The culture and diseases of the sweet pea

THE CULTURE

OF THE SWEET PEA

[;j TATmENHAII

yNIVERSITY OF B.C. LIBRARY DUPL

3 9424 05045 648 9

nCEAGH ITEM
KOCESSING-CME

THE LIBRARY

THE UNIVERSITY OF
BRITISH COLUMBIA

DEPT. AGRICULTURf

i^CB 20 1935

COURT HOUSE,
VANCOUVER, B. C.

OtC 1 1 1923

OTHER WORKS
BY THE SAME AUTHOR

Diseases of Truck Crops and their Controi
[In Preparation]

Diseases of Greenhouse Plants
[In Preparation]

Diseases of the Sweet Potato
[In Preparation]

E. P. DUTTON & CO

new YORK

Digitized by tine Internet Arciiive

in 2010 witii funding from

University of Britisii Columbia Library

http://www.archive.org/details/culturediseasespeaOtaub

THE CULTURE AND DISEASES
OF THE SWEET PEA

BY

J. J. TAUBENHAUS, Ph.D.

Plant Pathologist and Physiologist in Charge. Experiment
Station, Agricultaial and Mechanical Colleee of Texas

NEW YORK

E. P. DUTTON & COMPANY

681 FIFTH AVENUE

Copyright, 1917
By E. p. DUTTON & COMPANY

PRINTED IN THE UNITED STATES OF AMERICA

TO

The reverend CHAIM HIRCHENSOHN
with love and deep affection

PREFATORY NOTE

The keen appreciation of the public of
the beauties of nature as expressed in the
building of parks and public gardens, in
the planting of street trees, and in the
adornment of private grounds and homes
by means of ornamental plants is one of
the most distinctive marks of an advanced
civilization. The success of these under-
takings means the overcoming of many
difficulties which the casual observer fails
to appreciate. It means not only the se-
lection and arrangement of varieties in
such manner as to meet with the most
sesthetical tastes of the public, but it fre-
quently means growing the plants under
new environmental conditions, the study
of soil and climate, the contest against
insects and diseases which continually

threaten the existence of these plantings.

vii

viii PREFATORY NOTE

It has long been known that unfavor-
able soil and climatic conditions and de-
structive insects were very important fac-
tors in plant culture, but it is only within
recent years that the public has begun to
appreciate that many of the difficulties in
growing plants, in fact, many of the fail-
ures are due to diseases. Most of these
diseases are due to fungus or to bacterial
organisms. Since most of these organisms
are so small that they cannot be seen ex-
cept with the aid of a microscope, the
grower has usually attributed the disease
to other causes. The appreciation of these
facts makes a work on the growing of any
group of ornamental plants in which the
importance of the control of the diseases
is given a prominent place very desirable.
Therefore, this work on the Growing of
Sweet Peas, by a worker who has made a
special study of the diseases is very timely.

PREFATORY NOTE ix

The sweet pea is a favorite flower with
the great majority of people. It is en-
joyed by both the high and the lowly, and
is within the reach of all. It is a profuse
bloomer and presents an untiring variety
of sizes and delicate colors. It is well
adapted to various conditions and can be
grown over a very large part of the world.

The author's training in plant pathology
and his large experience with diseases of
ornamentals is a guarantee of meritorious
character of the work. The work is both
practical and scientific; it is equally use-
ful to the layman, the commercial grower
and to the scientist; it deals not only with
the diseases of sweet peas, but with the
cultivation and other important questions
connected therewith.

MEL. T. COOK.
Rutgers College,

New Brunswick, N. J.
January, 1917. .

PREFACE

The sweet pea is unfortunately one of
those crops which has received scant con-
sideration in horticultural text books.
The field to be covered by the latter is so
large that their treatment of many a crop
is necessarily meager. Good articles on
the culture of the sweet pea are to be found
in various journals, but are not accessible
to the practical grower. The cultural di-
rections which seed concerns publish for
the benefit of their patrons are brief; and
Mr. Harrison Dick's ''Sweet Peas for
Profit" covers only one phase of the sub-
ject, namely, the greenhouse culture. As
no complete study of the sweet pea has
been published in America, it is felt that

this book may be very timely, especially

xi

xii PREFACE

since this delicate flower is gaining so rap-
idly in popularity.

The chief difficulty encountered by the
growers of the sweet pea is the combating
of diseases, in which they have had very
little help. Massee and Chittenden in
England have devoted some time to the
"Streak disease," but these workers have
been misled in their observations by at-
tributing this disease to the fungus Thie-
lavia. In the United States, floral pathol-
ogy is still in its embryonic stage, and the
sweet pea was not the first to claim the at-
tention of Pathologists. The author of
this book in the last three years has pub-
lished several papers on his own investi-
gations, taken up largely because of nu-
merous complaints from growers who met
with failure in their attempts to grow this
beautiful flower. Florists and gardeners
have often been hopelessly discouraged

PREFACE xiii

the first time they tried to grow sweet peas
because of total loss from disease. Others
who have grown them for years have been
meeting with difficulties that are consider-
ably reducing their profits. The layman,
particularly the housewife so proud of her
row of sweet peas by the house, has seen
many of them carried off by blights and
the remainder dry up and wither away.

Naturally the blame fell at once on the
seedsman, who was accused of supplying
a poor grade of seed. In seeking justifica-
tion, seedsmen attributed the growers'
failures to bad weather, to drought, or to
the green aphids. A few seed catalogues
and some popular articles on the culture
of the sweet pea asserted that the plant is
unusually free from disease, and that all
failures are due to overfeeding. Many
practical men do not realize that plants
have diseases just as do animals and hu-

xiv PREFACE

man beings. We shall here endeavor to
show that although bad weather, over-
feeding, etc., may be important factors,
they are not the fundamental reasons for
failure. We shall study the specific causes
that lead to the diseases of the sweet pea;
the definite parasitic forms of life such
as insects, fungi, and bacteria that live
upon this plant and bring about its de-
struction. The nature of the attacking
insects is still incompletely known and
there is urgent need of further investiga-
tion of them. Of the fungi, nine produce
serious diseases in either roots, stems, foli-
age, or blossoms of sweet peas. Only one
bacterial trouble, however, is so far known
to affect sweet peas, and that is the dreaded
"Streak." To these troubles may be added
eel worm, red spider, and mites, all of
which add considerably to the losses.
In the discussion which is to follow.

PREFACE XV

technical terms as far as possible will be
avoided, with the exception, however, of
the scientific names of the parasites. Pop-
ular terminology does not always distin-
guish between diseases of different nature
that are apparently alike. For example,
the term ''blight" is applied to diseases of
similar symptoms but of quite different
causes. Methods of controlling a disease
are directly dependent on a knowledge of
the nature and cause of the particular
trouble. Taking insect pests as an exam-
ple, it is essential to know whether they
are biting or sucking, each class requiring
different treatments.

The writer feels that no apology is
needed for allowing space in this book to
a discussion of the culture of the sweet
pea. No matter from what angle we look
at it, we cannot deny the fact that plant
diseases are directly dependent on the cul-

xvi PREFACE

tural conditions of the host. In other
words, the attack of most plant diseases
depends on some weak point in the cul-
tural methods which has weakened the
host at some phase in its life history. If
we accept the definition of disease as any
serious deviation from the normal; and
admitting as we do that proper cultural
conditions are necessary to maintain the
proper balance of health of a plant, it be-
comes self evident that a discussion of
culture requirements goes hand in hand
with any discussion on plant diseases. To
be more specific, it is very apparent that
the man who understands plant life in all
its aspects will be in a much better posi-
tion to also cope intelligently with any
problem of disease which may confront
him at any time. Since growers as a rule
must be their own plant doctors they can-
not be provided with too much informa-

PREFACE xvii

tion on cultural requirements of the par-
ticular crop with which they are coiicerned.

Although the writer had considerable
experience in growing sweet peas in the
open and in the greenhouse, he felt that
this ground could be so much better cov-
ered by eminent specialists such as Pro-
fessor Beal of Cornell University; Mr.
Cuthbertson, Messrs. Morse and Co., and
all the others who are here quoted.

It may perhaps be the opinion of a few
that a book on plant pathology should not
include a discussion on insect pests. The
writer, however, believes that in a specific
work of this nature such a discussion is in-
valuable. Insects are known to be car-
riers of numerous plant diseases. In this
work it would be rather difficult to give a
complete discussion of Mosaic, or in fact
of any of the other sweet pea diseases if
we were to leave out of consideration the

xviii PREFACE

damage caused by the Pea Aphis, or any
other of the insect pests here described.
The writer did not trust to his own knowl-
edge of Entomology. Insect specimens in
each case were submitted to the Depart-
ment of Entomology, United States De-
partment of Agriculture for identification,
and there due credit belongs.

This book is primarily intended to be a
practical treatise. The aim cannot be at-
tained if our study is to be deprived of its
scientific basis and its scientific value. It
is hoped this double character of the work
will make it a means of ready reference
for both growers and investigators.

During the past four years numerous
letters of inquiry have been received by
the writer from sweet pea growers rela-
tive to various difficulties, especially those
of a pathological nature. Although hesi-
tating to make hasty suggestions, we could

PREFACE xix

not turn a deaf ear to the numerous re-
quests from sweet pea growers as well as
from technical men who urged the prepara-
tion of a book of this nature. The writer
seriously solicits suggestions or criticism
of this work.

Acknowledgments are due to Professor
A. C. Beal, Mr. F. G. Cuthbertson, and
C. C. Morse and Co. for valuable contri-
butions on the culture of the sweet pea.
To Mrs. D. de Sola Pool (nee Miss Tamar
Hirchensohn), previously of the Faculty
of Hunter College, N. Y.; to Dr. Owen
Sypherd of Delaware College, to Dr. C.
H. Farr of the A. and M. College of
Texas, to Dr. M. T. Cook of Rutgers
College for suggestions in reading the
manuscript. To the Delaware Experi-
ment Station for figs. 7 to 21, 25 to 31, 38,
42, 43, and 45, all of which were origin-
ally taken by the author. All the other

XX PREFACE

figures have been accredited in their proper
places.

Last but not least, acknowledgment is
due my wife, Esther Michla Taubenhaus,
by whose inspiration this work was made
possible.

J. J. Taubenhaus.
College Station^ Texas,

CONTENTS

PAGE

Introduction i

CHAPTER

I History, Evolution, Classification and

Culture 9

II Culture of the Sweet Pea for Seeds . 60

III Culture of Sweet Peas Under Glass . 74

IV Diseases of Greenhouse Sweet Peas . . 90
V Field Diseases of Sweet Peas .... 135

VI Diseases Not Yet Known in America . 149

VII Insect Pests 152

VIII Diseased Seeds 176

IX Physiological Diseases 181

X Methods of Control 185

XI Spraying 204

Index 227

ILLUSTRATIONS

A Fine House of Sweet Peas . . . Frontispiece

riG. PAGS

1 Method of Growing Sweet Peas from Seed in

England 39

2 Trial Grounds of C. C. Morse & Co. ... 70

3 Field of Morse's White Spencer .... 70

4 Sweet Peas and Carnations 89

5 Root Rot caused by Rhizoctonia .... 99

6 Root Rot caused by Rhizoctonia .... 99

7 Hyphae of Rhizoctonia 102

8 Culture of Sweet Pea Rhizoctonia . . . .102

9 Culture of Fusarium Lathy ri 102

10 Chaetomium Spirochaete 107

11 Fusarium Wilt 110

12 Root Rot caused by Thielavia 113

13 Root Rot caused by Thielavia 114

14 Mycelium of Thielavia 116

15 Powdery Mildew 119

16 Sclerotia of the Sweet Pea Sclerotinia . . .119

17 Sclerotinia Wilt in Seedlings 120

18 Root Knot in Sweet Peas 124

19 True Legume Root-Nodules 124

20 Greenhouse Thrips 131

21 Red Spider 132

22 Triphleps Insidiosus 133

23 Anthracnose Disease on the Stem . . . .138

ILLUSTRATIONS

FIG. PACE

24 Anthracnosc Disease on the Leaf . . . .138

25 Bitter Rot of Apple 141

26 Sweet Pea Mosaic 141

27 Dwarfing of Plant due to Mosaic . . . .142

28 Plant Outgrowing Mosaic 144

29 Culture of the Streak Organism . . . .148

30 Sweet Pea Aphis Parasitized 148

31 Sweet Pea Aphis 153

32 How Aphids Feed 156

33 The Convergent Lady Beetle 159

34 Syrphid Fly 160

35 Green Lace Fly 162

36 Aphidius Testaceipes Ovipositing . . . .163

37 Aphelinus Nigritus 166

38 The Striped Blister Beetle 170

39 Variegated Cut Worm 171

40 White Grub (May Beetle) 174

41 Anthracnose Disease on Pods 177

42 Fusarium and Botrytis Fungi 178

43 Auto-spray No. One 180

44 The Drugstore Beetle 180

45 Soil Infected with Fusarium Lathyri . . .191

46 Spraying the Sweet Pea Field 218

CULTURE OF THE
SWEET PEA

INTRODUCTION

The ancients believed that diseases in
plants were induced by evil spirits. For
instance, the rust of wheat was thought by
the Romans to be caused by the evil spirit
Rubigo. The remedy then employed was
to frighten away the spirit by beating with
drums of various kinds. To-day, some
insist that all plant diseases are brought
about by conditions of environment such
as excessive sunshine, drought, rain or
dew. We may perhaps justify these views
when we consider that plants in their mute
way are unable to tell of their ailments.
The keen eye and the close observer, how-

2 CULTURE OF THE SWEET PEA

ever, have singled out on plants parasitic
organisms whose work brings about devi-
ations from the normal. To-day Plant
Pathology has become recognized as a
definite science. There is hence no reason
why we should tolerate certain plant dis-
eases when we realize the vast store of
scientific knowledge available. Indeed it
is highly imperative that any man who is
engaged in the growing of crops should be
able to recognize a diseased condition in
plants.

Like every science, Plant Pathology has
made slow progress in its beginning.
Scholars who considered it from a purely
speculative or philosophical point of view
only were interested in it at first. It was
really during the first half of the nine-
teenth century that Plant Pathology built
for itself a solid foundation, and gained
a place among the leading sciences. It

INTRODUCTION 3

seems that it was very difficult for schol-
ars previous to the nineteenth century to
believe otherwise but that parasitic fungi
were emanations or waste products of the
higher plants. It was DeBary who first
established definitely that healthy plants
may be attacked and penetrated by fungi.
This important discovery has forever dis-
pelled doubt as to the parasitic nature of
most plant diseases. Nevertheless, the
economic aspect of Plant Pathology could
not gain much impetus as long as growers
were content to lose annually from five to
forty per cent, of their crops. It required
severe epidemics to arouse the attention of
farmers in which cases they turned to the
scientist for help. An instance of this is
the epidemic of late blight of potatoes in
Ireland, in 1845, which practically re-
sulted in famine and great hardship to the
people. Unfortunately, there were no

4 CULTURE OF THE SWEET PEA

trained Pathologists at that time to cope
with the situation. A similar epidemic
was that of downy mildew of grapes in
France, in 1882. France, however, met
the crisis through one of her noble sons,
Professor M. Millardet, then of the Acad-
emy of Science at Bordeaux. His keen
observations and studies have evolved a
remedy for the grape mildew. Millardet
was in fact the first to show the value of
copper as a fungicide; and incidentally
also laid the foundation to modern meth-
ods of spraying and of disease prevention
in general. To-day Plant Pathologists
are everywhere investigating plant dis-
eases which cause serious epidemics. And
they are going farther, for the diseases of
every weed is important and will aid in
the solution of many problems regarding
disease in vegetables, fruits and crops.
Although nearly every Agricultural Col-

INTRODUCTION 5

lege or University in the United States
offers courses in Plant Pathology, the sup-
ply of trained investigators is neverthe-
less limited. Since every Experiment Sta-
tion is directly supported by state and
federal funds, it is natural that every
worker is more or less impelled to inves-
tigate diseases of plants which are of
greatest economic importance. For this
reason nearly all the research was directed
to fruit, cereal and forage crops. Flower
pathology is as yet in its embryonic stage.
To-day there are but few institutions of
learning which have established definite
divisions in the investigation of diseases
of ornamental plants. As stated in the
preface, the sweet pea diseases have
received scant attention, except those
worked by the writer. Even in this case
for lack of funds the investigations were
brought to an untimely end. The little

6 CULTURE OF THE SWEET PEA

that the writer was able to contribute was
made possible through the moral sup-
port of the American Sweet Pea Society;
and especially by money donations from
the various seedsmen and other lovers of
the sweet pea in the United States.

It is believed that the present work is
fulfilling an urgent need. There never
was a time when ornamental plants were
grown commercially on a larger scale than
to-day. In fact the sweet pea itself forms
an industry, the economic importance of
which cannot be overlooked. It is within
recent memory of all when the hollyhock
occupied the place of honor in every gar-
den. In every flower exhibit in this coun-
try or abroad it was king. To-day the
hollyhock is only mentioned as ancient his-
tory. Diseases have so crippled that beau-
tiful plant, that growers out of sheer dis-
couragement have ceased raising it. Now

INTRODUCTION 7

it is found occasionally near abandoned
houses or in neglected back yards. The
sweet pea is undergoing similar critical
periods. In England, for instance, the
"Streak" already constitutes a serious
menace to profitable sweet pea culture.
The same conditions are beginning to pre-
vail in the United States, and several per-
plexing diseases now threaten the eco-
nomic existence of one of the most delicate
of flowers.

' CHAPTER I

HISTORY, EVOLUTION, CLASSIFICATION AND
CULTURE ^

Among the annual flowers none excel
the sweet pea in beauty, usefulness, fra-
grance, and range of color. No annual
flower is more popular. If the rose is the
Queen of Flowers, the sweet pea is a truly
royal princess worthy of her train. This
flower has long been grown in England
and America; of late years it has been
gaining in favor in continental Europe;
and it is also extensively grown in far-off
Australia and Tasmania.

The sweet pea is a native of the island
of Sicily. It was first mentioned in 1695

* By Professor A. C. Beal of Cornell University.
9

10 CULTURE OF THE SWEET PEA

by an Italian monk who sent seeds to Eng-
land and Holland. In England sweet
peas were cultivated in many gardens.
The plant is one of the species of Lathy-
rus, which is a genus of Leguminosae. Un-
like other species of this genus, the sweet
pea has fragrance, and Linnaeus gave it the
name of odoratus. Its scientific name,
therefore, is Lathyrus odoratus. The
color of the original sweet pea was purple
in the standard, and sky-blue in the wings.
During the first one hundred years of
its history there was little improvement
in the sweet pea. A variety with white
flowers and another with pink and white
flowers were developed. The first half of
its second century of cultivation was sig-
nalized by the development of several va-
rieties, so that in i860 there were nine
known varieties. About this time seeds-
men began to take greater interest in

HISTORY AND EVOLUTION ii

sweet peas; but more varieties came in
slowly. Every flower, however, that has
won popular favor has had at least one
great genius to develop it. The greatest
genius in sweet peas was Henry Eckford,
who commenced crossing the best obtain-
able varieties about 1878, and began to
sell new varieties in 1883. Steadily he
kept at work until, at his death in 1905,
although the number had increased to
more than three hundred, he was to be
credited with originating most of the lead-
ing varieties. About 1890, the American
sweet pea growers began to appreciate the
beautiful varieties Mr. Eckford was send-
ing out and there was a wave of popularity
for the flower. The discovery that Cali-
fornia had a favorable climate for the pro-
duction of sweet pea seed enabled the
seedsmen to supply the greatly increased
demand. This development has con-

12 CULTURE OF THE SWEET PEA

tinued until the larger part of the world's
supply now comes from California.

Meanwhile the variety Blanche Ferry
was discovered growing in a garden in
New York State and was put on the mar-
ket in 1889. From this was developed the
varieties Early Blanche Ferry, Earliest of
All, Earliest White, and the whole race of
winter-flowering sweet peas. The Ameri-
can originators have given us many good
striped varieties, such as America, Aurora,
etc., and also such blues as Navy Blue and
Flora Norton. Other notable varieties
are Helen Pierce, Dainty, Janet Scott,
Emily Henderson, Phenomenal, Stella
Morse, Admiration, Shasta, and White
Wonder. The dwarf or Cupid sweet peas
originated in California and were offered
in 1896.

During the closing years of Mr. Eck-
ford's busy life, at a time when some grow-

HISTORY AND EVOLUTION 13

ers thought that the limit of development
in sweet peas had almost been reached, a
new type of sweet peas appeared. This
was the waved or Spencer type. The first
variety, Countess Spencer, sent out by Mr.
Cole (the originator) in 1904, was at once
very popular, and since that time there
has been an extraordinary interest in sweet
peas on both sides of the Atlantic. How-
ever, the greatest interest has been in Eng-
land, where a great many persons are in-
terested in originating new varieties and
a large number are placed on the market
each year. Numerous exhibitions are
held, and the National Sweet Pea Society
has over one thousand members.

Although the interest in sweet peas in
America is not so intense, yet this flower
is seen in almost every home garden,
where it is cherished for its special
beauty.

Dwarf :

14 CULTURE OF THE SWEET PEA

The sweet pea may be classified accord-
ing to the habit of the plant into

C\ b* jGrarden varieties
[Winter-flowering
jCupidi

[Bush varieties (now obsolete)
It is important to remember that the win-
ter-flowering varieties are absolutely dis-
tinct from the garden varieties in their
habit of growth. The Cupids are occa-
sionally grown because of their novelty.

Sweet peas are usually classified accord-
ing to the form of the flower. The earliest
known varieties of the sweet pea had flow-
ers in which the standards were reflexed
and deeply notched at the apex. The ef-
fort of Mr. Eckford and others was to
eliminate the notch and give the standard
greater substance so that it could hold it-
self erect. This brought about the open
form which often retained something of

HISTORY AND EVOLUTION 15

the apical notch. Then came the hooded
form, in which the edges of the standards
are rolled forward. There are various de-
grees of hooding in different varieties.
Extreme hoodings were at one time recog-
nized under the name of snapdragon va-
rieties, which were never more than a pass-
ing novelty. Finally, there is the waved
form in which the edges of the standards
and often the wings are beautifully
waved. This is the most handsome form
of sweet pea flower (the flowers are larger
and have longer stems) , and it is probable
that the other forms will pass away. The
older types, however, seed more freely, and
therefore it has been possible to produce
seed more cheaply. However, any one
who has grown the waved or Spencer va-
rieties will not again take up the culture of
the old varieties, and therefore in the
course of time the latter are doomed.

i6 CULTURE OF THE SWEET PEA

The following is a classification of
sweet peas according to form :

Garden type Winter-flowering Dwarf Type

type (Cupid)

Open form Open form Open form

Hooded form Hooded form Hooded form
Waved form Waved form

Sweet peas are classified also according
to color. The English Sweet Pea Society
recognizes thirty-two color classes as fol-
lows: Bicolor; Blue; Blush; Carmine;
Cerise; Cream, Buff, and Ivory; Cream-
pink (Pale) ; Cream-pink (Deep) ; Crim-
son; Fancy; Lavender; Lilac; Magenta;
Marbled and Watered; Maroon; Maroon
Purple; Maroon Red; Mauve (Dark) ;
Mauve (Pale) ; Orange-pink; Orange
Scarlet; Picotee Edged (Cream Ground) ;
Picotee Edged (White Ground) ; Pink
(Deep); Pink (Pale); Rose; Salmon
Shades; Scarlet; Striped and Flaked

HISTORY AND EVOLUTION 17

(Purple and Blue) ; Striped and Flaked
(Chocolate on Gray Ground) ; Striped and
Flaked (Red and Rose) ; White.

When one compares this with the fol-
lowing classification used in a prominent
seedsman's catalogue only fifteen years
ago, one can appreciate the marvelous de-
velopment in the sweet pea. This cata-
logue grouped all varieties under White,
Cream, Light Yellow, Light Blush,
Light Pink, Deep Pink, Rose, Red and
Scarlet, Shades of Orange and Salmon,
Pink and White, Blue and White, Claret
and Maroon, Striped and Variegated,
Lavender and Light Blue, and Blue and
Purple.

Varieties

Catalogues usually classify sweet peas
according to color with a separate list of
the winter-flowering varieties.

More than twelve hundred varieties

i8 CULTURE OF THE SWEET PEA

of sweet peas have been introduced.
Many varieties have passed into oblivion,
but there are large numbers in the
trade and every season witnesses a con-
siderable number of aspirants for public
favor. The following list is the result of
testing hundreds of varieties during the
last few years. It is a matter of personal
taste whether some of the colors, as repre-
sented by the color sections, are desirable
for any particular garden. The classifica-
tion will enable any one to select those col-
ors and varieties suited to individual
tastes.

WAVED VARIETIES

Bicolor — Mrs. Cuthbertson, Colleen

Blue — Margaret Madison, Flora Norton Spencer,

Blue Jacket
Blush — Lady Evelyn Eyre, Princess Victoria,

Florence Morse Spencer
Carmine — John Ingman
Cerise — Chrissie Unwin

HISTORY AND EVOLUTION 19

Cream, Buff, and Ivory — Primrose Spencer, Isabel
Malcolm, Primrose Beauty, Lady Knox,
Queen Victoria Spencer.

Cream-pink (Deep) — Mrs. Gibbs Box, Constance
Oliver

Cream-pink (Pale) — Mrs. Routzahn, Lady Mil-
ler, Mrs. Hugh Dickson

Crimson — King Edward Spencer

Fancy — Afterglow-
Lavender — Florence Nightingale

Magenta — Menie Christie

Marbled — May Campbell

Maroon — Nubian, King Manuel

Maroon-purple — Arthur Green

Maroon-red — Brunette, Red Chief

Mauve (Dark) — Tennant Spencer

Mauve (Pale) — Mrs. Heslington, Mauve Queen

Orange-pink — Edrom Beauty, Carene, Helen
Lewis

Orange-scarlet — Thomas Stevenson

Picotee edged (Cream ground) — Evelyn Hemus,
Mrs. C. V^. Breadmore

Picotee edged (White ground) — Dainty Spencer,
Elsie Herbert, Martha W^ashington

Pink (Deep) — Hercules, Countess Spencer

20 CULTURE OF THE SWEET PEA

Pink (Pale)— Elfrida Pearson

Rose — Marie Corelli, Rosabelle

Salmon Shades — Stirling Stent, Melba, Barbara

Scarlet — Bobbie's Scarlet, Scarlet Emperor, Red

Star
Striped and Flaked (Chocolate on gray ground)

— Senator Spencer
Striped and Flaked (Purple and blue) — Loyalty
Striped and Flaked (Red and rose) — ^America

Spencer, Aurora Spencer, Mrs. W. J. Unwin
White — White Spencer, Nora Unwin

VARIETIES OF OPEN AND HOODED FORMS

Bicolor — Blanche Ferry, Jeannie Gordon

Blue — Brilliant Blue, Navy Blue

Blue (Light) — Flora Norton

Blush — Modesty

Cerise — Coccinea

Cream, Buff and Ivory — Zarina, The Honorable

Mrs. E. Kenyon, Queen Victoria
Crimson — King Edward VII
Lavender — Lady Grizel Hamilton
Marbled — Helen Pierce
Maroon — Black Knight, Othello

HISTORY AND EVOLUTION 21

Mauve — Admiration, Mrs. Walter Wright,
Dorothy Tennant

Orange Shades — Henry Eckford, Miss Wilmott

Picotee edged — Dainty, Lottie Eckford, Phenom-
enal

Pink — Prima Donna, Lovely, Katherine Tracy,
Janet Scott

Rose and Carmine — Lord Roseberry

Scarlet — Queen Alexandra

Striped and Flaked (Chocolate on gray ground)
— Senator

Striped and Flaked (Purple and blue) — Princess
of Wales, Hester

Striped and Flaked (Red and rose) — America,
Aurora, Romona

White — Dorothy Eckford, Shasta, Emily Hender-
son, White Wonder

EARLY-FLOWERING VARIETIES

Bicolor — Earliest of All

Blue — Le Marquis

Lavender — Mrs. Alexander Wallace

Primrose — Earliest Sunbeams

Salmon-pink — Mrs. William Sim

22 CULTURE OF THE SWEET PEA

MARKET VARIETIES

Open and hooded varieties — Dorothy Eckford,
King Edward VII, Brilliant Blue, Lady Grizel
Hamilton, Prima Donna, Blanche Ferry

Waved varieties — Countess Spencer, Nora Un-
win, Asta Ohn, King Edward Spencer

Cultural Requirements
Site. Sweet peas should be planted
where they can get the maximum amount
of sunlight, and the rows should run north
and south. A free circulation of air is
beneficial, but the best site is one which is
not swept by strong winds, which break
the plants from their supports and injure
the stems of the plants. Any injury to the
stem of the plant invariably results in
smaller flowers and shorter flower stems.

Soil. Any garden soil is suitable for
sweet peas, provided it is sufficiently
drained so that in periods of excessive
rains the water will not lie upon the sur-

HISTORY AND EVOLUTION 23

face about plants, and thus cause them to
become yellow or to decay at the roots.
Soil suitable for growing vegetables usu-
ally gives good results, but extra care in
the selection and preparation of the soil
will be repaid in larger flowers, longer
stems, better colors, and a longer blooming
period.

Preparation. The sweet pea is a deep-
rooting plant, and in order to provide
suitable conditions so that the effects of
drought will be overcome, the preparation
of the soil must be deep and thorough.
Whatever the nature of the soil, unques-
tionably the best preparation can be made
by trenching the soil in the autumn. This
means turning the soil to a depth ranging
from 18 inches to as much as three feet.
In America this method is usually found
too expensive, and instead a trench 15 to
18 inches wide along the line of the rows

24 CULTURE OF THE SWEET PEA

is used. The soil is removed and replaced
with prepared soil made by composting
sod from an old pasture with manure. If
this method cannot be followed, the top
soil, to the depth of one foot, can be thrown
out on one side of the trench and the lower
soil broken up as deep as possible with a
pick. If a good application of stable ma-
nure can be mixed with the subsoil the re-
sults are better. Often a layer of leaves
or coarse manure placed in the bottom of
the deep trench serves to promote drain-
age. In all cases the trenches should be
from 18 inches to two feet deep, and it is
a good plan to work in all the manure pos-
sible. It does not matter in the fall-prepa-
ration of the soil if the manure is fresh,
but of course strawy manure will not do
except in the bottom of the trench. A
good application of lime should be made
while preparing the soil in the autumn.

HISTORY AND EVOLUTION 25

Many soils that have been cultivated for
a long time are acid, and therefore not
adapted for growing leguminous plants
such as clover or sweet peas even though
the soil may be fertile. The lime corrects
this condition, and also releases plant food
which otherwise would not soon become
available. Clay soils are made more open
and porous by the action of lime.

Planting
The Seed. Some primrose and white-
flowered varieties have white or light-col-
ored seeds, and some have black seeds.
The white seeds often rot in the soil, espe-
cially if they are planted early when the
soil is cold, or because their germinating
power has been impaired; also they fre-
quently split in the pod before harvesting
and in this condition are likely soon to lose
their vitality. For the foregoing reasons

26 CULTURE OF THE SWEET PEA

it is advisable to sow seeds of this color
close together and not so deep as the black-
seeded varieties.

In some seasons, sweet pea seeds are
slow in germinating. It is well to exam-
ine such seeds in order to ascertain their
condition. If the seeds are found dor-
mant but still fresh and plump, the seed-
coats should be cut with a sharp knife and
replanted; they will then germinate well.
This difficulty is not confined to the sweet
pea ; some of the other species of Lathyrus
behave similarly. The trouble usually
follows a very hot dry season, when the
seed becomes so excessively ripened as to
render the seed-coat impervious to water.
Sometimes, in order to expedite germina-
tion, the seeds are soaked ; a better method
for the amateur is that recommended by
Mr. Hutchins. He places the seed pack-
ets in moist earth for seven or eight days.

HISTORY AND EVOLUTION 27

He then takes them out and examines
them; the swollen seeds are planted, and
the others cut with a knife.

Fall Planting. Often the finest as
well as the earlier flowers are secured from
plants the seed of which was sown in the
fall. South of the latitude of New York
City this time of sowing can be recom-
mended. North of this line this method
cannot always be depended upon unless a
sandy, well-drained soil is chosen. If the
water does not lie upon the ground in win-
ter, and particularly if there is little or no
freezing and thawing, it is advisable to
give this method of planting a trial. The
same preparation of the soil is made as de-
scribed above, but care must be taken to
firm the soil so that it does not settle. The
trench or furrow should be filled so as to
allow for a slight settling of the soil, thus
producing a slightly crowning ridge. In

28 CULTURE OF THE SWEET PEA

this ridge a little furrow, two inches deep,
should be made ; or, if preferred, two small
furrows of equal depth six inches apart
may be made. The seeds should be sown
one or two inches apart in these furrows
and covered so that the surface is slightly
ridged for drainage. The most important
point in fall planting of sweet peas is to
plant so late that the plants do not appear
above the surface before freezing. In the
Northern states, if the plants appear above
the surface of the ground, they will be
killed by the winter. Seed that have only
"sprouted," however, will not be harmed.
In central New York it has been found
that after November 10 is the best time to
sow, but, of course, this varies with the
season.

After the ground freezes, a mulch of
manure should be placed over the row, and
if the snow remains upon the ground all

HISTORY AND EVOLUTION 29

the winter the conditions are most favor-
able. The approach of bright weather in
spring is the time to examine your sweet
peas to see whether they are growing.
Often the manure mulch keeps the soil
soggy and cold when the bare soil is be-
coming dry and warm. In such cases re-
move a portion or all of the mulch, leav-
ing it between the rows or near at hand,
so that if there should be a cold wave it
can be used to cover the plants. The
plants from fall-sown seed get an earlier
start than it is possible to secure by sow-
ing in the spring. The seed of standard
varieties of sweet peas is so cheap that the
fall-planting of sweet peas is an effort well
worth while.

Spring Planting. As soon as the frost
is out of the ground and the soil is in work-
able condition in the spring, a heavy ap-
plication of superphosphate of lime should

30 CULTURE OF THE SWEET PEA

be made and raked in. Care should be
exercised not to get the soil too loose, and
for this reason it is best to confine all stir-
ring of the soil to smoothing the surface.
Especially is this true with light soils,
which, if stirred deeply in the spring, must
be well firmed. Heavy soils that are
likely to bake may be improved by work-
ing in a light dressing of old, thoroughly
rotted manure.

Sweet peas should be sown as early in
the spring as the soil is dry enough to
work, even though it is probable that
heavy frosts will follow. The writer
thinks that one reason why even the most
inexperienced amateur usually has such
good average results with sweet peas, is
that he gets his annual "violent attack of
gardening fever" in early spring, and he
begins his operations at just the right time
for sweet peas to go into the ground.

HISTORY AND EVOLUTION 31

An essential requirement in growing
sweet peas is to plant early, while the
atmospheric conditions are such as to pre-
vent top growth before the plant has
started a vigorous root development. The
result is that, when warmer weather comes,
the top grows strong and heavy, the plant
branches out, and throughout the season
this increased vigor is evident. Experi-
ments made by sowing seeds every ten days
from the earliest practicable date until the
end of May indicate that early planting is
desirable.

Depth. If the preparation of the soil
has been made in the fall, it is advisable
to smooth the surface of the trench and
plant in this. When the preparation has
been made in the spring the soil must not
be left too loose — a condition that may
easily occur if a deep trench is made and
only loosely filled with soil and manure.

32 CULTURE OF THE SWEET PEA

One method recommended is to hollow
out a broad trench, twenty-four to thirty
inches wide and two inches deep, and then
sow the seed one inch deep in single or
double rows. The trench should be kept
open for six weeks in order to retain the
water. This system is very good in a gar-
den where all cultivation is given by hand ;
but where many rows are grown and cul-
tivation is done with a horse and culti-
vator, it is manifestly impossible to make
or to maintain such a trench. Further-
more, when horse cultivation is used there
is difficulty in keeping the young plants,
if planted below the surface, from being
covered during the early cultivations.
Therefore, planting on the level is neces-
sary in field culture. It is advisable, how-
ever, in garden culture, to plant so that
when covered the row will be two inches
below the ordinary level.

HISTORY AND EVOLUTION 33

The seed may be sown in single or dou-
ble drills as described under fall-planting.
It is advisable to sow the seeds one or two
inches apart; if it is suspected that a good
germination will not result, more seed
should be sown.

Thinning. Many persons do not thin
their plants, and in many cases the reason
that poor flowers are obtained is because
of overcrowding. On the other hand, the
practice of English growers of thinning
the plants so that they stand several inches
apart, will not bring successful results in
our climate. It is difficult to give instruc-
tions that will apply everywhere; but un-
der conditions in New York state thinning
the plants so that they are from four to
six inches apart has given the best results.

American sweet-pea growers almost in-
variably plant sweet peas in rows, but gar-
den lovers are advised to try the method

34 CULTURE OF THE SWEET PEA

of planting sweet peas in small circles or
even in clumps. Grown in this manner,
sweet peas may be effectively used in the
flower garden and in borders. The prepa-
ration of the soil is similar to that for the
other method of planting.

Sowing in Pots for Outdoor Bloom.
Many English growers practice sowing in
pots under glass, hardening the plants in
frames, and planting out. From his own
experience, the writer is inclined to look
on this method with favor, especially in
growing high-priced novelties or varieties
for exhibition.

In the greenhouse the seed may be sown
in February or March. Usually it is best
to sow about six weeks before one expects
to plant in the open ground. The seeds
are sown in three and one-half or four-
inch pots, using a good compost of rotted
sod, well-decayed manure or leaf mold,

HISTORY AND EVOLUTION 35

and sand. A little of the rougher portion
of the turf should be placed in the bottom
of the pot to insure drainage. Fill the
pots firmly to within one and one-half
inches of the top and sow four seeds at
equal distances apart, and cover them with
an inch of soil. Label each variety care-
fully as the seed is sown. The pots are
then placed in a cool greenhouse; and after
germination, if the weather is favorable,
transferred to cold-frames to harden the
plants. The pots may be placed in cold-
frames immediately after sowing, but they
cannot be sown as early as in the green-
house. The seeds of some of the new va-
rieties appear to have thick seed-coats, and
therefore do not germinate readily. Such
seeds should be clipped with a knife so that
the moisture can penetrate the seed-coats.
After the plants appear the pots should be
kept near the glass so that the plants will

36 CULTURE OF. THE SWEET PEA

be dwarf and sturdy. Care must be em-
ployed in watering so that the soil does not
become sour; and watering the pots in
frames should be done in clear weather so
that the plants will dry off before night,
for if the night is frosty the plants may
suffer. In severe weather the frames must
be protected by mats and banked up with
manure. The frames must be kept well
ventilated, and as warm weather advances
the sash should be entirely removed during
the day. Proper handling during plant-
ing out will insure success.

If the plants begin to form tendrils, a
few twigs should be inserted to support
the plants. Results of the neglect of this
important requirement will be apparent
later in the season. Except when grown
for market purposes, for which earliness
is an important consideration, it is advis-
able for the amateur to delay the sowing

HISTORY AND EVOLUTION 37

so that the plants in pots do not become
tall enough to require much support. The
usual practice is to plant these pot-clumps
twelve to eighteen inches apart in the row.
The entire potful is planted without dis-
turbing the twigs supporting the plants.
It is better to pick out the crock from the
ball since it loosens the tips of the roots
which, when planted, are encouraged to
strike down into the soil. Sometimes, the
roots are long, and therefore are wound
around the ball of earth in the pot; if they
are not loosened, they may continue to
grow in the same manner, thus not estab-
lishing connection with the soil prepared
for the plants. It is essential to keep the
roots growing down into the cooler,
moister soil. No difficulty will be experi-
enced in planting sweet peas from pots,
provided they have been given a good
watering the day before planting, which

38 CULTURE OF THE SWEET PEA

will aid in keeping the ball of earth entire
when the plants are knocked out of the
pots. If the soil is dry when the planting
is done, it will often be advisable to water
the plants when they are set. Under nor-
mal conditions, however, this practice is
not advised.

The Cordon System.^ After trans-
planting, pinch off the tip or growing
point of the plant and allow only two lat-
erals to develop. Pinch off all others and
thereafter allow only two shoots on each
plant. If the ground has previously been
well firmed down, the plants will be sturdy
and short jointed, producing an abundance
of blossoms. For the cordon system the
plants should be trained up on tall sticks
about ten feet high, which have been se-
curely fastened at their upper end to a
stretched wire. A good practice is to have

* By Frank G. Cuthbertson, Sweet Pea Specialist.

Fig. I. — Method of growing Sweet Peas for seed in

England. The vines are trained on tree boughs,

and the pods gathered by hand.

View at Dobbie and Co.'s seed farm, England.

HISTORY AND EVOLUTION 39

a double row of plants about ten inches
apart and a double row of stakes or sup-
ports. If stakes cannot be had, strings
may be stretched from a line of wire ten
feet high down to the plants and pegged
down. The shoots will have to be tied to
the stakes or strings as fast as they grow,
thus preventing the breaking of stems and
blossoms. The tendrils should also be cut
off, as well as all laterals as they appear.

By following the cordon system the
leaves will be very large and the flowers
will have standards of one and one-half
or two inches across.

Supports. Among English sweet pea
growers there is considerable unanimity
of opinion that sticks form the best sup-
port for sweet peas (fig. 1). The replies
of fifty-two leading experts, published in
the Sweet Pea Annual for 1907, show that
forty- three growers favor sticks (gener-

40 CULTURE OF THE SWEET PEA

ally hazel sticks) , five favor wire netting,
two favor either sticks or wire netting (the
netting if new to be painted) , one prefers
sticks and string, and the remaining one, a
correspondent from British Columbia, uses
telephone wire and string.

In this country, where good twiggy
boughs can be obtained such boughs un-
questionably form the best support to use
since they are the most natural. In many
places birch boughs can be obtained in
lengths of twelve to fourteen feet. These
may be prepared in the lengths desired.

The height of the support must be de-
termined by the grower. If the soil has
been prepared properly and the plants
look strong, and if the grower waters the
plants properly and gives them every care,
then the support should be six feet high.
If the soil is only moderately fertile or
has not been properly prepared, or if the

HISTORY AND EVOLUTION 41

grower does not intend to keep all seed-
pods picked off or cannot water the plants
in order to overcome drought, the support
should be kept down to four feet. The
variety has something to do with the
height of the support, whatever the care
bestowed, some varieties being naturally
dwarfs.

The sticks should be cut in late winter
or very early spring so that they are
rather green and tough enough to bear the
load until the end of the season. They
should be inserted in the soil at least a foot,
because when they are clothed with vines
to a height of six feet a strong windstorm
exerts a tremendous leverage on them. If
the sticks have not been inserted deeply,
or if they have become dead and brit-
tle, the row will go down under the force
of the wind and the great weight of the
wet vines. In order to guard against dis-

42 CULTURE OF THE SWEET PEA

aster, strong stakes are sometimes placed
every ten feet and wire is run lengthwise
through the sticks and fastened to the
stakes. It is desirable to have the sticks
more bushy at the top than at the base, so
that they spread out more than at the base ;
if not naturally so, leaning the sticks alter-
nately outward will produce this result.
This method gives greater freedom for the
vines when they are in flower.

After the sticks are inserted, a better ef-
fect is produced if the tops are clipped to
a level and straggling ends are cut back.
If the sticks are not "feathered" suffi-
ciently at the base for the plants to start
up on them, the clippings from the tops
may be inserted between the tall sticks.
Some growers make a practice — and it is
a good one — of providing a light support
when the plants are one to three inches
high, and later placing the tall sticks. For

HISTORY AND EVOLUTION 43

the light support they often use old rasp-
berry canes, in fact, anything of a light,
much-branched character. This affords
protection from high winds when the
plants are small.

Netting. When other systems of sup-
porting are to be employed, it is quite im-
perative to provide a support of small,
short twigs as soon as the seedlings begin
to produce tendrils. This method pre-
vents the rain from beating the small
plants down, and enables them to get up
to the other support. In city gardens,
owing to the difficulty in procuring suit-
able sticks, wire netting makes a very sat-
isfactory support. The peas do not cling
to it so well, but it is cleaner and neater
in appearance, and thus offers a compen-
sating advantage. The large mesh (four-
inch) is preferable; but in many places
this is not procurable and the ordinary

44 CULTURE OF THE SWEET PEA

chicken netting, or fence, is used instead.
Strong stakes at intervals not to exceed ten
feet are used to support the netting. One
advantage of wire netting is that if stakes
six feet high are used, a forty-two or forty-
eight-inch strip of netting may be placed
in position; and, if the season or soil is
favorable and the peas grow above this, a
narrow strip of netting may be added or
a string or wire stretched from stake to
stake over the row. A well-galvanized
netting can be used repeatedly for several
years, and will last longer if taken off in
the fall and stored.

String. Another method is to con-
struct a support of wire and string, or of
string alone. The ingenious grower can
construct all sorts of fanciful designs with
wire and string on posts set not over ten
feet apart. Sometimes a wooden strip is
nailed horizontally at the top and bottom,

HISTORY AND EVOLUTION 45

but often a wire is used instead. From
bottom to top, between these horizontal
strips or wires, a homemade network can
be constructed. When the peas are grown
in double drills, the construction described
above is made on each side in box-like
form.

When sweet peas are grown in single
drills, especially on a considerable scale,
the best and cheapest support is one made
by placing stakes at intervals of less than
ten feet and winding strong cord around
the row from stake to stake. The strings
are placed six to eight inches apart, or
closer if necessary. If the stakes are too
far apart — ten feet or more — the string
will stretch after becoming wet or even
damp, and the plants will fall over. If
appearance is not an object, anything will
serve for stakes, e.g., tailings from the
mills, poles, and the like. If neat stakes

46 CULTURE OF THE SWEET PEA

are used, the string method is very good
for the garden as the vines cling to it bet-
ter than to wire netting, which furthermore
becomes hot in the summer. At the end
of the season, if the stakes are worthless,
the whole support as well as the vines may
be burned.

The foregoing method applies to sweet
peas grown in rows. Sweet peas are some-
times grown in clumps and must be sup-
ported. Here again sticks are often fa-
vored, especially where the plants occupy
a circle six feet or more in circumference.
Wire netting cut in suitable lengths may
be made into cylinders for clumps of any
size.

Henry Eckford recommends a sweet pea
support consisting of four stakes, each in
two pieces three feet long. These are
placed ninety degrees apart around a cir-
cle and three-foot netting is stretched

HISTORY AND EVOLUTION 47

around them. When the peas reach the
top, if greater height is needed, the upper
half of each stake is fitted by means of a
mortise into the top of the one already
driven and another strip of netting is put
on.

An English seedsman advertises sweet
pea ladders for use in training the vines in
garden decoration. The ladders are made
six feet long and six inches wide. They
are used perpendicularly, the tops being
fastened to a horizontal wire. Two rows
are supported by leaning the tops together
and fastening them to an overhead hori-
zontal wire. Plants grown in circles may
be brought together in the center at the
top where the ladders are fastened to a
center stake. Sweet pea arches about six
feet high are sometimes made.

The ladders can be easily made with
two No. 10 galvanized wire rose stakes of

48 CULTURE OF THE SWEET PEA

the proper length, and some smaller wire
for the rungs or cross wires. These, of
course, should never be over six feet high
or they would seldom be covered. The
arches can also be made complete, if de-
sired, by merely making the ladder long
enough and bending it into the form of
an arch.

Cultivation

Tillage. Sweet peas need frequent
cultivation. A loose dust mulch upon the
surface must be constantly maintained in
order to retain the moisture for the plants.
Amateurs often fail because they do not
cultivate their sweet peas, but depend
upon artificial watering, which will not
bring the same results as stirring the soil.
The surface should be kept loose with a
rake, and if this condition is maintained
there is usually little need of artificial
watering.

HISTORY AND EVOLUTION 49

Watering. This practice often results
in more harm than good. During periods
of drought it may be advisable to apply
water. If so, apply liberally so that the
soil is thoroughly soaked. It is also im-
portant to remember that having begun
to water, it is necessary to keep it up until
the rains come. Two or three applications
a week will probably be required.

Mulching. A mulch of thoroughly
rotted manure around the plants will as-
sist in lessening the effects of a drought;
or if water is also applied, the mulch will
enable the plants to get the benefit of it
by preventing rapid evaporation.

DisPODDiNG. A long period of bloom
cannot be had unless the seed-pods are
consistently picked off. Even the best cul-
tural methods go for naught unless this
operation is given careful attention. The
importance of watering has been over em-

50 CULTURE OF THE SWEET PEA

phasized, whereas the true explanation of
success lies in the removal of all pods as
soon as the flowers wither. If delayed un-
til the seed-pods are well developed, their
removal is of little benefit to the plant.
If one desires to save seed, it is best to
mark vigorous plants and save seed from
them. As the plants usually flower freely,
few plants are necessary to supply all the
seeds required by the amateur. All plants
not required for seed production should be
kept free of seed-pods so that they will
continue to produce flowers. Cutting all
of the best flower spikes does not produce
the desired results, unless the plants are
gone over frequently, many short-stemmed
or inferior flowers will form pods and in
a very short time the strength of the plant
will be utilized in developing these in the
effort to reproduce itself. To obtain good
flowers for the longest period of time the

HISTORY AND EVOLUTION 51

grower must destroy promptly and thor-
oughly the withered flowers.

An English sweet pea expert has con-
cisely summarized sweet pea culture as
follows :

"Sweet Pea Culture, condensed in these
words. Trench deeply; manure liberally;
plant thinly; stake quickly; water freely;
dispod promptly."

Marketing

Picking. The ideal time to pick sweet
peas is two or three hours before they are
needed or are to be placed on the market.
This length of time is the period the
blooms should remain in water. During
this period many varieties will improve in
size and color, and of course it is desirable
to have flowers at their best when they are
to be sold.

If the flowers are to be shipped to mar-

52 CULTURE OF THE SWEET PEA

ket, the time in transit must be added.
These factors will govern the time of pick-
ing. It is best, however, to pick in the
morning or late afternoon.

The stage at which the flower spikes are
picked will depend upon the foregoing
factors, and also upon the weather and
temperature conditions. The spikes ought
to be picked when the upper flower is
about one-half open.

In picking, a knife or scissors should not
be used, but the spikes should be pulled.
A quick side pull, while holding the stem
near the base, will usually accomplish the
result without damage to the plant. As
soon as picked, the flowers should be
placed in water. Vases about eight inches
in diameter, and the same in depth, are
about right, since the stems can be plunged
six or seven inches. Sometimes eight-inch
pots are taken and the bottom opening

I

HISTORY AND EVOLUTION 53

plugged up so as to make sweet-pea vases.
These are excellent because they have the
best form to keep the flowers in the proper
position.

Packing
Sweet peas are bunched before packing,
twenty-five flowers usually being put in
each bunch. If the bunches are made flat
instead of round, they will pack much bet-
ter. Tie the stems near the base and
never near the flowers. A flat box for one
or two layers of bunches is the best pack-
age. The corrugated and folding paper
boxes will probably be found to give the
best results. It is essential that the
bunches be packed tight enough to prevent
bruising. Some make a practice of wrap-
ping each bunch in wax paper. The boxes
should be properly lined with paper before
the bunches are put in.

54 CULTURE OF THE SWEET PEA

Exhibiting Sweet Peas

The foundation for success in raising
sweet peas for exhibition is laid the previ-
ous autumn in the thorough preparation
of the soil, followed by a careful selection
of varieties, thin planting, and liberal cul-
ture. In order that good flowers may be
obtained for exhibition, it is best to remove
all flowers about a week before the date
of the exhibition, and to allow only the
spikes with the longest stems to develop.
The size of the flowers may be increased at
this time by the use of ammonia or nitrate
of soda applied to the soil.

All varieties subject to scorch or scald
should be shaded with cheesecloth or tif-
fany. If such varieties are planted to-
gether, the shading may be more easily ac-
complished. The varieties which have
orange in their coloration — that is, Henry

HISTORY AND EVOLUTION SS

Eckford, St. George, and Helen Lewis —
the salmon varieties, and possibly some of
the scarlets and blues, should be shaded
for four to six days previous to the time
the flowers will be needed. The shade
should be so arranged that it can be re-
moved at night.

The sweet peas having been well grown,
with stems twelve to fifteen inches long,
the next consideration is the cutting of the
flowers; for it is one thing to grow good
flowers, and quite another, but equally dif-
ficult, to exhibit successfully.

Sweet pea flowers, especially for exhi-
bition, should be cut while dry, preferably
in the morning or evening. The proper
stage of development will depend on the
number of hours that must elapse before
the judge can pass upon the exhibit.
Flowers cut the day before exhibiting
should be taken with the lower flowers

56 CULTURE OF THE SWEET PEA

open and the top ones in bud. Those with
four flowers on a spike may be taken with
the two lower flowers open, the third flower
opening, and the topmost one in bud.
The flowers should be placed immediately
in cool water and removed to a cool, dark
room or cellar until they are packed.
Here they are left until the latest moment
consistent with their timely arrival at the
exhibition hall, not more than six or seven
hours if possible.

When packing, the stems should be
squeezed in order to remove surplus water
and then wrapped in a strip of oiled paper.
Great care should be exercised not to get
water on the flowers. Each bunch should
be wrapped in tissue paper and the
bunches packed not too tightly as to crush
the flowers.

Everything is necessary to insure the
prompt arrival of the flowers at the exhi-

HISTORY AND EVOLUTION 57

bition hall, where they are unpacked and
loosely arranged so that they may resume
their natural form after the journey.

The flowers having been put in water,
the work of arranging the exhibition vases
should begin. George W. Kerr, an ex-
perienced exhibitor, gives the following
directions for the arrangement of flowers :

"In staging the flowers never crowd
them. Let every flower 'speak for itself.'
Twenty sprays make a nice vase, and the
best method of arranging them is to start
by putting some grass (cut two inches
long) in the mouth of the vase, as this
helps to keep the stems in position. Each
stem must be put in separately. Let every
flower be seen as far as possible and all
face one way, with the exception of such
varieties as have the back of the standards
tinted in coloring other than the ground
color of the flower, when the position of

58 CULTURE OF THE SWEET PEA

such might be judiciously varied. One or
two pieces of foliage — a little Gysophila
— or light grass, such as Agrostis neublosa,
might with advantage be used. But this
should not be overdone, and only if the
rules allow of it.

"In staging a collection of twelve varie-
ties, they should be placed in three rows,
the back rows being tiered eight or nine
inches above the other, and arrange the
colors so that they do not clash. Even if
the show schedule does not ask for it, name
each variety with a neat card placed at the
base of each vase."

Two very important points for the ex-
hibitor to observe are: (i) follow the
rules as to the number of stems per vase
and foliage allowed; (2) see to it that the
flowers are true to name. Varieties of dis-
tinct colors should be used and those that
are very nearly like others in the exhibit

HISTORY AND EVOLUTION 59

excluded. Finally, in placing the vases,
it is important not to lose sight of the fact
that a good color scheme is a great aid to
success.

CHAPTER II

CULTURE OF SWEET PEAS FOR SEEDS *

Laymen who visit a large seed farm in
California marvel at the acreage of sweet
peas in that state and wonder how the
enormous output will be disposed of. But
it must be borne in mind that California
grows fully 75 per cent of the sweet peas
used all over the world. About 50 per
cent of the sweet peas grown in California
are exported. Of these much is sent to
Great Britain, the remaining 50 per cent
to Holland, France, Germany, New Zea-
land, and Australia. The gardening pub-
lic of Great Britain, aided by the seeds-
men, quickly realized the possibilities of
the sweet pea as an exhibition and decora-

^ By C. C. Morse and Co. of California.
60

CULTURE FOR SEED 61

tive flower. Other countries are now grad-
ually taking more sweet peas and the fu-
ture may bring a larger export business.
In the United States only a small propor-
tion of sweet peas is grown. However,
the public is beginning to grow more of
that flower every year, and especially the
newer Spencer types. On an everage
the acreage of sweet peas in California
is about 2000 acres with about 50 per
cent Grandifloras, and 50 per cent
Spencers. The value of this crop to the
growers is about $250,000. The crop ob-
tained from an acre of sweet peas varies
very largely according to season, but an
average yield of Grandifloras would be
about 800 lb. per acre; that of a good
strain of Spencers about 250 lb. per acre.
Owing to the peculiar formation of the
floral parts, the Spencers are not so prolific,
as the Grandifloras. In the latter the keel

62 CULTURE OF THE SWEET PEA

of the flower is clamped, enclosing the
stigma and the anthers; whereas in the
Spencers, the keel is full or open and the
stigma protrudes farther out than the
anthers, thus interfering with complete
pollination. It would be hard to esti-
mate the value of the sweet pea seed to the
wholesalers and retailers of the United
States, but it is safe to put it down to about
$600,000. There is no acreage of sweet
peas worth mentioning grown in the
United States outside of California. A
few acres of high class varieties are grown
in England and in the other countries
above mentioned. Except in cases of
stock seed of new varieties, no sweet pea
seed is imported in California.

When most people think of California
as a seed growing state, they have the idea
that it is a land where the only thing the
grower has to do is to plant and to harvest,

CULTURE FOR SEED 63

and that California does the rest. The
seedman in California, however, has his
trials and troubles like all others and he
has all the scope he wants for his practical
ingenuity; probably there is more need of
it there than in any other state or country.
It may surprise many to learn that there
are comparatively few valleys or parts of
valleys suitable for sweet peas in Califor-
nia. This in itself already offers the
grower a chance to use the best of his skill
and mgenuity. In California, the sweet
pea does best in a rich heavy loam or a rich
sediment soil. Too heavy and too sandy
soils are unfit for that plant.

The best climate is one which never gets
too hot during flowering season, and the
best results have been obtained in valleys
where the fog rolls in from the ocean in the
evening, keeping the air moist and cool.
A hot spell during blossoming is often

64 CULTURE OF THE SWEET PEA

fatal to the crop, especially if it is grown
on light land; and if the rainfall has been
slight even on the heavier lands, the vines
burn up completely. When the soil is of
a loamy character and the climate foggy,
fifteen inches of rain are sufficient to carry
the crop.

The land is best when dry plowed, just
as soon as the previous crop is off in the
fall. Thus when the rain works through
the clods the particles of soil crumble and
become pulverized, leaving the soil in
good shape for early planting. In Cali-
fornia it has not been found necessary as
yet to apply any fertilizer to sweet peas.
They can be grown year after year on the
same land, often producing better crops
each year, provided, of course, that dis-
eases are kept out. To get the best results
in California, sow the seeds in November
or December if possible. As soon as the

CULTURE FOR SEED 65

clods can be broken down by a disk plow
or harrow, the work should be started.
The peas are drilled in rows about three
feet apart by a two-horse drill, sowing two
drills at a time and from eight to fifteen
pounds per acre. The acreage which can
be sown per day depends upon many
things such as the condition of the land
and the size of the plot to be planted, but
an average of ten acres per day would be
about right. The planter is set to place
the seeds about one inch deep, this being
deep enough for California conditions.

When the plants are high enough so that
the rows may be easily seen, the field is
cultivated by a two-horse "riding" culti-
vator; and if the weeds have started, the
plants are given their first hoeing. Dur-
ing the months of February, March, and
April, the cultivators are kept going over
the field until the meeting of the vines be-

66 CULTURE OF THE SWEET PEA

tween the rows prevents further cultiva-
tion. It is generally necessary to hoe the
crop three times.

Sweet peas are never given supports or
stakes in California. The vines meet in
the rows and by supporting one another
soon grow to quite a height. In a good
season they may grow five or more feet
high. In California each plant sends out
a very large number of shoots immediately
above ground so that the fields are very
thick and in flowering season are just one
mass of blossom.

The most important problem is that of
"rogucing" and of selection. This is es-
pecially the case with Spencer sweet peas.
The stock seed should be right; otherwise
enormous expense and labor are entailed
in rogueing the great mass of plants in
flower, and great damage is done. Should
some rogues be allowed to seed, the stock

CULTURE FOR SEED 67

is not only reduced in value, but the land
that the variety is grown on is fouled for
all time. Sweet peas will volunteer for
five or six years, often longer. It may
thus readily be seen that it pays the grower
to be careful of his stock when sweet pea
land is scarce. Rogueing sweet peas con-
sists in taking out all wrong colors and
wrong types. The color rogues are fairly
easy to see, but it takes a trained eye to
pick out the type rogues; and this work
has to be most carefully done. Should a
Grandiflora plant be allowed to remain in
a crop of Spencers, it would spoil the lat-
ter in a short time. The rogues are cut
out with a knife below the level of the
ground so that the plant will not sprout
again and give further trouble.

The careful grower has his stock seed
grown and selected carefully before he
plants his acreage. He knows the pedi-

68 CULTURE OF THE SWEET PEA

gree of his stock and if he has done his
work thoroughly he can depend on a crop
true to type.

The season of harvest varies. Cutting,
which is done with the mower, usually
commences in July. Judgment must be
exercised as to the proper time for har-
vest. The vines are ordinarily cut when
it is considered that most of the pods are
ripe. Immediately after cutting, the vines
are piled on large pieces of canvas which
are placed on the ground where the crop
has been growing. These sheets are gen-
erally forty feet square. When the vines
are thoroughly dry the thrasher and sepa-
rator are hauled to the patch and a port-
able gasoline engine supplies the driving
power. The fields of sweet peas are so
planned that the thresher will not by any
chance let any seed drop elsewhere than
on the area occupied by the variety. After

CULTURE FOR SEED 69

each variety is finished the separator is
thoroughly cleaned out and run empty for
a while so that no seed will be left in to
mix with the next variety to be threshed.
Stock seed is generally threshed by flail
in order to avoid all possible chance of
mixture. After this the seed is taken to
the cleaning house and put through a se-
ries of fans and screens to take out all
chaff and small and broken seeds.

The raising of new varieties is very in-
teresting. All careful breeders work on
the Mendelian principle, and since the
realization of the importance of these laws,
there has been less unfixed stock put on
the market. The following is a brief
statement of the procedure for raising new
varieties. The flower to be pollinated
must be in a very young stage, generally
a bud before the color even begins to
show. As the sweet pea blossom sheds its

70 CULTURE OF THE SWEET PEA

pollen in the bud stage, the selection has
to be made carefully. The buds being se-
lected, the keel is split open with a sharp
knife and all the stamens are carefully re-
moved. The stigma is carefully examined
to see that no pollen has been deposited
accidentally. Then pollen is carefully
gathered from the other parent and depos-
ited with a fine camel's hair brush on the
stigma of the flower from which the sta-
mens have been removed. The artificially
pollinated blossom is now wrapped in a
paper bag which is securely fastened to ex-
clude all possibilities of further pollina-
tion. It is necessary to make a large num-
ber of such crosses to obtain results, as it
often happens that a large per cent of the
flowers thus crossed fail to set seed. The
seeds from the successful crosses are care-
fully gathered and planted separately the
second year (figs. 2 and 3) . No particu-

Fig. 2. — Trial grounds of C. C. Morse and Co., San Juan,

Cal.

^aJiiaa-is^£i.if^^

'/s?.-

Fig. 3. — Field of Morse's White Spencer on C. C. Morse
and Co.'s Sweet Pea ranch at San Juan, Cal.

CULTURE FOR SEED 71

lar notice need be paid to the plants of the
first year's cross ; and all the seeds may be
saved together. The second year, how-
ever, it will be found that there is a large
variety of blossoms. Close inspection is
then given to each plant to determine
whether it has the merits desired. Some
plants will no doubt be found to contain
special merits ; their seeds should be saved
separately and grown another year or
two to determine if they will come true
to type.

Every careful seed grower must operate
for his seed peas a trial ground in which
are grown all varieties for comparison and
test. A sample of each crop is taken be-
fore it is shipped to the customer and a
sample of all selected stock is taken. The
various samples of each variety are ar-
ranged together and any novelty of simi-
lar color is also arranged with the variety

72 CULTURE OF THE SWEET PEA

which it is said to supersede. The sam-
ples are planted alongside each other.
Trial ground rows are generally about ten
steps long, and a six-foot space is left be-
tween the rows. Each sample is given a
number which is recorded. If rogues ap-
pear, their percentage is noted. Improve-
ment in select stock seed is looked for and
a value put on each novelty. The trial
ground is an important part of the equip-
ment of the seed farm, and too much study
and time cannot be given to it. Points to
be noted in judging a stock seed are the
size of flower, length of stem, number of
flowers on each stem, color, brightness and
lasting quality, texture of flower, vigor of
growth, length of blooming period, and
the amount of seed produced.

The sweet pea is not an easy crop to irri-
gate and it can be done only with care

CULTURE FOR SEED 73

and judgment. Generally one irrigation
should be given and that before the pods
are set on the vines.

CHAPTER III

CULTURE OF SWEET PEAS UNDER GLASS *

The production of sweet peas under
glass is being extended every year due to
increase in prominence as a cut flower, and
hence their economic value in winter.
Greenhouse sweet peas as a cut flower rank
third on the market, coming after the roses
and carnations. They are thus grown in
nearly every state in the Union, usually,
however, in the vicinity of large cities.
Philadelphia, New York, Buffalo, Boston,
Chicago, Detroit, Milwaukee, Omaha, St.
Louis, Kansas City, Denver, and a num-
ber of other large cities offer good mar-
ket opportunities for winter flowering

^ Abstract of Commercial Sweet Pea Culture by Ant.
C. Zvolanek.

74

CULTURE UNDER GLASS 75

sweet peas. In the warmer states sweet
peas are grown out of doors during the
winter, requiring but very little shelter.

For sweet peas under glass it is neces-
sary to have a suitable house (see Frontis.) .
The sides of the house should be at least
eight feet high, the upper being of glass.
If the houses are but seven feet high, the
side rows strike the glass when the vines
are about half grown, thereby giving half
a crop. The ridge of the house should be
from twelve to fifteen feet high. The
higher the vines grow, the more and bet-
ter flowers. For December and January
cuttings, large houses are necessary so that
the sun may penetrate every corner.
Sweet peas sown in October as, for exam-
ple, after chrysanthemums, will not bloom
before February.

The ideal soil is sandy loam. Red shell
soil is good if taken about six inches below

76 CULTURE OF THE SWEET PEA

the surface; very coarse gravelly soil if
well fertilized answers the purpose. Soil
taken from swampy places, provided it is
not heavy clay, is good, but cannot be used
the same year. It should be spread out
about sixteen inches thick on high ground
and left there to winter over. The rain
will wash out any alkali which it may con-
tain. In the following spring, about June,
compost may be made of this soil. Some
air slaked lime and coarse bone is added,
together with the necessary manure.

Solid beds of good soil two, or two and a
half, feet in depth are the best. If sweet
peas follow a tomato crop, which is on the
wane by the middle of August, the beds
should be deeply trenched, bringing the
bottom soil to the surface. In the bottom
of the trench three inches of decomposed
cow manure are worked in ; one foot from
the surface three inches more of the same

CULTURE UNDER GLASS 77

material are added. The house is allowed
to remain in this condition until nearly
time for sowing the seed. The soil then
is usually dry and needs to be moistened
enough to cling together when it is worked
next time with the spade. This time it is
necessary to go down one foot and mix
the top layer of manure with the surface
soil ; then make it as level as possible and
thoroughly water it with a strong dose of
liquid horse manure. In about three days,
depending on the weather, the house will
be ready for the planting.

Sweet peas may also be grown on a bench
with a few inches of soil, but the result will
be a weak growth and a crop of short
stemmed flowers. These soon play out, as
there is not enough soil or food for the
vines to live on.

There are a great many varieties of the
winter flowering type of sweet peas, the

78 CULTURE OF THE SWEET PEA

old grandiflora being the best known. Ac-
cording to Zvolanek the new Winter
Orchid-flowering sweet peas are preferred
to the old type. The principal thing is to
select the best selling colors. In this re-
spect the Pink and White Orchids seem
to have no equal for mid-winter flowering.
Of the white varieties there are the White
Orchid, Bridal Veil, Venus, and Mrs. M.
Spanolin. Of those of lavender shades
the best are Lavender Orchid, Lavender
Pink, and Lavender Nora, which is a clear
lavender of the Winter Unwin type. The
last named has large sized flowers, the
average of which are as large as any of the
Orchid-flowering type. In light pink,
there are Mrs. A. A. Skach, Mrs. J. Manda,
and Dolansky Orchid. In dark rose there
are the Orchid Beauty and President Wil-
son. The best in orange pink is the
Orange Orchid, and to this the Orange

CULTURE UNDER GLASS 79

Nora and Orange Bird are close seconds.
Both of these are of the Winter Unwin
type. The colors above mentioned are
suitable to grow in large quantities. In
the dark blue, the new orchid-flowering
Mrs. M. Anderson is commendable, and
second only to the Blue Jay or the Winter
Unwin. In red, the Red Orchid is the
best. All light pink varieties produce
much brighter colors if grown so as to
bloom after the middle of January, when
the weather is sunnier than in December.
To obtain a good crop of flowers for the
Christmas trade, seed should be sown any-
where north of Washington, D. C, be-
tween the tenth and twentieth of August ;
this time, too, will depend somewhat on
the weather. Warm and bright days in
the fall at the time of sowing will help
the main crop in maturing early in Novem-
ber when the price of sweet peas is very

8o CULTURE OF THE SWEET PEA

low. On the other hand, if the weather is
cool and cloudy at the time the seed is
sown, the flowers will probably be too late
for Christmas trade. It is much better to
have the crop in January, as during that
month and the following months the prices
are usually as high as during the Christmas
week.

When the beds have been well prepared
the soil is pressed down and raked smooth.
Rows are then opened at least five feet
apart and the seed sown about three inches
apart in the row, and covered to about one
and a half inches deep. Seeds should not
be sown in a soil which is too wet and
sticky. It is better to wait a few days
until conditions are right. White sweet
pea seeds, if planted in dry soil and
watered soon after being sown, will sel-
dom germinate. After the seed is sown,
rake the surface of the bed very fine to the

CULTURE UNDER GLASS 81

depth of about one inch. This raking will
make a fine soil mulch on the top, which
conserves the moisture, besides keeping
the soil cool, a condition necessary for suc-
cessful germination. Under these condi-
tions no watering will be necessary for at
least ten days or as long as moisture may
be found about four inches below the sur-
face. Sometimes three weeks elapse be-
fore it becomes necessary to water the beds.
This method encourages the seeds to send
their roots deep into the soil in the direc-
tion of more water. Plants with deep
roots can withstand the hottest days with-
out damping off, a condition which often
follows when the moisture is kept on the
surface. If the soil becomes too dry after
a while, water well down to the base, keep-
ing the surface well worked. After sow-
ing, the temperature should be kept as low
as possible; and if the seed is sown in

82 CULTURE OF THE SWEET PEA

August when the weather is extremely
warm the glass should be kept white-
washed as long as the hot weather con-
tinues. After the seedlings appear above
ground they may be sprayed several times
each day during hot spells.

To prevent slow germination the seed
may be soaked in water for about fifteen
hours just before sowing. This will cause
the seed to soften and swell so that when
sown they will germinate quickly. Those
which still remain hard after the soaking
should be rubbed against a fine flat file,
taking one seed in each hand and striking
once or twice over the file just enough to
cut the hard skin. The seeds treated in
this way should be dropped back into the
water, and within another fifteen hours
they will be soft, swollen, and ready to
sow.

CULTURE UNDER GLASS 83

After the sowing, the greenhouse should
be kept as cool as possible, admitting air
day and night as long as the weather will
permit. The cooler the temperature of
the house when the plants are started the
stronger and healthier they become. Late
in the fall some heat is necessary. The
temperature at night, however, should not
be higher than 40 to 44 degrees Fahren-
heit; otherwise the young plants will be-
gin to bloom early before the roots have
had a good start. The winter sweet peas,
if sown in August or later, and properly
cultivated, should be at least thirty inches
high before the blooms appear. Some-
times during warm and bright days in the
fall the plants show a tendency to bud
very early. In this case, the buds should
be picked off as soon as they appear.
When the plants are between two and a

84 CULTURE OF THE SWEET PEA

half to four feet high, they should all be-
gin to bud. At this time the temperature
should be raised every night by one or two
degrees. If the temperature averages 44
degrees F., make it 45 degrees the next
day, and so on until 52 is reached. This
is the highest and safest temperature for
the older winter grandifloras at night.
When in bloom, the temperature may be
raised to 60 degrees F. during cloudy days
and 68 during bright days. All the new
Winter Orchid-flowering sweet peas in the
first stage need the same treatment as that
just described above. But as these begin
to bud and flower the temperature should
be raised to 55 degrees F. at night, 60 to
65 for cloudy days, and 70 to 72 during
bright days. This higher temperature is
necessary for the new strains, as the flowers
are larger and the number to a single stem
correspondingly more numerous ; the addi-

CULTURE UNDER GLASS 85

tional warmth prevents the falling of the
buds and encourages brighter colors.

After the plants have reached the height
of about six inches they should be given
something to climb on. The best and
cheapest way is to run one wire on the bot-
tom and another from eight to ten feet
above each row, connecting these two
wires with strings as is done in the grow-
ing of smilax. Strings should also be run
lengthwise of the row, about every ten
inches, as the plants advance in growth.
At the same time it is well, occasionally,
to help the vines to climb on the strings.
The upper wire must be the strongest, for
when the sweet peas are in full bloom they
are usually ten feet high, and the vines of
one row one hundred feet long will weigh
over a ton. If at any time the upper wire
should break, all the flowers become
bruised, crooked, and of very little value.

86 CULTURE OF THE SWEET PEA

In order to divide the weight, wooden or
iron supports should be placed under the
upper wire every eight feet.

After the sweet peas have been in bloom
for some time and begin to produce short
peduncles it is time to feed them a little.
The best food is liquid or pulverized cow
or sheep manure. It is doubtful if nitrate
of soda is beneficial then. During blos-
soming the house should not be fumigated
with hydrocyanic gas for although this
will destroy many insects it will also de-
stroy most of the buds which are forming.

It is preferable to pick the flowers in the
afternoon, as at that time the greatest
number of flowers are open. Where thou-
sands of flowers are picked daily, the most
experienced help should go over the rows
first, picking only the best blossoms with
the longest peduncles, ten selected flowers
to a bunch. The second and less reliable

CULTURE UNDER GLASS 87

help are put to pick the second grade of
blooms, putting twenty-five sprays to a
bunch; and finally the third hands should
gather all the crooked and short stemmed
blossoms. If the flowers are to be shipped
a long distance to be sold the next day,
pick all flowers having three or more
blooms or buds to a stem. As soon as a
certain number have been picked they
should be placed in water, but not in deep
vases or large pails as the blossoms may
become wet and lose their fragrance.
After the flowers have stood in water for
about three hours they are ready to be
shipped.

One of the most successful crops to grow
after sweet peas is tomatoes. In small
and moderately warm houses, or propagat-
ing beds, the tomato seed is sown in No-
vember and then transplanted in small
pots and repotted several times afterwards

88 CULTURE OF THE SWEET PEA

until the plants are finally placed in five- or
six-inch pots. After Easter the sweet peas
which are then beginning to play out, are
replaced by these tomato plants. They
are planted 16 to 20 inches apart and
trained to a single stem. By June or July,
the tomato crop ought to be on the wane
and the house is at once prepared again
for sweet peas. Violets are also success-
fully grown in rotation with sweet peas.
These should be planted the latter part of
September. The beds should be five to
six feet wide, with a space of twelve inches
on the north side for one row of sweet peas,
all the rest being planted in violets. Both
of these flowers may be planted at the
same time, since the violets, too, need a
low temperature not over 40 degrees F.
The sweet peas will grow slowly at first,
probably not being over three feet in
height by the last of February. By this

Fig. 4. — Sweet Peas and Carnations grown in the

same house.

Courtesy of Lord and Burnham.

CULTURE UNDER GLASS 89

time the violets will have almost finished
blooming, or at any rate their market price
will be low. This is the time to discard
the violets and to raise the temperature to
suit the sweet peas; and which will pres-
ently produce a splendid crop. Chrys-
anthemums or carnations (fig. 4) may also
be grown with sweet peas. In a house
with early varieties such as "Golden
Glow" and "Pacific," the chrysanthemums
will be all done by October 20th. If
sweet peas are sown in four-inch pots
about September lOth, they will be large
enough to be put in place by the time
the chrysanthemums are gone. The soil
should be prepared and the sweet peas
planted in place at once, so that they may
begin to bloom by the latter part of Janu-
ary. Other things may be grown between
the sweet pea rows, namely, all kinds of
bulbs and flats with small ferns.

CHAPTER IV

DISEASES OF GREENHOUSE SWEET PEAS

Recent investigations have shown
that failures with greenhouse sweet peas
may be readily accounted for. Sickness
and death, not considering accidental
death, both in plants as in animals, are due
either to insects or to certain definite forms
of parasitic plant life, also known as germs
or microbes. Sweet peas need plenty of
air and sunshine and a cool climate.
These conditions are far from being satis-
fied in the greenhouse. Plants, like ani-
mals, when placed in unnatural surround-
ings, become a ready prey to disease.
Sweet peas under greenhouse conditions
are forced to grow in an unnatural way.

The parasitic fungi which attack sweet
90

DISEASES IN GREENHOUSE 91

peas are minute microscopical forms of
plant life, devoid of the green matter
known as chlorophyll. Structurally, a
fungus consists of one cell or of several
cells, connected end to end, forming
threads known as mycelium. The fungus
gains access to the interior tissue of the
plant, and deprives the latter of the food
it needs for its welfare. This action re-
sults in slow death or in a sudden collapse
of the affected host. In the case of pow-
dery mildew, mentioned later, the fungus
lives on the surface of the leaves, and sends
delicate suckers into the epidermis to ob-
tain its food from the tissue of the host.

Parasitic bacteria are smaller forms of
life than are the fungi, but their mode of
attack is not very different. With the ex-
ception of the large mushrooms, which are
also fungi, most others are invisible to the
naked eye and must be studied under a

92 DISEASES OF THE SWEET PEA

compound microscope. When grown in
pure culture, however, they are plainly
visible as colonies of aggregate individ-
uals.

Insects are divided into two classes : one
class derives its food by sucking the plant
juices and is known as "suckers" ; the other
class chews and eats solid parts of roots,
stems, foliage, or blossoms, and is known
as "biting." All insects undergo certain
changes (metamorphosis) , beginning as
larvae and ending as adult beetles, bugs,
or butterflies. Not all animals which are
parasitic on plants are insects, as, for ex-
ample, the eel worm. The latter belongs
to the Arthropoda of the Animal Kingdom,
its body being composed of many segments
with no legs.

Red spiders and mites, likewise plant
parasites, are not insects. These belong
to the Arachnida or true spiders. Books

DISEASES IN GREENHOUSE 93

of the same nature as the present work
generally discuss fungi, bacteria, and in-
sects under different headings. This
precedent will not be closely followed
here, but all three will be taken up from
the point of view of their economic im-
portance rather than in the light of their
systematic relationship.

As a rule plant diseases do not spread so
rapidly in the greenhouse as in the field.
The restrictions of wind currents and the
lack of easy access of insects are, no doubt,
factors in keeping in check many diseases.
There are, however, some indoor condi-
tions such as moisture and temperature,
which if not properly attended to, will re-
sult in great financial loss by favoring the
spread of disease.

Upon proper watering depends much of
the success of crops grown under glass.
The amount of water and the way it is ap-

94 DISEASES OF THE SWEET PEA

plied as well as the amount of moisture in
the air of the greenhouse may determine
the presence or absence of disease. A rela-
tively high percentage of moisture in the
soil or in the air favors damping off. The
humidity of the atmosphere in a green-
house is usually much higher than that out
of doors. From this it follows that good
ventilation should be provided. Over-
watering of sweet peas gives rise to un-
healthy conditions, especially in cloudy
weather, when evaporation and transpira-
tion are arrested. Thus the soil becomes
flooded with water which interferes with
the respiration of the roots and the plants
become more susceptible to diseases which
may be present in the soil in the green-
house. An excess of moisture in the air
also favors the development and spread
of the powdery mildew. During bright
sunny weather there is little danger from

DISEASES IN GREENHOUSE 95

overwatering, since transpiration and
evaporation are then very active. What
is true of "damping off" and the mildews
is also true for root knot. The minute eel
worms cannot thrive unless there is suffi-
cient moisture in the soil. Neither can
they thrive in soils that are flooded, since
they must have air to live. This is taken
advantage of in open fields where root
knot is controlled by flooding the land.
Overwatering, or any form of injudicious
watering, is no doubt an important factor
in predisposing the sweet pea plants to the
attacks of Thielavia, Rhizoctonia, Chae-
tomium, and Fusarium root rots. It is
therefore well to provide some means of
drainage, especially where the beds are
solid and in the ground. It is a good
practice to lay at the bottom of the beds
from one-half to one foot of ashes or a
layer of broken bricks or crushed stones.

96 DISEASES OF THE SWEET PEA

This will help to drain off the excess of
water likely to be applied by unskilled or
inexperienced help.

Water is not the only important factor
in controlling or increasing fungous pests
under glass. Temperature also plays an
important role. Damping off of green-
house sweet peas is best controlled by
keeping the greenhouse at a temperature
of 50 to 60 degrees F. A temperature of
80 to 90 degrees F. with a high moisture
content of the air will cause all young
seedlings to damp off, if the fungus is
present in the soil. It is doubtful if tem-
perature greatly influences the control of
collar rot, although a temperature of 90
degrees will be more favorable to the fun-
gus than a temperature of 50 degrees F.
Nevertheless, a low temperature will not
considerably check this disease when it
once gets a start. In greenhouses where

DISEASES IN GREENHOUSE 97

collar rot has become established, steriliza-
tion of the soil is the only remedy. Sweet
peas grown in the greenhouse are subject
to moisture conditions quite different from
those grown outdoors. Natural light is
less in winter, and in order to induce
growth under adverse conditions heat is
used as a stimulant. This produces plants
readily susceptible to disease. As these
difficulties cannot be avoided, it is essen-
tial to start with sterilized soil in the
benches.

Most sweet pea growers do not change
their greenhouse soil every year. As time
goes by, and the crop is grown successively
in the same place, the soil soon becomes
sour. This condition naturally tends to
encourage the development of a parasitic
flora in the soil which is detrimental to
sweet pea culture.

The following is a quick method to de-

98 DISEASES OF THE SWEET PEA

termine soil acidity, based on the use of
litmus paper, devised by Mr. J. E. Har-
ris,* who found that some kinds of litmus
paper are not suitable. Experiments have
shown that Kahlbaum's litmus paper is the
best for the purpose. It is so sensitive that
it is necessary to leave it in contact with
the soil particles only for a moment or two.
Soil only very slightly acid will change the
litmus paper to a distinctly red color.
Acid soils are easily corrected by the use
of lime. The latter favors Thielavia rot
but this is no consideration where sterilized
soil is used.

RHIZOCTONIA ROOT ROT

Corticium vagum B. and C.

No mention is made in literature of a
Rhizoctonia disease of sweet peas, al-

^ Harris, J. E., Soil Acidity and Methods for its De-
tection. Science. N. S. XL: 491-493, 1914.

I

Fig. 5. — Root Rot caused by Rhizoctonia.
Healthy and diseased plants.

Fig. 6. — Root Rot caused by Rhizoctonia.
To the right the soil was inoculated
with the fungus, resulting in no ger-
mination ; to the left, check.

DISEASES IN GREENHOUSE 99

though the same fungus is recorded on
other hosts. During the winters of 1911
and 1912, it was found by the author on
greenhouse sweet peas from different lo-
calities. Through correspondence, Pro-
fessor A. D. Selby reports its presence in
Ohio; Dr. W. G. Sackett, in Colorado; and
Professor E. C. Stackman, in Minnesota.
There seems no doubt that the Rhizoctonia
root* rot of sweet peas is much more wide-
spread than is reported. The nature of
the trouble is unknown to the growers.
Outdoors, Rhizoctonia also attacks the gar-
den pea, bean, lettuce, carrot, celery, cow
peas, and a number of other hosts.

Symptoms. Severely infected plants
have practically no root system (fig. 5).
In slightly infected plants, only one or two
rootlets may be destroyed. The fungus
produces a browning effect of the root be-
fore total destruction sets in. In very

loo DISEASES OF THE SWEET PEA

early stages of the disease infected seed-
lings are seen to have a wilted appearance;
as the disease progresses they fall over and
collapse. The fungus is not often con-
fined to the roots alone. It frequently
works its way up to the stem, producing a
constricted area which marks it off from the
healthy part above. The fungus being a
soil organism is usually introduced with
manure; infection may take place at any
part of the roots, or at the lower end of the
stem. When the latter is the case, reddish
sunken spots are observed at the base of the
stem. It seems that Rhizoctonia is pri-
marily a seedling disease of the sweet pea,
although older plants too are found to be
affected with the same fungus, but are not
killed outright since they linger for a con-
siderable time without producing blossoms
of commercial or ornamental value.

DISEASES IN GREENHOUSE loi

Pathogenicity. The pathogenicity or
the disease producing power of the sweet
pea Rhizoctonia may be readily proven by
planting disinfected seeds in sterile soil
and also in pots which were inoculated
with a pure culture of the fungus (fig. 6) .
The best material is a culture which has an
abundance of sclerotia.

The parasite has two stages — the Rhi-
zoctonia, and the sclerotial stages. The
Rhizoctonia stage consists of long and
narrow mycelial branches varying in color
from hyaline to reddish brown (fig. ']a).
These threads are either imbedded in the
substratum in which they grow, or they are
aerial, depending on the media on which
the fungus is grown. These mycelial
threads are the most active and are more
concerned in the parasitism of Rhizoc-
tonia. The sclerotial stage consists of

102 DISEASES OF THE SWEET PEA

numerous sclerotia which are made up of
closely interwoven short barrel-shaped
hyphae (fig. ']b) .

FIG. 7. a YOUNG hyph(£ of Rhizoctonia from sweet pea.

b BARREL-SHAPED hyphce FROM ScUvOtia OF THE SAME
FUNGUS.

Rhizoctonia solani Kuhn produces only
micro or small sclerotia, whereas Corticium
vagum B. and C. produces macro or large
sclerotia. After repeated attempts the
Corticium or perfect stage of the sweet pea
Rhizoctonia could not be obtained in pure
culture. This accords with the findings of

Fig. 8. — Pure culture of the Sweet Pea
Rhizoctonia, showing large and
smaller sclerotia of the fungus.

Fig. 9. — Pure culture of Fusarium

lathyri, the cause of Sweet Pea

Wilt.

DISEASES IN GREENHOUSE 103

Shaw ^ and Rolfs,^ who could not obtain
the perfect stage on culture media but
found it several times on the host. How-
ever, as the sweet pea Rhizoctonia pro-
duces macro-sclerotia (fig. 8) , and as al-
ready pointed out by Shaw, the macro-
sclerotia produce the Corticium stage, the
sweet pea organism is therefore referred to
as Corticium vagum B. and C,

Pathological Conditions of the
Host. Practical men, no doubt, like to
know what happens to the host plant when
it is attacked by the fungus. Rhizoctonia
when attacking hosts other than the sweet
pea, is found to parasitize the cambium
layer or growing part of the plant. With
the sweet pea, conditions are somewhat

* Shaw, F. J. F., The morphology and parasitism of
Rhizoctonia. Mem. Dept. Agr. India, Bot. ser. IV :

115-153' 1912.

^ Rolfs, F. M., Potato failures, a second report.
Colo. Agr. Expt. Station Bui. 91, 1904.

104 DISEASES OF THE SWEET PEA

similar. The fungus attacks the phloem
or food tracts and makes its way into the
parenchyma cells as well as to the epider-
mal cells. The effect produced is loss of
turgidity, wilting, and early collapse of
the host.

Growers should not fail to recognize
Rhizoctonia root rot in its initial stage.
To allow this fungus to get a foothold
would mean the ruin of an otherwise prom-
ising crop.

CH^TOMIUM ROOT ROT

Chcztomium spirochcete Fatt,

In the autumn of 1912, Professor A. C.
Beal of Cornell University sent me for
diagnosis diseased specimens of green-
house sweet peas. The trouble was read-
ily located in the roots. A fungus was
found invading the interior tissues of the
roots, but no fruiting stage of any kind to

DISEASES IN GREENHOUSE 105

help identify the fungus could be dis-
covered. Crush cultures were made at
once from the diseased material. Some
forty poured plates of nutrient agar were
made. In five days a pure culture of a
fungus appeared in all the plates with the
exception of one, which showed a Fusa-
rium. The cultures were watched closely
and in two weeks perithecia developed.
The fungus proved to be an ascomycete
belonging to the genus Chaetomium, and
determined by Mrs. Flora Patterson as
C. spirochcete Fatt. In mid winter of that
same year, more diseased specimens were
sent in to my laboratory by a grower in
Illinois. These were greenhouse plants
showing the same symptoms as those ob-
served on the plants sent by Professor Beal.
Cultures made from this material gave the
typical fungus Chaetomium spirochaete.
A search through the literature showed that

io6 DISEASES OF THE SWEET PEA

several species were recorded but none
were stated to be parasites.

Symptoms. At the first glance Chaeto-
mium root rot is difficult to tell from
Thielavia. Infected plants lose their
green color, become pale and yellow, and
cease growing. The root system is usu-
ally found wanting or partly destroyed.
The disease seems to be primarily a seed-
ling trouble.

Pathogenicity. The fact that a pure
culture of Chddtomium spirochczte was ob-
tained from numerous platings of dis-
eased material from two different states
at once led to the supposition that the or-
ganism was the cause of the disease. In-
oculations with pure cultures of the fun-
gus into healthy seedlings proved the
organism to be a weak parasite, favored
by an excess of moisture in the soil.

The Fungus, The mycelium of the

DISEASES IN GREENHOUSE 107

fungus is hyaline, closely septate, and
branched (fig. 10^) when grown in the
substratum of the media. The aerial my-

FIG. 10. a SHOWING mycelium of Chstomium Spirochete,
b HAIRS, c and d asci. e ascospores.

celium consists of long unbranched fila-
ments varying in color from light to deep
lemon. The yellow seems to be produced
within the fungus hyphae which later is
also transmitted to the media. In pure
culture the fungus produces its perithecia

io8 DISEASES OF THE SWEET PEA

or fruit bodies in about two weeks after
sowing. These perithecia are covered
with dark hair-like appendages. The
hairs are straight or coiled at the apex
and septate at unequal intervals, and cov-
ered with very minute pointed warts (fig.
10^). The asci are very evanescent and
can only be seen in very young cultures
just as the perithecia are forming. In old
cultures the ascus wall is easily ruptured
so that it is difficult to make out the ar-
rangement of the ascospores within.
There are eight ascospores in each ascus
(fig. 10^ and d) . The ascospore is apicu-
late (fig. 10^) at both ends. Its wall is
smooth, light brown when young and dark
when old. It will germinate readily
in distilled water or in any nutrient
broth.

Chaetomium root rot is not likely to
prove troublesome in greenhouses where

DISEASES IN GREENHOUSE 109

the ventilation and the watering are prop-
erly attended to.

FUSARIUM ROOT ROT

Fusarium lathyri Taub.

There is no record in the mycological
literature of a Fusarium disease of the
sweet pea. Numerous complaints from
florists showed that sweet peas often did
not grow well under glass because of a
root rot which developed early and in some
cases destroyed the entire planting. Cul-
tures made by the writer from infected ma-
terial or from the infected soil gave in each
case a pure culture of Fusarium.

Symptoms. The disease produces a
sudden flagging of the leaves accompanied
by sudden wilting and collapse of the seed-
ling. Usually a fair percentage of the
seeds germinate and the plants reach the

no DISEASES OF THE SWEET PEA

height of about eight to ten inches when
they are attacked by the fungus. If the
collapsed seedlings are allowed to remain
on the ground, the dead stems will soon be
covered with the sickle shaped spores.
Eventually the dead tissue rots and dis-
integrates and is soon invaded by small
fruit flies which now begin to distribute
the spores of the fungus to different places
in the same house.

Pathogenicity. The pathogenicity of
this fungus is readily proven by inoculat-
ing a pure culture (fig. 9) of the fungus
into healthy seedlings planted in sterile
pots and soil. The seeds germinate and
grow up to a height of seven to eight inches
and then succumb to the parasite which
was artificially introduced into the soil

(fig. 11).

The Fungus. The mycelium of the
fungus is hyaline, branched and septate.

Fig. II. — Fusarium Wilt or Root Rot. At left, healthy
plant; at right, infected.

DISEASES IN GREENHOUSE in

At an early age the hyphae begin to form
chlamydospores or resting spores. These
are round hyaline bodies often filled with
oil globules and are formed in the center
of the hypha. Usually also the chlamydo-
spores are born at the tip end of the hyphse
in chains of twos, threes, and even fours.
Old cultures consist largely of a mass of
chlamydospores. There are also two other
types of spore forms, and these appear as
early as the third day in the pure culture.
These are micro-conidia or small one-celled
spores, and macro-conidia or large cycle-
shaped spores, varying from two-celled to
four-celled. The usual form is three-
celled. In old cultures the macro-conidia
shrink so that the septa become slightly
prominent. These old macro-conidia soon
lose their protoplasm, or they break up,
presenting a granular appearance. In
young cultures the outer wall of the chla-

112 DISEASES OF THE SWEET PEA

mydospores is smooth, but in old cultures
it becomes slightly warty or covered with
minute points. No perfect stage has been
found to accompany this fungus, either on
the host or in pure culture.

Fusarium root rot is a serious disease
which threatens to undermine the growing
of greenhouse sweet peas. The grower
should do everything possible to prevent
its introduction into the house. In places
where this disease has already gained a
foothold, soil sterilization becomes a nec-
essary part of sweet pea culture under
glass.

THIELAVIA ROOT ROT

Thielavia basicola Zopf.

In 1912, Chittenden ^ was asked by the
National Sweet Pea Society of England to
investigate the ''streak" disease of the

* Chittenden, F. J., Diseases of the Sweet Pea, Sweet
Pea Annual: 14-24, 1912. London.

Fig. 12. — Root Rot caused by Thielavia.

Roots of diseased and healthy plants

of the same age compared.

DISEASES IN GREENHOUSE 113

sweet pea. In his report before that so-
ciety, Chittenden gives an accurate de-
scription of the "streak," so that there can
be no doubt that he had the disease well in
mind, that is, he described it as a stem dis-
ease. Chittenden, however, attributed
"streak" to Thielavia basicola Zopf, In
this Chittenden erred, for streak has since
been found to be caused by a bacterium.
Massee,* too, made the same mistake, for
he also considered Thielavia as the cause
of "streak." Streak however is different
from Thielavia root rot.

Symptoms. Plants severely infected
with Thielavia have practically no root
system, since the roots are destroyed by the
fungus as rapidly as they are formed (fig.
12) . All that is left of the root system is

^ Massee, George, A disease of sweet peas, asters and
other plants. Roy. Bot. Gard. Kew Bui. of Misc. In-
form. No. 1:44-52, 1912, London.

114 DISEASES OF THE SWEET PEA

a charred blackened stub. The fungus
sometimes works upon the stem to a dis-
tance of two to three inches above ground.
It is probably due to this that some work-
ers have mistaken this disease for the
"streak." Although their root system is
destroyed, affected plants seem to lin-
ger for a long time. Diseased plants,
however, cease growing, and maintain
a dwarfed sickly appearance (fig. 13).
These are useless for any purpose, as they
fail to bloom and merely contaminate the
beds by their presence.

Pathogenicity. Healthy seedlings
may be readily infected by placing a pure
culture of the fungus in the soil. In two
to three weeks the roots of the infected
plants will be thoroughly diseased. Over-
watering does not seem to be a necessary
factor in infection, although it no doubt
helps to weaken the plants and furthfe.

Fig. 13. — Root Rot caused by Thielavia. A healthy
plant contrasted with a diseased plant.

DISEASES IN GREENHOUSE 115

aids the fungus in its destructive work.
Thielavia basicola also attacks a number
of hosts other than the sweet pea. Pure
cultures of the fungus obtained from cow-
pea, violets, parsnip, and tobacco, when
inoculated on the sweet pea will readily
infect the latter. This shows that the dis-
ease will cross from other hosts to the sweet
pea and vice versa.

The Fungus. The mycelium of Thie-
lavia basicola is hyaline, septate and
branched. The mycelium becomes some-
what grayish with age. Three kinds of
spore forms are produced — endospores,
chlamydospores, and ascospores. Endo-
spores are so called because they are formed
inside a special thread of the mycelium
(fig. \\a). This is the spore form that
commonly occurs in pure cultures of arti-
ficial media and on the host. The endo-
spore case is formed on terminal branches

ii6 DISEASES OF THE SWEET PEA

FIG. 14. a Endospores. h c Chlamydospores breaking
UP INTO INDIVIDUAL SPORES, d Chloniydosporcs un-
broken, f Ascospores. e single perithecium.

with a somewhat swollen base and a long
tapering cell. The endospores are formed
in the apex of this terminal cell and are
pushed out of the ruptured end by the
growth of the unfragmented protoplasm of
the base. They are hyaline, thin walled,
and oblong to linear in shape. The chlam-

DISEASES IN GREENHOUSE 117

ydospores (fig. 14.I? to d) are thick walled,
dark brown bodies, borne on the same my-
celium as the endospores. This type of
spore is formed in great abundance on the
host and particularly within the affected
tissue. The ascospores (fig. 14/) are len-
ticular in shape and are borne in asci (or
sacs) within black perithecia (fig. 14^) .
This stage, however, has not been found on
the sweet pea or in pure culture.

Thielavia is perhaps next in importance
to Fusarium root rot. The fungus is
often introduced with manure or more
commonly with diseased violets, since this
flower is profitably grown in conjunction
with sweet peas.

Growers, therefore, cannot be too care-
ful in trying to keep out Thielavia from
the greenhouse.

ii8 DISEASES OF THE SWEET PEA

POWDERY MILDEW

Microsphd^ra alni {Waller} Salm.

The sweet pea mildew was described by
Massee ^ as being prevalent in England.
Erisiphe polygoni was thought to be the
cause both of the sweet pea and the garden
pea mildew. In the United States, Pro-
fessor Stewart ^ was the first to record the
finding of powdery mildew on sweet peas
in the United States. However, Stewart
did not find the perithecial stage which
would help in the determining of the
fungus.

Powdery mildew is a very prevalent dis-
ease on greenhouse sweet peas, although
it is also very common on out-of-door
plants. The fungus which causes mildew

^ Massee, George, Fungoid diseases of the sweet pea,
Sweet Pea Annual: 20-21, 1906, London.

^ Stewart, F. C, Notes on New York plant diseases.
New York (Geneva) Agr. Expt. Station BuL 328:394,
1910.

Fig. 15. — Powdery Mildew, healthy and diseased leaves.

Notice the white covering of the affected leaves, due to the growth
of the mildew fungus on the surface of the former.

Fig. 16. — Germinated sclerotia of the Sweet Pea
Sclerotinia which had wintered outdoors.

DISEASES IN GREENHOUSE 119

grows on the surface of the leaves, thus
giving them the white powdery appearance
(fig. 15) . Affected leaves eventually lose
their green color, shrivel and fall off pre-
maturely. The perfect stage of this fun-
gus is found on fallen and dead leaves.
Powdery mildew is perhaps universally
found in every greenhouse where sweet
peas are grown. It is worse in over-
watered houses, and in overheated houses
with excess of moisture. Powdery mil-
dew is perhaps the easiest disease to con-
trol.

STEM OR COLLAR ROT

Sclerotinia libertiana Fckl.

Observations seem to indicate that this
disease is limited to sweet peas grown un-
der glass. A special effort was made to
find this disease outdoors, but without suc-
cess. Under certain conditions unfavor-

120 DISEASES OF THE SWEET PEA

able to the host this fungus may attack a
variety of plants in the open. That this
fungus has not been found to attack sweet
peas out of doors does not preclude its ap-
pearance in the field at any time in the fu-
ture.

Symptoms. Collar rot is usually a
seedling disease which causes "damping
off." It is most severe in poorly venti-
lated houses or in beds which are over-
watered and lack the proper drainage.
The disease does its work quickly. Af-
fected plants first show a wilting of the
tip and flagging of the leaves, and then the
seedling falls over and collapses (fig. 17) .
The fungus, Sclerotinia libertiana^ al-
though a soil organism, cannot attack the
roots of its host. The parasite penetrates
the collar of the stem, completely invad-
ing the inner vessels, thus cutting off the
upward flow of water from the roots to the

^ r^^^'^WTCTf

DISEASES IN GREENHOUSE 121

parts above. Plants which have recently
died have a water soaked appearance, and
later covered by a white weft of fungus
mycelium, and by sclerotia which appear
irregularly on or within the affected stem.

Pathogenicity. The pathogenicity of
this fungus may be readily established by
inoculating healthy seedlings with a pure
culture of the fungus. The latter is easily
re-isolated and the disease produced at
will. Moisture is the main factor in fa-
voring infection.

The Fungus. Sclerotinia lihert'iana, is
a fungus too well known to plant patholo-
gists and even to practical growers to re-
quire much description. Under green-
house conditions, the same fungus causes a
serious disease on lettuce, cucumbers, to-
matoes, violets, and many other plants.
When grown on artificial media, there are
no differences observed on the different

122 DISEASES OF THE SWEET PEA

strains isolated from the sweet pea, lettuce,
cucumbers, tomatoes or violets. More-
over, any one of these strains will produce
a disease on any of the hosts enumerated.
When the sclerotia, after being placed out-
doors in the cold to over winter, are taken
in and placed on moist sand kept at room
temperature, they germinate and produce
the typical grayish stalks with their apo-
thecia or fruit bodies (fig. 16) . The latter
contain the asci in which are the ascospores
of the fungus.

Like Thielavia basicola^ and because of
its omnivorous nature, the fungus Sclero-
tinia libertiana may prove a great draw-
back to the culture of greenhouse sweet
peas. The parasite is usually carried with
the manure or may be introduced on other
diseased plants. Failure to recognize col-
lar rot or carelessness in maintaining

DISEASES IN GREENHOUSE 123

proper conditions in the house may entail
serious losses to the grower.

ROOT KNOT OR EEL WORM

Heterodera radicicola (Greef) Milller

Root Knot, [nematode galls) no less
important than Rhizoctonia and Fusarium
root rots, causes great loss to greenhouse
sweet peas. It does not, however, produce
a damping off in young seedlings. It
seems very probable, too, that root knot
in the case of the sweet pea opens the way
to the attacks of Rhizoctonia and several
other root troubles, producing also the
greatest amount of damage in light sandy
soils.

Symptoms. The disease is character-
ized by swellings on the roots. These are
either small knots formed singly, in pairs,
or in strings, thus giving the affected root

124 DISEASES OF THE SWEET PEA

a beaded appearance; or else the swellings
are very large (fig. 19) so as to be mistaken
for bacterial nodules, which occur nor-
mally in great abundance. Root galls,
however, cannot be mistaken for legume
nodules, since the latter in the case of the
sweet pea are lobed and are attached at one
end (fig. 18) ; whereas, the root galls pro-
duce a swelling of the entire surface of the
part affected. Infected plants usually
linger for a long time, but they can be dis-
tinguished by a thin growth and yellow
sickly looking leaves and stems.

Distribution. The eel worm of the
root knot, as it is more often called, seems
to be of wide distribution, being found
in Europe, Asia, Africa, Australia, and
both North and South America. Al-
though it is found in most parts of the
world, there are many localities in which
the pest has never been known.

Figs. i8, 19.— Root knot of Sweet Peas, a root trouble which
may be mistaken for the true legume root nodules.

The insert cut in the top left-hand comer shows the normal root nodules
of the Sweet Pea formed by nitrogen-fixing bacteria.

DISEASES IN GREENHOUSE 125

Life History. The eel worm is a very
minute organism seldom exceeding one-
twenty-fifth of an inch in length, and since
it is semi-transparent, it cannot be easily
detected with the naked eye. In search-
ing for eel worms, endeavor to break a fresh
knot. Close examination will usually re-
veal two types of worms : a spindle shaped
worm, the male, and a pearly white pear
shaped organism, the female, firmly em-
bedded in the gall tissue. The female is
very prolific, depositing no less than 400
to 500 eggs during her lifetime. The eggs
are whitish semi-transparent bean shaped
bodies and too small to be noticed without
the aid of a magnifying glass. The time
which elapses until the eggs hatch depends
largely upon weather conditions. With
warm days the eggs hatch sooner than in
colder weather. Upon hatching, the
young larvae either remain in the tissue of

126 DISEASES OF THE SWEET PEA

the host plant in which they have emerged,
or, as is more often the case, leave the host
and enter the soil. This is the only period
during which the worms move about to any
great extent in the soil, where they either
remain for some length of time or immedi-
ately penetrate another root of the host.
The nematodes in most cases become com-
pletely buried in the root tissue, establish-
ing themselves in the soft cellular struc-
ture which is rich in food. The head of
the worm is provided with a boring appa-
ratus consisting of a sharply pointed spear,
located in the mouth; this structure not
only aids it in getting food but is also
valuable in helping the young worms to
batter through the cell walls before becom-
ing definitely located. The two sexes
during development are indistinguishable
up to fifteen or twenty days, both being

DISEASES IN GREENHOUSE 127

spindle shaped. In the molting or shed-
ding of the skin, there is a marked change
in the case of the female, especially in the
posterior region of the body, which no
longer possesses a tail-like appendage.
Fertilization occurs soon after this molt,
and many radical changes occur in the
shape and structure of the organization of
the worm. The fertilized female in-
creases rapidly in breadth and becomes a
pearly white flask- or pear-shaped indi-
vidual. This creature is far from being
worm-like and may therefore be over-
looked by one unfamiliar with the life his-
tory of the eel worm. The adult male is
much like that of the larvse, being spindle
shaped in outline. The male does not
cause as much damage to root tissue as the
female, and its purpose in life seems to be
only that of fertilizing the female, for

128 DISEASES OF THE SWEET PEA

after this function has been performed it is
quite probable that the male worm takes
no more food.

Omnivorous Nature of the Eel
Worm. Root knot injury is not confined
to sweet peas alone. There are two hun-
dred and thirty-five species of plants
known to suffer from it. This number in-
cludes all the important families of flow-
ering plants, gymnosperms, and ferns. Of
the greenhouse plants practically all are
subject to root knot. Violets, carnations,
chrysanthemums, tomatoes, cucumbers,
and lettuce are often ruined by this pest.

Among the plants which are not affected
by eel worm are the following : crab grass,
red top, Johnson grass, rye, corn, perennial
rye grass, timothy, and Zinnia. For the
purposes of greenhouse rotation none of the
foregoing plants is of any value. Should
root knot attack sweet peas outdoors, how-

*

DISEASES IN GREENHOUSE 12^

ever, especially where they are grown on a
large scale for seed purposes, rotation of
crops will have to be resorted to.

THRIPS *

Heliothrips hcsmorrhoidalis Bouche

The damage done to the sweet pea by
Thrips is confined mostly to the foliage.
Thrips feed by sucking on the juices of the
sweet pea plants. New places and new
leaves are continually attacked so that the
affected parts are full of tiny pale spots.
In severe attacks the spots unite and form
regular white blotches. Ordinarily it is
on the under surface of the leaves that the
mites feed, but when they become very
numerous they also migrate to the upper
surface. Both sides of the affected foliage
thus become covered with minute drops of

^ For a more detailed technical description, see Bull.
64 Bur. Ent. U. S. Dept. Agr.

130 DISEASES OF THE SWEET PEA

a reddish fluid secreted by the thrips. As
these drops dry they gradually turn black.
As the attack progresses, the leaves lose
all their green color, become limp, and
drop off.

Life History of Thrips. An adult
thrip is about one-twenty-fourth of an inch
in length, and is dark brown in color, with
the tip of the body somewhat lighter. The
female deposits her eggs within the leaf
tissue, and these hatch after about eight
days. The young larvae feed in the same
way as the adults, but it is the young
which in feeding exude the reddish drops
previously mentioned. In reaching full
growth the larvae undergo two resting
stages — prepupa and pupa, during which
they take no food and remain motionless.
Twenty to thirty days after the eggs have
hatched the adult is ready for reproduc-
tion (figs. 20a to c) .

DISEASES IN GREENHOUSE 131

FIG. 20. GREENHOUSE TllvipS, a EGG. h LARVA FIRST
STAGE. C LARVA FULL GROWN. (AFTER RUSSELL.)

Besides the sweet pea, thrips feed on
lilies, azaleas, croton, dahlia, phlox, ver-
bena, pink, and ferns, and on a number of
other ornamentals, both in the greenhouse
and in the open.

RED SPIDER

Tetranchys himaculatus Harv.

Even more dangerous to sweet peas than
mites are Red Spiders (fig. 21), which at-

132 DISEASES OF THE SWEET PEA

FIG. 21. THE RED SPIDER, ENLARGED. (aFTER BANKS.)

tack both leaves and stems, the method of
attack and the resulting injury somewhat
resembling that of mites. However, the
spots caused by red spiders are reddish in-
stead of a pale white.

Life History. The adult female is usu-
ally brick red in color and the male is red-
dish amber. Frequently, however, the
color of the red spider changes according to
locality and food plants. The female lays

DISEASES IN GREENHOUSE 133

50 to 60 eggs, depositing about six per day
for a period of nine days or so. The eggs
hatch after about four days. After two
days' activity, the young larvse pass into

FIG. 22. TRIPHLEPS INSIDIOSUS, AN ENEMY OF THE RED
SPIDER. (after MCGREGOR.)

the pupal or resting stage. The adults
mate and the female is soon capable of
laying.

In the greenhouse the red spider mi-
grates from the tomato and other plants to
the sweet pea. The violet especially is a

134 DISEASES OF THE SWEET PEA

favorite host. Outdoors the red spider
may attack sweet peas, tomatoes, wild and
cultivated violets, beans, cowpeas, dahlia,
Jamestown weed, wild blackberry, and
the wild geranium. Although red spiders
have few natural enemies, yet the insect
Thriphleps insidiosus (fig. 22) frequently
helps to keep it in check.

CHAPTER V

FIELD DISEASES OF SWEET PEAS

As previously noticed, the diseases which
affect sweet peas under glass may also be
present out-of-doors. In fact the fungi
such as Thielavia, Rhizoctonia, Fusarium,
Sclerotinia, etc., are all known to induce,
very commonly, diseases on plants in the
field. Indeed their appearance in the
greenhouse indicates their presence some-
where in the field or in the manure pile,
whence they are usually introduced into
the soil. The spread of these fungous
pests is favored by unnatural conditions
which may occur in the field as well as in
the greenhouse. Continuous foggy and
damp hot weather, together with infected

135

136 DISEASES OF THE SWEET PEA

soils, will naturally cause loss and disease.
Thielavia root rot commonly found in the
greenhouse produces a similar disease on
sweet peas in the field. In the latter case
it assumes greater economic importance,
especially on trial grounds. Root knot
has so far been encountered only on green-
house sweet peas. It will doubtless be
found in the field, however, before long.
The same is also true for the Rhizoctonia
root rot, the Fusarium root rot, and the
Sclerotinia collar rot. Growers of sweet
peas on a large scale for seed or for orna-
mental purposes should be on their guard
to prevent the introduction of these trou-
bles into their soils. It is much easier to
prevent infection than to eradicate a dis-
ease that has once gained a strong foot-
hold. Powdery mildew, a common leaf
trouble in the greenhouse, is found also
outdoors to some extent. On irrigated

FIELD DISEASES 137

sweet peas it assumes the nature of an epi-
demic and may cause death of all the
foliage.

ANTHRACNOSE

Glomerella rufomaculans (Berk.) V. Sck.
and Sp.

Of all field diseases Anthracnose is per-
haps the most dreaded in the United
States because of the great losses it occa-
sions. Anthracnose on the sweet pea may
exist wherever apples are suffering from
bitter rot, for, as the writer has definitely
proven, bitter rot of apples and anthrac-
nose of sweet peas are caused by the same
fungus, Glomerella rufomaculans.

Symptoms. The symptoms of anthrac-
nose are varied. Sometimes it is mani-
fested by a wilting or dying of the tips
(fig. 23) which become whitish and brittle

138 DISEASES OF THE SWEET PEA

and readily break off. At other times the
injury extends further down and involves
the entire branch. On the leaves the dis-
ease starts as whitish spots, which enlarge
until all the green gradually fades en-
tirely, hence causing death (fig. 24) .
Such infected leaves become brittle and
soon drop off. Examination of an in-
fected leaf with a hand lens shows that it
is peppered with minute salmon colored
pustules. At the time of blossoming the
fungus also attacks the peduncle at the
point of union with the buds, producing a
bud blight ; or the fungus attacks both the
flower bud and the peduncle, in which case
both dry up but do not fall off. The most
easily distinguishable symptoms of this
disease are on the seed pods. Infected
pods lose their green color, become shriv-
eled, and are soon covered with salmon
colored patches which frequently attract

Fig. 23. — Anthracnose Disease of Sweet Pea on stem
and peduncles.

Fig. 24. — Anthracnose Disease affecting Sweet
Pea leaf.

FIELD DISEASES 139

attention. The disease is often worse
where green Aphids are very active. In
this case the older vines may be affected at
any point. Very often, too, the harder
vines may escape the disease which attacks
the thin blades on each side. Here the af-
fected blades become white and dry and
break at handling. If not disturbed they
become covered with pink pustules or
fruits of the parasitic organism.

The anthracnose, like the "streak," is of
great economic importance. When once
introduced into a field the disease spreads
rapidly, often destroying the entire crop.
Unlike "streak," the anthracnose may at-
tack young seedlings, a condition some-
times found in the greenhouse. In the
field, the disease starts about July 1, when
the plants are in full bloom and in the
prime of beauty. This is also the time
when the bitter rot disease of the apple

140 DISEASES OF THE SWEET PEA

(fig. 25) makes its appearance in the
orchard. The fungus is carried over win-
ter on cankered limbs and mummied fruits
of diseased apples or on the diseased pods
of the sweet pea as well as in the soil.

Mode of Infection and Period of In-
cubation. The anthracnose of the sweet
pea is mainly a disease of the tender parts
of the plant. Infection usually starts first
at the tips, although, as previously shown,
the fungus may attack the older parts of
the plant once they have been injured by
green Aphids or by red spiders. The
spores of the parasite usually germinate in
from six to twenty-four hours, according
to the amount of moisture present. The
germ tubes enter the host by breaking
through the epidermal cells of either leaf
or stem.

The period of incubation varies from
three to five days, according to the amount

Fig. 25. — Bitter Rot of Apple induced by the same fungus

which causes Anthracnose of the Sweet Pea,

viz. Glomerella rufomaculans.

Fig. 26. — Sweet Pea Mosaic, showing, a. leaflet
affected with the disease, b. healthy.

FIELD DISEASES 141

of moisture in the atmosphere. The
acervuli or spore pustules appear within
five days after wilting begins, unless the
weather is dry, when they may not appear
until considerably later.

MOSAIC DISEASE OF THE SWEET PEA

Sweet Pea Mosaic is a serious disease.
It greatly checks greenhouse peas and is
equally injurious to sweet peas grown out-
of-doors. Although the cause of the
trouble is not as yet known, nevertheless
all indications tend to show that it is in-
duced by a definite pathogenic organism.
The same or a similar mosaic is known to
attack a number of plants such as tobacco,
egg plant, pepper, tomatoes, and clovers.
Its occurrence on the sweet pea has been re-
corded only by the author * though it has

^ Taubenhaus, J. J., Present knowledge of sweet pea
diseases. Florist Exchange 34: 108-110, 1912.

142 DISEASES OF THE SWEET PEA

probably been seen by a number of grow-
ers.

Symptoms. Mosaic is readily distin-
guishable by a yellow dotting or mottling
of the leaf, presenting in some instances
a beautiful mosaic structure, whence its
name (fig. 26) . Affected leaves linger for
a time but they eventually lose all their
chlorophyll and soon drop off. Another
symptom of this disease is a curling of
leaves (fig. 27) resembling the curling in-
duced by the green Aphids, but in this
case the insects have no association with
it. The disease makes its appearance after
the seedlings are from two to three weeks
old. Often, the trouble is so serious and
the curling so pronounced that the plants
thus affected cannot make any headway
and remain dwarfed. An attempt is made
by these curled plants to produce a few
flowers, but the latter are borne on very

Fig. 27. — Mosaic Disease causing dwarfing

of the plant and a rolling of the tip

leaves.

FIELD DISEASES 143

short peduncles as compared with the long
peduncles of healthy plants of the same va-
riety. Frequently, however, the affected
plants outgrow the disease entirely, and
thus a distinct line of demarcation is ob-
served between the previously diseased
part and the healthy part of the new
growth (fig. 28) . In rare cases, infected
plants seem to thrive in spite of the dis-
ease. Such plants should be selected for
the purpose of breeding resistant strains.
Pathogenicity. Like peach yellows
and the mosaic disease of tobacco and
tomato, mosaic of the sweet pea can be
reproduced by puncturing with a sterile
needle from the diseased leaf into a healthy
one. As yet it has not been possible to
find an organism associated with the dis-
ease. Nevertheless the disease is conta-
gious. It takes from ten to fifteen days for
the disease to appear when artificial inocu-

144 DISEASES OF THE SWEET PEA

lation is carried out. The symptoms pro-
duced in artificially inoculated plants are
similar to those in the field.

STREAK DISEASE

Bacillus lathyri Manns and Taub.

Streak is the only bacterial disease
which aifects this plant and no disease
of the sweet pea is so little known to
the growers. The attention of Professor
Manns and the author was called to it
in the course of our investigations, that
is to say, only about three years ago.
It probably has existed, however, a long
time in this country, since it attacks so
many other members of the legume family,
the red clovers particularly, upon which
it causes trouble of considerable economic
importance. In England this disease is
ruining the sweet pea crop every year. In
this country it has gained a strong foothold

Fig. 28. — Mosaic Disease, shewing where the
plant has outgrown the trouble.

z indicates the area where the disease has ceased
activity.

FIELD DISEASES 145

and it is to be found wherever clovers are
grown.

Symptoms. Like the bacteriosis of the
bean, streak makes its appearance in the
season of heavy dew. On the sweet pea
the disease usually appears just as the
plants begin to bloom; it is manifested by
light reddish brown to dark brown spots
and streaks (the older almost purple)
along the stems, having their origin usu-
ally near the ground, which indicates dis-
tribution by spattering rain and infection
through the stomata or through insect in-
jury. The disease becomes distributed
quickly over the mature stems until the
cambium and deeper tissues are destroyed
in continuous areas, and the plant dies
prematurely. From the stem the disease
spreads to the petioles, flowers, peduncles,
and pods, the symptoms in these cases be-
ing similar to those on the stems. On the

146 DISEASES OF THE SWEET PEA

leaves, however, the disease appears as
small circular spots, which gradually coal-
esce and eventually involve the entire leaf,
which when killed presents a dark brown-
ish appearance.

Pathogenicity. The pathogenicity of
the causative organism may be proven by
diluting a pure culture of the organism in
sterile water and by spraying it on the
healthy plants with an atomizer. This is
done in the evening when the temperature
is cooler and there is less chance for evapo-
ration of the infectious liquid which is ap-
plied. The disease makes its appearance
from seven to ten days after artificial in-
fection and the symptoms are similar to
those produced in nature. The organism
may be re-isolated from the artificially in-
fected plants and the disease induced again
at will on healthy plants, in each case the
uninfected check plants remaining healthy.

FIELD DISEASES 147

Natural or artificial infection can only
take place on mature plants which have
started to bloom. All attempts to inocu-
late plants in all stages of growth previous
to the blooming period have failed. It
seems that the host previous to blooming
possesses certain protective properties
which inhibit the growth of the parasite.
The disease in the field does not make its
appearance until the plants have started
to bloom.

Over 1,500 plate cultures of incipient or
young lesions were made from the sweet
pea and clover. The organism may almost
invariably be taken in pure cultures from
the young lesions in the stems of sweet
peas when the surface is properly steril-
ized. The parasite is a yellow organism
which will grow luxuriantly upon any
nutrient media containing sugars. On
standard nutrient glucose agar the colonies

148 DISEASES OF THE SWEET PEA

appear within 24 to 36 hours. The center
becomes granular and the colonies have a
marked tendency to become stellate or au-
riculate (fig. 29) .

Morphological studies show the organ-
ism to be a comparatively small rod-shaped
bacillus, which in fresh cultures is rarely
found in chains, and seldom united in twos
or fours. The flagella or appendages of
the organism are not easily demonstrated ;
they are shed so readily that usually not
more than two to five may be found in
stained material and these are generally
quite short. However, when the proper
material is selected, carefully fixed and
stained, the flagella may be demonstrated
to be very long and delicate, and to be
from 8 to 12 in number and well dis-
tributed peritrichially.

Fig. 29.— Pure culture of the streak
organism, Bacillus lathyri.

Fig. 30. — Sweet Pea aphis parasitized by a fungus,
Empusa aphidis.

CHAPTER VI

DISEASES NOT YET KNOWN TO ATTACK
SWEET PEAS IN AMERICA

In an article in the Sweet Pea Annual,
Massee ^ describes a pea blight and a pea
spot, which as far as is known have not
yet made their appearance in this country.

PEA BLIGHT

Peronospora trifoliorum DeBy.

According to Massee, this disease is very
destructive to peas, lupines, and most
other plants of the pea family. The dis-
ease may appear and spread quickly when
the plants are only a few inches high, or
it may attack older plants. In dry

^ Massee, G., Fungoid diseases of the sweet pea.
Szveet Pea Annual, pp. 20-21, 1906, London.

149

150 DISEASES OF THE SWEET PEA

weather the mycelium of the fungus
spreads in the tissue throughout the leaf,
which soon assumes a sickly yellow-green
color, and finally bleaches, shrivels, and
dies without showing any or only a small
amount of the mold on the surface. In
damp cloudy weather infected leaves show
yellow patches, which soon become covered
on one or both surfaces with a very delicate
grayish lilac colored mold.

The summer spores are produced on the
leaves or on any other part of the host.
The winter or resting spores are imbedded
in the tissue of the host that has been pre-
viously killed by the fungus. The resting
spores have a very thick smooth brown
wall.

Peronospora vic'icz also produces a dis-
ease on sweet peas.

DISEASES NOT YET KNOWN 151

PEA SPOT

Ascochyta pisi Lib,

According to Massee, this disease attacks
sweet peas, French beans and several other
leguminous crops. The first indications of
disease is the appearance on the pods of
pale green spots of variable size and irreg-
ular shape. These blotches continue to in-
crease in size for some time and eventually
become whitish, bordered with a dark line,
and the surface is studded with minute
black points which are the pycnidia or spore
sacks of the fungus.

It should be remembered that both Asco-
chyta pisi and Peronospora trifoliorum are
fungi very prevalent on other hosts in this
country. It is only a matter of time until
these parasites will be found to attack
sweet peas. Growers, therefore, should be
on their guard against these two troubles.

CHAPTER VII

INSECT PESTS
THE SWEET PEA APHIS

Macrosiphum pisi Kalt,

Of all the sweet pea insects, not one
perhaps rivals in economic importance the
green aphis. Specimens were submitted
to Professor Chittenden of the United
States Department of Agriculture, who
identified them as M. pisi Kalt. Since
this pest is the same which also attacks the
garden and field pea we will quote in part
Professor Chittenden/

Description. "The pea aphis is one of
unusual size among those found infesting

^Chittenden, F. H., The pea aphis (Macrosiphum
pisi Kalt.) U. S. Dept. Agr. Bur. of Entomol. Circ. 43
Second Edition, 1909.

15a

INSECT PESTS 153

gardens, and the largest of the green
species which attacks the pea and related
plants (fig. 31 ato e). The general color

FIG. 31. SWEET PEA Apllis, a WINGED FEMALE. b SAME
FROM SIDE WITH WINGS FOLDED IN NATURAL POSITION,
AS WHEN FEEDING. C AptcrOUS FEMALE. d NYMPH
IN LAST STAGE. ( AFTER CHITTENDEN.)

of the insect is uniform pea green, the same
color as the insect's favorite food plant.
The eyes are prominent and reddish brown
in color. The antennae are lighter than the
body and the tubercules prominent. The
legs are long and conspicuous.

154 DISEASES OF THE SWEET PEA

"Like the gipsy moth, the pea aphis seems
to have been present in this country for
about twenty-five years before it became a
pest. It is now found practically wher-
ever the garden pea and the sweet pea are
grown, causing much injury to both hosts.

"The reasons why the species has be-
come so troublesome a pest are many:
First, because of its ravages to a crop hith-
erto little troubled by insects except the
pea weevil, which has always been present
in gardens and fields and has come to be
looked upon as a necessary evil. Second,
it is a species never before noticed so far
as records go as having been destructive to
peas of any kind in this country. Third,
because of the great difficulty in keeping it
in check.

"Although garden and field peas are the
crops most injured by this pest, sweet peas
and red and crimson clover, as well as

INSECT PESTS 155

vetches, are affected. Attacks begin on
the young pea vines; the 'lice' gather in
clusters at first under and within the termi-
nals, and as the leaves become covered they
attack also the stems and by their numbers
and veracity sap the life of the plant.
Whole areas of vines are seen covered with
the aphis."

How THE Aphids Multiply. The
*'lice" spend the winter in the egg stage.
When the young sweet pea seedlings ap-
pear in the spring the lice hatch from the
eggs, and instead of being partly males
and partly females, all are females, known
as stem mothers. These without the in-
tervention of the male give birth to a sec-
ond generation, all of which are likewise
females. These females in turn give birth
to a third generation of females and in this
manner a large number of successive gen-
erations are produced, in none of which

156 DISEASES OF THE SWEET PEA

FIG. 32. SHOWING HOW APHIDS FEED AND THE NECESSITY
OF A CONTACT SPRAY TO KEEP IT IN CHECK. (COURTESY
OF THE KENTUCKY TOBACCO PRODUCTS CO.)

do any males occur. This form of repro-
duction without the intervention of the
male is known as parthenogenesis. On the
approach of cool fall weather a generation

INSECT PESTS 157

composed of both males and females are
produced, the sexes mate, and eggs are
laid which pass the winter on dead stems
or in the ground. According to present
knowledge the eggs hibernate on clover or
vetch. The sweet pea aphis derives its
food by sucking on the plant juices (fig.

32).

The sweet pea aphis is not only a pest
by itself, but it also aids in carrying the
virus of mosaic from plant to plant.
Moreover, plants which have their juices
constantly depleted by numerous sucking
aphids are thereby weakened and easily
fall the prey to diseases, especially streak
and anthracnose. If the green aphis could
be successfully controlled, nearly 80 per
cent of the other troubles would be pre-
vented from getting a start.

Greenhouse sweet peas are not exempt
from the attacks of the aphis. In the

158 DISEASES OF THE SWEET PEA

greenhouse, too, the prevalence of the aphis
is always correlated with an abundance of
mosaic, as well as with weak spindly
plants.

The sweet pea aphis is very prolific. It
is estimated that each individual if al-
lowed full sway would be the progenitor
of 423,912 aphids in one season. These
lice, however, are fortunately kept in check
by natural enemies. The list of insects
known to feed on the sweet pea aphid
includes seven species of lady beetles, three
species of Syrphus or lace wing fly, a sol-
dier beetle, and a few minute four winged
Hymenopterous parasites.

Lady Beetles. Hippodamia converg-
ens. It behooves every grower to learn to
recognize this friendly insect. Its eggs
are laid in clusters, found everywhere on
board fences or on trees. The eggs are
small, salmon color, and pointed at both

INSECT PESTS

159

ends. The larvae as they emerge from the
eggs soon begin to feed on very small in-
sects. Their body is long, very rough,
hairy, and dark with red or yellow mark-
ings on its back. As soon as they reach
maturity they attach themselves by the
tail end to some twig and there pupate.
From this stage emerges the adult lady
beetle. The sexes mate and the females
lay the eggs which are to begin a new life
cycle (fig. 33 <2 to r) .

FIG. 33. THE CONVERGENT LADY BEETLE (Hippodomia COH-

vergens) an enemy of the sweet pea aphis, a

ADULT BEETLE. b PUPA. C LARVA. (AFTER CHITTEN-
DEN.)

i6o DISEASES OF THE SWEET PEA

Syrphid Flies. Syrphus ribesii. In
company with the plant lice are seen
greenish, flat sticky looking ''worms,"

FIG. 34. SYRPHID FLY, Syrphus Americafius, whose larva

FEEDS ON THE SPRING GREEN APHIS AND ALSO ON THE
SWEET PEA APHIS, O FEMALE FLY. b SECOND ABDOM-
INAL SEGMENT OF MALE. (AFTER WEBSTER AND PHIL-
IPS.)

which are pointed at one end and seem
to have no distinct head, eyes, or legs.
These are larvae or maggots of a two-
winged fly commonly known as Syrphid
or Flower Fly. The maggots obtain
their food by puncturing the body wall of

INSECT PESTS 161

the aphid and by sucking out its con-
tent. When the maggot is full grown
it seeks some sheltered spot where it
pupates and becomes transformed into the
adult fly. The adults are dark, with
transverse yellow bands across the abdo-
men (fig. 34 a and b) . They are swift
fliers and are often mistaken for bees.
They feed on the nectar of flowers and be-
cause of this habit are often called Flower
or Honey Flies. On hot days they are
very numerous and are called Sweat Flies.
They lay their eggs on vines attacked by
the aphids.

Green Lace Wing. Chrysopa calif or-
nica. This insect is called Aphis Lion be-
cause of its destructiveness to all green
plant lice. The larvae of these beneficial
flies are provided with two long curved
mandibles upon which the aphids are held
prisoners until they are sucked dry. They

i62 DISEASES OF THE SWEET PEA

FIG. 35. GREEN LACE FLY (Chrysopha oculata) an enemy

OF THE SWEET PEA APHIS, O EGGS. b FULL GROWN
LARVA. C FOOT OF SAME. d LARVA DEVOURING AN
INSECT, e COCOON. / ADULT INSECT, g HEAD OF SAME.
h ADULT NATURAL SIZE. (AFTER MARLATT.)

are then released and others caught and
destroyed in a similar way (fig. 35 ^ to A) .
Aphiduis. Of still greater importance in
the natural control of the sweet pea aphis,
is the parasite known as Aphiduis testa-
ceipes (fig. 36) . The adult female of this
fly possesses a long sharp pointed ovipos-
itor which pierces the body wall of the

INSECT PESTS 163

louse depositing her eggs within its tissue.
When the female Aphiduis comes in con-
tact with an aphis, she quickly thrusts her
abdomen beneath its thorax and head, giv-
ing the aphis a quick stab, and deposits her

FIG. 36. Aphiduis testaceipes ovipositing in the body of

AN APHIS. ENLARGED. ( AFTER WEBSTER.)

eggs in its body. After being stung by her
enemy, the aphis kicks up the posterior
part of the abdomen as though in pain.
It is probable that only one egg is depos-
ited within the body of each attacked aphid.
The €gg upon hatching gives birth to a
small legless larva which begins at once to
feed upon the interior vital parts of the
louse. The latter soon becomes less active,

i64 DISEASES OF THE SWEET PEA

loses its natural color, then turns gray and
dies, remaining attached to the part of the
plant upon which it has been feeding.
When the larva is fully developed it
pupates and cuts a circular hole on the
top of the body of the now ''mummied"
aphis, emerging as a winged insect to at-
tack other living aphids in the same way
as its mother. The circular hole cut by
the escaped parasites is always a sure sign
of the presence of these beneficial in-
sects.

In the summer of 1911, the author no-
ticed that Aphiduis testae eipes alone de-
stroyed and kept in check what seemed an
epidemic of the sweet pea aphis. On the
other hand, in the summer season of 1912,
this beneficial parasite was rather scarce.
It is, therefore, interesting to know the con-
ditions which determine its presence or
absence. The following are observations

INSECT PESTS 165

recorded by Webster and Philips : ^ The
dispersion of Aphiduis may be accom-
plished by the larvae in the bodies of the
winged aphids whence it is carried from
place to place and also by the wind.
While the young larvae are within the
body of the aphis they are not easily de-
tected. It is only when the larva becomes
nearly full grown that it may be detected,
and then only by an expert observer.
There may be millions of larvae of Aphiduis
in a field and yet present no visible indi-
cation of their presence. A few warm days
bring about their final development,
whereupon the presence of the leathery
brown bodies of the parasitized aphids be-
gin to attract the attention. Climatic con-
ditions are important factors in determin-
ing the abundance of Aphiduis.

* Webster, F. M., and Philips, W. J., The spring grain
aphis or "green bug." U. S. Dept. Agr. Bur. Entom.
Bull. 110, 1912.

i66 DISEASES OF THE SWEET PEA

Aphelinus. Another insect which par-
asitizes the sweet pea aphids is Aphelinus
nigritus^ 3. parasite also known to attack a
number of other green plant lice (fig. 37) .

FIG. 27- Aphelinus Nigritus; a parasite of the sweet

PEA Aphis. (after WEBSTER AND PHILIPS.)

This insect, however, is not so active as
the Aphiduis previously mentioned.

Fungous Pests. The fungi which help
to destroy the sweet pea aphids are not
as yet well known. Empusa aphidis (fig.
30) is the only fungus which has received
some attention and study. The others re-

INSECT PESTS 167

main to be investigated. The develop-
ment of Empusa aphidis depends upon
rather warm, humid weather for its spread
and is retarded by drought. This fungus
was found fairly active during the sum-
mer of 1912. It is possible to cultivate
the fungus artificially and it may be used
to inoculate broadcast the aphids in the
field.

THE TWELVE-SPOTTED CUCUMBER BEETLE

Diabrotica 12 punctata Oliv.

The larva of this insect feeds on roots
and stalks of corn and on a number of
other plants but as far as is known does not
feed on roots and stems of sweet peas. It
is the adult beetle of this insect that is
troublesome to outdoor sweet peas. The
beetle is one of the earliest pests seen to
feed on the plants, as soon indeed as they
are no more than six inches high. The in-

i68 DISEASES OF THE SWEET PEA

jury is confined to the leaves, where it ex-
tends over large areas. The beetle is often
known as the 12 spotted cucumber beetle,
the color of its body being yellowish green
and its wing covers marked by twelve
black dots. Besides the sweet pea, the
adult beetle also feeds on cucumber,
squash, and melon blossoms. It also feeds
on alfalfa, clover, cotton, rye, and to-
bacco. This species is abundant in the
Southern states; although its range in the
North is also very wide. Despite its being
an early species, the beetle is also found
feeding on sweet peas which have long
passed blooming.

The Blister Beetles. Epicauta sps.
Blister beetles feed on sweet pea plants
from the beginning of the seedling stage
up to maturity. Two species of blister
beetles are troublesome to sweet peas; the
black and the striped.

INSECT PESTS 169

The Black Blister Beetle. Epicauta
pennsylvanica DeG. As the name implies,
this bettle is uniformly black. It meas-
ures a little over a quarter of an inch in
length. It feeds on a wide range of plants
such as the potato, tomato, cabbage, carrot,
beet, corn, bean, aster, clematis, zinia,
sweet pea, and a number of other ornamen-
tals. In the absence of other food it is
commonly found feeding on different rag-
weeds (Ambrosia sp.), on golden rod, on
amaranth, and on iron weed. This beetle,
too, has a wide range of territory.

The Striped Blister Beetle. Epi-
cauta vittata Fab. This species is about
half an inch in length with blackish wing
covers, each of which is bordered with yel-
low and has a yellow stripe down the cen-
ter (fig. 38) . It injures potatoes, toma-
toes, beets and mangels, turnips, beans,
peas, radishes, melons, corn, clover, alfalfa.

lyo DISEASES OF THE SWEET PEA

FIG. 38. THE STRIPED BLISTER BEETLE. (AFTER CHITTEN-
DEN.)

and sweet peas. According to Professor
Chittenden ^ the beetle lays its eggs on
plants or on the ground. From each egg
hatches a small long-legged larva, which
runs actively in search of a grasshopper
egg pod which it enters and feeds upon.
Afterwards it casts its skin several times
and finally becomes transformed into a
beetle.

There are also a number of caterpillars
which feed on the sweet pea, but they have
as 3^et not been studied carefully.

^ United States Department of Agriculture, Year
Book, 1898.

INSECT PESTS

171

SOIL INFESTING INSECTS

Variegated Cutworms. Feridroma
saucia. These are common garden pests
attacking a number of other plants as
well in addition to the sweet pea (fig.
39 a to /) . Cutworms are troublesome
the first year when sweet peas are planted

FIG. 39. VARIEGATED CUT WORM^ 0 I\IOTH. h LARVA
FEEDING. C LARVA RESTIXG. d EGGS LAID ON DEAD
TWIGS. e CLUSTER OF EGGS M.\GNIFIED. ( AFTER CHIT-
TENDEN,)

172 DISEASES OF THE SWEET PEA

on old sod. They are sometimes intro-
duced into a new place with the compost.
The larvae of cut worms have the habit
of cutting herbaceous plants at the stem
end. The injury is inflicted at night or
on dark days: the worms return to the
ground as soon as the sun appears. The
adult of the cutworm is a moth which
lays her eggs in old fields or pastures where
there is plenty of grass for the young larvae
to feed upon. As the young hatch, they
feed on roots of grass. The first season
the young cutworms usually attain about
half an inch in length. As winter ap-
proaches they build earthen cells in the
ground and thus protect themselves from
cold weather. In the spring, if the field
is allowed to remain in grass, plenty of
food is on hand for them. However when
the sod is plowed under, and other garden
crops planted, such as the sweet pea, the

INSECT PESTS 173

natural food supply of the worms is cut
off and they are compelled to feed on the
cultivated plants. These are severely in-
jured if the insects are abundant.

Wire WORMS Melanotus communis are
a prominent pest of field crops. They
are the young of click beetles, also known
as snapping bugs. Wire worms are brown
hard bodied larvae of nearly uniform size
throughout. They bore into various seeds
after planting or work on the roots of
various plants, often causing serious in-
jury. The eggs are laid on old pasture
land, and the larvae which hatch from them
normally work on the roots of grasses. If
the sod is replaced by any other cultivated
crop, the larvae are forced to feed on that
crop for want of its normal host plant.
Sweet peas often suffer from this pest,
although the injury is not apparent until
they are in bloom.

174 DISEASES OF THE SWEET PEA

Differing from cut worms, wireworms
pass from tfiree to five years in the larvae
stage; hence wireworms of different ages
may be found in the same place feeding
side by side.

White Grubs. Lachno sterna sp.
White grubs are the larvae of May beetles
(fig. 40 ^ to /). They are injurious to a

FIG. 40. WHITE GRUB OR MAY BEETLE, O BEETLE. 6
PUPA. C FULL GROWN LARVA OR WHITE GRUB. (AFTER
CHITTENDEN.)

number of cultivated plants, the sweet pea
being included. May beetles lay their
eggs in sod, in corn fields, or in the garden.
The grubs hatch about the middle of July
and begin feeding on roots, growing

INSECT PESTS 175

slowly, and requiring two years or more
to become full size. Larvae of proper age
and size change to pupae in midsummer
and the adult stage is reached by Septem-
ber, but the beetles remain in the earthen
cells made by the larvae until the following
spring. Thus it is seen that the life cycle
of white grubs is similar to that of wire-
worms. Larvae of different ages are pres-
ent in the soil at all times in the year;
hence injury caused by them may be con-
tinuous.

CHAPTER VIII

DISEASED SEEDS

Anthracnose. Under the discussion
of anthracnose we have already seen that
disease may be transmitted with the seed.
In that case infection starts on the pods
and the disease works inwards, gradually
penetrating the seed coat and the seed
proper (fig. 41). Such seeds when har-
vested have a shriveled appearance and
when planted with healthy seeds introduce
the trouble into the soil.

Streak. Another disease that may be
transmitted with the seeds is the "streak."
In examining infected plants we can read-
ily see that the disease has invaded the

pods and the seeds within. When such

176

iV

y

' A "

.

JB.^

l8K

A

^

v^^. ..^

L ^^

>?*

i^^

\<S

(^^.

■Wt ■ • S

,^^

j^s^V'^

:■. -<

f ;^? ';■•

; ' \^^

''*'^^-^^;-v i^

■'■■'^ ^

■^4!c:/..'i

K^l

-"^^

/J2;V^j*5' ;:;

^.5«s:.5

r^^

?\--

' :^'

.yv- ^p

-^?^s?H-^a^ -

• . ,^,

^tmx'.^^^^m

Kg^jfl^^^^^H

■^'^Tfh'-U;

/^^^i

'^P'^'.*i>>^''- -^

Y^-;ZiSs^

KnP^^

•J??'-'*<

^' -vt-^^ - &!*■<'■

• jJ^S?^.

»i(95^Fiv-

\JI^:]^

r"J'^

'Mg .

"l^j^'- 0

r^M

t '^S

'-■^-■r
-f^..

>? ^!r^-

ol

Iviw^;,-^

/ 7w£^,.-..^:

E J

m^m

i^^^H

.''■/-.

ijdM

Bs^;- A"' '7-i^^B

a^^''^"^

K^'-^^l

•^ "^

WM

ife^^^B

^Pm ^

KflH

-1

V

' f

^

Fig. 41. — Anthracnose Disease of pods and seeds.
The arrows shew the diseased spots.

DISEASED SEEDS 177

seeds are planted, they may introduce the
parasite into the soil.

Shriveled Seeds. Sweet pea seeds, as
sold by seedsmen, as put up in small paper
packages. In very few cases are all the
seeds plump and full. A certain per cent
are shriveled and give the appearance of be-
ing diseased. Such seeds are not always
diseased. These shriveled seeds often ger-
minate as readily as the plump ones, and as
they swell cannot be told from others. It
seems that the shriveling is correlated with
loss of water, and this seems to be charac-
teristic of some varieties more than of
others. However, it is difficult to tell
whether such seeds in the long run produce
weaker plants which are more susceptible
to disease. A small percentage of the
shriveled seeds fail to germinate. Some
of these no doubt are hard seeds which can-
not germinate because of their impervious

178 DISEASES OF THE SWEET PEA

seed coats. Others upon culturing in the
laboratory are found to contain a variety
of fungi, such as Alternaria, Fusarium,
Clonostachys, Rhizopus, and Botrytis (fig.
42) . These seem to play the role of sap-
rophytes on the growing plants, but they
may be weak parasites, capable of attack-
ing these few shriveled seeds which may
lack in vigor and resistance.

The Drug Store Beetle.* Sitodrepa
panicea. This minute beetle (fig. 44)
is of considerable economic importance
to seedsmen, since sweet pea seeds in the
storehouse are very frequently seriously
injured by it. This pest is often found
feeding on dry bread, and because of
this, it is known in Europe as the bread
beetle. In this country it is found to

*See also Bull. 4. Bur. Entom. U. S. Dept. Agr.,
1896.

Fig. 42. — To the left, Fusarium and Botrytis fungi from
shriveled and non-germinated Sweet Pea seeds;
to the right, shriveled seed soaked 3 minutes in a
2% formaldehyde solution.

DISEASED SEEDS 179

be a very common pest in drug stores,
whence its name. It also invades mills,
granaries, and warehouses of all kinds.
It also invades the kitchen where it feeds
on red pepper, flour, and all sorts of
breakfast foods. It also eats ginger,
rhubarb, chocolate, dried fruits, beans,
peas, coffee, rice, and other seeds of every
description. Its larva is often found as a
book worm. The larva of this beetle is
so voracious that it is said to "eat anything
except cast iron." It is also the larva of
this beetle that is so fond of sweet pea
seeds, tunneling the inside, and thus com-
pletely destroying the germinating power
of the seed. The adult beetles mate and
the female lays her eggs on sweet pea seeds
and elsewhere. The young upon hatching
at once begin to tunnel into the seeds. In
the storehouse there are usually four broods

i8o DISEASES OF THE SWEET PEA

formed during the winter and if allowed
free range may destroy large quantities of
seed.

Seedsmen whose storehouses are serious-
ly infested with these pests will find relief
by the use of bisulphide of carbon evapo-
rated at the rate of one pound of the chem-
ical to each i,000 feet of cubic space.
While fumigating, the room should be
closed tightly and care taken to keep away
lighted cigars, matches, or burning candles.

Fig. 43.— Auto Spray
No. I.

Courtesy of E. C. Brown Co.,
Rochester, N. Y.

^ •

#

'%

m

J-- ^

#^ iS

*1 .

1 «

'1

• ^

•

•' '<

-5

•

•>

%

* »

^^•

» ^

•

•

1

1

#•

^

^

1 •»

Fig. 44. — The Drug-store Beetle, an enemy to stored
Sweet Pea seeds.

CHAPTER IX

PHYSIOLOGICAL DISEASES

Physiological diseases are those dis-
turbances of the normal activity of a plant
which are not induced by fungi, bacteria,
or insects.

Bud Drop. The young flower buds at a
very early age, turns yellow and drops off.
This disease is sometimes confused with
the drop produced by the anthracnose dis-
ease. In the latter case the flower develops
into a normal spike, but it is attacked soon
by the fungus, Glomerella rufomaculans^
which girdles it at the point of attachment
between the flower and the peduncle. In
this case the blossom falls off, leaving be-
hind the beheaded peduncle. In bud drop,

i8i

i82 DISEASES OF THE SWEET PEA

however, the minute young blossoms fail
to develop, and drop off while very young.

This form of drop is attributed to an
unbalanced condition of food elements in
the soil. This may occur in a soil that has
been excessively fed or in a soil that is
lacking in plant food. Bud drop has ac-
tually been found in the laboratory on
sweet pea plants grown in pots which re-
ceived heavy applications of manure, and
in pots filled with a very poor clay soil.
The trouble has been overcome by the ap-
plication of 150 lb. of muriate of potash
and 600 lb. of acid phosphate per acre.
As a result of this treatment the drop
ceased within a week, and a luxuriant crop
of flowers was produced. An application
of a balanced fertilizer to the pots above
mentioned readily helped the plants to
overcome the drop.

Root Burn. This trouble, probably, is

PHYSIOLOGICAL DISEASES 183

a physiological disease. It is induced by
the excessive use of fertilizers. The fol-
lowing facts from the letter of a grower
who wrestled with this trouble will help to
confirm the belief in the physiological
nature of this disease: "The seeds were
sown November 1 in pots and planted De-
cember 15 in the beds in the greenhouse.
Previous to the planting, the beds were
well manured with horse manure, which
was applied six months before planting.
Besides this, wood ashes were also applied
at the rate of 1,500 lb. to 4,500 square feet
of bed space. This would be equivalent
to nearly seven and one-half tons per acre.
About one month after planting, some of
the plants turned yellow and died ; others
remained dwarfed and offered a languid
appearance." Upon examining some of
the plants, they were found to be dwarfed
and to have a sickly yellowish look. The

i84 DISEASES OF THE SWEET PEA

roots were dwarfed, blackened as though
burned, resembling the injury of Thielavia
root rot. Upon testing the soil it was
found to be strongly alkaline. Hard wood
ashes, contain about 30 per cent caustic
lime and from 5 to 12 per cent potash. It
was the excess of both of these substances
that made the soil so alkaline, the roots of
the sweet peas becoming burned and inhib-
iting growth. This kind of injury could
be considered purely physical ; nevertheless
any injury which interferes with the nor-
mal functions of the parts of the plants
also results in a disturbance in its metabol-
ism, and is therefore considered as a physio-
logical trouble. A remedy for this was
found in the use of acid phosphate, fol-
lowed by a good drenching of water. This
helped to neutralize the alkalinity and to
balance the food rations in the soil.

CHAPTER X

METHODS OF CONTROL

Growers who expect to find in these
pages a *'cure all" for their sweet pea trou-
bles will be disappointed. Once a tender
sweet pea plant is invaded by fungi or bac-
teria it can rarely be cured. Insects, how-
ever, may be destroyed, since it is possible
to poison them, although the task is often
difficult because they are not easily ac-
cessible.

The problem, therefore, is one of pre-
vention. Sweet pea growers would win
ninety per cent of the battle if they would
realize the importance of preventive meth-
ods. Here, as elsewhere, the old dictum

holds true, "an ounce of prevention is

i8s

i86 DISEASES OF THE SWEET PEA

worth a pound of cure." Yet even here,
the personal element is the determining
factor in success. Growers too often work
by "rule o' thumb." Some have their pet
theories as to causes of disease; others have
their remedies, favorite fungicides in-
tended to act as a cure all but which do not
often yield the promised results. Progres-
sive growers find it profitable to keep in
close touch with Plant Pathologists in the
various Experiment Stations. More than
this, every grower should develop the
power of keen observation, for plant dis-
eases are too often not detected until too
late.

RESISTANT VARIETIES

The most promising means of control is
the use of resistant varieties. It is true
that resistant varieties will encourage the
lazy man to neglect his seed, disregard ro-
tation, and overlook all sanitary methods ;

METHODS OF CONTROL 187

nevertheless, resistant varieties are often
the only protection against complete an-
nihilation of a species by disease. In pass-
ing through a sick field, one cannot help
but notice that not all the plants of the
same kind are subject alike in the same
way to the disease. Some are killed out-
right ; others are partly affected, or if badly
affected, resist the disease; and still others
are not at all diseased. If, therefore, we
are able to select the seed from the resistant
strain and multiply it rapidly, we will ob-
tain resistant plants capable of producing
100 per cent healthy plants in a sick soil.
That this is possible there can be no doubt.
A strain of cowpeas has been obtained
which is resistant to wilt, and a strain of
clover has also been obtained which is re-
sistant to anthracnose. Of course, it can-
not be expected that a strain will be re-
sistant to every disease, but there is no

i88 DISEASES OF THE SWEET PEA

doubt that we may obtain strains resistant
to more than one disease.

SEED TREATMENT

It was previously shown that the seeds
are capable of carrying anthracnose and
possibly also the streak disease. It is
therefore unwise to plant sweet pea seeds
without first treating them. Heating the
seed in hot water at various temperatures
of 100 degrees, 90, 80, 70 and 60 de-
grees C. from one second to five minutes
does not seem to yield promising results.
Soaking the seed in sulphuric acid from
five to fifteen minutes helps to accelerate
germination, especially of the hard seed;
and it also destroys all harmful germs
which adhere to the seed coat. After soak-
ing the seeds in the sulphuric acid, they
should be thoroughly washed in running
water, then dried and planted in the usual

METHODS OF CONTROL 189

way. Treating the seed with the acid for
one hour will greatly reduce its percentage
of germination, and by prolonging the
treatment to one and a half hours, germina-
tion will be inhibited altogether.

Soaking the seed in a solution of one
pint of formaldehyde in 30 gallons of
water for ten minutes will also destroy
spores which adhere to the seed coat. The
formaldehyde treatment however does not
seem to help the germination of the seed.
It should not be expected that the seed
treatment will remove all evils. It is only
beneficial in that it kills all spores of
parasitic fungi which may adhere to the
seed coat. Seeds which are diseased and
which have their interior tissue invaded by
parasitic organisms will not be benefited
by the treatment, since the chemical cannot
penetrate the seed to reach the interior
lodging parasite. The use and selection

190 DISEASES OF THE SWEET PEA

of clean, healthy, plump seeds is as im-
portant as the seed treatment.

CONTROL OF SICK SOILS

The habit of many growers of sweet
peas is to use the same soil in the beds for
a period of years. It is even claimed that
this practice tends to produce stronger
vines. This may be true as long as the soil
remains uninfected. However, no sooner
does contamination set in with either Rhi-
zoctonia, Fusarium, Thielavia, Chaetom-
ium, or the eel worm, than it becomes diffi-
cult, if not impossible, to obtain a stand of
sweet peas. The remedy of course is to
throw out the old soil and bring in fresh
dirt free from disease. This unfortunate-
ly is not always a safe method, for the rea-
son that the new soil too may be contami-
nated, or that it may readily become in-
fected as soon as it is placed in the

Fig- 45- — Soil infected with Fusarium lathyri, the cause
of Sweet Pea Wilt : a. the soil was steam-sterilized,
resulting in a perfect stand; b. check unsterilized.
The seedlings in both pots are of the same age.

METHODS OF CONTROL 191

previously contaminated bed. Infected
greenhouse soil may be rendered useful
and free from disease by either the steam
or the formaldehyde methods of steriliza-
tion.

(a) Steam Sterilization. This method
is practical in the greenhouse (fig. 45)
or on seed beds only where the areas are
limited. Its use is possible only where
steam is to be had from a boiler capable
of producing from 80 to 90 lb. pressure.
The method of sterilization is as follows :
before planting, prepare the soil in the
regular way, adding the necessary amount
of manure and fertilizers. At the bottom
of the bed or bench, pipes or drain tiles are
laid parallel to each other two feet apart.
The pipes are perforated with 1-6-inch
holes throughout. These pipes or tiles are
closed at the farthest end so that the steam
may come out through the cracks or holes.

192 DISEASES OF THE SWEET PEA

The other end of the tiles or pipes fits into
a cross-pipe which is connected with the
main steam pipe in the boiler. The steam
is now turned on and as fast as it escapes
from the holes it penetrates and heats the
soil in the bench or bed. The steam is
turned on from one to two hours according
to the constancy and strength of the pres-
sure. A good method of determining when
to turn off the steam is to bury a few raw
potatoes at the surface of the bed and cover
them with some straw or sacking. When
the potatoes are cooked the sterilization
has been completed. This method of ster-
ilization has the advantage of killing the
eel worm and all the other soil troubles as
well as the weeds. As above described, it
is somewhat expensive in the initial cost of
installation. But once put in, it serves a
number of years, and the pipings too may

METHODS OF CONTROL 193

be used for sub-irrigation, a very desirable
method of watering the beds.

A cheaper method of steam sterilization
is the "inverted pan method," which may
also be used to sterilize seed beds and
frames outdoors. The method has given
excellent results and because of its sim-
plicity and small cost is recommended
for use in large or small areas. It is the
invention of Mr. A. D. Shamel of the
United States Department of Agricul-
ture. The apparatus consists ©f a gal-
vanized iron pan 6 ft. by 10 ft. and 6 in.
deep, which is inverted over the soil to
be sterilized, and steam is admitted under
pressure. The pan is supplied with steam
hose connections, has sharp edges which
are forced into the soil on all sides to pre-
vent the escape of steam, and is fitted with
handles for moving it from place to place.

194 DISEASES OF THE SWEET PEA

the weight of the entire pan not being over
400 lb. The soil to be sterilized is pre-
pared as in the previous method, a few
potatoes being buried to gauge the amount
of heat produced. The steam is kept at
as high a pressure as possible, 80 to 100
lb. being best, for one to two hours accord-
ing to the pressure maintained. When
one section of the bed is treated, the pan
is lifted and carried to an unsterilized por-
tion and the operation is repeated until the
entire bed is steamed.

(b) Formaldehyde. When steam ster-
ilization is not feasible because of the
absence of a steam boiler or for some other
reason, the formaldehyde treatment is the
next best. It will kill Thielavia, Fusar-
ium, Rhizoctonia, Pithyium, and Chaeto-
mium in infected soils. It is doubtful,
however, if it will entirely remove eel
worms from such soils. The formalde-

METHODS OF CONTROL 195

hyde method is applied as follows:
The beds are thoroughly prepared in the
same way as in other methods of steriliza-
tion and are drenched with a formalin solu-
tion composed of one pint of commercial
formaldehyde to 25 gallons of water, one
gallon of this solution being used to each
square foot of bed space. The solution
should be put on with a watering can and
distributed as evenly as possible over the
bed so as to wet the soil thoroughly to the
depth of a foot. It will in most cases be
necessary to apply this solution two or
three times, as the soil will not absorb this
quantity of liquid at one time. After the
treatment the beds should be covered with
heavy burlap to keep in the fumes for a
day or so, and then aired for a week before
planting. Stirring the soil at this time
helps the escape of the formaldehyde
fumes.

196 DISEASES OF THE SWEET PEA

(c) Infected Areas. In the green-
house, damping off or any other of the soil
troubles usually starts at one part in the
bed and from there spreads all over the
bed. Where only a few of these centers of
infection occur, much damage may be pre-
vented by immediately removing the in-
fected plants and soil from the bed to-
gether with the surrounding area somewhat
beyond the last signs of disease.

(d) Cultural Considerations. Every
factor which leads to a weakening of the
plants should be eliminated. In the green-
house, overfeeding as well as underfeed-
ing, overwatering, and excessive high tem-
peratures with lack of ventilation should
be avoided.

(e) Other Preventive Methods in
the Greenhouse. Usually the soil in
the greenhouse is infected with manure,
with potted plants started early in a cold

METHODS OF CONTROL 197

frame, or with diseased tomatoes, the
violets, and a number of other hosts grown
as alternating crops. It goes without say-
ing that the grower should not knowingly
bring in sick soil into the greenhouse, nor
should a sick soil from indoors be dumped
in the open where sweet peas or any other
crops are likely to be grown for ornamental
or commercial use. Care should be taken
to allow no access to diseased violets or
diseased plants of any kind.

CONTROL OF OUTDOOR SICK SOILS

Unlike greenhouse soils, affected areas
outdoors are not so easily treated. In a
small garden plot, as in the home garden
for instance, a sick soil may be sterilized
either with steam, using the inverted pan
method, or with formaldehyde, as in the
case of the greenhouse. Where sweet peas
are grown on a large scale, as for seed pur-

198 DISEASES OF THE SWEET PEA

poses, the problem of handling sick soils
becomes a more difficult matter. In this
case neither the formaldehyde nor the
steam methods are applicable, since either
is too expensive when used on a large scale
and hence is not practical. There are,
however, other control measures which may
prove helpful.

(a) Cleanliness. It is a common prac-
tice to allow sweet pea plants which have
passed their usefulness to winter over in
the field. As spring comes, the dead vines
are plowed under. In cases of fall plow-
ing and sowing the old vines are immedi-
ately turned under. Should these vines
have suffered from disease the previous
season, they would at once re-infect the soil.
As time goes on the land may become so
contaminated as to be unfit for sweet peas
for a number of years. To obviate this
the old vines should be burned as soon as

METHODS OF CONTROL 199

they pass all usefulness and as soon as they
have sufficiently dried. The expense and
the labor of this operation should not in-
fluence the grower to neglect this. This is
especially true for the seedsman whose
success depends largely on clean lands in
order to produce clean seed which will
meet the market requirements.

(b) Manure. Florists and growers
often dump potted plants on the manure
pile or on the compost. Such plants may
often be infected with some of the soil
troubles to which the sweet pea is sus-
ceptible. The use of such infected manure
or compost may mean the ruin of an entire
field. To avoid outdoor contamination of
our sweet pea soils, extreme care must be
taken that no contaminated manure or
compost find its way into the plantations,
(c) Crop Rotation. This is an essen-
tial and effective means of controlling soil

200 DISEASES OF THE SWEET PEA

sickness. With this system the parasite is
starved out for lack of the proper hosts.
With the sweet pea, the selection of hosts
for proper rotation is a difficult one. So
many of the cultivated and ornamental
plants, for instance, are subject to the root
rots which also attack sweet peas. The
safest method, perhaps, for seed grow-
ers, would be to have sweet peas alternated
every second or third year with a cereal
such as sweet corn, sugar cane, or millet.
Where soils are already badly affected,
sweet peas should be grown on the same
land every fifth or sixth year.

(d) Fertilizers. Outdoor sweet peas
are not as yet known to suffer from eel
worm attacks. However, should this oc-
cur, increase of fertilizer will undoubtedly
prove to be a good method of handling
root knot by forcing the growth of the root

METHODS OF CONTROL 201

system. Observations show that nema-
tode injury is confined to the upper roots
of the plant, that is, those which are 12 to
16 inches deep. Hence, if the roots are
induced to penetrate deeper in the soil,
part of the injurious effect will be over-
come. Potassium salts have been found
to be beneficial, especially in soils poor in
potash. It has been found in Germany
that the sugar beet nematode removes
equally all mineral salts from the roots.
Therefore to improve such a condition we
would need to add only that mineral which
was originally lacking. This may explain
the effect of potash in combating this dis-
ease.

Control of Soil-Infesting Insects.
Spraying the soil will be of little value in
the control of underground insect pests.
Where wire worms are causing injury to

202 DISEASES OF THE SWEET PEA

the roots of sweet pea plants, sow corn
which has been soaked for ten days in water
containing arsenic or strychnine before the
sweet pea seeds are planted. The larva
will attack the poisonous corn kernels and
die. Another way is to scatter poisoned
and sweetened corn meal dough which will
act as a bait.

White grubf may be controlled by the
use of bisulphide of carbon and kerosene
emulsion. The latter is diluted about ten
times and poured on the ground about the
infected plants. This, however, is a risky
procedure. Fall plowing is a valuable
remedy since many of the grubs are thus
exposed to the cold winter weather and
killed.

Cut worms may be controlled by the use
of a poisoned bran made as follows: to
three ounces of molasses add one gallon
of water, and sufficient bran to make a

METHODS OF CONTROL 203

fairly stiff mixture. To this add Paris
green or arsenic and stir well into a paste.
A heaping teaspoonful of the mixture is
scattered here and there over the infested
land.

CHAPTER XI

SPRAYING

General Considerations. The or-
chardist, the nurseryman, the gardener,
and the florists have already learned the
necessity of spraying. It often determines
whether they shall lose a large part of the
crop or get from it the largest possible
profit obtainable. It is doubtful if sweet
pea growers have come to this important
realization. Many writers on sweet peas
have in the past attempted to give the im-
pression that this species is usually free
from insect and fungous pests. This has
unfortunately led to an indifference that
resulted in the quick dissemination of a

number of dangerous diseases. The streak

204

SPRAYING 205

which is causing so much loss to sweet peas
in England has gained a strong foothold in
this country, yet prominent growers and
seedsmen strenuously deny the existence
of this disease here. The anthracnose is
another serious disease, and yet few grow-
ers have a first hand knowledge of its ex-
istence. The time is rapidly coming when
the sweet pea like every other important
crop will have to be sprayed. The grower
who fails to do so will be crowded out be-
cause of competition with others more
careful. It is true that spraying is no
pleasant pastime for the grower ; neverthe-
less, it is a necessary evil, if evil it may be
called.

Spraying has two aims : to kill the insect
and animal pests, and to control fungous
diseases. The substances which are used
for the one are without effect on the other.

Insecticides. All animal and insect

2o6 DISEASES OF THE SWEET PEA

pests are best controlled by the use of poi-
sonous mixtures applied in the form of
liquid sprays or powders. Insecticides
may be classified as internal or stomach
poisons, and external or contact poisons.
The former kill the biting insects which
take it into the stomach with the food; the
latter kill by direct contact, and either
causes an irritation of the surface of the
body or clogs the respiratory openings of
sucking pests.

(a) Stomach Poisons. Paris green is
one of the best known of stomach poisons.
When chemically pure, it is composed of
copper oxide, acetic acid, and arsenious
acid. It destroys cutworms, caterpillars,
beetles, grubs, slugs, etc. On the sweet
pea it should be applied preferably as a
liquid, using one pound of the poison and
one pound of lime to two hundred gallons
of water. Paris green tends to sink to the

SPRAYING 207

bottom of this mixture, and to avoid this
it must be constantly stirred while being
applied. This chemical is often adulter-
ated with white arsenic, causing it to badly
scorch the treated plants.

For sweet peas, the use of arsenate of
lead is to be preferred to Paris green, since
it is less liable to scorch the foliage, and
adheres better. Its chemical composition
consists of acetate of lead and arsenate of
soda. It is applied to the best advantage
as a liquid, using about three pounds to
100 gallons of water.

Arsenite of zinc may also be used. It is
a very finely divided fluffy white powder
which distributes and adheres well to the
foliage. It is intermediate between Paris
green and lead arsenate in strength, and
costs less than either.

It is essential when arsenicals are used
to see that they are correctly labeled, and

2o8 DISEASES OF THE SWEET PEA

kept under lock and key as they are poison-
ous to man and animals.

Hellebore or white hellebore is some-
what less dangerous than the arsenicals.
However, it loses its insecticidal value by
being exposed to the air. It is a specific
against slugs in the greenhouse.

(b) Contact Poisons. All the tobacco
or nicotine products sold principally as ex-
tracts or powders belong to this class. A
common brand much used is the prepara-
tion known as "Black leaf 40," diluted 1
part to 700 or 800 of water. An addition
of soap at the rate of two bars to each lOO
gallons of the solution increases its effec-
tiveness by making it spread out better.
Aphine, Sulpho tobacco, and a number of
other products found on the market are
usually valuable as contact poisons if prop-
erly tested out and guaranteed by the
dealers.

SPRAYING 209

Fungicides. These are poisons used to
control fungous pests. As previously
stated, some parasitic fungi live on the sur-
face of the leaves and stems and are there-
fore easily controlled. An example of this
is the sweet pea mildew. Other fungi, and
these are by far in the majority, are those
which live parasitically in the tissue of the
host, and therefore cannot be reached.
Fungicides are only helpful in preventing
entrance of the parasite in the host. Fun-
gicides are ineffective in controlling insect
pests, as are insecticides in controlling
fungous pests.

(a) Bordeaux Mixture. This is the
standard fungicide, especially valuable in
controlling the sweet pea anthracnose.
The strength used should be 3 lb. of cop-
per sulphate, also known as blue stone, 4
lb. lime, and 50 gallons of water. The
easiest way to prepare it is to dissolve thor-

210 DISEASES OF THE SWEET PEA

oughly the blue stone in 25 gallons of
water. Use the best quality of lime and
slake it in a little hot water, being careful,
however, not to flood it while slaking, nor
to let it become too dry. When the slak-
ing is completed, add enough water to
make 25 gallons. Mix the lime water and
the blue stone solutions, using first one
part of lime water, then another part of
the blue stone. Strain and use at once.
It is essential that the lime shall not be
air slaked before it is used.

The lime water and the blue stone solu-
tions will keep a long time if they are kept
in separate receptacles and well covered.
However, after they are once combined, it
must be used the same day. Bordeaux
mixture more than a day old is useless.
Where Bordeaux is used extensively, stock
solutions of lime and blue stone should be
prepared and ready for use.

SPRAYING 211

(b) Ammoniacal Copper Carbonate.
The objection to the use of Bordeaux is
that it stains the leaves and foliage of the
sweet pea plant. This is not a serious ob-
jection when sweet peas are grown for
seeds or even commercially as a cut flower.
However, when grown in conservatories
or in public parks for ornamental purposes,
the use of Bordeaux becomes objection-
able. In this case ammoniacal copper car-
bonate may take the place of Bordeaux,
since the former is a colorless material. It
is prepared as follows :

Copper carbonate 50Z.

Ammonia (26° Baume') 3 pints

Water 50 gallons

This fungicide should be used as soon as
it is made, as the ammonia evaporates
quickly.

(c) Potassium Sulphide. This is a
valuable fungicide for the control of the

212 DISEASES OF THE SWEET PEA

sweet pea mildew. The following strength
is recommended :

Potassium sulphide 40Z.

Water 10 gallons

(d) Sulphur. Flowers of sulphur are
often used in greenhouses to control the
sweet pea mildew. It may be applied
either by hand or with a duster.

There are a number of other fungicides
on the market which are not mentioned.
They should be thoroughly tested before
they are used. Considerable discretion
should be exercised before using a new
fungicide which claims to be a "cure all."

Combination Sprays. In the discus-
sion of the foregoing chapters on fungous
and insect pests, it is seen that the sweet
pea is subject to the attacks of more than
one disease. Spraying, if properly done,
is effective in controlling or in keeping in

SPRAYING 213

check all the pests which attack all the
parts of the plant above ground. The va-
rious spray solutions which may or may not
be combined are indicated by Cooley and
Swingle ^ in the following table :

Tobacco

Lime

Bordeaux

extracts

sulphur

mixture

Paris green yes

no

yes

Arsenate of lead yes

yes

yes

Arsenite of zinc (ortho) yes

*

no

Arsenite of lime yes

no

yes

Lime sulphur yes

....

....

Bordeaux yes

....

....

* The advisability of making these two combinations
needs further investigation.

Each of these preparations is mixed and
applied just as if it were used alone. A
combination of the ammoniacal copper
carbonate with an arsenate would be un-
safe, since the ammonia renders the arsenic

* Cooley, R. A., and Swingle, D. B., A spraying pro-
gram for Montana orchards. Montana Agr. Expt. Sta-
tion, Circ. 17: 119-151, 1912.

214 DISEASES OF THE SWEET PEA

more soluble, and hence may result in the
burning of the sweet pea foliage. How-
ever, it may be mixed to advantage with
the tobacco products.

Careful investigations of Professor
Safro, Entomologist to the Kentucky To-
bacco Product Co., show that "Black leaf
40" may be used in combination with such
spray chemicals as lime sulphur, arsenate
of lead, arsenite of zinc, and iron sulphate
for controlling sucking and chewing in-
sects and fungous diseases, the soap in this
case being omitted. Professor Safro's
work further shows that ''Black leaf 40"
may be safely combined with Bordeaux,
and the desired results obtained. Profes-
sor Safro writes as follows: 'Tor pur-
poses of spraying sweet peas, add to every
100 gallons of Bordeaux three-fourths of
a pint of 'Black leaf 40.' As far as safety
to the foliage is concerned, much greater

SPRAYING 215

strengths of nicotine may be added to the
Bordeaux, but no additional effectiveness
will be given to the mixture as an insecti-
cide. Any nicotine solution that is used
for Aphis containing four-hundredths of
one per cent nicotine will be effective if
the work is thoroughly done."

For greenhouse purposes the Auto Spray
No. 1 is a very desirable spraying machine
(fig. 43) . It may also be used outdoors on
small garden lots. In California, where
large acreages of sweet peas are grown for
seed, a gasoline sprayer is the proper ma-
chine. However, as the plants reach three
to four feet and as the rows begin to touch,
spraying by power machinery which has to
be drawn by horses becomes prohibitive.
In this case two to three Auto Sprays No. l
will answer the purpose very well.

2i6 DISEASES OF THE SWEET PEA

PRINCIPLES INVOLVED IN SPRAYING
SWEET PEAS

It should be remembered that to destroy
chewing insects such as caterpillars, etc.,
the stomach poison must be evenly dis-
tributed all over the plant. This should
be done as soon as the presence of the pest
is suspected. Intelligent and observant
growers will, of course, remember the time
of appearance of the pest every year, al-
though the time depends somewhat on the
climate of each season. In destroying the
green aphids the contact poison should be
distributed as evenly as possible on the in-
sect itself. It is, therefore, best to spray
for aphids as they are actually found
working on the plants. With chewing in-
sects and with fungous pests, however, the
applications are made even before the par-
asites appear. Before spraying it is nec-
essary to have well in mind the organism

SPRAYING 217

which is to be destroyed, and the proper
ingredients used. To keep fungous pests
in check it is necessary to have the plant
covered with the fungicide all the time
infection is feared or suspected. It must
be remembered that spraying for fungi is
a form of insurance. It protects the plant
from becoming infected. However, when
the parasite penetrates the host, spraying
is of little value in saving the infected
plant although it will protect others which
are as yet healthy. It is essential that the
sweet pea grower be ever ready to spray
on time (fig. 46) . Sometimes the retarda-
tion of even a day may yield negative re-
sults. The timely destruction of one in-
sect, or of one spore, undoubtedly means
the destruction of countless generations of
these pests.

Thoroughness is as important in spray-
mg as it is in everything else in life. Es-

2i8 DISEASES OF THE SWEET PEA

pecially is this true for the control of
fungous diseases. A spore accidentally
lodged on a portion of a leaf overlooked
by the sprayer is like a fortified city
guarded by rusty cannon.

Difficulties in the Spraying of
Sweet Peas. The difficulties in spraying
sweet peas is that the average fungicide
will not stick. This is especially true
where coarse nozzles are used; the liquid
in this case collects into large drops and
then rolls off. This difficulty is eliminated
by the use of very fine nozzles, since the
finer the spray the greater the success.
The use of stickers often helps to make
the spray liquid adhere better to the foli-
age. With the sweet pea the use of soap
answers well the purpose of a sticker.
Add two to three pounds of soap to about
every lOO gallons of the spray mixture

0)

a
■*->

(U

o
">>

Oi

\0

I
1

SPRAYING 219

used. Where combination sprays are used
the soap is to be omitted.

Spraying Greenhouse Sweet Peas.
Under greenhouse conditions, insect and
fungous pests are more easily controlled
than out of doors. In the greenhouse, con-
ditions are more nearly under the control
of the grower. By proper cultural care
many troubles may be kept in check, so that
spraying may be dispensed with. There
are, however, certain days when the
weather is such that proper ventilation is
difficult if not harmful. The greenhouse
air then becomes saturated with moisture,
which favors the development of mildew.
At other times the house is allowed to get
too dry and red spiders and aphids make
their appearance. Theoretically red spi-
ders and mites may be controlled by fre-
quent syringings with plain water. Prac-

220 DISEASES OF THE SWEET PEA

tically, however, the syringing is not al-
ways done in the proper way to become
effective. In this case spraying with a
standard contact poison becomes necessary.
Next to red spiders, the only insect that is
of economic importance is the green aphid.
Both of these may be kept in check by the
use of "Black leaf 40/' using a dilution of
one part to one thousand (by volume).
Aphin or sulpho tobacco may answer the
same purpose. Some growers prefer the
use of nico fume tobacco papers. With
these all that is necessary is to hang the
paper on any convenient nail and to light
the end of it. Should mildew appear it
may be readily controlled by dusting with
flowers of sulphur, or by spraying with po-
tassium sulphide, dissolving four ounces
of the chemical in ten gallons of water.
The solution should be used at once, as it
loses its strength by exposure to the air.

SPRAYING 221

Outdoor Spraying of Sweet Peas.
Under our present conditions, it is difficult
to raise a crop of sweet peas outdoors with-
out its becoming infested with most of the
pests enumerated in this book. Spraying
therefore becomes a necessity. However,
the grower cannot afford to spray for each
pest separately. A combination of spray
mixtures becomes imperative so that one
application may reach at the root of many
evils. Red spider, the green aphid, the
chewing insects, as well as the fungous
diseases of stems and leaves, may be con-
trolled by a combination of the following
materials in the following given propor-
tions :

1. Make the regular 5-5-50 Bordeaux
formula.

2. If the green aphid is present add to
every 100 gallons of the Bordeaux three-
fourths of a pint of "Black leaf 40."

222 DISEASES OF THE SWEET PEA

3. To each 100 gallons of 1 and 2, add
1 lb. of arsenate of lead to keep in check
the biting insects. If Paris green is used
instead of arsenate of lead, add one pound
of extra lime to every pound of the above
insecticide used. These formulae apply to
sweet peas grown on large scales. On
smaller plots, such as the home garden, the
same formulae hold good except that cal-
culations are made so that less of the spray
mixture is prepared at one time.

With outdoor sweet peas, spraying
should begin as soon as the plants are six
inches high and should be continued until
the plants are about to lose their useful-
ness. The frequency of the applications
will depend largely on the weather. The
more it rains the more often spraying is
necessary. The object should be to keep
the plants covered a large part of the grow-

SPRAYING 223

ing period with spray materials. Under
ordinary conditions, spraying every other
week is a desirable practice.

INDEX.

INDEX

So-

car-

Acid phosphate, 182
Acid soils, 25, 36
Agrostis neublosa, 58
Alfalfa, 168, 169
Alternaria, 178
Ambrosia sp., 169
American Sweet Pea

ciety, 6
Ammonia, 211
Ammoniacal copper

bonate, 211
Anthracnose, 137, 141,

157, 176, 181
Aphids, 142, 155, 157, 158

161, 163
Aphine, 208
Aphelinus, 166
Aphelinus nigritus, 166
Aphiduis, 162, 163, 165,

166
Aphiduis testaceipes, 162,

164
Apple, 139
Arachnida, 92
Arsenate of lead, 207
Arsenate of soda, 207
Arsenicals, 207

Arsenate of zinc, 207
Ascochyta pisi, 151
Auto Spray No. 1, 215
Azaleas, 131

Bacillus lathy ri, 144

Balanced fertilizer, 182

Beal, A. C, 9, 104

Beans, 134, 169

Beets, 169

Bench, 77

Bisulphide of carbon, 180

Blackberry, wild, 134

Black blister beetle, 169

Black leaf 40, 2c8, 214

Black leaf 40 and lime sul-
phur, 214

Black leaf 40 and arsenate
of lead, 214

Black leaf 40 and arsenate
of zinc, 214

Black leaf 40 and iron
sulphate, 214

Black leaf 40 and Bor-
deaux, 214

Blister beetles, 168

Blue stone, 209

227

228

INDEX

Bordeaux mixture, 209,

219
Botrytis, 178
Bud drop, 18 1

Camel's hair brush, 70
Carnation, 89
Caterpillars, 170
Chaetomium root rot, 104-

109
Chaetomium spirochaete,

104
Cheesecloth, 54
Chrysopa calif ornica, 161
Chittenden, F. J., 112, 113,

152, 170
Christmas trade, 79
Chrysanthemums, 89
Clover, 168, 169
Cleanliness, 198
Climate, 63
Clonostachys, 178
Clump method, 34, 45
Cole, 12

Collar rot, 97, 119, 123
Combination sprays, 212,

213
Contact poisons, 208
Control of sick soils, 190,

197
Cooley, R. A., 213
Copper carbonate, 211
Copper sulphate, 209
Cordon system, 36

Corn, 128, 169

Corticium vagum, 98

Cotton, 168

Cow pea, 115, 134

Crab grass, 128

Crop rotation, 199

Croton, 131

Cucumber, 122

Cultivation, 48

Cultural considerations,

196
Culture under glass, 74
Cupid sweet peas, 11, 12
Cuthbertson, F. G., 38
Cut worms, 202

Dahlia, 131, 134
Damping off, 95, 96
DeBary, 3
Diabrotica 12 punctata,

167
Diseased seed, 176
Dispodding, 49
Downy mildew of grapes,

4
Drug store beetle, 178

Early flowering, 21
Eckford, Henry, 11, 12, 14,

46
Eel worm, 123
Empusa aphidis, 166, 167
Epicauta Pennsylvanica,

169

INDEX

229

Epicauta vittata, 169
Erisiphe polygoni, 1 18
Evaporation, 94
Exhibiting, 54, ^^

Fall planting, 27, 28
Ferns, 131
Fertilizers, 76, 181
Field diseases, 135
Flail, 69

Flower pathology, 5
Formaldehyde, i8'9, 194
Fungicides, 209
Fusarium, 178
Fusarium lathy ri, 109
Fusarium root rot, 109-
112

Geranium, wild, 134
Glomerella rufomaculans,

137, 181
Grasshopper, 170
Green lace wing, 161
Grubs, 174
Gysophila, 58

Hard wood ashes, 184
Harris, J. E., 98
Heliothrips hsemorrhoi-

dalis, 129
Hellebore, 208
Heterodera radicicola, 123
Hippodamia convergens

158

History of the sweet pea,

9

Hollyhock diseases, 6
Honey flies, 161
Hutchins, 26

Infected areas, 196
Infected manure, 196
Insect pests, 152, 171
Insecticides, 205
Introduction, 1
Irrigation, 72, 73

Jamestown weed, 134
Johnson grass, 128
Judging, 72

Kentucky Product Co., 214
Kerr, G. W., 57
Kew Bulletin, 113

Labeling, 35
Lady beetles, 158
Lachnosterna, 174
Lathyrus odoratus, 10
Lathy r us species, 27
Lettuce, 122
Light, 97
Lilies, 131
Lime, 98, 209
Lime water, 210
Lime application, 25
Litmus paper, 98

Macrosiphum pisi, 152

230

INDEX

Maggots, 160, 161
Mangels, 169
Manns, T. F., 144
Manure, 86, 199
Manure mulch, 28, 29
Marketing, 51
Market varieties, 22
Massee, G., 113, 118, 149

151
May beetle, 174
Melanotus communis, 173
Melons, 169
Mendelian principle, 69
Metamorphosis, 92
Methods of control, 185
Microsphera alni, 118
Millardet, M., 4
Mites, 92
Moisture, 93, 94
Morse, C. C, 38, 60
Mosaic, 141-144
Mulching, 49
Muriate of potash, 182

Nematode galls, 123
Netting, 43, 44, 46, 47
Nicotine, 215
Nozzles, 218

Orchid flowering, 78, 84

Packing, 53, 56
Paper boxes, 53
Paris green, 206, 207

Parsnip, 115
Parthenogenesis, 156
Patterson, Flora, Mrs., 105
Pea blight, 149-150
Pea spot, 151
Peach yellows, 143
Perennial rye grass, 128
Peridroma saucia, 171
Peronospora trifoliorum,

149, 151
Peronospora vicise, 150
Philips, W. J., 165
Phlox, 131
Physiological diseases, 181-

184
Picking, 51, 52, 86
Pink, 131
Planting, 25, 31
Pollination, 69, 70
Potato, 169

Potato blight, epidemic, 2
Potassuim sulphide, 211
Powdery mildew, 118, 119
Preparation, 23, 27

Radish, 169

Rag weed, 169

Red shell soil, 75

Red spider, 92, 131-134,

142-145
Red top, 128
Resistant varieties, 186
Rhizoctonia root rot, 98-

104

INDEX

231

Rhizopus, 178
Rogueing, 66, 67
Rolfs, F. M., 103
Root burn, 182
Root knot, 123-129
Rye, 128, 168

Sackett, W. G., 99

Safro, Prof., 214

Sclerotinia libertiana, 119

Scorch or scald, 54

Sclerotia, 122

Seed, 25

Seed treatment, 35, 82, 188

Selby, A. D., 99

Selection, 66, 67

Shading, 54

Shamel, A. D., 193

Shaw, J. F. J., 103

Shriveled seed, 177

Site, 22

Sitodrepa panicea, 178

Slow germination, 26

Soap, 218

Soil acidity, 98

Soil insects, 171

Solid beds, 76

Sowing, 34, 35

Sowing in pots, 34

Spencer varieties, 15, 61,

62, 67
Spraying, 204
Spraying formula, 221,

222

Spring planting, 29
Stackman, £. C, 99
Steam sterilization, 191
Stewart, F. C, 118
Stickers, 218
Stomach poisons, 206
Streak, 7, 113, 157, 176
String, 44, 45, 85
Striped blister beetle, 169
Sulpho tobacco, 208
Sulphur, 212
Supports, 36, 37, 38, 40,

41, 42, 44, 45, 46, 66,

88
Sweat flies, 161
Sweet Pea Annual, 39,

112, 118, 149
Swingle, D. B., 213
Syrphid fly, 158, 160
Syrphus ribesii, 160

Taubenhaus, J. J., 141
Temperature, 83, 84, 88,

93' 96
Tetranchys bimaculatus,

131

Thielavia basicola, 112
Thielavia root rot, 98, 1 12-

117
Thinning, 33
Thrips, 129-131
Tillage, 48
Timothy, 128
Tobacco, 115, 168

232

INDEX

Tomato, 87, 88, 122, 133,

134

Transpiration, 94, 95
Trench method, 32
Trial ground, 71
Triphleps insidiosus, 133,

134
Turnip, 169

Twelve spotted cucumber
beetle, 167

Variegated cutworms, 171

Varieties, 10, 12, 13, 14,

15, 16, 17, 18, 19, 20,

21, 22, 54, ^i;, 58, 78,

79
Vases, 52, 57, 59

Ventilation, 36
Verbena, 131

Violets, 88, 89, 115, 122,
133. 134

Watering, 36, 37, 48, 49,

81, 93, 94, 95
Wax paper, 53
Webster, F. M., 165
White grubs, 174, 202
White hellebore, 208
Wind currents, 93
Wire, 85
Wireworms, 173, 174

Zinnia, 128

Zvolanek, A. C, 74, 78

University of British Columbia Library

DATE DUE

lOMOM-9-57.

V.S,

Ui

UJ

</)

<r

Ld

fy'i

AGRICULTURE

FORESTRY

LIBRARY

■i.i>
— i

■«.'>
I

FORESTRY

AGRICULTURE

LIBRARY

IK 1

J

fl»_r.f:i i^n, ._;:: :::

ik il 1 L.^'HH,

■■?

: F

!i!!!!!!!l!r