. This powder loses its strength rapidly
and must be fresh to be of any value. It may be used as a
dry or liquid spray. If a dry spray is desired, mix the helle-
bore with flour at the rate of one to three pounds, respec-
tively. For a liquid spray use one ounce of hellebore to three
gallons of water. As the hellebore loses its poisonous prop-






PLANT DISEASES AND PESTS


erties quickly, it may be safely applied to fruits and veg-
etables just before harvest.

Pyrethrum
Pyrethrum is a yellowish powder made by grinding the
dry flowers of the plant. The destructive power of this mate-
rial is due to an essential oil. It may be used in the same
manner as suggested above for hellebore and in the same
proportions. This material is also valuable as a spray for
fruits and vegetables that are ripening. If one will close up
rooms that are infested with flies and mosquitoes and then
fill the air with pyrethrum and keep the rooms closed over
night, most of the insects will either be killed or stupefied
and drop to the floor.

Poison Bran Mash for Grasshoppers
Probably the best poison for this purpose is called "Kansas
Grasshopper Poison." This is made as follows:
Bran .............................. 20 pounds
Paris green, or white arsenic .......... 1 pound
Syrup ............................. 2 quarts
L em ons ............................ 3
W ater ............................. 31/ gallons
To prepare this mash mix the bran and the poison thor-
oughly in a wash tub while dry. Squeeze the juice of the
lemons into the water and chop the pulp and peel into fine
bits and add to the mixture. Dissolve the syrup in the water
and then wet the bran and poison with the mixture, stirring
so as to dampen the mash thoroughly. The amount of water
here given is sufficient to properly moisten the bran.

Poisoned Baits for Cutworms
In addition to the Kansas grasshopper poison, which is
successful against cutworms, the following poison mash
gives excellent results:
Wheat or rice bran .................. 50 pounds
Arsenic or Paris green ............... 1 pound
M olasses ........................... 1 quart
Water to moisten.






26 DEPARTMENT OF AGRICULTURE

Mix the poison and the bran together dry. Dilute the
molasses in a gallon or two of water and add it to the poison.
Mix thoroughly and add only enough water to make the mix-
ture moist but not sloppy.
Poisoned baits of clover are often successful against cut-
worms. For this purpose cut a small quantity of clover or
alfalfa and chop this into rather fine bits. Then spread it out
and spray with Paris green at the rate of one-fourth pound
to twenty gallons of water. After the poison is dry on the
clover it is ready to be distributed in small bunches around
the base of the plants that are liable to attack by the cut-
worms. This poisoned clover should be made late in the
afternoon and distributed just before dark so that it will be
attractive to the worms when they come from their hiding
places at night.

Caution.-These particles of clover or alfalfa which have
been sprayed will retain the poison for some time. If the
worms do not eat this freely it should be collected and burned
and not allowed to dry up and blow around where stock and
poultry may get it.

Ant Poison

The following formula is especially valuable against those
ants which are attracted to sweets. This formula is best
prepared by a druggist:

White Arsenic ..................... 1/4 gram
Cane sugar ........................ 20 grams
W ater ..................: .........100 c.c.

The arsenic is dissolved in a portion of the water by boiling
and the sugar in the remaining portion. The two solutions
are then mixed and water is added to make up for the eva-
poration. Some color of fruit paste should be added to warn
of the poisonous nature of this solution. For use this poison
may be put in shallow dishes which are placed in the locations
frequented by the ants. The use of this poison is not advis-
able where there are small children in the home.






PLANT DISEASES AND PESTS


CONTACT INSECTICIDES
Contact sprays are applied to the insects and only inci-
dentally to the plants. With these the great aim is to apply
the material so carefully that it will certainly come in con-
tact with all the insects, as a mere spraying of the foliage
is of no value whatever.

Lime-Sulphur Wash
The lime-sulphur wash has always been the standard
remedy for the San Jose scale, and during the last few years
has come into wide use throughout the country. The lime-
sulphur wash is a chemical combination of the lime and the
sulphur. It has also been found to be an efficient fungicide,
and the spring applications just before the buds start are
very effective in killing the winter spores of various fungous
diseases.
The material is used both as a winter spray, when the
trees are dormant, and as a summer spray; but the solution
for the summer is much weaker. Materials of the proper
strength for winter use must never be used on trees that are
in leaf, as it will burn the foliage. The most effective season
to apply the winter strength of lime-sulphur is the early
spring, just before the buds begin to swell. It may be applied
in the fall, however, any time after the leaves drop.
There are three ways of preparing the winter wash of
lime-sulphur: by diluting the commercial concentrated solu-
tion to the required strength; by making a concentrated solu-
tion at home, and diluting when needed, and by making a
solution which, when finished, is ready for use without dilut-
ing.
Commercial Concentrated Lime-Sulphur
The leading manufacturers and dealers in insecticides are
now selling a concentrated lime-sulphur solution which
is made ready for use by merely diluting to the desired
strength. This is sold at a price that makes the final product
cost 21/2 to 3 cents per gallon,-nearly as cheap as it can be
made at home and with the saving of time and a disagree-
able job.






28 DEPARTMENT OF AGRICULTURE

Commercial concentrated lime-sulphur is a clear, reddish-
brown liquid. For use, this material is simply diluted with
water. The amount of water to be added is usually indicated
on the container, but it is best to test the strength. This is
done with a hydrometer, which will indicate the specific
gravity. These hydrometers, made especially for testing the
lime-sulphur mixture, may be obtained from Bausch & Lomb
Optical Company, Rochester, N. Y., and other dealers in
laboratory glassware. The dilutions should be made accord-
ing to the table given later.
Since the spray is quite clear it shows but little on the
trees. Some prefer to add lime to the material after it is
ready for the spray tank, but the lime should be added before
the final straining. For this purpose either lump or air-
slaked lime may be used, at the rate of six to eight pounds
to fifty gallons of the spray. There is no real advantage in
adding the lime, but it is easier to tell when the tree has been
well coated with the spray.

Home-made Concentrated Lime-Sulphur
If suitable appliances are at hand it is feasible to make up
concentrated lime-sulphur at home, which can be diluted for
use when needed. It is absolutely necessary to keep the
finished product sealed from the air. It is also essential that
the purity of the materials to be used are guaranteed, and it
is highly important that only the best grade of lime should
be used. Lime which is less than 90 per cent pure should be
discarded. In most cases it will be found that the commer-
cial concentrate is safer to use.
The New York Experiment Station has made extensive
experiments on the best methods of making and diluting
lim -sulphur, and the following is quoted:

Geneva Station Formula for Making Lime-Sulphur
Lime, pure ........................ 36 pounds
Lime, 95 per cent pure .............. 38 pounds
Lime, 90 per cent pure .............. 40 pounds
Sulphur, high grade, finely divided.... 80 pounds
W ater ............................ 50 gallons






PLANT DISEASES AND PESTS


In making, slake the lime in about ten gallons of hot
water, adding the lumps slowly so as to avoid too violent
boiling. The sulphur must be well moistened and made into
an even paste without lumps. Then pour the paste grad-
ually into the slaking lime, stirring constantly to prevent
the formation of lumps. When the slaking has finished
add the full amount of water and boil gently for an hour.
If kettles and fire are used, water must be added from time
to time to make up for the loss due to the evaporation.
It is much better if the cooking can be done with live
steam in a closed vessel, but an open fire will do. When
the boiling is done in this way the mixture will be more
likely to increase the volume and it will not be necessary
to add any water.

Regular Home-Made Lime-Sulphur Solution
Lime (good stone) ................. 20 pounds
Sulphur ........................... 15 pounds
W ater ............................ 50 gallons

This material when finished is of the proper strength for
use as a winter spray without any further dilution. It
contains much sediment and must always be carefully
strained before use.
Place the stone lime in an open iron kettle and add a
few gallons of hot water; then gradually add sulphur, which
has been made into a paste. Add about twelve gallons of
hot water and boil hard for an hour, stirring constantly.
Dilute with enough water to make fifty gallons.







30 DEPARTMENT OF AGRICULTURE

Dilutions for Dormant and Summer Spraying with
Lime-Sulphur Mixtures

Amount of Dilution. Number of Gallons of
Water to One Gallon of Lime Sulphur Solution
Reading on __ _
Hydrometer
For San Jose For Summer
Scale of Winter For Blister Spraying of
Strength Mite Apples
36 .............. 9 121/2 45
35 .............. 83/. 12 431/2
34 .............. 81/4 111,/ 411/2
33 ..............| 8 11 40
32 .............. 71/2 101/ 37%/
31 .............. 714 10 361/
30 .............. 63/4 91/2 3414
29 .............. 61/2 9 323/4
28 .............. 6 81/2 31
27 .............. 53/ 8 291/2
26 .............. 51/4 71/2 273/
25 .............. 5 7 26
24 .............. 41/2 61 241/4
23 .............. 41/4 6 223/
22 .............. 3 3/ 51/2 211/
21 .............. 313/2 5 193/
20 .............. 31,4 4 | 1814
19 .............. 3 41/4 17

Kerosene Emulsion
Kerosene emulsion is a very valuable insecticide for the
destruction of sucking insects, such as plant-lice, scale-
insects, etc., and for the destruction of insects hibernating
in rubbish or collected in large masses on tree trunks, etc.
Kerosene emulsion is not a poison, but kills by closing up
the spiracles or breathing pores of the insects. The ingre-
dients of the emulsion are kerosene, soap, and water in the
following proportions:
Laundry soap ...................... 1 pound
Boiling water ...................... 1 gallon
Kerosene ......................... 2 gallons

A low grade of kerosene, which is cheap, is as satisfac-
tory as the higher priced illuminating oil and, if desired,






PLANT DISEASES AND PESTS


soft soap may be substituted for the ordinary laundry soap.
The soap forms a coating around each minute particle
of oil, "emulsifying" it and permitting of its then being dis-
solved or diluted with water. Both the soap and oil are active
agents in destruction of the insects.

Preparation.-To prepare the emulsion, shave one pound
of laundry soap (or soft soap) into one gallon of soft water
(rain water). Have the water boiling hot. As soon as the
soap is all dissolved remove the solution from the fire and
add the two gallons of kerosene. At once agitate the ma-
terial violently. Continue for at least five minutes. This
is best done by the use of a bucket spray pump; turn the hose
or nozzle back into the bucket or tub so that the material is
constantly forced vigorously through the pump. In a few
minutes a smooth, creamy emulsion is formed, without any
free oil. This will get thicker as it cools, but if it is properly
made no free oil will separate out. This is the "stock solu-
tion" and will keep indefinitely if sealed from the air. (Do
not try to make the emulsion by stirring with a paddle, or
similar means, for this does not cause sufficient violent agita-
tion to thoroughly emulsify the oil.)

Dilution.-For use on trees or shrubs that are dormant,
the stock solution may be diluted with five to seven parts of
water, forming a spray containing 8 to 11 per cent of oil. On
trees or plants that are in leaf, one should dilute the stock
solution with ten to fifteen parts of water, thus making a
spray containing 4 to 6 per cent of oil. Soft-bodied insects,
such as plant lice, are usually killed with a 5 to 6 per cent
solution. The following table shows how to dilute the stock
solution to secure any desired per cent of oil:

For 4 per cent. strength, add 15 2/3 gals. water to 1 gal. stock solution.
For 5 per cent. strength, add 12 1/3 gals. water to 1 gal. stock solution.
For 7 per cent. strength, add 8 1/2 gals. water to 1 gal. stock solution.
For 10 per cent. strength, add 5 2/3 gals. water to 1 gal. stock solution.
For 12 per cent. strength, add 4 1/2 gals. water to 1 gal. stock solution.
For 15 per cent. strength, add 3 1/2 gals. water to 1 gal. stock solution.
For 20 per cent. strength, add 2 1/3 gals. water to 1 gal. stock solution.

Kerosene emulsion is best applied on bright, sunny days
when the wind is blowing, since a considerable quantity of






32 DEPARTMENT OF AGRICULTURE


the oil will evaporate quickly, and the danger of injury to the
plants will thereby be reduced.

Commercial Tobacco Extracts
There are now on the market highly concentrated ex-
tracts of tobacco. For use these liquids are diluted with
water according to the concentration of the brand and the
insect which is to be killed. Usually the tobacco sprays will
spread more readily and evenly on the plants if soap is added
to the solution at the rate of one pound to fifty gallons. It
has been found that strong tobacco sprays may kill the eggs
of some plant-lice. The weaker dilutions of tobacco extracts
are especially valuable for destroying soft-bodied insects, as
plant-lice. "Black Leaf 40," "Nico-Fume," "Sulphate of
Nicotine," and "Black Leaf Extract," are some of the trade
names for the tobacco extracts. The cost of these extracts
may seem prohibitive, but when diluted the spray is not any
more expensive than other materials for the same purpose.

Home-Made Tobacco Extracts
It is possible to make an extract at home from the to-
bacco stems or dust. Place one pound of the stems or dust
in one gallon of water and heat to just the boiling point for
one hour, making up for any loss of water. This solution
should never be allowed to actually boil, as some of the active
principles will be lost in the vapors. Dilute this mixture
with two parts of water and add soap at the rate of one pound
to fifty gallons of spray.

Whale Oil Soap
Whale oil or fish oil soap is commonly found for sale in
the hard form, made from caustic soda. The potash soaps
are much to be preferred, as they dissolve more readily in
water. This soap solution is especially valuable for use
against soft-bodied sucking insects, but it is not generally
effective against the more resistant sucking insects. For
plant-lice, dissolve this soap in water at the rate of one pound
to seven gallons. The hard soap must be shaved into a small







PLANT DISEASES AND PESTS


quantity of boiling water and the mixture stirred for some
time. After the soap has been dissolved, cold water may be
added to make the above formula.

Laundry Soap
If whale oil soap is not available, it will be found that a
simple solution of laundry soap is very effective for spraying
plant-lice. Any good grade of laundry soap may be used for
this purpose. The formula of one pound to seven gallons of
water has proven very effective against plant-lice. Laundry
soap does not dissolve readily, and it is best to shave it into a
liberal quantity of boiling water and stir frequently. When
the dissolution of the soap is complete, cold water may be
added to make the above formula.

Sulfur

Dry sulfur or powdered sulfur, sometimes called flowers
of sulfur, is often used as a contact insecticide, especially
against the red spider. The dry sulfur should be thoroughly
dusted over the foliage in an effort to hit all the spiders. It
is best to apply sulfur when the foliage is moist with dew.
Hydrated lime mixed in equal parts with the sulfur will make
it more adhesive. Sulfur becomes effective only when the
sun vaporizes it; so if applied when the sun is not shining it
will remain inactive until the first bright day.
Repellents.-A repellent is any material which is applied
to a plant or animal that may be of service in driving away
any insect that might attack it. Dry air-slaked lime is of
service in driving away some pests. It should be dusted
directly on the insects which are feeding upon the plant.
Tobacco dust acts as a repellent to some insects, especially
the root-feeding insects. Naphthalene flakes or moth balls
act as a repellent for insects that infest stored products.
Bordeaux mixture, a fungicide, acts as a repellent for many
insects, especially for some forms which feed upon potatoes
and tomatoes. The various fly sprays which are applied to
stock merely act as repellents.






34 DEPARTMENT OF AGRICULTURE

Protective Tree Washes
1. Dissolve one pound of hard soap in three gallons of
water. Add one-half pint of crude carbolic acid and two
ounces of Paris green. Then add enough lime to make a thick
paste, such as will be easy to apply to the trees.
2. Dissolve sixteen pounds of hard soap in eighty gallons
of boiling water. Then add two quarts of crude carbolic acid
and enough freshly slaked lime to make a thick paste.
3. Slake one bushel of lime in a small quantity of warm
water. Add ten pounds of sulfur, which has been previously
made into paste. Then add one-half gallon of gastar and
dilute with water to fifty gallons.
4. Dissolve seventy pounds of quicklime in fifty gallons
of water. Add six pounds of caustic potash and two and
one-half pints of crude carbolic acid.
These washes should be painted on the trunks and lower
limbs of the trees, and the application should be very thor-
ough to be effective. Every small crevice in the bark should
be well coated with the wash. Unless rains occur immedi-
ately after the application is made, two or three applications
will be sufficient during the summer.

Fly Repellents
There are a great many home-made and proprietary ex-
ternal remedies for repelling flies from stock. Many of them
have a value, but many more are of no service whatsoever.
The most common defect of many of the repellents is the
very short period during which they are effective. Some
repellents are undoubtedly poisonous and should be used with
extreme care. The qualities to be sought in a satisfactory
repellent are absence of toxic or other detrimental properties,
a decided repellent action on the flies, and a long period of ef-
fectiveness. The following has given satisfactory results
over the country:
No. 1. The Moore formula:
Fish oil ...........................100 parts
Oil of tar .......................... 50 parts
Crude carbolic acid ................. 1 part






PLANT DISEASES AND PESTS


No. 2. The Bishop formula:
Fish oil ............................ 1 gallon
Oil of tar ......................... 2 ounces
Oil of pennyroyal .................... 2 ounces
Kerosene ........................... 1 pint
This mixture is very effective in keeping flies from live
stock when applied lightly with a brush.
No. 3. The Parrott formula:
Fish oil ............................ 2 quarts
Crude carbolic acid .................. 1 pint
Oil of pennyroyal ................... 1 ounce
Oil of tar .......................... 8 ounces
Kerosene sufficient to make one gallon of the mixture.
The cost of this is given at 80 cents a gallon. It must be
applied with a hand atomizer and not with a brush.
Fumigants
Fumigation is available only for insects that can be treat-
ed in an enclosed space. This method is good for the treat-
ment of pests which attack stored products and for green-
Shouse pests.
Carbon Bisulphide
This material is most extensively used against insects
which attack stored products. Household goods may be
fumigated with this material if the proper precautions are
taken. It is used to some extent for root-feeding insects by
injecting it into the soil. Carbon bisulphide is a clear, yellow
liquid with a very strong and disagreeable odor. When ex-
posed to the air it evaporates very quickly and the fumes
being heavier than air go to the bottom of the enclosed space.
The fumes are not so effective below temperatures of 600 F.
and a larger dose is required under such conditions. Any
material to be fumigated should be placed in as small a space
as possible, since it is the confined area and not the contents
that determines the dosage. The bisulphide should always
be put in shallow dishes and placed on top of the material
that is to be fumigated. The amount of bisulphide necessary
for a single application varies considerably according to the






36 DEPARTMENT OF AGRICULTURE

insect that is to be killed. One pound to a thousand cubic
feet is sufficient for many insects, but as much as ten pounds
is required for others.
Do not allow any fire or source of fire, as a lighted cigar,
to be near the fumigation or the stored bisulphide. The
fumes from carbon sulphide are highly inflammable and
under certain conditions explosive. Use the same precaution
in handling this material that would be used in handling
gasoline. The fumes should not be inhaled as they cause
suffocation which results in dizziness.

Carbon Bisulphide Emulsion
Carbon bisulphide emulsion consists essentially of seven
parts of carbon bisulphide and three parts of an emulsifier.
The emulsion is used at the rate of one quart to fifty gallons
of water and this diluted mixture is applied at the rate of
three pints to the square foot of surface. In making the ap-
plication one-half the required amount is applied and after a
few minutes the remaining half is put on. The ground tem-
perature should be above 45 degrees F. The dosage must be
exact since an under-application will not kill the grub and
an over-application may produce serious burning to the
grasses.
Pa. Bul. Vol. 12 No. 4, April 1, 1929. p. 14. The Japanese
Beetle in Pennsylvania.
Sulphur
The fumes of burning sulphur have long been recognized
as a standard remedy for the fumigation of dwellings. It is
an excellent remedy for bedbugs in empty houses. The seri-
ous objections to the use of sulphur fumes are: they will
bleach fabrics; they will tarnish brass; they will destroy
vegetation, and they will destroy the germinating power of
seeds.
Tobacco
For fumigating greenhouses tobacco fumes are univer-
sally used. This material can be employed where the most
tender plants are grown, and it is especially effective in con-






PLANT DISEASES AND PESTS


trolling plant-lice. Many outdoor plants, as melons, and low
shrubs or trees, may be fumigated with tobacco fumes by
means of especially constructed covers. The methods of fumi-
gation are to burn tobacco stems, or dust, or to vaporize some
of the liquid extracts, or to burn some of the punk papers
now for sale. This last method is most satisfactory as it is
possible to designate the proper amount of paper to be burned
in a given confined space.

Hydrocyanic Acid
This is the most active fumigant known. It is made by
combining water, sulphuric acid, and potassium cyanide.
This gas is a deadly poison to all plant and animal life, and
it should not be used unless the operator has had experience
or unless proper directions are carefully followed.



STANDARD SPRAYS AND SOLUTIONS USED IN THE
OVERCOMING OF PLANT DISEASES
Bordeaux Mixture is used for the control of fungous dis-
eases of many vegetables and fruits and as a deterrent of
flea-beetle attack. It can be purchased in convenient pack-
age form from seed dealers or prepared at home from blue-
stone (copper sulphate), and fresh stone or lump lime (quick-
lime).
Dissolve the bluestone in a wooden or earthenware ves-
sel, using hot water. Dilute with half the water. Do not
use tin or other metal containers, as they would be spoiled.
Slake the lime by adding water, a little at a time. When
reduced to a milky fluid, dilute with the rest of the water and
strain through double cheese-cloth or a brass wire strainer
of 18 meshes per inch and pour into it the bluestone solution.
Stir well and apply at once. This is best when prepared fresh
for each using.
Mercuric chlorid (corrosive sublimate) is used for treat-
ing seed potatoes and cabbage seed for diseases. It may be
purchased at drug stores in the form of tablets. Dissolve






38 DEPARTMENT OF AGRICULTURE


two large tablets in a quart of water to make a 1 to 1000 solu-
tion. For larger quantities use 21/2 ounces to 15 gallons of
water. Corrosive sublimate is a deadly poison. It attacks
metals and, therefore, must be used only in a wooden, glass,
or earthenware vessel.
Formaldehyde (formalin) is used for treating seed po-
tatoes, seeds, and soil, to prevent diseases. This is a clear
solution of 40 per cent formaldehyde gas in water. It is very
irritating to the eyes and to cuts, but not poisonous. It does
not attack metals. Use teaspoonful to a teacupful of water,
1 ounce to 2 gallons of water, and 1 pint or pound to 30 gal-
lons of water (for potatoes and onions). It is not an insecti-
cide.
Lime is used to control cabbage clubroot. It neutralizes
soil acidity and therefore tends to increase scab on potatoes.
It acts at the same time to a limited extent as a deterrent
against certain insects which may be in or on the soil, such
as maggots and grubs, and is a good remedy for slugs. Air-
slaked or hydrated lime is the best form to use.
Lime-sulphur is a valuable spray for fruit trees applied
during the dormant season, but not suited for use on vege-
tables. Experiments have shown that potatoes are injured
rather than benefited by it.

Methods Successfully Used in Sterilizing Seed Beds
Steam tile are used to sterilize the soil by placing lines of
2-inch to 3-inch glazed tile lengthwise in the beds to be steril-
ized, 2 to 21/2 feet apart and 15 inches below the surface, and
these are left there permanently. They provide drainage
for the beds, may be used for subirrigation, and are available
at any time for sterilizing the soil, the only labor being the
covering of the beds with boards or tarpaulin and the con-
necting of the tile with a boiler by means of a piece of steam
hose. It is advisable to spade up the soil, so that the steam
may more readily penetrate it.
Steam pans furnish another method of steaming, by
means of admitting steam under inverted galvanized iron






PLANT DISEASES AND PESTS


pans, 6 by 10 feet and 6 inches deep. This has been used in
the sterilization of tobacco seed beds and in greenhouse beds,
and has given very satisfactory results. The use of steam at
pressure of 80 to 100 pounds and treatment for half an hour
to an hour after the soil has reached a temperature of 212F.,
as indicated by soil thermometers, has given the best results.
Formaldehyde sterilization is accomplished by drenching
the soil with a 1 to 100 or 1 to 200 solution of standard
formaldehyde (40 per cent), at the rate of 34 of a gallon per
square foot of area, several days before the soil is to be used.
Formaldehyde, however, does not rid the soil of nematodes,
as steaming does. This method has been used to excellent
advantage in the sterilization of lettuce beds for the preven-
tion of fungous diseases.



FUNGICIDES AND INSECTICIDES

Many of these mixtures can be obtained already prepared
from reliable dealers, which saves much time and trouble in
mixing them. The following precautions should be taken
into consideration:
1. Care should be taken to keep all substances employed
in spraying where they cannot be gotten at and used by mis-
take. All substances should be correctly labeled.
2. Solutions and mixtures containing copper sulphate,
corrosive sublimate and arsenate of lead should be made in
wood, glass or earthen vessels.
3. Arsenical solutions should not be applied to fruits, etc.,
within two weeks of the time they are to be used as food.
4. Trees should not be sprayed when they are in blossom,
as the bees, which are necessary to fertilize the flowers, may
be destroyed.
5. Florida growers interested in spraying and other
means of checking insect pests, not fully covered herein,
should write the director of the Florida Experiment Station
at Gainesville, for further information.






40 DEPARTMENT OF AGRICULTURE

Bordeaux Mixture
4 pounds copper sulphate (blue vitriol).
4 pounds lime unslakedd).
25-50 gallons of water.
Dissolve the copper in hot or cold water, using a wooden
or earthen vessel. Slake the lime in a tub, adding the water
cautiously and only in sufficient amount to insure thorough
slaking. After thorough slaking, more water can be added
and stirred in until it has the consistency of thick cream.
When both are cold, pour the lime into the diluted copper
solution of required strength, straining it through a fine-
mesh sieve or a gunny cloth, and thoroughly mix. The stand-
ard mixtures are:
(a) 25 gallons (full strength solution, or 4-4-25 formula).
(b) 50 gallons (half strength mixture, or 4-4-50 formula).
It is then ready for use. Considerable trouble has fre-
quently been experienced in preparing the Bordeaux mix-
ture. Care should be taken that the lime is of good quality
and well burned, and has not been air-slaked. Where small
amounts of lime are slaked, it is advisable to use hot water.
The lime should not be allowed to become dry in slaking,
neither should it become entirely submerged in water. Lime
slakes best when supplied with just enough water to develop
a large amount of heat, which renders the process active. If
the amount of lime is insufficient, there is danger of burning
tender foliage. In order to obviate this, the mixture can be
tested with a knife blade or with ferro-cyanide of potassium
(1 oz. to 5 or 6 ozs. of water). If the amount of lime is in-
sufficient, copper will be deposited on the knife blade, while
a deep brownish-red color will be imparted to the mixture
when ferro-cyanide of potassium is added. Lime should be
added until neither reaction occurs. A slight excess of lime,
however, is desirable.
The Bordeaux mixture is best when first prepared. Stock
solutions of lime and copper can be made and mixed when
required.
The following, known as the 6-4-50 formula, is in very
general use:






PLANT DISEASES AND PESTS


6 pounds copper sulphate.
4 pounds lime.
50 gallons water.
Bordeaux Mixture for Peach Foliage
The Bordeaux mixture, as ordinarily applied, frequently
injuries to some extent the foliage of the peach, etc., causing
a shot-hole effect on the leaves. This injurious effect has
been shown to be largely obviated by the use of the follow-
ing:
3 pounds copper sulphate.
6 pounds lime.
50 gallons water.
This is known as the 3-6-50 formula. Some experimenters
have also recommended the following for peach foliage:
(a) 2-2-50 formula (Cornell Agr. Exp. Sta. Bull. 180).
(b) 3-9-50 formula.
The latter contains three times as much lime as copper
sulphate.
Bordeaux Resin Mixture
5 pounds resin.
1 pound potash lime.
1 pint fish oil.
5 gallons water.
To make resin solution, place resin and oil in a kettle and
heat until resin is dissolved. Cool slightly and then add lye
slowly and stir. Again place the kettle over the fire, add the
required amount of water and allow the whole to boil until
it will mix with cold water, forming an amber-colored solu-
tion. Take 2 gallons of the resin solution and add to it 10
gallons of water. Mix this with 40 gallons of Bordeaux mix-
ture.
Recommended for asparagus rust on account of its ad-
hesive properties. (N. Y. Agr. Exp. Sta. (Geneva) Bull.
188).
Saccharine of Copper
4 pounds copper sulphate.
4 pounds lime.
4 pints molasses.
25 gallons water.






42 DEPARTMENT OF AGRICULTURE

Slake 4 pounds of lime and dilute the same with water.
Dissolve 4 pints of molasses in a gallon of water and mix with
the lime. Stir thoroughly, and let it stand for a few hours.
Dissolve 4 pounds of copper in 10 gallons of water and pour
it into the lime-molasses solution, while stirring briskly.
Allow the mixture to settle. Draw off the clear, greenish
solution for use. Recommended in France as a substitute
for the Bordeaux mixture.
Ammoniacal Copper Carbonate
5 ounces copper carbonate.
3 pints ammonia (260 Beaume).
50 gallons water.
Dissolve the copper carbonate in ammonia. This may be
kept any length of time in a glass-stoppered bottle and di-
luted to the required strength. The solution loses strength
on standing.
Eau Celeste
(Blue Water)
2 pounds copper sulphate.
1 quart ammonia.
50 gallons water.
Dissolve the copper sulphate in 6 or 8 gallons of water;
then add the ammonia and dilute 50 or 60 gallons of water.
Copper Carbonate Mixture
1 pound copper carbonate.
40 gallons water.
Mix the copper carbonate with small quantity of water
to make a paste; then dilute with the required amount of
water. For fruit rot of the peach, etc. (Delaware Agr.
Exp. Sta., Bull. XXIX.)
Copper Acetate
6 ounces copper acetate (diabasic acetate).
50 gallons water.
First make a paste of the copper acetate by adding water
to it; then dilute to the required strength. Use finely
powdered acetate of copper, not the crystalline form. For
the same purpose, and of the same value, as the preceding
formula.






PLANT DISEASES AND PESTS


Copper Sulphate Solution
(Strong Solution)
1 pound copper sulphate.
25 gallons water.
Apply only on trees without foliage.
Copper Sulphate Solution
(Weak Solution)
2-4 ounces copper sulphate.
50 gallons water.
For trees in foliage.
Potassium Sulphide
3 ounces potassium sulphide.
10 gallons water.
Valuable for gooseberry mildews, etc.
Potassium Permanganate
1 part potassium permanganate.
2 parts soap.
100 parts water.
Recommended in France for black rot and mildew of the
grape, etc.
Iron Sulphate and Sulphuric Acid
Water (hot), 100 parts.
Iron sulphate, as much as will dissolve.
Sulphuric acid, 1 part.
Prepare solution just before using. Add the acid to the
crystals, and then pour on the water. Valuable for treat-
ment of dormant grape vines affected with anthracnose,
application being made with sponge and brush.
Corrosive Sublimate
(For Potato Scab)
2 ounces corrosive sublimate.
15 gallons water.
Dissolve the corrosive sublimate in 2 gallons of hot water.
Then dilute to 15 gallons, allowing the same to stand 5 or
6 hours, during which time thoroughly agitate the solution
several times. Place the seed potatoes in a sack and immerse







44 DEPARTMENT OF AGRICULTURE

in the solution for 11/2 hours. Corrosive sublimate is very
poisonous; consequently, care should be taken in handling it,
nor should the treated potatoes be eaten by stock. The solu-
tion should not be made in metallic vessels.
Formalin
(For Potato Scab)
8 ounces formalin (40% solution).
15 gallons water.
Used for the same purpose as corrosive sublimate, but not
poisonous. Immerse the seed potatoes for two hours.


INSECTICIDES


Paris Green-Dry
1 pound Paris green.
20-50 pounds flour.
Mix thoroughly and apply evenly; preferably when dew
is on the plant.
Paris Green-Wet
1 pound Paris green.
1/2 pound quicklime.
200 gallons water.
Slake the lime in part of the water, sprinkling in the Paris
green gradually; then add the rest of the water. For the
peach and other tender-leaved plants, use 300 gallons of
water. Keep well stirred while spraying.
Arsenite of Lime
1 pound of white arsenic.
2 pounds of fresh burned lime.
1 gallon of water.
Boil together for 45 minutes and keep in a tight vessel.
Add 1 quart of this to a barrel (50 gallons) of water, for use.
This insecticide has been recommended by a number of
experimental stations, but has not yet been sufficiently tested
at the Massachusetts Station to receive an endorsement.






PLANT DISEASES AND PESTS


Arsenate of Lead
4 ounces arsenate of soda (50% strength).
11 ounces acetate of lead.
150 gallons of water.
Put the arsenate of soda in 2 quarts of water in a wooden
pail, and the acetate of lead in 4 quarts of water in another
wooden pail. When both are dissolved, mix with the rest of
the water. Warm water in the pails will hasten the process.
For the elm-leaf beetle, use 25 instead of 150 gallons of
water.

Whale Oil Soap
2 pounds potash whale oil soap.
1 gallon hot water.
For winter use only.

Kerosene Emulsion
1 pound hard soap, shaved fine.
1 gallon water.
2 gallons kerosene.
Dissolve the soap in the water, which should be boiling;
remove from the fire and pour it into the kerosene while hot.
Churn this with a spray pump till it changes to a creamy,
then to a soft butter-like mass. Keep this as a stock, using 1
part in 9 of water for soft-bodied insects, such as plant-lice,
or stronger in certain cases.

Mechanical Emulsion
A substitute for the last. Made entirely by the pump,
which draws water and kerosene from separate tanks and
mixes them in the desired proportion by a mechanical device.
Several pumps for the purpose are now on the market.

Resin-Lime Mixture
5 pounds pulverized resin.
1 pound concentrated lye.
1 pint fish or other animal oil.
5 gallons water.






46 DEPARTMENT OF AGRICULTURE

Place the oil, resin and 1 gallon of hot water in an iron
kettle and heat till the resin softens, then add the lye and
stir thoroughly. Now add 4 gallons of hot water and boil
till a little will mix with cold water and give a clear amber-
colored liquid; add water to make up 5 gallons. Keep this
as a stock solution. For use, take 1 gallon of stock solution,
16 gallons water, 3 gallons milk of lime, 1/4 pound Paris green.
The object of this preparation is to obtain an adhesive
material which will cause the poison to adhere to smooth
leaves. It has been highly recommended by the New York
State (Geneva) Experiment Station.

Lime, Salt and Sulphur
Oregon formula:
50 pounds unslaked lime.
50 pounds flowers of sulphur.
50 pounds common salt.
Slake the lime in enough water to do it thoroughly, add
the sulphur and boil for an hour at least, adding water if
necessary. Then add the salt and boil 15 minutes more. Add
water to make 150 gallons, and spray hot through a coarse
nozzle.
Lime, Salt and Sulphur
Marlatt's formula (from Smith) :
30 pounds unslaked lime.
30 pounds sulphur.
15 pounds salt.
60 gallons water.
Boil with steam for 4 hours, and apply hot.

Carbolic Acid Emulsion
1 pound hard soap, shaved fine.
1 gallon water.
1 pint crude carbolic acid.
Dissolve the soap in the water, boiling; add the carbolic
acid and churn as for kerosene emulsion. Use 1 part of this
with 30 parts of water.






PLANT DISEASES AND PESTS


Hellebore
1 ounce hellebore.
1/2 gallon water.
Steep the hellebore in a pint of water and gradually add
the rest of the water. Hellebore may also be dusted over the
plants, either pure or mixed with flour or plaster.

Insect Powder; Pyrethrum
Mix with half its bulk of flour and keep in a tight can for
24 hours; then dust over the plants. Or,
100 grains insect powder.
2 gallons water.
Mix together, and spray.


COMBINED FUNGICIDES AND INSECTICIDES


Bordeaux Mixture and Paris Green
4 ounces Paris green.
50 gallons Bordeaux mixture.

Bordeaux Mixture and Arsenate of Lead
1 gallon arsenate of lead (made by formula No. 20).
50 gallons Bordeaux mixture.

Bordeaux Mixture and Arsenate of Lime
11/ quarts arsenate of lime (made by formula No. 19).
50 gallons Bordeaux mixture.

Soap Mixture
(Used for White Fly)
1 bar soap (10-cent size).
3 gallons water.
Apply warm, as it thickens on cooling.
Recommended for rose mildew, red spider, plant-lice, etc.
Any common laundry soap, particularly the yellow resin
soaps, dissolved 1 pound of soap to 15 or 20 gallons of water,






48 DEPARTMENT OF AGRICULTURE

is an efficient application for white fly, red spider, plant-lice,
etc. The addition of 1/4 pound of Paris green to each 50 gal-
lons of soap solution adds to its efficiency. There is probably
no better formula for white fly than the above.
Equal parts of soap solution and sulphur wash-made by
dissolving 20 pounds of sulphur with 10 pounds of caustic
soda is a most excellent general application.

Sulphur Wash

First mix 20 pounds of flowers of sulphur into a paste
with cold water, then add 10 pounds of pulverized caustic
soda (98%). The dissolving lye will boil and liquify the
sulphur. Water must be added from time to time to prevent
burning, until a concentrated solution of 20 gallons is obtain-
ed. Two gallons of this is sufficient for 50 gallons of spray,
giving a strength of 2 pounds of sulphur and 1 of lye to 50
gallons of water. An even stronger application can be made
without danger to the foliage. This mixture can also be used
in combination with other insecticides.
The chemical combination of sulphur and lime, known as
bisulphide of lime, is perhaps a better liquid sulphur solution
than the last as a remedy for mites. It may be very cheaply
prepared by boiling together, for an hour or more, in a small
quantity of water, equal parts of flowers of sulphur and stone
lime. A convenient quantity is prepared by taking 5 pounds
of sulphur and 5 pounds of lime, and boiling in 3 or 4 gallons
of water until the ingredients combine, forming a brownish
liquid. This may be diluted to make 100 gallons of spray.
Almost any of the insecticides with which the sulphur
application may be made will kill the leaf or rust mites, but
the advantage of the sulphur arises from the fact that it
forms an adhering coating on the leaves, which kills the
young mites coming from the eggs, which are very resistant
to the action of the insecticides and result in the plants being
reinfested unless protected by the sulphur deposit.
For spraying machinery address State Market Bureau,
Jacksonville, Florida.






PLANT DISEASES AND PESTS


ZINC SULPHATE SPRAYS FOR VEGETABLE CROPS
BY G. R. TOWNSEND
Associate Plant Pathologist, Everglades Experiment Station


Abnormal conditions of several crops growing in the
Southern Coastal Plains have been found to be caused by a
deficiency of available zinc in the soils. Experiments have
shown that these abnormalities can be overcome by apply-
ing zinc sulphate to the soil, or by spraying the plants with
a solution of this material. Pecan, tung and citrus trees and
corn have responded to one or both of these methods of treat-
ment.
More recently, the failure of beans growing on saw-grass
soil in the Florida Everglades has been traced to a lack of
zinc. Such failure has not been observed on the older soils
of the Lake Okeechobee region, but has come to the attention
of the Everglades Experiment Station only on newly cleared
land at some distance from the lake. While zinc sulphate
may be found useful for vegetable crops throughout the
state, its value has been demonstrated only for the area of
peat soil in the Everglades lying more than two miles from
the shores of Lake Okeechobee.
The symptoms of zinc deficiency in beans are a yellowing
and withering of the foliage, followed in the most severe
cases by the death of the plant. Beans will grow normally
on zinc-deficient soil for three or four weeks, but after that
period the plants cease to grow, become pale, and the leaves
develop longitudinal streaks of dead tissue. The principal
veins remain green longer than the rest of the leaf. In the
final stages of the disease entire branches of the plant col-
lapse and wither.
Zinc deficiency in beans differs from manganese defici-
ency which occurs chiefly on burned peat or on marl
soils. Manganese deficiency develops earlier in the growth
of the plant than zinc deficiency, and is characterized at first
by a mottled yellowing. In the later stages of manganese
deficiency bean leaves have a brilliant yellow color and are
marked by rows of black dots along the principal veins.






50 DEPARTMENT OF AGRICULTURE

Furthermore, beans affected by manganese deficiency show
response to treatment in 30 hours, while four or five days are
required for definite response to be seen in plants treated for
zinc deficiency.
Copper deficiency which occurs in raw saw-grass soils
causes symptoms on beans which are not readily distinguish-
ed from those of zinc deficiency. Copper deficiency seems to
be of a more transitory nature than either zinc or manganese
deficiencies.
Zinc sulphate may be dissolved in water and sprayed on
plants with knapsack sprayers or power driven machines. In
the first tests five pounds of 89 percent zinc sulphate were
dissolved in 50 gallons of water. This was adequate to cor-
rect the deficiency in beans and did not burn the foliage.
Subsequent experience of growers has shown that two
pounds of 89 percent zinc sulphate in 50 gallons of water is
fully effective. The tests which have been conducted with
vegetable crops have shown no need to add lime to the spray.
Zinc sulphate may be added to either Bordeaux mixture or
manganese sulphate solutions if these sprays are being used.
However, the effectiveness of the zinc or manganese sprays
probably is greater when they are not mixed with other
materials. Some recommended formulas are given below:
2 pounds 89% zinc sulphate
50 gallons water
2 pounds 89% zinc sulphate
4 pounds 83% manganese sulphate
50 gallons water
2 pounds 89% zinc sulphate
50 gallons 2-3-50 Bordeaux mixture

The proper time to apply zinc sulphate sprays is before
the crop shows the need for treatment. This can be done if
previous experience has shown the land to be deficient in zinc.
It is best to make the application before the crop is three
weeks old. Recovery of diseased plants has been observed
when they were five weeks old before the spray was applied.
Usually a second application will not be needed.
Plants which have been very sickly and stunted have been
observed to recover and show a luxuriant growth within two





PLANT DISEASES AND PESTS


to three weeks from the time of application. Beans which
respond in this manner will yield a normal crop, whereas
without spraying the crop may be a failure.
Cabbage, peas and potatoes also have been observed to
fail on zinc deficiency saw-grass soil, and these plants also
respond to zinc sprays. In general the symptoms are similar
to those on beans. The plants grow normally for two or three
weeks, but later show a loss of color and sudden blighting of
portions of leaves, or wilting of the entire plant. When peas
and cabbage are sprayed a soap spreader should be added to
the spray.
Zinc sulphate can be obtained from dealers in agricultural
supplies. Its cost is approximately the same as that of blue-
stone and manganese sulphate. There are several grades of
zinc sulphate on the market. These differ in the amount of
water which they carry in combination with the zinc. The
zinc sulphate with the least water is a pure white salt. It
contains the equivalent of 36 percent metallic zinc, or 89
percent water-free zinc sulphate.


MANGANESE SULPHATE SPRAYS FOR
VEGETABLE CROPS
BY G. R. TOWNSEND
Associate Plant Pathologist, Everglades Experiment Station

The yellowing of vegetable crops growing on slightly acid
to alkaline soils is frequently due to a deficiency of available
manganese. This element, which seems to be essential for
the production of chlorophyll in plants, is nearly insoluble
in soils having pH values from 6.2 to 8.0. Too much lime in
a soil will create such a condition; it exists naturally in marl
and limestone soils, and may occur also as the result of burn-
ing peat or muck soils. Where the amount of manganese is
naturally low, this partial insolubility will create a deficiency
in the amount available for the growth of plants.
Experiments have shown three ways in which manganese
deficiency may be overcome. These are by applying man-
ganese to the soil, by making the soil more acid or by spray-






52 DEPARTMENT OF AGRICULTURE

ing the plants with a solution of manganese sulphate. Addi-
tions of manganese sulphate with the fertilizer produce a
concentration of available manganese sufficient for the
growth of one or two crops on neutral or alkaline soils.
Usually 25 to 50 pounds of manganese sulphate per acre per
year will maintain production on peat soils which are neutral
or alkaline in reaction. Somewhat more than this is required
where the peat soils show large amounts of brown ash.
It is possible to increase the availability of the manganese
in a soil by making it more acid. This can be done by the
application of sulphur. The amount of sulphur needed will
depend upon the type of soil and its alkalinity. For burned
peat soils in the Everglades the use of 50 to 100 pounds of
sulphur per acre is sufficient, except where the soil contains
large amounts of ash.
Neither of these methods is more effective than spraying
the plants with manganese sulphate solutions. Experi-
ments with beans on burned peat soils in the Everglades have
shown that the yellowing due to a deficiency of available
manganese can be prevented by the application of manganese
sulphate solutions to the foliage of affected plants. Beans
which have become very yellow will recover and produce a
normal crop after being sprayed with manganese solutions.
Usually one application is sufficient, but two or three appli-
cations will be helpful where the soil is quite alkaline.
Spraying with manganese is more economical in material
than the use of manganese or sulphur in the fertilizers be-
cause less manganese is needed. It has been found that 10
pounds of manganese sulphate sprayed on an acre of beans
is as effective as 25 to 50 pounds applied with the fertilizer.
Furthermore, it is not necessary to apply the spray until the
need is shown by the plants, while soil treatments must be
made before the need is shown. Spraying is more effective
on the most alkaline soils where manganese applied to the
soil is rendered insoluble in a short time.
Yellowing of the foliage alone is not always a sign that
manganese is needed. It may occur from a variety of other
causes of which root-knot, root-rot, a flooded soil, and defici-
encies of copper or zinc are common. When the yellowed






PLANT DISEASES AND PESTS


plants are growing on burned peat or marl soils one may be
practically certain that a deficiency of manganese exists.
Bean plants growing on such soil will be green for two or
three weeks and then begin to show a yellow mottling be-
tween the veins of the leaf. In the later and more severe
stages of the disease, the bean leaves become golden yellow,
and often have small dark spots along the veins. Ultimately
the plants die. If there is any doubt as to the cause of the
yellowing a few plants should be sprayed with a manganese
solution. The normal green color will begin to return to
sprayed foliage within 30 to 48 hours if there has been a
deficiency of manganese.
The usual procedure for spraying is to dissolve four
pounds of manganese sulphate in 50 gallons of water, and to
apply this solution with knapsack sprayers. Fifty gallons
of the solution is enough for an application on one to one and
a half acres of vegetable crops. For crops such as beans no
spreader need be mixed with the spray. When peas or cab-
bage are to be sprayed the use of a soap spreader is advised.
Lime may be added to the solution if there is any tendency
to burn the foliage with the manganese spray. This seldom
happens, however, and the addition of lime is not recom-
mended for spraying beans, peas, potatoes, and tomatoes.
When it is desirable to apply other sprays, the manganese
may be mixed with them. Some recommended mixtures are
given below:
4 pounds 83% manganese sulphate
50 gallons water
4 pounds 83% manganese sulphate
2 pounds 89% zinc sulphate
50 gallons water
4 pounds 83% manganese sulphate
50 gallons 2-3-50 Bordeaux mixture
Manganese sulphate is available at growers' supply
houses, where it usually may be had in two grades. One
grade is a granular yellow material suitable for use in fertil-
izers. It contains 63 percent of manganese sulphate. The
fine gray powder used for mixing manganese sprays con-
tains 80-83 percent manganese sulphate and is readily soluble
in water.






54 DEPARTMENT OF AGRICULTURE

Plant Diseases and Pests

Part Two


GENERAL GARDEN INSECTS AND PESTS
BY J. R. WATSON
Entomologist, University, Gainesville, Florida


There are a number of insects that attack practically all
garden crops and could not well be included under only one
of them. They are treated here.

Heat Treatment for Seeds
A temperature of from 120 to 130 degrees Fahrenheit,
if maintained for a half hour, is fatal to practically all insect
life. If a bag of seed can be placed in an oven, with a dish
of water to supply moisture, and kept at a temperature of
120 to 130 degrees F. for from 20 to 30 minutes, insects in
it will be killed and the germinating power of the seeds will
remain unimpaired.
Scavengers
Many insects breed in injured and rotting fruits and
vegetables. The most common of these are sap beetles
(Nitidulidae) and pomace flies.
Sap beetles are small, with wings too short to cover the
abdomen. They quickly invade an orange that has split from
any cause but do not, as is often supposed, cause the splitting.
Pomace flies are small two-winged flies that lay their eggs
in rotting fruits and vegetables. These hatch into maggots
that develop in the rotting material. They do not attack
sound fruit.
Grasshoppers
These insects are particularly annoying on early fall
crops. At that time native vegetation is becoming dry and






PLANT DISEASES AND PESTS


unattractive and the grasshoppers, many of which are then
in the late nymphal or the adult stages and consume more
vegetation than the very young, flock to the farmers' crops.
There are many genera and species of grasshoppers.
One of the most common and troublesome is the red-legged
grasshopper. This is one of the smaller kinds but makes
up in numbers what it lacks in size. On flatwoods and muck
lands the lubberly locust is often troublesome. This is the
largest grasshopper in Florida. The young are black with
reddish markings. There are two color-forms of the adults.
Some are of a striking yellow color and others are almost as
black as the larvae. These grasshoppers have very short
wings and are incapable of flight.
Grasshoppers lay their eggs in the ground in waste
places at a depth of 1 or 2 inches. Cultivation will destroy
the eggs when they are laid in cultivated land; consequently
it is in small fields surrounded by waste land that grass-
hoppers are most troublesome. As the proportion of land
under cultivation in a neighborhood increases, these insects
become less of a pest.
Control.-Birds, including domestic fowls, especially tur-
keys, are very fond of grasshoppers. The general farmer
should keep a flock of turkeys, for their insecticidal value if
for no other reason. They would, of course, be out of place
on a truck farm or town lot. The lubberly locust is, however,
distasteful to all birds and will not be eaten by them.
The cheapest and most effective method of dealing with
grasshoppers is by means of poisoned baits, of which the
so-called "Kansas formula" is the best. It has proven very
satisfactory wherever tried. It is
Bran or shorts ...................... 25 pounds
Paris green or white arsenic (oxide) .. 1 pound
W ater ............................. 21/2 gallons
Lemons, oranges, or cantaloupes ...... 3 or 4
Syrup .............................. 2 quarts

Cottonseed meal may to advantage be substituted for half
of the bran.






56 DEPARTMENT OF AGRICULTURE

The Paris green and bran should be thoroughly mixed
(dry). Lead arsenate should not be used. It does not work
as well. The lemons should be thoroughly grated or chopped
very fine, rind, pulp, and juice, and added to the water.
Moisten the bran with the water until the whole is damp, not
sloppy, so that when sown broadcast over the land it will fall
in small flakes. Last of all add the syrup and thoroughly
knead it into the bran. This should be sown in the early
morning, about sunrise or before. Grasshoppers do not eat
at night, and consequently have a good appetite in the early
morning, and the bait should be on hand for their breakfast.
If sown in small flakes over the field there will be no like-
lihood of chickens or other domestic animals picking it up,
nor will wild birds be endangered. Ordinarily there will be
no danger to chickens or other fowls eating the dead grass-
hoppers as the fowls will not get enough arsenic in this way
to harm them.
Mole-Crickets
These are flat, like other crickets. Their front legs are
greatly enlarged and fitted for burrowing (Fig. 56). They
live deep in the ground during the
Sday-time, coming out at night to
feed. They are very destructive to
vegetation, particularly in gardens
Sand seed beds. They make, just
beneath the surface of the ground,
runways resembling those of moles
but very much smaller.
There are at least two native
species of mole-crickets that are
somewhat destructive in truck
patches, especially in low ground
where there is considerable vege-
table mold. In addition, the West
Indian mole-cricket or changea"
(Fig. 57) is becoming very trouble-
some in some sections of the State.
FIG. 56.-Native mole-
crigcet. Natural size. Control.-Sulphur placed in the
(Original.)






PLANT DISEASES AND PESTS


seed drill is said to act as a deterrent. Mole-crickets may be
kept out of seed beds by a gauze floor. At the time the seed
bed is made, dig out the earth to the depth of a foot or so and


place in the bottom a layer of gal-
vanized or copper wire mosquito
netting. It should come up at the
sides and project a couple of inches
above the ground.
Plants set out in the field may
be protected by banding them.
For this purpose melt off the tops
and bottoms of tin cans and place
the cylinder over each plant, sink-
ing it into the earth to some depth.
Instead of the tin cans, tarred
paper may be used.
Mole-crickets may be poisoned
by a mixture of cotton-seed meal,
bran, Paris green and syrup as ad-
vised for grasshoppers. Better re-


V


FIG. 57.-"Changa," or
West Indian mole-
cricket. Natural size.
(Porto Rico Exp. Sta.)


suits have been obtained by substituting commercial egg
mash for the bran.
Like other insects which live in the ground, mole-crickets
may be poisoned by carbon bisulphide. Sink into the infested
garden several holes to the square yard. These can be made
with a cane, if the soil is a bit moist, and should go down to
a depth of one foot. Pour into each hole an ounce of the
liquid, and quickly cover the hole. Care must be taken to
keep the liquid away from the plants or they also will be
killed; also keep the liquid away from fire or lights as it is
very inflammable.
Another and cheaper liquid which can be used in the same
manner is a solution of sodium cyanide in water, about an
ounce to two gallons of water. Calcium cyanide flakes or
granules can also be used.
If the garden is known to be infested at planting time it
should be treated before it is planted. For this purpose
scatter calcium cyanide in the furrow or treat it with sodium
cyanide and ammonium sulphate as advised for root-knot.


-_J


_Ns






58 DEPARTMENT OF AGRICULTURE

Or the garden may be treated as follows: Plow it and level
it off smooth and compact the surface with a roller or the
back of a shovel. If the soil is dry, first wet it. Leave it over
night. The following morning go out with a solution of
cyanide in water, or carbon bisulphide. The presence of the
mole-crickets will be revealed by their galleries and by little
piles of soil freshly thrown up. Wherever such signs are seen
punch a hole to a depth of a few inches and pour into it a fluid
ounce or two of the sodium cyanide solution or a tablespoon-
ful of carbon bisulphide. Repeat the operation every night
until no more signs of their presence are seen.
To reduce the number of mole-crickets in badly infested
ground, plow deeply several times in the spring, from March
to June, when they are breeding most actively. Allow
chickens, and especially turkeys, to follow the plow for they
are very fond of these insects. Pasture hogs on the field
when possible. When mole-crickets are flying during March
or April (they do not fly much at other seasons) great num-
bers can be caught in light traps. Suspend a lantern in the
field and place under it a pan of water on the surface of which
there is a thin layer of kerosene.

Moles
Moles are a nuisance in lawns and gardens because of the
extensive tunnels they make beneath the surface of the soil.
In making these tunnels they break off the roots of the plants
and cause the soil over the tunnels to dry out. Contrary to
common opinion, they do not feed extensively on vegetation
but are mostly insectivorous in their diet. They are fond of
"white grubs" which are the larvae of May-beetles or June-
bugs. These white grubs are most abundant on land that has
been allowed to grow up in grass during the summer. The
first step in fighting moles is to get rid of the white grubs.
This can be done by raising some cover crop such as cowpeas,
velvet beans or peanuts on the land to keep down the grass
during the summer, and also by turning pigs in on the land
for a few weeks before the garden is plowed. (See white
grubs under potatoes, page 128, for further suggestions.)
Although, by eating the white grubs, moles perform a good






PLANT DISEASES AND PESTS


service to the grower, like some other troubles, the remedy is
often worse than the disease.
Control.-Moles may be discouraged from burrowing in
the garden by tramping the soil solidly into their runways
or crowding a brick or a stone into it where it enters the
garden from the outside, making sure, of course, that the
mole is not in the garden when this is done. The presence of
the mole is best detected in the early morning by the ridges of
fresh dirt or the movement of the soil as he forces his way
through it. In the latter case the mole can at once be dug out
and either killed or, better, carried off to some pasture
or waste land where his activities will be beneficial rather
than harmful.
Moles make two types of tunnels. One is the feeding
tunnel which is but a few inches below the surface of the
ground. The other is larger and located much deeper, a
foot or more. This is the main highway for the moles in
going from one end of their range to the other. Moles may
be trapped by uncovering this main roadway and placing in
the breach a mole trap, several of which are on the market.
In sandy soil these will often spring out of the soil when
sprung by the mole. This can be largely prevented by tying
a weight to the trap. Nine parts of finely ground beef steak
thoroughly mixed with one part of a rat poison containing
phosphorus has been used to control moles.

Mice
The prevalent idea that moles feed largely on the roots
of plants arises from the fact that their runways are com-
monly used by field mice which do the damage. Stopping
up the runways will discourage the mice as well as the moles.
In the kitchen garden both moles and mice may often be
drowned out by turning the garden hose into the runway.
The mice may be poisoned by putting in the runways some
corn that has been soaked in arsenic, Paris green or alkaloid
strychnine.
These mice are known as field mice or white-footed mice,
belonging to the Peromyscus polionotus group. They are







60 DEPARTMENT OF AGRICULTURE

small mice about five inches long, white underneath and gray
or brownish gray above. They live in burrows in the ground,
the entrance of the burrow being in an open place with a
small mound of soil thrown up in front of it. These burrows
are generally less than two feet deep and about three and a
half feet long, the burrow turning up at the back and the
end being just under the surface of the soil so that the mice
often break through at that point when one is digging them
out. These mice are very prolific, young being found
throughout the year. The litters vary in size from two to
six. These mice are capable of producing a second litter in
less than 25 days after the first is born, so that if food con-
ditions are favorable and natural enemies lacking a very
large population may be produced in a short time. Hawks,
owls, skunks, and snakes are natural enemies of these mice
and should be protected. It is easier for the farmer to pro-
tect his chickens from these predators than to control the
mice in his fields.
The mice are most abundant in old fields so that the great-
est trouble is likely to occur on old ground or in new ground
adjacent to old fields. They cause damage by digging up
newly planted seed. In cage tests it was found that on the
average a mouse could eat about two dozen seeds in a night
and in newly planted fields seeds which the mice dug up were
found stored in their burrows. Thus, during the week or 10
days that the seeds are in danger, less than a dozen mice per
acre can ruin a stand of melons or corn.
A poison bait was found to give the best control. Such a
bait may be prepared as follows:
Mix together one ounce of powdered alkaloid strychnine
and one ounce of baking soda. Sift this over eight to 10
quarts of rolled oats, stirring well to get a uniform distribu-
tion throughout the mixture. Warm the oats in an oven,
taking care that they are not scorched. Sprinkle hot beef fat
over the oats at the rate of six tablespoonfuls per quart of
oats and stir until all of the particles of oats are thoroughly
covered. It is best to make this bait up on the same day it is
to be used. In distributing it in the field a teaspoonful should






PLANT DISEASES AND PESTS


be placed at about 20 foot intervals about two days before
planting. The above quantity should treat about four acres.
It is of the greatest importance in making this bait to use
only the alkaloid strychnine. Local druggists very often do
not carry this and the strychnine sulphate that they do carry
in stock is not nearly so effective as the other. A number of
growers who have used the strychnine sulfate for years
found that they got far better results when they changed to
the alkaloid strychnine. Therefore, growers should estimate
the amount of alkaloid strychnine they will need and have it
ordered so that it will be on hand at planting time. This may
save replanting and enable the grower to get melons on the
market a week earlier, which is an important factor in Flor-
ida.
It is the practice of some growers to soak their seed be-
fore planting to hasten germination. From the standpoint
of mouse control this is a desirable practice as it shortens the
time during which damage from mice is likely to occur.

Salamanders
The so-called "salamander" of Florida is a ground squir-
rel much more nearly related to the pocket gopher of the
West than to the true salamander, which is a frog-like ani-
mal with a tail. If they invade the garden they may be
poisoned by the bait given above for mice or their burrows
opened and small steel traps set in their runways.

Gophers
The so-called "gopher" of Florida is a burrowing turtle.
These gopher turtles live in deep burrows which are easily
located because of their large size and the mounds of subsoil
thrown up at the entrance. The animals feed on the melon
vines for the most part, early in the morning or late in the
afternoon, staying in their burrows most of the day. The
following method of control can be used.
Break up corn cobs into three or four inch lengths and
soak them in carbon bisulphide. Throw the pieces down the






62 DEPARTMENT OF AGRICULTURE

burrow. They are heavy enough to roll down quite a distance
so that the fumes are given off near the "gopher". As soon
as the cobs have been thrown into the burrow close the en-
trance by packing the soil tightly about it. A few days later
the results should be checked. If the gopher has emerged a
larger dose should be administered. After a little experience
a grower should be able to gauge the amount of carbon bisul-
phide to use.

Ants
One of the nuisances with which the gardeners and truck-
ers have to contend is ants. The amount of damage they will
do depends to a large extent on the species. Following are
mentioned some of the ways in which they are annoying in a
garden.
They eat off growing plants, such as cabbage. Most
species feed to a limited extent only on growing vegetables,
but many species seem to object to the presence of vegetation
about their nests. This is particularly true of the large yel-
low agricultural ants which will keep a space many feet in
diameter about their nests absolutely free from vegetation.
The leaf-cutting ants which are found in the southern part
of the State, cut off and remove to their nests a large number
of leaves. They do not use these directly for food, but to
grow a kind of fungus of which they are particularly fond.
They were the first mushroom growers. They are partic-
ularly annoying to citrus trees in the tropics where they
abound.
One of the most annoying habits of ants is that of carry-
ing away seeds from seed beds. They are particularly fond
of lettuce and romaine seed. They use the seeds for food
and will begin to carry them to their nests as soon as planted
and will continue their pernicious activities all through the
germination period and until the young seedlings have used
up all of the material in the seeds. Ants often cover up
plants by building mounds over them.
Ants are very fond of the honeydew given off by aphids,
some jassids, mealy bugs and other scale insects. For the






PLANT DISEASES AND PESTS


sake of this substance many kinds will tend those insects,
sometimes driving away their enemies and more commonly
carrying those pests from one plant to another. (See gar-
den aphid under cabbage plant-lice, page 83.)
Ants in the truck patch and garden, especially those that
sting, are somewhat of an annoyance to workers.
Control.-Ants are best destroyed in their nests. For
this purpose carbon bisulphide can be used but sodium
cyanide is cheaper. Dissolve the cyanide in water, an ounce
to two quarts of water. With a cane or sharp stick punch a
hole to the depth of a foot or more in the center of the hill and
pour into it a few ounces of the solution. The dosage to be
given as well as the depth of the hole will depend upon the
size and depth of the nest. As soon as the liquid has soaked
away, cover up the hole with dirt and tramp it solid. The
gas given off will penetrate the galleries of the nest and kill
most of the ants and their young. It is best to do this in the
early morning when most of the ants are "at home." All of
the nests within 50 or 60 feet of the seed bed should be treat-
ed. As recorded under the head of fumigation, cyanide is one
of the most powerful poisons known, either when inhaled or
swallowed. It should also be kept out of open sores. Some
ants will probably escape the first treatment. These will,
however, lose all interest in the seed bed and will go slowly
about, cleaning the dead ants out of the nest. Their slow
and languid motions are in sharp contrast to their feverish
activity of the previous day. The survivors will probably,
in the course of a few days, start small new nests in the
vicinity. These in turn may be treated.



The following is from J. R. Watson, Entomologist and
Head of Department, University of Florida, in reply to a
letter received from Jacksonville, Fla., June, 1938:
"In regard to trouble with ants: For large nests and deep
ones, carbon bisulphide is about the best thing to use. Just
punch a hole in the middle of the nest and pour down it about
an ounce or so of carbon bisulphide, according to the size of






64 DEPARTMENT OF AGRICULTURE

the nest, and by stepping on it compact the soil so as to re-
tain the gas. Carbon bisulphide will penetrate the burrows
of the nest better than any other common material.
"Judging from your description, however, you probably
have the so-called 'carpenter' ants. These ordinarily do not
nest out in the yard but in a piece of rotten wood, or in such
things as bamboo you mention, particularly if there is a lot
of trash in the clump as there is apt to be. They may, how-
ever, be nesting in some rotting timber in the building. If
you find they are issuing from some hole in the building, pour
a little carbon bisulphide down this hole, remembering of
course that you have a fire risk and you must keep all fire, in-
cluding pipes and cigarettes, away as long as there is any
odor remaining.
"I note you have had no results with arsenate of soda in
sugar and water. Perhaps you have been making this too
strong. If you use too much arsenic the ants will not touch
it. Follow the directions given in the press bulletin.
"Mr. C. F. Mershon, 223 East Ashley Street, of your city,
is agent for a very good bait for ants. This contains thalium
as the poisonous principle. Thalium is very powerful stuff
and you must not use this bait where children or other care-
less people might get hold of it.
"It is not probable that the ants come into your place from
your neighbors property unless your neighbors are very
close indeed. Fifty or 100 feet is about as far as these ants
will ordinarily go. One thing is certain, where you have
these ants around you you will have no termites as ants are
mortal enemies of termites."

White-Fringed Beetle
The following is from Arthur C. Brown, Grove Inspector
of State Plant Board, in reply to a letter received from Rich-
mond, Va., June, 1938:
"This insect was first noted doing considerable damage
to cultivated and wild plants a little over a year ago. It was
reported that it was found in a portion of Okaloosa and






PLANT DISEASES AND PESTS


Walton Counties, Florida, and in the southern portion of
Covington County, Alabama. The town of Florala, Alabama,
is about the center of the Florida-Alabama infested area.
The damage is caused by the larvae eating the roots of
several of our cultivated crops, as well as wild plants. The
adults emerge from the ground during the summer in large
numbers and, while they cause some damage to the foliage
of plants in their eating, it is not as great as that caused by
the larvae attacking the roots.
"The Bureau of Entomology and Plant Quarantine, United
States Department of Agriculture, undertook to carry on
some control measures in cooperation with the States of
Florida and Alabama in the summer of 1937. Inspection so
far has disclosed the presence of this pest in Pensacola, in
several counties in the southern part of Mississippi, and in
the vicinity of New Orleans. How it was introduced into
the United States no one is prepared to state. How much
damage it will cause to our cultivated crops is another ques-
tion that remains to be answered. At present it would ap-
pear that it may be a major pest of corn, cotton, peanuts,
chufas and velvet beans. The government is undertaking to
do considerable research work in the vicinity of Florala,
where they have established a laboratory under the direc-
tion of Mr. H. C. Young. They also have a field control office
at Florala, of which Mr. L. J. Padget is in charge. The main
office is under the direction of J. M. Corliss, Box 989, Gulf-
port, Mississippi.
"More detailed information as to the host list and the
possible economic importance of this pest should be secured
from Mr. Corliss or from his chief, Dr. Lee A. Strong, Chief,
Bureau of Entomology and Plant Quarantine, United States
Department of Agriculture, Washington, D. C."


Root-Knot (Heterodera Mariana)
(See Page 163)






66 DEPARTMENT OF AGRICULTURE

Other General Pests
The following named pests attack a large number of
vegetables and could have been treated appropriately under
this general heading. They are: Fall army worm or grass
worm (see under corn, page 97); red spiders (see under
peas, page 121) ; garden aphid (see under cabbage, page 83) ;
and cut-worms (see under cabbage, page 75).


BEANS

Bean Leaf-Hopper (Empoasca fabae Harr.)
Several species of jassids severely attack snap beans,
especially those planted early in the fall. Their ravages are
often so severe as to discourage the planting of beans at that
season.
Jassids obtain their food by sucking the juices of plants.
If the insects attack in sufficient numbers the plants will
become stunted in growth, fail to bear well, turn yellow and
finally die.
Several species are concerned in this injury. The most
abundant is Empoasca fabae or bean leaf-hopper. This is
also called the potato leaf-hopper in the North because it is
there especially injurious to potatoes. It is a light green
insect, 1/8 of an inch long. Under a lens the eyes of the living
insect are white but they quickly turn brown after death.
The bug lives on a variety of plants but is partial to cowpeas
and beans. There are many generations a year.
Control.-Bordeaux applied to beans has a distinct ten-
dency to delay the development of leaf-hoppers and if put on
before the leaf-hoppers become abundant it will usually pre-
vent an infestation. It seems that leaf-hoppers are very
sensitive to copper and the plants absorb enough copper
through the leaves to slowly poison leaf-hoppers. Once they
become abundant this, of course, is too slow.
The best control measure for leaf-hoppers is pyrethrum
in sulfur as a carrier. This enables the farmers to control






PLANT DISEASES AND PESTS


downy mildew at the same time they control the leaf-hop-
pers.
It is very important that one raising beans in the fall
should keep a belt several rods wide entirely around the bean
field clear of all herbaceous vegetation. This can be done by
either plowing the strip and giving it frequent cultivation or
cutting the vegetation off and burning it before the beans
come up. This belt around the field in which there is no
vegetation is very effective in checking the migration of the
hoppers from the surrounding vegetation.
On the lower East Coast the bean jassid is more injurious
to the winter and early spring crops of beans.

Three-Cornered Hopper (Stictocephala festina)
In addition to the smaller leaf-hopper, Empoasca fabae,
beans are commonly infested with a much larger one. This
is yellowish-green in color, about a quarter of an inch long
and half as wide. As viewed from above, its outline is that
of a long triangle. This and its habit of feeding on alfalfa
have resulted in its being known in the West as the "three-
cornered alfalfa hopper." It is also a pest of tomatoes,
watermelons, and cowpeas in Florida. We have also found it
common on hickory, oak, goldenrod, and summer haw
(Viburnum). Control measures would be the same as for
the smaller species.

Bean Leaf-Roller (Eudamus proteus)

Another insect which is very troublesome to the early
fall-planted crop is a caterpillar which rolls up the edges of
the leaves after cutting slits in them. From these shelters
the caterpillars range over the leaves which are often so
badly eaten that no pods can be formed.
The caterpillar (Fig. 58), which grows to an inch in
length, is a light greenish-yellow, velvety insect. The brown-
ish-yellow head is attached by a neck which is much narrow-
er than usual in caterpillars so that there is a marked con-
striction between the head and thorax.






68 DEPARTMENT OF AGRICULTURE






FIG. 58.-Bean leaf-roller: Larva. Much enlarged.
(Original.)

In the summer the larva will complete its growth in 14
days, but in October and November, 30 or more days are
required. The larva then forms the pupa on the plants and
in 6 days the bluish butterfly emerges. The insect belongs
to the group of butterflies known as "skippers," doubtless
because of their habit of darting quickly from plant to plant
in search of nectar or a place for an egg. The eggs are de-
posited on beans and other legumes, especially beggarweed,
and hatch in 4 days in summer. This group of butterflies
when at rest, hold their wings at an angle of about 45 degrees
instead of horizontal or perpendicular as do other butterflies.
This species may be distinguished from other skippers by its
larger size, 2 inches across the outstretched wings, and by
the prolongations ("tails") of the hind wings.
The insects are scarce in the spring and early summer so
that early beans are not troubled. But by the first of Sep-
tember the butterflies are abundant and beans become
heavily infested.
Control.-The insect can readily be killed by spraying
with lead arsenate. However, beans are easily injured by
arsenicals so not over 12 ounces of the powdered, or a pound
and a half of the paste, form of lead arsenate should be used
to 50 gallons of water, and to this should be added, before
using, a pound of hydrated lime or the milk obtained from
slaking 2 pounds of quick lime in water. However, it is
cheaper to dust beans for this pest,-one part of lead ar-
senate to 10% hydrated lime, or 5 pounds of lead arsenate
can be added to the pyrethrum-sulphur dust.

Bean-Weevil (Bruchus obtectus)
There are two or three species of weevils that infest
beans. The most common is Bruchus obtectus (Fig. 59).






PLANT DISEASES AND PESTS


The others are more common on cowpeas and will be treated
under that heading. The ravages of this insect on dried
beans are very conspicuous; in fact, if not checked, it will
entirely destroy seed beans. They also damage snap beans.
The infested pods show wart-like swellings where the female
punctures them to lay eggs in the cavity of the pod. She
gnaws out a narrow slit and then inserts her ovipositor in
the hole and lays the egg. These "speckled" pods should not
be confused with those having spots
caused by the fungus, Colletot-
richum. Those spots caused by the
fungus are sunken instead of ele-
vated and attain a much larger size.
The egg hatches in from 1 to 3
weeks, according to the prevailing 6
temperature, into a small, worm- FIG. 59-Bean-weevil (Bru-
like larva. This requires from 11 ,husobtectus): a, Adlt
beetle, much enlarged: b,
days to 6 weeks to become full infested bean. (From U. S.
Bur. of Ent.)
grown and then changes into the
pupa. From 5 to 18 days later the adult emerges. This is
an ashy black beetle about a tenth of an inch long, with hard
wing-cases and somewhat flattened body.
Nothing can be done to protect the beans in the field from
the ravages of this insect. The best method of control is to
plant clean seed in a field that has not recently produced a
crop of cowpeas or beans. Breeding in dried beans can be
prevented by keeping the beans in cold storage (32 to 34
degrees F.) for two months or more, or they may be fumi-
gated as recommended for stored seeds.

Lesser Corn Stalk-Borer (Elasmopalpus lignosellus Zell.)
This insect is injurious to corn in the states farther
north; in Florida it does more damage to cowpeas and beans,
although it is injurious to corn. Next to the bean-jassid it
is the most injurious insect on fall-planted beans. It often
destroys almost the entire stand if control measures are not
adopted. The insect is a bluish-green caterpillar (Fig. 60, d)
which bores into the stem at the surface of the ground and
tunnels up and down in it, causing the young plant to wilt and







70 DEPARTMENT OF AGRICULTURE


d bb
FIG. 60.-Lesser corn stalk-borer (Elasmopalpus lignosellus):
a, Mole moth; b, Wing of female moth; c, moth, showing the
resting position of the wings; d, caterpillar; f, pupa. About
three times natural size. (From U. S. Bur. of Ent.)

die quickly. If the cowpea-plant gets a good start before it is
attacked it is not easily killed and may produce some pods,
so that the damage is not as noticeable, but a bean is usually
killed outright. The full-grown caterpillar is about a half-
inch long. It is quite smooth; i. e., it is not noticeably hairy.
There is a large brown spot on the back of each segment
(joint). The head is brown and hard and the first joint of
the thorax is black. The adult is a small, brownish moth
with cream-colored markings (Fig. 60, a). It belongs to the
same family as Crambus (see root webworms under corn,
page 98) and rolls its wings about its abdomen in the same
manner (Fig. 60, c).
The female lays her eggs on the stem near the surface
of the soil and the caterpillar feeds on the surface of the
roots until about half-grown, when it bores into the stem.
Control.-The caterpillars, working inside of the stems,
are safe from any poison that could be applied to the crop.
The young on the roots are also safe. The only means of pre-
venting their spread through a field is to pull up and destroy
all infested plants. Rotation of crops should be practiced.
Beans should not be planted on land that has just grown
beans, peanuts, cowpeas, turnips or corn, as they are all host
plants.






PLANT DISEASES AND PESTS


Other Bean Pests
Other insect-pests attacking beans are: Root-knot nema-
tode (see under general garden pests, page 65); cutworms
(see under cabbage, page 75); corn ear-worm (see under
corn, page 92), sometimes mines the pods; cabbage looper
(see under cabbage, page 78), sometimes eats the leaves;
cowpea pod-weevil (see under cowpeas, page 102); grass-
hoppers (see under general garden pests, page 54) are
troublesome in the fall; pumpkin bug (see under cowpeas,
page 103) and other plant-bugs (see under potatoes, page
127) are among the most troublesome enemies of the bean
grower; garden aphid (see under cabbage, page 83); wire-
worms (see under corn, page 95); flea-beetles (see under
beets, page 73); and striped cucumber-beetle (see under
cucumbers, page 110).

LIMA BEANS

Gall Worm (Monoptiloba sp.)
In addition to the pests of other beans, lima beans are
attacked by a caterpillar that bores into the stems. The
plant thus attacked forms a large swelling or gall about the
larva. In this gall the larva lives, feeding on the tissue until
its growth is complete. The adult insect emerges as a small
moth, and lays eggs on the stems of the plant. These galls
are very common on lima beans in Florida.
The attacks of this caterpillar do not usually become
severe until summer, hence lima beans planted early usually
produce a fair crop. The only practical means of prevent-
ing this injury seems to be to plant as early as possible and
fertilize and cultivate well.
Bush lima beans are not as much injured as the climbing
varieties.

BEETS

Blister-Beetles
These long, slender beetles feed on a variety of truck
plants, including beets, tomatoes and potatoes. In the







72 DEPARTMENT OF AGRICULTURE

Northern States these insects are known as "old-fashioned
potato bugs" to distinguish them from the more recently
introduced "Colorado potato-beetles." They are known in
parts of Florida as "Yankee bugs," perhaps from the bluish
color of certain species. The adult beetle crushed against
the skin causes a blister, hence the name "blister-beetle."
It is also called "Spanish fly," certain species being the
source of the drug of that name.
Eight species of blister-beetles are more or less trouble-
some to vegetation in Florida. The most common one is the
gray blister-beetle (Epicauta heterodera) which has no
stripes. The striped blister-beetle (E. vittata) (Fig. 61) is
frequently seen.
The work of all the species is about the same except that
each shows a preference to different plants. They strip all
the softer parts of the leaves, leaving only the
midribs. The beetles usually feed in colonies,
S sometimes so large that they quickly strip and
ruin a patch or an entire field.
If the colony is small the quickest way to
exterminate it is to collect the beetles in a pan
FIG. 61.- of kerosene. They are quick to take alarm and
s r i ed the collector must work rapidly. If the colony
Blister-
Ne atur a is large the plants should be sprayed with lead
sFroi z arsenate. The larvae feed on the eggs of grass-
s. Bur. of hoppers and are beneficial to agriculture. For
this reason it is better, wherever possible, to
drive the beetles from the field rather than to poison them.
To do this, use a bundle of twigs with which to whip the
plants and work with the wind, driving the beetles quite a
distance to prevent their quick return. It may be necessary
to repeat this driving frequently.

Beet Leaf-Miner (Pegomyia vicina)
This insect belongs to a large class made up of small
pests which often escape the notice of the trucker because
of the small size of the insect and the wound inflicted, while
the unthrifty condition of the injured plants is laid to a lack






PLANT DISEASES AND PESTS


of fertilizer or water. Collectively they inflict severe dam-
age.

This maggot-like larva of the two-winged fly frequently
burrows in the tissue of beet leaves. If they become nu-
merous they will materially check the growth of the plants.

In its protected position, the grub cannot be reached by
any insecticide, but the grower can check an outbreak by
destroying all infested leaves. This at least should be done
when the beets are gathered, if not before. If the infested
leaves are left in the field the grubs have opportunity to enter
the ground, go into the pupal stage and emerge later as flies.

Flea-Beetle

This is a small oval beetle (Fig. 62) that gets is name
from the habit of quickly springing several inches when dis-













a





b
e
FIG. 62.-Strawberry flea-beetle: a, Adult; b, eggs on
leaf; c, side-view of young larva; e, dorsal view of
larva; f, pupa. Greatly enlarged. (From U. S. Bur.
of Ent.)

turbed. Two species are more or less troublesome in Florida
to beets, cabbage, cucumbers, tomatoes and related plants.






74 DEPARTMENT OF AGRICULTURE

They eat the epidermis on one side of the leaf and the soft
interior cells but leave the veins and other hard parts.
Bordeaux mixture is usually efficacious in preventing
injury by these insects. The mixture can be made more
efficient by the addition from 8 to 16 ounces of powdered lead
arsenate (or 1 to 2 pounds of the paste) to 50 gallons of the
Bordeaux.
One common species of the flea-beetle is usually very
abundant on evening primrose (Oenothera sp.) from which
they often spread to cultivated crops. These weeds should
be destroyed around the edges of truck fields as well as in
the fields.

Striped Morning-Sphinx (Celerio lineata)
The larva of this very common hawk-moth feeds occa-
sionally on beets, although its common host plant in Florida
is purslane. It has the size and general appearance of the
tomato worm and belongs to the same family. Its life his-
tory is similar and the control measures are the same.

Larger Beet Webworm
There are two species of small moths of the genus
Hymenia (or Zinckenia) whose caterpillars attack the beet.
The larger one is the spotted beet webworm (Hymenia
perspectalis). This larva is a small green caterpillar with
purplish dots on its head. The adult moth is a little over
an inch in width across the wings. It is cinnamon-brown
in color with narrow white bands in the middle of the front
wings. The eggs are about 1/50 of an inch in diameter and
are laid on the leaves of the beets and, particularly, careless-
weed (amaranth). The latter is probably its original host
plant.
Small Beet Webworm (Hymenia fascialis)
This small webworm is much more abundant than
Hymenia perspectalis. During July the moths collect about
the blossoms of catnip and other plants in great numbers.
As with the other species the beet is a minor host plant for
this insect, whose larvae live chiefly on wild plants. The





PLANT DISEASES AND PESTS


moth is smaller than the other species and the white bands
of the wings are larger. Either species can be controlled
with lead arsenate.
Cutworms
These greedy pests seem to be especially fond of beets,
the leaves of which they cut off. If this is repeated con-
tinuously the plant is unable to grow. For control see cab-
bage.
Other Beet Pests
Other insects which attack beets are: Wireworms (see
under corn, page 95) ; white grubs (see under potatoes, page
128); bean-jassid (see bean leaf-hopper under beans, page
66); harlequin cabbage-bug (see under cabbage, page 87);
sweet-potato caterpillar (see under sweet potatoes, page
138); 12-spotted Diabrotica or corn root-worm (see under
corn, page 101); and cabbage looper (see under cabbage,
page 78).


CABBAGE
Many cabbage insects also attack collards, cauliflower,
brussels sprouts, kohlrabi, and Chinese cabbage.

Cutworms
Cutworms are very fond of any succulent plant, and are
troublesome to most truck and garden crops. Cabbage is
one of the chief sufferers from their attacks. They gnaw
off the young plants just above the ground, making them
w-orthless.
Cutworms are the almost harmless larvae (Fig. 63, a, b)
of any of several species of moths of the Noctuid family.
The moths are night-fliers and are commonly seen about
lights. They are grayish or brownish in color and most of
them have on their fore wings small silvery markings, dots,
dashes, or commas (Fig. 63, d, e).
In Florida they do not hibernate but are active and breed
throughout the year, although neither the moths nor the






76 DEPARTMENT OF AGRICULTURE


caterpillars are active during













a ;


FIG. 63.-Cutworm moth (Mamestra
chenopodii): a, b, Larva; c, pupa; d,
moth; e, wing of moth, enlarged.
Natural size. (From U. S. Bur. of
Ent.)


the coldest nights of the
winter. The caterpillars
will remain active at a
lower temperature than
the moths, but the latter
are to be seen about lights
during warm evenings
even in midwinter. The
worms suspend operations
during the coldest nights
only when the tempera-
ture drops below 45 de-
grees.

There are no definite
broods, caterpillars of all
sizes, eggs and moths are
to be seen at one and the
same time.

Control.-- The moths
by preference lay their
eggs (Fig. 64) on grasses


in heavy sod land. The larvae feed on
the grasses. Consequently, on land that
has no considerable grass, the cutworms
are most troublesome. As long as the grass
is available there is so much food in pro-
portion to the number of worms that their
feeding is scarcely noticeable. But when
such land is plowed, the normal food sup-
ply of the caterpillars is cut off and they
are concentrated upon the relatively small
amount of vegetation of the farmer's crop.

When grass land is plowed measures
should be taken to kill the cutworms pres-
ent before the crop is planted. To do this,
prepare the land ten days or two weeks
before the cabbages are set out. During
this time many of the cutworms will leave


FIG. 64.-Eggs of
cutworm moth
(Agrotis sauci ':
a, Single egg,
greatly enlarged;
b, egg mass on
twig. Natural
size. (From U. S.
Bur. of Ent.)






PLANT DISEASES AND PESTS


or die of starvation and the remainder develop a good ap-
petite. A day or two before the crop is to be set out, cut
some green and succulent plants, such as collards, rape,
cowpeas, etc., and dip them into a strong solution of Paris
green; about an ounce to a gallon of water. Scatter this
about the field after sunset, for the hungry cutworms to feed
upon during the night. Instead of the green material the
following described poisoned bait may be used:

A. Bran ........................... 20 pounds
Cottonseed meal .................. 5 pounds
Paris green ..................... 1 pound
B. Water .......................... 2 gallons

Mix the bran, cottonseed meal and Paris green thorough-
ly while still dry; then wet "A" with "B" until it is decidedly
damp, not sloppy, and of such consistency that it will fall
in fine flakes when sown broadcast over the land. This
should be put out after sunset so that it will be fresh and
attractive when the worms come out to feed in the night.
If the following day is cloudy, the bait will remain attractive
for the second night, otherwise it will need to be renewed if
the cutworms have not been brought under control. If
properly sown it will fall in such small flakes that fowls or
other birds will not pick it up. In a cabbage field, better
protection will be given to the plants at a smaller expendi-
ture for material if, instead of being sown broadcast, the
bait is placed in small piles about the stalks of the cabbage.
For protecting other crops it may be scattered along the
rows. Instead of both cottonseed meal and bran, either may
be used alone, in which case 25 pounds is used. Stale bran
or meal should not be used in making this bait. The mixture
must be made up fresh each day from sweet fresh material.
In a small garden or in a field where there are but few
cutworms, the easiest, quickest and cheapest method of deal-
ing with them is to walk through the patch in the early morn-
ing and look for plants which were cut off during the preced-
ing night. By scratching the earth away from the base of






78 DEPARTMENT OF AGRICULTURE

the plant the culprit will usually be found at a depth of not
more than an inch. They may be collected and fed to
chickens.

Cabbage Worms

At least five species of caterpillars feed on cabbages and
related plants in Florida. The most common one during the
cabbage growing season, the winter, is the cabbage looper.

Cabbage Looper (Autographa brassicae).- This larva
(Fig. 65, a) of a Noctuid moth is closely related to cutworms,
which it resembles in general shape. It does not have the
cutworm manner of
feeding but works
on the surface of
cabbage leaves both
day and night. It
injures the leaves
by eating holes in
/ them and also dam-
ages the appearance
6 of the heads by soil-
ing them with its
excrement. The
caterpillar is light
FIG. 65.-Cabbage looper: a, Larva; b, pupa; green in color and
c, adult. Natural size. (From U. S. Bur.
of Ent.) grows to a length of
more than an inch.
The eggs, yellowish-green in color and about a fiftieth of
an inch in diameter, are scattered over the surface of the
leaves. The caterpillar requires about 3 weeks for growth
and spends about 2 weeks in the pupal stage.

The adult moth (Fig. 65, c) also looks much like those of
cutworms, and, in the attitude of Gainesville, may be active
all winter.

The Cabbage Plutella (Plutella maculapennis). The
cabbage plutella (Fig. 66, a), a much smaller caterpillar than






PLANT DISEASES AND PESTS


the looper, is common
on cabbages. It is
less than a half-inch


than the looper. When W
disturbed it drops d
quickly from the
plant, spinning a silken
thread which it uses
FIG. 66.-Cabbage plutella: a, Larva; d, e,
to remount when the pupa; f, moth; h, moth at rest. Two
and one-half times natural size. (From
danger is over. On u. s. Bur. of Ent.)
the under side of the
leaf, it makes small round holes, rarely extending through.
Like the looper, this caterpillar is active all winter in the lat-
titude of Gainesville and south. The cocoon placed on the
leaf is a loosely-woven affair through which the pupa (Fig.
66, e) may be seen plainly.

The adult (Fig. 66, f) is a small moth 5/8 of an inch across
the expanded wings, which are gray with a border of lighter
areas. When the wings are folded in the resting position
(Fig. 66, h) these areas form diamond-shaped patches along
the back. For this reason the moth is also called the "dia-
mond-back" moth.

The life history occupies from two to three weeks in
summer. It spends about three days in the egg stage, from
one to two weeks in the larval, and from four to eight days
in the pupal stage. Therefore, if one wishes to effect a thor-
ough clean-up of a heavy infestation of this insect, he should
give the plants a second spraying about ten days after the
first (two weeks in winter).


Cabbage Butterflies

The caterpillars of these white butterflies are injurious
to late cabbage and collards. They do not seriously trouble






80 DEPARTMENT OF AGRICULTURE

the main winter-grown crop of cabbage be-
cause they are not active at that season.

Imported Cabbage Worm (Pontia rapae).
-In the northern and western parts of the
State the most common cabbage butterfly is
the imported cabbage worm, a pest which
was brought to this country about 1856. It
has since spread over the entire country,
reaching Florida about 1890, but has never
become as abundant as in the Northern
States.
FIG. 67.-Im-
The full-grown caterpillar (Fig. 67, a) is ported cab-
about 11/4 inches long, bright green with a fl; a, arva-
yellowish line down the middle of its back tural size
and a row of spots of the same color along its Bur. of Ent.)
sides. Two or three weeks are required for
its growth. It then crawls to some sheltered place and there
transforms into the pupa (Fig. 67, b) and 8 or 10 days later,








FIG. 68.-Imported cabbage but- FIG. 69.-Imported cabbage but-
terfly: Female. Natural size. terfly: Male. Natural size.
(From U. S. Bur. of Ent.) (From U. S. Bur. of Ent.)

in warm weather, the butterfly (Figs. 68, 69) emerges. But
those which enter the pupal stage in the late fall remain
there all winter, at least in the northern part of the State.
The eggs are white or yellow in color and are scattered over
the surface of the leaf.
Native or Southern Cabbage Worm (Pieris protodice).-
This worm (Fig. 72, a) is similar in appearance to the im-
ported worm but has four longitudinal yellow bands. The
butterflies can be distinguished by comparing the illustra-






PLANT DISEASES AND PESTS


tions (Figs. 68, 69, 70, 71). The nature of the injury it in-
flicts is identical with that of the species last named.









FIG. 70.-Southern cabbage but- FIG. 71.-Southern cabbage but-
terfly: Male. Natural size. terfly: Female. Natural size.
(From U. S. Bur. of Ent.) (From U. S. Bur. of Ent.)

Gulf White (Pieris monuste).-This butterfly has a yel-
low caterpillar (Fig. 73, a) with four longitudinal stripes of
a purplish hue. It is 11/2 inches long. The butterfly (Fig.
73, c) is the largest of the group, measuring nearly 3 inches
across the expanded wings. This is by far the most com-
mon and troublesome caterpillar on cabbage and collards
grown during the late
spring and summer in -
the southern part of
the State.
Control. Any or / a
all of these caterpillars
on young plants are
easily controlled by
means of arsenicals.
One can use Paris FIG. 72.-Southern cabbage butterfly: a,
Larva; b, pupa. Natural size. (From
green but either lead u. s. Bur. of Ent.)
or calcium arsenate is
preferable. One pound of Paris green or 2 pounds of lead or
calcium arsenate powder is put into 50 gallons of water. This
liquid usually does not stick well to cabbage plants on ac-
count of the "bloom," a waxy coating. To make it stick, add
soap when the mixture is made, at the rate of 5 or 6 pounds
for 50 gallons of water, according to whether the water is
hard or soft. Any alkaline laundry soap will do. Flour-
paste is also a good substance to make the arsenic compound
stick to cabbage leaves. A paste made by boiling 2 pounds






82 DEPARTMENT OF AGRICULTURE

of flour in 2 gallons of water may be added to 50 gallons of
the arsenical solution.
A spreader recommended by the Illinois Agricultural
Experiment Station is made by dissolving 5 pounds rosin and
1 pint fish-oil soap in a gallon of water in an iron kettle.
Then add 4 gallons of water and 1 pound of concentrated lye
or potash and boil for a few minutes. When ready to spray,
add to 32 gallons of water 2 gallons of the above solution, 6
gallons of milk obtained by slaking quick lime in water
(strain it so as not to clog the sprayer), and 1/2 pound of
Paris green or 2 pounds of powdered lead arsenate.
A new "spreader" worked out by the U. S. Department
of Agriculture is a solution of cactus. Thirty pounds of
cactus is chopped fine and allowed to soak over night in 50
gallons of water. This is strained and the arsenic added. In
those parts of the State where some of the wild species of
"prickly pears" or spineless cactus grow, this should make a
cheap "sticker."
Arsenical poisons may be used dry if applied when the
cabbages are wet with dew or rain. It is well to use a filler of
cheap flour
or air-slaked
or hydrated
lime, mixing
about six-
teen parts of
the filler to

poison.
Of the
three com-
p o u n d s,
Paris green
is the least
satisfactory.
Its arsenic
Content is
variable and
FIG. 73.-Gulf white butterfly: a, Larva; h, pupa; c,
adult. Natural size. (From U. S. Bur. of Ent.) after the






PLANT DISEASES AND PESTS


cabbages begin to form heads arsenicals must not be used
as any arsenical residue on the product going to market will
subject it to seizure and destruction by the government.


Cabbage Plant-Lice

The common aphid on cabbage is the garden aphid or
so-called green peach-aphid (Myzus persicae), although the
cabbage plant-louse (Brevicoryne brassicae) (Fig. 74) and
the turnip louse (Aphis pseudo-brassicae) are also found.

The garden aphid is bright green in color and smooth,
while the others have
a more mealy look,
and the turnip louse is
quite hairy. The
Character of the dam-
age, the life history,
and the means of con-
trol are the same for
Z 6 < all three species and
FIG. 74.-Cabbage aphis: a, Winged fe- practically the same
male; b, wingless female. Greatly en- for all aphids.
large. (From U. S. Bur. of Ent.)

Aphids suck the juices from the plant on which they
live, stunting its growth, causing the leaves to curl, turn
yellow, and finally, the plant to die. They multiply with
great rapidity, often beginning when only a week old and
producing several young each day. During warm weather,
which means the entire year in Florida, the individuals of
most species bring forth young parthenogenetically, that is,
without mating between the sexes. Indeed, during that time
of the year males are usually not produced at all. Usually
the young are born alive and active, the eggs hatching be-
fore they are laid. But with the coming of winter, in more
northern states, males and true females are produced and
eggs are laid which do not hatch until spring. Most individ-
uals never acquire wings, but from time to time winged in-






84 DEPARTMENT OF AGRICULTURE


dividuals are produced and spread the species from plant
to plant.
Farther north the green peach-aphid spends the winter
in the egg stage on peaches, plums, etc. The first two or
three generations in the spring feed on the tender unfolding
buds of those trees. The first generation is pink in color but
their young are green and never become pink. The second
or third generations usually develop wings and leave the
trees for tender vegetables where they live all summer. This
annual migration is common among aphids, and the last gen-
eration returns to the trees in the fall to lay eggs, enabling
the species to get an earlier start in the spring than would
be possible were it necessary to wait for herbs to grow.
Aphids give off a sweet substance called honeydew of
which ants are very fond. For the sake of this honeydew
ants carefully tend aphids, often protecting them from their
enemies which they drive away. They may carry the aphids
or their eggs from place to place where the "pasture" is good,
carry the eggs into their nests to winter over, or even build
adobe sheds over them for protection from rain and enemies.
For this reason aphids are often called "ants' cows." Hence
it happens that the presence of excited ants on a plant is
often the most evident sign of the presence of aphids.
Remedies.-For the control of aphids on cabbage, the
best remedy is to spray the plants with a solution of tobacco
extract. For directions for making this see melon aphis
under watermelons, page 153. On cabbages a spreader of
soap and flour-paste should be used as recommended in the
discussion of cabbage worms. If the worms and the aphids
are both present on the cabbages, the tobacco can be added
to the lead arsenate spray, killing both pests at one time.
Dusting the plants with tobacco dust is of some benefit,
and will often keep down the number of aphids and prevent
an outbreak, but will not control effectively an outbreak that
has gained headway. These outbreaks often start on plants
scattered through a field and by pulling them up and destroy-
ing them a general outbreak can be forestalled or at least de-
layed.






PLANT DISEASES AND PESTS


Enemies.-Aphids are a very attractive article of diet to
a, large number of enemies which are usually able to hold
them in check. Only the wonderful rate of reproduction of
the aphids enables them to have a surplus with which to start
a destructive outbreak after supplying the "market" of their
enemies.

The smaller birds, such as wrens, fly-catchers, and warb-
lers, destroy great numbers of aphids. A flock of young
chickens, if given the freedom of the garden, will do excel-
lent work in ridding it of aphids.

In a colony of aphids, dead ones may be found which are
so greatly swollen as to be nearly spherical in shape. These
have been killed by the larva of a minute wasp-like parasite
which lives in the interior of the aphid, consuming its vitals.
The parasite pupates in the dead aphid and when the adult
parasite is ready to emerge it bites a hole in the top of the
aphid and crawls out. The egg from which the parasitic
larva hatches is laid inside the aphid which the female para-
site pierces with her ovipositor.

Several kinds of soft-bodied larvae move among the
aphids and destroy them. Some are legless maggots which
impale aphids on their sharp anterior ends and suck the body
fluids. These are the larva of a family of two-winged flies,
known as syrphus-flies. There are many species. Another
larva is flat, wedge-shaped, with well-developed legs and a
pair of jaws with which it pierces the aphids. These are
aphid-lions. The adults are lace-winged flies (Chrysopa),
bright green insects which measure nearly an inch across
the four gauzy wings and have bright golden eyes. The eggs
are laid in groups and are raised on stalks a half-inch above
the surface of the leaf. This arrangement prevents those
first born from using for their food the unhatched eggs in
the group. A similar larva (Hemerobius) makes a case to
cover its body out of the remains of the victims which it has
sucked dry. This case is carried about by the larva, hence
it is called a "trash-bug." The adult is similar to the golden-
eyed lace-wing, but is brown.






86 DEPARTMENT OF AGRICULTURE

Aphids are the choice food of many lady-beetles and their
larvae. The species most common in Florida truck patches
and gardens are the convergent lady-beetle and the blood
red lady-beetle, although the twice-stabbed lady-beetle, so
common and beneficial in citrus groves, is occasionally found.

During the rainy season aphids are subject to attack by
fungi, particularly Empusa aphidis. This fungus often
destroys in a few days the aphids from whole fields.

The heavy rains of the Florida summer are directly de-
structive to aphids which are knocked off the plants and
beaten to death on the ground.

Cabbage Root-Maggot (Phorbia fuscipes)
These small, soft-bodied legless maggots (Fig. 75, a)
which often do great damage to the roots of cabbage and
related plants in the North are comparatively uncommon in
Florida. The first indications of their presence on the roots
are a check to the growth of the plants which wilt during the
heat of the day and show a bluish, sickly color. The plants
finally turn yellow and wilt down completely. If these plants
are pulled up it is found that the roots have been eaten off,
and perhaps the main stem mined, by the maggots, which
are about 3/4 of an
inch long when fully
grown.
The adult (Fig.
75, c) is a two-winged
fly, similar in appear-
ance to the house- or
c typhoid-fly but much
e_ smaller and with a
proportionally longer
abdomen. The fe-
Smale lays her eggs on
the stem of the plant
FIG. 75.-Cabbage root-maggot (Phorbia Or on the ground near
brassicae): a, Larva; b, pupa; c, female
fly. About four times natural size. (From by.
U. S. Bur. of Ent.)







PLANT DISEASES AND PESTS


Remedies.-Repellents placed about the roots of the
plants when first set out are of some benefit in discouraging
the females from laying their eggs on the plants. Perhaps
tobacco dust is about as practicable as any. Carbolic acid
emulsion may be used. Liberal fertilization will enable the
plants to outgrow the damage done by a few maggots. Re-
peated shallow cultivation will destroy many of the eggs laid
on the ground about the bases of the plants. The grower
should destroy all heavily-infested plants and should avoid
planting cabbage on land that has just borne a crop of in-
fested cruciferous plants whether cabbage, cauliflower, col-
lards, rape, mustard, or turnips. The maggot will breed in
wild plants of this family and all such found near the field
should be destroyed.
Cabbages in an infested seed bed can be treated with
carbon bisulphide. To do this, make holes with a stick three
or four inches from the infested plant and slanting obliquely
under it. Pour in about a teaspoonful of the carbon bisul-
phide and quickly tramp the soil solid to confine the fumes.
In the Northern States it has been found profitable after
setting the plants in the field to protect them from the at-
tacks of this insect by using tarred paper discs. These are
cut open along one radius and fitted closely about the plant.
It is doubtful if the attacks of the insect in Florida fields are
sufficiently common to make this precaution profitable except
in the case of some particularly valuable plants.


f 9
F(l. 76.-Harlequin cabbage-bug: a,
1), Nymphs; d, e, eggs, greatly en-
larged: f, g, adults. Slightly en-
larged. (From U'. S. Bur. of Ent.)


Harlequin Cabbage-Bug or
Calico-Back
(Murgantia histronica)
This strikingly-colored
insect, a native of the Mexi-
can region, has been slowly
working its way eastward
and northward. It is not as
yet abundant in Florida but
may be seen occasionally on
late cabbage and is quite






88 DEPARTMENT OF AGRICULTURE

common and destructive to collards that are carried through
the summer.
The adult (Fig. 76, g) is black and orange and is 2-5 of an
inch long. Both the adult and young suck the juices of the
plants into which they inject a poison. A few bugs are suffi-
cient to cause a plant to turn yellow and die.
The eggs (Fig. 76, c, d, e) are deposited on the under side
of the leaves, usually in two rows. They are keg-shaped,
white, with black bands and a small black spot on each side,
increasing the resemblance to a keg with its hoops and bung-
hole. They hatch in 3 or 4 days. The young are at first
yellow, developing the orange markings later.
They are usually present in such number as to make hand
collecting practical, but hand collecting of the young is less
satisfactory because of their small size. Should these be-
come abundant they can be killed by kerosene emulsion.
Destroy all infested, dying plants. In the northern part of
the State a crop of late cabbage can be partly protected by
planting an early trap crop of mustard, radishes or turnips.
When this trap crop becomes infested it may be sprayed
with kerosene emulsion or pulled up and burned.

Cabbage Hair-Worm Or
Cabbage Snake
(Mermis albicans)
This whitish, thread-
like worm (Fig. 77), which
sometimes grows to be 2 to
9 inches long, is frequently
found in cabbage heads. It
is an internal parasite of
FIG. 77.-Cabbage hair-worm or cab- grasshoppers and caterpil-
bage snake. (From U. S. Bur. of grasshoppers and caerpil-
Ent.) lars and it gets into the cab-
bage by crawling out of infested insects. It is therefore a
friend of the grower. In spite of its repulsive looks and the
many stories which are told of its poisonous nature, it is en-
tirely harmless to mankind.






PLANT DISEASES AND PESTS


Southern Squash Bug (Anasa armiger)
This insect sometimes attacks cabbage and collards. It
breeds on these plants, as eggs and nymphs are found there.
Control is similar to that of the squash bug, page 132.

Other Cabbage Pests
The following named insects also infest cabbage in Flor-
ida: Blister-beetles (see under beets, page 71); flea-beetles
(see under beets, page 73); onion thrips (see under onions,
page 118) ; wireworms (see under corn, page 95) ; nematodes
(see root-knot under general garden pests, page 65); and
grasshoppers (see under general garden pests, page 54);
serpentine leaf-miner (see under cowpeas, page 105).


CANTALOUPE
The insect pests of this crop are identical with those of
cucumbers. (See cucumbers, page 106).


CARROT
The common insect pests of this crop are: Cutworms (see
under cabbage, page 75); garden aphid (see cabbage plant-
lice under cabbage, page 83) ; black blister-beetle (Epicauta
pennsylvanica) (see blister-beetles under beets, page 71);
celery caterpillars (see under celery, page 91); and carrot-
beetle (Ligyrus gibbosus) (see May-beetles under potatoes,
page 128).


CELERY

Celery Leaf-Tyer (Phlyctaenia ferugalis)
During some seasons this insect is extremely injurious
to celery. The eggs are laid on the leaves. The larvae feed
chiefly on the new and tender leaves above the "heart" of the
celery. As the caterpillars get older they descend the stalks






90 DEPARTMENT OF AGRICULTURE


and feed near the bases of the stalks until ready to pupate.
During the later stages of growth the caterpillar spins a
more or less conspicuous web of silk under which it feeds,
hence the name of webworm. The larva is a pale yellowish
caterpillar and quite hairy. The adult is a small brownish
moth.
Control.-This insect is best controlled by dusting the
plants with pyrethrum. This may be used straight or mixed
with an equal weight of sulphur.


Semi-Tropical Army Worm (Prodenia sp.)

This insect, which feeds chiefly on grasses, sometimes
attacks celery in injurious numbers. It is a large caterpil-
lar with reddish brown markings. It is closely related to the
sweet potato caterpillar. The same poison baits which are
recommended for that insect will also control this cater-
pillar.

Garden Flea-Hopper (Halticus citri)

This is a minute black plant-bug (Fig. 78) that attacks
the leaves of cowpeas, beggarweeds, peppers, and a great










d
FIG. 78.-Garden flea-hopper: a, Short-winged female; b, full-winged
female; c, male; d, head of male in outline. Eight times natural size.
(From U. S. Bur. of Ent.)

variety of weeds. The attacked spots turn yellow, giving the
plant a spotted, "peppered" appearance. The insect may be
controlled readily by tobacco extracts.






PLANT DISEASES AND PESTS


Celery Caterpillar (Papilio polyxenes)
This caterpillar sometimes strips the leaves from celery
and, as the caterpillar is rather large, a single one can inflict
much damage. It is
conspicuously colored
in green and black. It
a is a close relative to the
Common "orange dog"
(Papilio cresphontes)
and, like that species,
when disturbed, it
thrusts out a yellow
FI(. 80.-Tarnished plant-bug: Adult and horn-like process from
young. About four times natural size.
(From U. S. Bur. of Ent.) the head accompanied
by a strong pungent odor. This seems to protect the insect
from birds and possibly other foes. It grows to a length of
2 inches. The pupa is fastened to a support partly by a
silken thread about its middle. In from 12 to 15 days, in
summer, there issues from it a swallow-tailed butterfly. This
is smaller than the adult of the orange dog and much darker
in color. It is called the black swallow-tail.
Both the caterpillar and its work are so conspicuous
that hand-picking will usually be the most economical
means of control. As celery is commonly sprayed with
Bordeaux for fungous troubles, lead arsenate can be added
(1 pound to 50 gallons of Bordeaux) and this, as well as all
other biting insects, be killed.
Other Caterpillars.-Several other caterpillars attack
celery; among them are the celery looper (Autographa
falcifer), an insect closely related to the cabbage looper.

Plant-Lice
At least two species of aphids commonly attack celery
in Florida. One is the common garden aphid or green peach-
aphid (Myzus persicae). The other, Macrosiphum lactucae,
is much larger. The control measures are the same as those
given under cabbage, page 84.






92 DEPARTMENT OF AGRICULTURE

Other Celery Pests
Other insects injurious to celery are: Flea-beetle (see
under beets, page 73); cutworms (see under cabbage, page
75); and cabbage root-maggot (see under cabbage, page
86); red spider (see under peas, page 121).


FIELD CORN AND SWEET CORN
Sweet corn is attacked by all the common pests of corn
and there are many of them. Some show a decided prefer-
ence for sweet corn. Only the more important insects at-
tacking corn will be considered here.

Corn Ear-Worm, or Bud-Worm (Heliothis obsoleta)

This common pest of cotton, corn, tomatoes, beggarweed,
etc., prefers sweet corn to any other of its host plants. Early
in the season the moth lays her eggs on the young corn. The
early generation of larvae which hatches from these eggs
works in the corn as a "bud-worm." (At least two other
caterpillars that do very similar damage to corn are known
as "bud-worms.") When mature the caterpillars enter the
ground, pupate, and in seven days emerge as moths which
in turn lay their eggs on the silk of the corn which is by this
time beginning to appear. The second generation of larvae
on the corn eats the silk and then enters the ear and feeds
upon the developing kernels. Later generations develop on
cotton, beans, beggarweed, etc. The insect also attacks toma-
toes. But whether working in corn as the "bud-worm" or
"ear-worm," in tomatoes as the "fruit-worm," on cotton as
the "bollworm," or fully exposed on beggarweed, it is the
same insect. So abundant is this pest in Florida that it is
almost impossible to find an ear of sweet corn that has not
been attacked by at least one of these caterpillars.
Control.-The work of the first generation in the corn is
usually noticeable when the corn is about knee high. At this
stage it is not difficult to poison the caterpillars by spraying
or dusting some of the arsenic compounds into the infested






PLANT DISEASES AND PESTS


buds. The writer has dusted undiluted lead arsenate and
zinc arsenite powder into the buds without producing any
harmful effects, but it is safer and more economical to mix
the poison with from 2 to 4 times its bulk of air-slaked or
hydrated lime. The dusting is best done in the early morn-
ing when the plants are wet with dew. The agitation result-
ing from brushing against the stalks will usually be sufficient
to cause the dew to run down into the bud, carrying the
poison with it. In a small garden the poison can be applied
by means of a tin can
punched full of holes.
On a large scale the well- ;
known bag-and-pole
method may be used, but
the most even distribu- e-
tion will be secured by
the use of a dusting ma-
chine. It is important
that this early generation
should b destroyed, if FIG. Sl.-Corn ear-worm: Adult. One
d besroyed and a half times natural size. (Orig-
possible. Not only will final )
the injury to the buds be checked, but the number of cater-
pillars in the following generation, which works in the ears,
will be lessened.
When the silks appear on the young ears of corn they can
be dusted by means of the same apparatus. The caterpillars
feed on the exposed silks for only a few days before enter-
ing the ear, where they are safe from insecticides, so it will
be necessary to repeat the dusting every three or four days.
This is too expensive for a crop of field corn, but on such a
high-priced crop as sweet corn it is worth while.
In a small patch in the garden the worms can often be
removed from the tip of the ear before they have inflicted
material damage. In removing the worms it is not well, how-
ever, to open the ears to such an extent as to expose the
kernels, as other animals such as birds, Carpohilus and other
insects will then attack them. Woodpeckers and bluejays
are occasionally seen feeding on the worms and the ears of
sweet corn.






94 DEPARTMENT OF AGRICULTURE

Life History.-The eggs are whitish, oval, prominently
ribbed, and about a twentieth of an inch in diameter. They
are scattered over the corn. Those from which the bud-
worm hatches are laid on the leaves; those of the ear-worm
on the silk. They hatch in 3 or 4 days.
The caterpillars vary from a delicate pink to black. They
are marked with rather narrow longitudinal lines. They re-
quire about 17 days for growth in summer, becoming 11/
to 2 inches long. The caterpillar then bores a hole in the side
of the ear or stalk and enters the ground to a depth of 2 to
5 inches where it forms the pupa. Here it remains for a
week or two in summer or all winter if it is the last fall brood.
The pupa lies in an earthen cell. It is about 3/4-inch long.
It is at first green in color but soon turns to a light brown.
The moth (Fig. 81) which issues from this cocoon varies in
color from a dusky yellow to grayish and expands from 1lX
to 2 inches. Unlike most moths it may fly in broad daylight,
but the eggs are usually laid at sunset.

Carpophilus
If the husk is removed from an ear of corn in the milk by
any cause, such as a woodpecker in his hunt for a corn ear-
worm, it is at once attacked by these scavenger beetles,
which are also common in decaying fruits. The beetles are
brown and about 1/s of an inch in length. Their wing-covers
are so short that they do not reach the end of the abdomen.
The beetles seem unable to penetrate the husk of an un-
injured ear, but very commonly get into the burrows made
by the corn ear-worm and cause further damage. They often
breed among the kernels which blacken and decay, thus spoil-
ing many ears that would otherwise be usable. The larvae
are small, whitish, and maggot-like. Control measures are
obviously those which control the corn ear-worm.

The Corn Lantern-Fly (Peregrinus maydis)
This insect and the bud-worm are the worst enemies of
late-planted corn in Florida. In the latter part of August
the lantern-fly becomes extremely abundant and severely






PLANT DISEASES AND PESTS


infests practically every stalk of young corn, and quickly
kills it. Stalks that have reached the tasselling stage are not
severely injured.
This lantern-fly is a slender yellowish-green insect about
a sixth of an inch long. Its wings are longer than the body,
and are clear except for some dark-brown markings near
the tip.
They collect in large numbers in the bud and in the axils
of the leaves. These colonies are usually composed of nu-
merous young of all stages, and a few winged adults.
The most effective and the quickest means of controlling
this pest is to dust the buds of the corn with nicotine sul-
phate-lime dust.

Wireworms, "Drillworms"
These long, slender, hard, wiry "worms" are the larvae
of click-beetles. They feed below the surface of the ground
on the roots and stems of plants into which they often bore.
The infested plant is stunted, turns yellow and may die. The
larvae are particularly destructive to sprouting seed, eating
the inside.
The adults are called click-beetles from their habit of
throwing themselves into the air with an audible click when
placed on their backs. They are also called "skip jacks" and
"snap beetles."

There are dozens of species of wireworms in Florida and
at least a half-dozen injure corn. As their habits, life his-
tory, type of soil infested, and control measures differ for
each species, it will be necessary to take up the more im-
portant ones separately.
Spotted Click-Beetle.-The most common wireworm in
Florida corn fields is the young of the spotted click-beetle
(Monocrepidius vespertinus) (Fig. 82). This is a thick wire-
worm about 1/2-inch long and is found in both dry and wet
land but is more destructive in the former. It is also found
on cowpeas.






96 DEPARTMENT OF AGRICULTURE















FIG. 82.-Spotted click-beetle: Adult; pupa; larva; and egg: greatly
enlarged. (From So. Car. Agr. Exp. Sta.)


The eggs are laid in the summer. They hatch in about
9 days, according to Dr. A. F. Conradi and H. C. Edgerton
(So. Car. Agr. Exp. Sta. Bul. 179), and the larvae feed until
the following spring when they pupate in the ground at a
depth of from 3 to 5 inches, remaining there about two
weeks. The earliest adults were taken at Gainesville on
June 7 by Mr. Dozier. They are from 1-5 to 1-3 of an inch
long.

Fall plowing and frequent cultivation of the corn will
destroy many of these insects, particularly if chickens or
other birds follow the plow. They are seldom found at a
greater depth than 4 inches. A few seeds of cotton planted
at the same time as the corn is said to be of benefit.
They prefer the cotton to the corn and while they are feed-
ing on the cotton, the corn has an opportunity to germinate
and get a start.

The nighthawk is an important enemy of the beetles
which fly at dusk, the time when these birds are on the wing.
Nighthawks should be protected by the farmer.

Monocrepidius Lividus.-Associated with the last-named
species in about the same class of soil is Monocrepidius livi-
dus. This is perhaps the second most common wireworm in







PLANT DISEASES AND PESTS


Florida. Control measures are the same as for the above
named species.
Corn and Cotton Wireworm.-Unlike most wireworms,
this one (Horistonotus uhleri, Horn) works mostly in sandy,
light, dry soils. It differs also from the other species in its
appearance. It is long and white and has a soft skin instead
of the hard, chitinous covering like the others. Control meas-
ures are about the same as those used against the larva of
the spotted click-beetle.
Corn Wireworms (Melanotus sp.)-These are not as com-
mon as the other species. Like most species of wireworms
they are found mostly in low, poorly-drained land, especially
if it was in grass the previous year. Draining and liming the
land, with deep and thorough cultivation, are important.
The larvae are about 11/4 inches long, brown in color and
have three small projections on the posterior end. Some
species require several years for growth. The adults are
brown and from a half to 3/ of an inch in length.
Other wireworms sometimes injurious to corn in Florida
are Lacon curtus and Lacon rectangulus. The control meas-
ures are similar to those for the last-named.

Fall Army Worm, or Southern Grass Worm
(Laphygma frugiperda)
This well-known pest of grass attacks corn as a second
choice when all of the grass within easy range has been
eaten. Army worms are so named from their habit of as-
sembling in vast numbers and marching in mass formation
to new pastures. These marches come as a result of exces-
sive numbers exhausting the food supply in the place where
they hatched. The word "fall" was prefixed by entomolo-
gists in the Northern States and is a misnomer in Florida.
The destructive armies usually form in July and August, but
sometimes as early as April. At other seasons, and during
the years when no armies are formed, a few of these cater-
pillars are found, feeding apart like cutworms.
Control.-These isolated caterpillars may get into the
tips of growing corn and become "bud-worms" where they






98 DEPARTMENT OF AGRICULTURE

may be controlled by the same measures as given for the
corn ear-worms when working as bud-worms. (See page
92.) The armies may be repelled with fair success by the
"Kansas bait," (see page 55), or the food-plants may be
sprayed or dusted with lead arsenate, Paris green or any
other arsenical. This is applied best while the caterpillars
are working on grass, before entering the cornfield.
The eggs are laid mostly on grasses in masses of fifty or
more and hatch in about ten days. The caterpillars require
about two weeks in which to become full-size, which is about
11/4 inches long. They are rather slender. Their color is
brown with a narrow yellowish-gray stripe along the middle
of the back and a brownish-black one along the side. On
the head the central line branches, making a conspicuous
V-shaped white mark, which helps to identify the cater-
pillar. The body is covered with small black prominences
from each of which a short, stiff, black hair arises. The
adult is a moth resembling those of cutworms, to which it
is closely related.
Root Webworms (Crambus sp.)
These also are caterpillars that often do severe damage
to young corn in the spring. In April, 1914, they destroyed
many acres about Gainesville and other places. They always





Z f -..-.


d ~j


FIG. 83.-Bill-bug (Sphenophorus callosus): a, Larva;
enlarged. (From U. S. Bur. of Ent.)


d, adult. Greatly


k






PLANT DISEASES AND PESTS


do more damage than they are charged with, much of their
work being attributed to cutworms. There are several
species of these insects, but all of the caterpillars are red-
dish, pinkish or brown, with conspicuous dark spots on their
backs. Like cutworms, they feed at night, but do not cut the
plant off. Instead, they strip it of is leaves, make channels
on the surface of the stalk, or mine the center. They con-
struct a tube of silk just below the surface of the ground and
hide in this during the day. This will
distinguish them from cutworms. Fur-
thermore, they try to escape when dis-
turbed instead of curling up and "play-
ing possum" like cutworms. The adult
insects are small, light-colored moths
which are always plentiful in sod land.
When at rest they roll their wings
around their bodies instead of laying
them back
more or less
flat like most
moths. .
Control.-
Severe injury
by these cater-
pillars is con- !
fined to land i|
which had con-
siderable grass
during the pre-
ceding year. (
Such land, if
intended for
corn, should be
broken as early a a
in the fall as
practicable. FIG. 84.-Injury to corn by bill-bugs. (From
Aside from the U. S. Bur. of Ent.)
matter of insect control, this is also the best procedure from
the cultural standpoint, as it conserves the moisture during






DEPARTMENT OF AGRICULTURE


the dry winter. Some relief can be obtained by dusting or
spraying the young plants with lead arsenate.

Bill-Bugs (Sphenophorus spp.)
Other insects that injure young corn are species of snout
beetles called "bill-bugs" (Fig. 83). They feed on the young,
tender leaves, making parallel rows of holes, after the pat-
tern of sap-suckers on trees (Fig. 84). This is done when the
leaf is rolled up in the bud and each row of holes is produced
by a single puncture.

Like the last-named insect, this one is injurious only on
land that grew much grass during the preceding year. Eggs
are laid on grasses in low wet land, where alone bill-bug
injury is ever severe. The young feed chiefly on the roots
of grasses, but one species (S. robustus) may live in the pith
of the corn stalk.

The measures recommended for use against root web-
worms (page 98) are also the ones to be used against bill-
bugs.

Corn-Leaf Blotch-Miner (Agromyza parvicornis)

This larva of a minute black fly makes irregular shaped
blotches in the leaves of corn and some grasses by eating the
tissue from between the lower and the upper epidermis. Its
injuries are most noticeable and serious on young corn. The
egg is laid in the corn leaf and hatches in 3 or 4 days in sum-
mer. The larva feeds from 3 to 12 days in summer. It
breeds during the winter in southern Florida (Jl. Agr. Re-
search, April 12, 1916).

The insect cannot be reached by any insecticide. The
only course is to pull up and destroy badly infested plants,
and by good care, keep the others in such a vigorously grow-
ing condition as to overcome the injury. An excess of corn
should be planted so that a good stand will remain after the
requirements of the flies have been met and the infested
plants pulled up.




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