The culture and diseases of the sweet pea

Front matter

OF TH E; SWEE T ?EA

.J.IAUBENHAUS if lifc

■H^m

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 undertakings means the overcoming of many difficulties which the casual observer fails to appreciate. It means not only the selection and arrangement of varieties in such manner as to meet with the most aesthetical tastes of the public, but it frequently 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 unfavorable soil and climatic conditions and destructive insects were very important factors 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 failures 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 except 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 enjoyed 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 useful 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 consideration 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 directions 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 subject, 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 rapidly 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 attributing this disease to the fungus Thielavia. In the United States, floral pathology is still in its embryonic stage, and the sweet pea was not the first to claim the attention of Pathologists. The author of this book in the last three years has published several papers on his own investigations, taken up largely because of numerous 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 considerably 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 justification, 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 huxiv PREFACE

man beings. We shall here endeavor to show that although bad weather, overfeeding, 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 destruction. The nature of the attacking insects is still incompletely known and there is urgent need of further investigation of them. Of the fungi, nine produce serious diseases in either roots, stems, foliage, 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. Popular terminology does not always distinguish 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 example, 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 culxvi PREFACE

tural conditions of the host. In other words, the attack of most plant diseases depends on some weak point in the cultural 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 becomes 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 position to also cope intelligently with any problem of disease which may confront him at any time. Since growers as a rule must be their owri plant doctors they cannot be provided with too much informa-

PREFACE xvii

tion on cultural requirements of the particular crop with which they are concerned.

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 covered by eminent specialists such as Professor 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 invaluable. Insects are known to be carriers 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 knowledge of Entomology. Insect specimens in each case were submitted to the Department of Entomology, United States Department of Agriculture for identification, and there due credit belongs.

This book is primarily intended to be a practical treatise. The aim cannot be attained 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 relative to various difficulties, especially those of a pathological nature. Although hesitating to make hasty suggestions, we could

PREFACE xix

not turn a deaf ear to the numerous requests from sweet pea growers as well as from technical men who urged the preparation 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 contributions 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 Experiment Station for figs. 7 to 21, 25 to 31, 38, 42, 43, and 45, all of which were originally 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 l

CHAPTER

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, however, have singled out on plants parasitic organisms whose work brings about deviations 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 diseases 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 nineteenth 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 scholars 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 dispelled 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 resulted in famine and great hardship to the people. Unfortunately, there were no 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 Academy 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 methods of spraying and of disease prevention in general. To-day Plant Pathologists are everywhere investigating plant diseases 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 supply of trained investigators is nevertheless limited. Since every Experiment Station is directly supported by state and federal funds, it is natural that every worker is more or less impelled to investigate 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 that the writer was able to contribute was made possible through the moral support 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 garden. In every flower exhibit in this country or abroad it was king. To-day the hollyhock is only mentioned as ancient history. Diseases have so crippled that beautiful plant, that growers out of sheer discouragement 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 prevail in the United States, and several perplexing diseases now threaten the economic 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, fragrance, 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

1 By Professor A. C. Beal of Cornell University. 9 io CULTURE OF THE SWEET PEA

by an Italian monk who sent seeds to England and Holland. In England sweet peas were cultivated in many gardens. The plant is one of the species of Lathyrus, which is a genus of Leguminosae. Unlike other species of this genus, the sweet pea has fragrance, and Linnseus 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 signalized by the development of several varieties, so that in i860 there were nine known varieties. About this time seedsmen began to take greater interest in

HISTORY AND EVOLUTION n

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 obtainable 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 leading varieties. About 1890, the American sweet pea growers began to appreciate the beautiful varieties Mr. Eckford was sending out and there was a wave of popularity for the flower. The discovery that California had a favorable climate for the production of sweet pea seed enabled the seedsmen to supply the greatly increased demand. This development has continued 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 market 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 American 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. Eckford's busy life, at a time when some growers 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. However, the greatest interest has been in England, where a great many persons are interested 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.

The sweet pea may be classified according to the habit of the plant into

^,. ,. [Garden varieties Climbing :-L- r n

[ W lnter-nowenng

-p. r [Cupids

[Bush varieties (now obsolete) It is important to remember that the winter-flowering varieties are absolutely distinct from the garden varieties in their habit of growth. The Cupids are occasionally grown because of their novelty.

Sweet peas are usually classified according to the form of the flower. The earliest known varieties of the sweet pea had flowers in which the standards were reflexed and deeply notched at the apex. The effort of Mr. Eckford and others was to eliminate the notch and give the standard greater substance so that it could hold itself erect. This brought about the open form which often retained something of the apical notch. Then came the hooded form, in which the edges of the standards are rolled forward. There are various degrees of hooding in different varieties. Extreme hoodings were at one time recognized under the name of snapdragon varieties, which were never more than a passing 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 varieties 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 follows: Bicolor; Blue; Blush; Carmine; Cerise; Cream, Buff, and Ivory; Cream-pink (Pale) ; Cream-pink (Deep) ; Crimson; 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

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

When one compares this with the following classification used in a prominent seedsman's catalogue only fifteen years ago, one can appreciate the marvelous development in the sweet pea. This catalogue 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 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 considerable 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 represented by the color sections, are desirable for any particular garden. The classification will enable any one to select those colors 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

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 Miller, 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. W. Breadmore

Picotee edged (White ground) — Dainty Spencer, Elsie Herbert, Martha Washington

Pink (Deep) — Hercules, Countess Spencer

Pink (Pale) — Elfrida Pearson

Scarlet — Dobbie'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

Orange Shades — Henry Eckford, Miss Wilmott

Picotee edged — Dainty, Lottie Eckford, Phenomenal

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 Henderson, White Wonder

EARLY-FLOWERING VARIETIES

Bicolor — Earliest of All

Blue — Le Marquis

Lavender — Mrs. Alexander Wallace

Primrose — Earliest Sunbeams

Salmon-pink — Mrs. William Sim

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 Unwin, 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 surface about plants, and thus cause them to become yellow or to decay at the roots. Soil suitable for growing vegetables usually 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 deeprooting 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, unquestionably 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 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 manure can be mixed with the subsoil the results are better. Often a layer of leaves or coarse manure placed in the bottom of the deep trench serves to promote drainage. 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 possible. It does not matter in the fall-preparation 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.

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 whiteflowered varieties have white or light-colored seeds, and some have black seeds. The white seeds often rot in the soil, especially if they are planted early when the soil is cold, or because their germinating power has been impaired; also they frequently split in the pod before harvesting and in this condition are likely soon to lose their vitality. For the foregoing reasons it is advisable to sow seeds of this color close together and not so deep as the blackseeded varieties.

In some seasons, sweet pea seeds are slow in germinating. It is well to examine such seeds in order to ascertain their condition. If the seeds are found dormant 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 germination, the seeds are soaked ; a better method for the amateur is that recommended by Mr. Hutchins. He places the seed packets in moist earth for seven or eight days.

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