n IT . 4- .ifPll'JiSsJf* "ll^fjlilf41'!'!! *J §• "«a3iV*>t» S.c-5-i l^i^ttttplfalstl d ^ !i:§2i.6InaesM & ail 03 2 u-5 *|«-g C 3 5 0~ ftisti •5 c •> ^ c irtHi1 t25c"3agg- 85 *i 3 X S S C. 5, ^ LUTHER BURBANK HIS METHODS AND DISCOVERIES AND THEIR PRACTICAL APPLICATION PREPARED FROM HIS ORIGINAL FIELD NOTES COVERING MORE THAN 100,000 EXPERIMENTS MADE DURING FORTY YEARS DEVOTED TO PLANT IMPROVEMENT WITH THE ASSISTANCE OF The Luther Burbank Society AND ITS ENTIRE MEMBERSHIP UNDER THE EDITORIAL DIRECTION OF John Whitson and Robert John AND Henry Smith Williams, M. D., LL. D, VOLUME IV ILLUSTRATED WITH 105 DIRECT COLOR PHOTOGRAPH PRINTS PRODUCED BY A NEW PROCESS DEVISED AND PERFECTED FOR USE IN THESE VOLUMES NEW YORK AND LONDON LUTHER BURBANK PRESS MCMXIV Copyright, 1914, by The Luther Burbank Society Entered at Stationers' Hall, London All rights reserved Volume IV— By Chapters Foreword Page 3 I Quick Possibilities in Fruit Improvement — Specific Needs, and How n to Accomplish Them II Practical Orchard Plans and Methods —How to Begin and Carry on the Work HI Doubling the Productiveness of the Cherry —More and Better Cherries. IV The Responsiveness of the Pear —What HP.S Been Done Is But the Beginning V Fuzzy Peaches and Smooth-Skinned Nectarines —Two Fruits Which Beg for More Improvement yr The Apple — A Fruit Worthy of Still Further Improvement. —New Apples and How 177 to Make Them ........................................ yjj The Transformation of the Quince —What Was Only a Cooking Fruit 211 Now Delicious Raw ................................... VIII The Apricot and the Loquat —An Opportunity for 241 the Experimenter .............................. TV Citrus Fruits — And Fruits From the Tropics —New Experiments Well 273 Worth Trying ................................ List of Direct Color Photograph Prints ..... 349359 FOREWORD TO VOLUME IV We begin, now, to take up with greater detail, practical combinations of method — particularly as applied toward producing new orchard fruits. In this volume Mr. Burbank has covered practically all the simple orchard fruits save the plum and the prune. Although the purpose, here as before, is to be as specific as possible, yet the facts are carried through in narrative form, showing, always, how the actual method employed fits into the scheme of work as outlined in Volumes I, II and III. From this volume the reader will glean much of practical interest and value from Mr. Burbank's experience with laying out orchards, to making orchards pay, and to the practical management of orchards — with an eye always to the bearing of Mr. Burbank's work upon the improvement of the human plant THE EDITORS. The Plumcot This remarkable fruit was produced by Mr. Burbank bg hybridizing the Chinese plum and the apricot. Most plant breeders held that so wide a cross was impossible, and in point of fact the hybridization was not effected without difficulty. The story is told in detail in the text. The hybrid prod- uct is virtually a new species, of which Mr. Burbank has developed many varieties. QUICK PoSSffilLITIES IN FRUIT IMPROVEMENT SPECIFIC NEEDS, AND How TO ACCOMPLISH THEM THE old pear tree out there in the corner of your garden was perhaps planted by your father's father. The twig you cut from it today may take root and become a thrifty tree that will bear fruit to gladden the hearts of your grandchildren long years after you are dead. And that possibility puts the tree on a very different footing as the friend and companion of man from that occupied even by the best-prized members of the company of forage plants and garden vegetables. When you work with fruit trees you are mak- ing permanent records. You are building on a rock. You are reaching out your hands to future generations, and erecting a monument that will remain as a testimonial to your foresight and wisdom long after you are gone. And doubtless this fact of the permanence of [VOLUME IV — CHAPTER I] LUTHER BURBANK • the tree, accounts in large measure for the interest with which almost anyone will take up the culture of fruits if given the opportunity. Not that we are always thinking of posterity; but one can develop an enthusiasm about the production of something having an element of permanency that does not attach to such transient things as annual or bien- nial plants. The fruit tree in the old orchard is like an old friend when we get back to it. The mere view of it brings up reminiscences of our youth, and the tree that we planted in childhood may remain as a stimulus to us in old age. There is no friendlier compact than that be- tween man and the fruit tree. It is an age-long compact withal. Not so ancient as the compact of bees and flowers — for as compared with the archaic and honorable order of insects man is a parvenu — but far older than human civilization none the less. Indeed, it was probably the fruit tree, giving an example of fixity of habitat, that encouraged man to give up the life of a nomad and establish a fixed abode. Not unlikely it was the evidence presented by the fruit tree that first suggested to man the possi- bility of raising a supply of foods from the soil, and thus lured him away from the precarious [8] LUTHER BURBANK pursuits of the hunter and fisher and put him on the road to future greatness. And all along the road of advancing civiliza- tion the friendship with the fruit tree has been kept up. Yet it is only in comparatively recent times, probably, that rapid progress has been made in aiding our coadjutors of the pomological world to step forward and better themselves as man had long ago bettered himself with their assistance, To be sure, our forebears developed many forms of fruit that were not lacking in pal- atability; but the great advances in the improve- ment of orchard fruits are matters of the nine- teenth century. Recent progress in this field has been almost as wonderful as progress in the fields of mechanics and electricity. The orchard fruits of today that find their way to the markets are so different in size and quality from the fruits with which our grandparents were satisfied — even though some of them are grown on cions grafted on the old trees — as to seem to belong almost to different orders, certainly to dif- ferent species from the fruit stocks from which they have been developed. Yet what has been done is only the beginning. We speak of "perfected" fruits, and in a sense the word is justified, so conspicuous are the good [10] ON SPECIFIC NEEDS qualities of the new fruits as contrasted with the old. But no fruit has really been perfected, in the sense of having reached the limits of improve- ment. There are numberless opportunities for better- ment even in the case of the very finest varieties of fruits of every kind. The successive chapters of the present volume will be devoted to specific suggestions as to the betterment of each of the important classes of orchard fruits. In the present chapter, it is my purpose to take a general survey of the field, pointing out various lines of betterment not so much with reference to any particular fruit, al- though we shall constantly draw our illustrations from specific fields, as with reference to the entire class of orchard fruits. The suggestions here outlined are the result of lifelong association with trees of the orchard. Probably not less than half my experiments of every character have been conducted in connec- tion with one form or another of fruit trees. And a very large proportion of my most im- portant new products, considered from an eco- nomic standpoint, have been products of the orchard. As TO MERE SIZE Almost the first thought that comes to one [11] LUTHER BURBANK who goes into the average orchard and looks about with a really observant eye is that orchard trees in general are not well-adapted to man's needs in the matter of size. I have in mind certain orchards of New England and Long Island, for example, in which the apple trees seem to have done their very best to rival the elms and oaks in size. Their trunks and main central branches rise, barren of fruit- producing branches, to a height of twenty or even thirty feet. The strength of the tree has gone to producing wood instead of fruit-bearing twigs. Such fruit as does appear is suspended so high that long ladders are required to reach it when it has ripened. This is obviously all wrong. There is no reason why the apple tree should be permitted to grow high into the air even if it has the inherent pro- pensity to do so. By proper trimming, the young tree can be made to assume a spreading form, so that it will bear most of its fruit within easy reach. Moreover, it is easily possible through selective breeding to develop an apple stock that will have no tendency to grow into tall, or otherwise ill- shaped trees, but will naturally take on the com- pact, low-growing habit that is to be desired in a fruit tree. [12] LUTHER BURBANK What is true of the apple is equally true of its cousin the pear. This tree also has been per- mitted in the old-time orchards to develop the pernicious habit of too slender upright growth and undesirable tallness, too much like a wildling. These defects have been corrected with some of the newer varieties, to be sure, but these have not been introduced universally. The same criticism applies to the cherry. Everyone knows how often this tree is seen grow- ing in the New England dooryard, with trunk like that of the sturdiest oak, and with its inviting clusters of red fruit suspended at such a height as to be quite beyond reach of everyone but the birds. A well-trained cherry should renounce this tantalizing habit and make its wares reasonably accessible to the wingless biped that has fostered it. The other notable members of the company of orchard trees, namely the plum, peach, quince and orange, have in the main developed a more commendable habit of growth. Their trees are for the most part not too large, and the best varieties have a spreading form that leaves little to be desired. But some of these, and in particu- lar the peach and orange, have other faults that urgently call for correction. [14] ON SPECIFIC NEEDS The peach in particular is a tender and short- lived tree, peculiarly subject to the attacks of insects and to fungoid pests. Seemingly the developers of this luscious fruit have been so concerned to foster the remarkable qualities of the fruit itself that they have neglected the tree on which the fruit grows. So the peach orchard, instead of outlasting a human generation as it should, is an ephemeral growth, the indi- vidual trees of which are in good bearing only for a few years, after which they must be replaced. The peach grower is always uprooting the dead trees in one part of his orchard and planting new ones in another. THE QUESTION OF STAMINA Unfortunately the peach is so specialized that it will not thrive on any roots except its own. It should be possible, however — at least the project is one that invites the experimenter — to develop a more vigorous and longer-lived race of peaches. Something could doubtless be done by mere selec- tion, taking cions for grafting or raising seedlings from the hardiest and most vigorous trees of the orchard. It has been shown that it is possible to hybridize the peach with its hardier relative the almond. Probably in successive generations there might be developed a hybrid stock of trees that would retain all the good qualities of the peach [15] LUTHER BURBANK and yet would be as long-lived and vigorous as the almond, and hardier and more resistant than either. It is true that no very striking results have yet been produced by crossing almond and peach, though many unusually vigorous and rapid-grow- ing trees have been produced which will far out- grow the most vigorous individuals of either species. But hybridizing, followed by rigid and persist- ent selection, is a practical method that is still in its infancy. It is not so very long since orchardists in general, supported by technical botanists, de- nied the possibility of hybridizing different species. My long series of varied experiments were perhaps more directly instrumental than any other influence in showing the fallacy of this belief. The reader will recall that I have in many instances interbred species belonging to different genera; and that the interbreeding of different species in my orchards and gardens is a commonplace. Yet it is still true that there are many cases in which there are seeming barriers erected between plants that obviously are closely related, which prevent the advantageous hybridizing and grafting of one species with another. And the peach is a case in point. It accepts the [16] 3 ~ 3 a '* § ~- "2? . B ^ LUTHER BURBANK pollen of its nearest relations (except the almond) unwillingly, and as yet no useful product has come of such union. Yet the peach is not more isolated in this re- gard than its relative, the apricot, seemed to be until I was able, after many futile efforts, to break through the barriers and hybridize that fruit with the plum. The hybrid that resulted, named the plumcot, is virtually a new species. It combines the good qualities of both parents and is a very valuable addition to the list of orchard fruits. It seems not unlikely that some future ex- perimenter will be able to effect a correspondingly useful hybridization of the peach; then the way will be open for the development of a race of peaches that will combine with the existing quali- ties of fruit production the qualities of hardiness and resistance to disease that the present peach tree so notably lacks. BIG FRUIT AND FREE BEARING Size of fruit and prolific bearing are charac- teristics of such obvious desirability that they cannot be overlooked even by the tyro. Yet the average amateur, who has a group of fruit trees in his garden or even a fair-sized orchard on his country place, is content to buy large, handsome, and well-seasoned fruits in the market, taking it for granted that his own trees [18] ON SPECIFIC NEEDS cannot be expected to supply similar products. But in point of fact it is well within the possi- bilities to produce good orchard fruits wherever the trees exist that produce any fruit at all. Con- ditions of soil and climate cannot, of course, be ignored. One cannot grow oranges in Canada or grapefruit in New England — as yet. But if you have apple trees or pears or plums or cherries that bear fruit, it is a matter of your own choice whether they shall bear good fruit or bad. All that is necessary is that you should send to some reputable nurseryman or orchardist and secure cions of good variety for grafting on your trees. All apple trees are closely related, the culti- vated varieties being without exception of mixed strains. The same is true of pears and plums and cherries. In each case you may graft on your native stock cions of any variety of the same species, or a dozen or a score of different vari- eties, and, if the work is done properly and at the right season, the new twigs will soon become a part of the old tree as regards vitality and capacity for growth and fruiting; but — as we have learned in earlier chapters — they will retain their inherent hereditary tendencies as to quality of fruit. Growing side by side, on the same tree, you may have summer apples and winter apples, sweet [19] LUTHER BURBANK apples and sour, green varieties and red varieties. And all this without any necessity for experi- mentation on your part. You need have no knowl- edge of plant breeding except an understanding of the simple technique of grafting. The professional experimenters have supplied the material; you have but to avail yourself of the results of their work. Of course, if you wish to go a step farther there are inviting fields that you may enter. With the materials furnished by a single old apple tree you may become a plant developer. You may plant the seed of any choice apple purchased in the market and from the seedlings you will develop an interesting variety of fruits, some of which may seem to you better than any existing varieties. We have already caught glimpses, in the out- lines of my work already given, of the possibili- ties of the development of various orchard fruits as to size and flavor and other desirable qualities. If you desire to try your hand at similar im- provement either of the fruit now growing on your ungrafted trees, or of that growing on cions of improved varieties, it will require only reasonable attention to the principles already outlined in earlier chapters of this work, together with a fair degree of patience and persistency, to insure some measure of success. [20] ON SPECIFIC NEEDS There is one additional hint that it might not be amiss to emphasize. In selecting seed for planting, it is desirable, of course, to select the largest and best specimens. But it should be re- called that the real test of quality in a tree is not the production of exceptional individual fruits, but the size of the average fruit that it bears. Exceptional conditions of nutrition may cause a single apple to grow very large on a limb that as a rule produces only fruit of meager propor- tions. Seedlings from this exceptional fruit do not inherit the exceptional quality of their parent. It is the germ plasm of the tree itself that counts. Seed from a very small apple of a good variety will produce better offspring than the seed of a very much larger individual specimen of a poor variety; so it is far better to select the poorest fruit of a good variety rather than the best of an ordinary variety. This principle should be borne in mind in un- dertaking plant development of any kind, not merely with reference to orchard fruits. It is the inherent properties of the plant organism as a whole that will determine the average character of the fruit. BREEDING FOR QUALITY As to the special qualities of fruit that call for improvement, details, of course, differ with dif- [21] LUTHER BURBANK ferent species. We have seen that sugar content is an all-important item in the case of the prune; and that sweetness and flavor and color are mat- ters of importance in the case of the cherry. We have also seen with what relative ease varieties may be developed that surpass their parent forms in these regards. An interesting illustration of the possibility of breeding new qualities into a fruit or accentuating old ones, to which reference has not hitherto been made, is manifested by one of my new cherries, which, through selective breeding, became so sweet that its sugar content acts as a preservative, quite as in the case of the sugar prune. These cherries, instead of decaying rapidly after ripening, dry on the tree in a state of perfect preservation. This particular feature is of no present commercial value, but the case illustrates the possibility of altering the inherent qualities of a fruit, and of doing this in the course of a few generations through systematic selection. The same thing is illustrated by another of my cherries which, by careful attention to a combina- tion of qualities that would ordinarily be quite overlooked, had its stem so strongly anchored to the stone that when the fruit is picked the flesh tears away leaving stem and stone on the tree. Now it will be recalled that, in the case of the [22] ON SPECIFIC NEEDS prune, it is a serious defect to have the fruit so firmly attached to the stem that it clings to the tree after ripening. A prune must drop of its own accord when ripe or the prune dealer will have none of it. But the quality that would make a prune commercially worthless, when accentuated in the cherry, becomes a mark of possible excep- tional value. The cherry that leaves its stone on the tree might conceivably fill a special purpose. So this variation in the inherent properties of the cherry might produce a new race of commercial value to meet an exceptional need. It requires but little ingenuity to suggest pos- sible developments that would similarly give added value to the fruits of various species. For example, there is the matter of color in the pear. Unlike most other fruits, this one, as every- one knows, is for the most part lacking in the brilliant color that purchasers of fruit in the market usually find so attractive. But there is no reason why pears of various brilliant and at- tractive colors should not be developed just as colored apples have been developed. Our native crab apple is dull greenish brown or dull red, and unattractive in color even when ripe. Of course this is not the direct progenitor of the cultivated apple, but it obviously belongs to a closely related strain, and it shows us the apple [23] 'i^ljsl* ON SPECIFIC NEEDS in a state of nature and gives us a clue as to what qualities of fruit are advantageous to the apple itself, and what ones have been bred into the stock to meet the demands of the fruit developer. So the fact that the wild crab apple is dull in color suggests that the variously pigmented coat of the cultivated apple is an artificial product, not primarily beneficial to the plant itself, that man has developed through selection. It is not unlikely that the relatively thin skin of the cultivated apple, coincidentally developed, makes pigmentation desirable, to protect the tis- sues of the fruit from too much sunlight. The fact that many apples redden where exposed to the sun, and remain green where protected by the shadow of a branch or leaf, suggests that such is the case. Be that as it may, the point I wish to emphasize at the moment is that the pigmented coat of the apple has been produced mostly by unconscious artificial selection. There can be no doubt that the pear could be similarly given a brightly col- ored skin should anyone care to take the trouble to make the experiment in selective breeding. Indeed, a few varieties of partly red pears have been developed, and have proved a valuable nov- elty in the market. Other and better varieties, variously tinted, should follow. [25] LUTHER BURBANK It has been suggested that a globular or apple- shaped pear with a short stem would be acceptable to the packers because it would crate more com- pactly and carry better than the ordinary pear. But this would rob the fruit of one of its distinctive characters, so on the whole the change would probably not be an improvement. In the matter of size, also, it would appear that the pear, in its best varieties, has attained a maximum develop- ment. To make it much larger would be detrimental, as it would probably be torn from the tree by the wind. Even now some varieties are so large that they break away from the tree before ripen- ing, and so these varieties are avoided. The Beurre Clairgeau, one of the best of pears, is little grown for this very reason. But in matter of flavor there is still oppor- tunity for indefinite variation. Some European cultivators have recently produced remarkably pleasing and varied flavors in this fruit. An illus- tration of how the flavor of a fruit may be rad- ically modified is furnished by my Apple Plum, which, while retaining the characteristic attributes of its race, curiously simulates the apple in the matter of form and even in taste and texture. Another instance is my Bartlett plum, which out-Bartletts the Bartlett pear in its own peculiar [26] ON SPECIFIC NEEDS quality and flavor. Yet others are the Pineapple quince, which has the flavor of the pineapple it- self, and the Sunberry, which has the exact flavor of the blueberry intensified. Corresponding modifications of the pear as well as of all other fruits lie within reach of the patient experimenter. LEAVING OUT THE CORE But perhaps the most inviting field of all, in connection with the possible development of or- chard fruits, is that having to do not with the form or texture or flavor of the pulp but with the seed of the fruit. Of course it must not be overlooked that, from the standpoint of the fruit itself, or rather from the standpoint of the tree on which it grows, the seed is the only really essential part of the fruit. Ail of the embellishment of juicy pulp and highly pigmented skin is but the lure put forth by the plant on behalf of the seed, in the interests of self- preservation. The really essential part of the entire structure is but an infinitesimal cell lodged at the heart of each kernel of the seed. Indeed, we may go even one step further, with the aid of the microscope, and say that the nucleus of a single cell, born of the union of the nuclei of two germ cells, is the really important part not [27] S '2 -aS^.LS'SSgs 8*3^8, liiiMs^iiiifii a a fr 2 2.. r«lHS .5*3 &l?ll!3i* §• i LUTHER BURBANK merely of the fruit but of the tree on which it grows. For within the infinitesimal structure of the nucleus, by the most mystifying of all Nature's feats of jugglery, are lodged those hereditary fac- tors or determiners that will ultimately transmit the traits of the ancestral tree to the tree of the future. In the widest sense it is true that the sole pur- pose of the entire plant is to produce a certain number cf these germinal nuclei, each represent- ing the union of a pollen grain with an ovule; each carefully encased in the structure that we call a seed; and each capable of reproducing, with sun- dry modifications, the characteristics of the parent plant, or, in a profounder view, the blended char- acteristics of the entire ancestral race which the plant represents. When we consider the seed in this way it does not seem strange that all the resources of Nature should concentrate on the development of the fruit structure in which the all-important seed or cluster of seeds finds lodgment. And by the same token it is comprehensible that Nature will hold to the seed with the most unwavering persistency. And so it is not strange that the plant experi- menter should be able to alter the size and texture and quality of the fruit pulp far more readily than [30] ON SPECIFIC NEEDS he can modify the core or stone that lies at its center. Yet from man's standpoint this inevitable cen- tral structure, forming the heart of every orchard fruit, is a conspicuous detriment. And it is alto- gether desirable that fruits should be developed in which the stony or fibrous covering of the seed is eliminated, or in which the substance of the seed itself has been substituted by juicy tissues. Everyone knows that this much desired modifi- cation has been effected, or all but effected, in the case of the so-called navel orange. An accidentally discovered mutant, doubtless a pathological speci- men, was seized on by some keen-eyed observer, and a race of seedless oranges was developed by selection, and widely disseminated by grafting. Also there are seedless grapes. The reader will recall the long series of experi- ments through which I was enabled, by taking advantage of a similar malformation in a wild European plum, to develop by hybridization and selective breeding a race of stoneless plums. Everyone knows, also, that there comes to us from the tropics a familiar fruit, the banana, that is seedless; although perhaps it is not so well known that this fruit has lost its seed through being propagated for long generations by division. The precise steps through which this development [31] LUTHER BURBANK has taken place in the case of the banana are not matters of record. But its condition is similar to that of the sugar cane and of the familiar horse- radish in our gardens, both of which have been so long propagated by division that they have aban- doned the habit of seed formation. The banana in its wild state was practically filled from end to end with large, hard, bullet-like seeds or stones, with just enough pulp surrounding them to make the fruit attractive to birds and wild animals that could not destroy the seeds. In this state it was practically worthless to man. Had not a patho- logical form appeared without seeds, which must be cultivated solely by division, the banana would be a practically useless fruit to-day. And, for that matter, the potato furnishes us with an even more familiar illustration of the re- nunciation of the most primitive and important of all plant functions, that of seed bearing, which has developed under cultivation within the past half century. But among orchard fruits of temperate zones the orange and the stoneless plum, as just in- stanced, are the only examples of plants that have been thus profoundly modified — although a seed- less (but not coreless) apple and pear, in the ex- perimental stage of development, have been an- nounced. These examples, however, are stimu- [32] s. -i _. Ji £ P * sr X ~ 3" a ~ 2. o ^. Q £• * ® f»OO,&" ^»S5IS* ^ «U||S £ ?> fc *" O M s **«at ' " ™ due In toe that continue growf/i cultivated after transplantation. LUTHER BURBANK chard sap the ground and take the nourishment that the tree imperatively needs. But if the sur- face soil is turned under this vegetable matter will in itself constitute a fertilizer. Unless the soil is unusually rich this should be supplemented with artificial fertilizers, of which nitrates, phosphates and complete mineral fertilizers often appear to have the best effect in rejuvenating an old orchard. In case the soil is a sandy loam, subject to rapid leaching, it may be desirable to sow a so-called "cover crop" to prevent the too rapid washing away of the plant foods in the rainy season. If a leguminous crop is grown, such as clover, crimson clover, cow peas, or vetch, these crops will in them- selves add to the nitrogen of the soil, as their roots, have the power of taking this from the air. But it is urged by some eastern orchardists that care should be taken to avoid too much nitrogen. The roots of the tree reach down to rich subterranean sources that are likely to be well supplied with nitrogen, because the nitrates are very soluble and are pretty rapidly leached or filtered into the sub- soil. After preliminary treatment it has been found in many states best to sow a crop of clover, often with other perennial grasses, as a permanent crop, which should be cut and all material left on the ground for the protection and support of the or- [48] ON PRACTICAL PLANS chard. This has been found to be an extremely profitable method both in the old neglected and in the new orchards of New England and in the orchards of the northwestern Pacific coast. A small space about the trunk of the tree should be kept free from grass. The experts of the Indiana Experiment Station recommend as a fertilizer, for soil of fair natural fertility and where a leguminous nitrogen-gather- ing cover crop such as just suggested may be grown, the additional use of a fertilizer having the following formula : "A thousand to fifteen hundred pounds per acre of a mixture containing one part (100 pounds) each of ground bone, acid phosphate and muriate of potash. On soils that are some- what exhausted, 125 pounds nitrate of soda may be added in addition. "In order to get the greatest returns from this fertilizer it should be thoroughly worked into the soil. This can be accomplished very well by ap- plying it to the surface just before plowing. The plowing and working of the ground will get the fertilizer pretty thoroughly incorporated, and the tree will soon show the beneficial effect of its pres- ence. Hoe the ground often and keep it cultivated until midsummer, then sow a cover crop that will protect the ground until it is turned under the fol- lowing spring." [49] LUTHER BURBANK After these reformatory measures have been carried out, it remains to guard the trees against the attacks of insects with some protective spray. The particular insect or fungus-destroying mix- ture required will of course depend upon the indi- vidual case. The Bordeaux mixture is doubtless used more than any other single spray for fungus diseases and for the codling moth in apples. A lime-salt-sulphur solution is the general mixture for San Jose scale. In general, it should be re- called that spraying is a preventive measure rather than a cure. Bordeaux mixture, for example, will prevent the appearance of the fungus disease com- monly called scab. The attacks of the codling moth may be met in the same manner; but as there is a second crop of these moths, another spraying may be necessary later in the season. BATTLING THE PESTS I should add that as to this matter of fighting plant diseases and pests with the spray, as also in the matter of the renovation of neglected orchards, I must offer advice rather at second hand. My own orchards, as a matter of course, have not been neglected. While my orchards are cultivated thoroughly, so that a weed is seldom seen, very little fertilizer is used and rarely any spraying, as my object is to obtain varieties that are immune to fungus and insect diseases, and which will [50] Nursery Stock Awaiting Final Transplantation Here bunches of seedlings such as those shown in the preceding illustration have been set out temporarily en masse to keep them in condition until time can be found for their, indi- vidual transplantation. In cold weather and in dry soil the seedlings may thus be preserved almost indefinitely, retaining their vitality and being ready to take on growth when transplanted individually. LUTHER BURBANK thrive in ordinary soils and under ordinary sys- tems of cultivation. No pampered pets are offered from my grounds for general culture. I would urge any orchardist who operates on a large scale to consider the matter of selecting as far as possible varieties of fruit trees that are more or less immune to disease, rather than to depend on the at best somewhat precarious method of warding off the enemies by spraying. Prevention is better than cure with plants no less than with human beings. But of course the renovator of an old orchard, whose task is at the moment under consideration, must work with the materials sup- plied him and cannot ignore the fungus and insect pests that attack his trees; although by dint of proper grafting he may hope presently to trans- form the character of the trees in such a way as to give them partial immunity. The orchardist of the future will have still better ones in these re- gards. PLANNING A NEW ORCHARD So much for the renovation of the old orchard. I have spoken thus at length on this aspect of the subject because of its obvious importance, and because it aims at the correction of a widespread condition and has to do with the possible restora- tion of properties in the aggregate of enormous value. [52] The Choice of Seedlings To economize space, seedlings may be grown close together during the first few months, until the individuals have revealed their qualities. Then, of course, the weaklings will be weeded out and room given for the thrifty ones to con- tinue growth. This picture illustrates the difference in growth — notably in sturdiness of stem — between two seedlings from the same lot of seeds. It is obvious that the orchardist will preserve the one at the left, as the much likelier fruit- producer. LUTHER BURBANK It takes time to grow a tree, and it is peculiarly fortunate that the would-be fruit grower can se- cure almost anywhere an abandoned orchard that may almost immediately be restored to a condition of productivity. But of course the orchardist who wishes to operate on an extensive scale will not be content with the renovation of an old orchard, however lucrative that process may prove, but will wish to produce a new orchard that may lack the defects of the old one. The ancient tree made over will still retain, in such important matters as height and spread of limb, the evidence that it really belongs to a past generation, however insistently the fruit that its grafted branches bear may seem to belie the evi- dence. But the trees of the new orchard may be trained in accordance with modern ideas; and it is not to be denied that ideas as to tree pedagogy have changed as rapidly in recent years as have the best conceptions of human pedagogy. Take the very important matter of height of tree as a case in point. Not long ago the orchard- ist, in developing a young tree, was careful to see that it was trained in the nursery so that its lowest branches were several feet from the ground. But the well-informed orchardist of today heads his tree in such a way that the bearing [54] Selecting Among Peach Seedlings Here two peach seedlings are shown between which it may be somewhat difficult to decide. The one at the right if somewhat larger and sturdier, but that at the left is much better formed, its branches being upright, growing at the ideal angle of about forty-five degrees. The latter will therefore make better trees, but the one at the right has qualities of color of stem, and of sturdiness that mag make its preservation desirable. Two quite different varieties of peach may be expected from these two seedlings of the same stock. LUTHER BURBANK branches start only eighteen inches or two feet from the ground. Where formerly high ladders were required to pluck the fruit, a modern orchardist, for a good many years after his trees are in bearing, can stand on the ground and reach the main bulk of the fruit; and even that which falls is not mutilated and bruised as it used to be. Also the trees are much less apt to be broken or blown over by the wind. And in this I am not referring to such "freak" trees as, for example, my little bush-like quinces, scarcely waist high yet almost breaking under the weight of mammoth fruits. I am speaking of the commercial orchard, and have in mind in par- ticular the apple tree, because it is with regard to this tree that the most conspicuous transforma- tion has been effected. Plum trees and peach trees were never very large, but it used to be taken for granted that the apple tree should be of gigantic proportions; so the half dwarf trees on which the best apples of today are grown might seem to the casual observer to belong to a different family of plants from their progenitors. GAUGING YOUR CLIMATE As to other desirable qualities, much depends upon the location of the orchard and the market that the orchardist has in view. [56] ON PRACTICAL PLANS It goes without saying that the varieties to be selected must be of a character adapted to the climate and soil of the chosen region. As to this, the restrictions imposed by Nature are more or less familiar to every fruit grower. In general, you may judge to a certain extent from observa- tion of what is already grown in your neighbor- hood as to what kinds of trees will thrive there. The chief restrictions are those imposed by con- ditions of temperature, and of course temperature is influenced not merely by the latitude but by dis- tance above the sea level and the neighborhood of large bodies of water. The presence of moisture in the air has a pro- tecting influence, chiefly in that it prevents radia- tion of heat at night. Every orchardist knows that the danger from frost increases in proportion as the night is clear. The now familiar method of fighting frost by burning brush or oil supplies direct heat, but also supplements this by filling the air with smoke, which retards the radiation of heat. It is familiarly known that seaboard regions have much milder winters than inland regions of the same latitude. Again, inland regions of low altitude, such as the Mississippi Valley, may be adapted to the growth of a fruit that would inevitably winter- [57] LUTHER BURBANK kill if grown on the high plateaus of Wyoming. In general, it may be said that no region at higher altitude than about six thousand feet is adapted for fruit growing. In putting out catalogs of new fruit it is often desirable to state the minimum temperature that a new production will stand. I have done this, for example, in announcing my spineless cac- tus. As to average annual temperature, it may be convenient to recall that there is likely to be a mean annual difference of three degrees for each hundred miles of latitude. Thus, for example, the mean temperature at the southern line of Iowa will be found to be about three degrees lower than the mean temperature at the northern line; and this difference might, in case of a given fruit, make it folly to plant in northern Iowa a fruit that might live in the southern part of the state. As already pointed out, however, one of the main objects of the plant developer today is to produce hardy varieties, and doubtless it will be possible in the future to grow most varieties of or- chard fruits in regions that are now regarded as lying wholly beyond the northern limits of their possible culture. STUDYING YOUR MARKET Of course the proximity of the market is an item of chief importance. Yet the experience of [58] LUTHER BURBANK the California plant developer may be cited as showing that nearness to market is by no means an absolute essential. For of course it is well known that the California fruits are now chiefly grown for shipment to the Atlantic seaboard. So nearness to a railroad is even more important, as hauling fruit for any great distance before it is packed for eastern shipment is a great detriment to its shipping and keeping qualities. Except in a few cases, like that of the prune, it is always necessary for the California plant developer to consider the shipping quality of his fruit. A fruit to be shipped a long distance must be of firm flesh, a good color, and a reasonably tough skin. And especially it should be uniform in size and of such shape as to admit of econom- ical packing. Moreover, it should ripen at a season when the same kind of fruit is not abundant in the distant market. So it may happen that a fruit otherwise valu- able may lack this essential marketing quality, and hence must be avoided. This is the reason why my Abundance plum is not so popular in Cal- ifornia as it is in the Eastern States, as it will not stand a long shipment so well as other varieties. To the eastern fruit grower this is not important, as he lives near the market. But from the Califor- nia standpoint, such plums as the Wickson, the [60] ON PRACTICAL PLANS Burbank, the Formosa and the Climax, all of which are excellent shippers, are generally preferred. The advantages of entering the market at a particular season are illustrated by the Burbank cherry, which ripens so early that it reaches the eastern markets when almost no other fruit is on hand. The fact that these cherries often bring two or three times the market price to be secured a few weeks later shows the practical importance of this detail. Another seemingly minor point that the pro- spective orchardist should not overlook is the question of the color of the varieties of fruit he is to select. Color is one of the most important char- acteristics of the fruit from the market man's standpoint. The purchaser at the fruit stand will very generally pick out the highly-colored fruit without considering its quality. The prospective fruit raiser should bear this in mind in selecting his stock. THE ORCHARD SITE In dealing with an old orchard the fruit grower must obviously take the trees as he finds them. But in developing a new orchard he should give very careful attention to the exact topographical conditions. The matter of drainage of the soil is important, and also the question of exposure to the sunlight and wind. [61] LUTHER BURBANK If your orchard site slopes toward the south, and does not lie in the shade of mountains nor where it is subject to the equalizing influence of a large body of water, the trees are likely to be so stimulated by the nearly perpendicular rays of the sun as to blossom before the time of the last frost. Early blossoming might at first thought be consid- ered an advantage; but in point of fact it is a gen- eral rule that plants which blossom early ripen their fruit late, whereas those that blossom late are usually early ripeners. The obvious explana- tion is that the trees that flower late and ripen early have had to adapt themselves to short sea- sons. The wisdom of their course is emphasized when we see the early blossoms of trees on a southern slope cut off by a late frost, while trees otherwise situated in the neighborhood have not yet come to blooming time. The danger of entire loss from late frosts may be obviated, however, by the selection of varieties that will mature fruit even after the blossoms have been frozen. I have developed such varieties of fruit trees in a number of instances. There are also varieties that have a long blooming season, and these may be depended upon to put forth new blossoms even if the earlier ones were blasted. But in general it is desirable to select a variety of [62] t?!!tm^!:!?>; ! i LUTHER BURBANK tree that naturally blooms late enough to avoid these frosts. This is especially important in view of what has just been said about frosts waylaying trees on a southern exposure, because precisely such ex- posure is of value at the other end of the season, to hasten the ripening of the fruit. This is not only important in the case of fruits designed to meet an early city market, but it applies to many varieties that tend to ripen late in the fall and which thus may suffer from the early frosts of autumn. It should be recalled that the warm southern exposure also tends to take the moisture from the soil early in the season, so varieties planted in such a location should be able to resist drought. Trees planted on a hillside will probably have natural drainage. Otherwise it may be necessary to drain the soil with tile or with open ditches, or else to select varieties of fruit that are known to thrive in a moist, cool soil. Such varieties must necessarily have an unusually large leaf surface and shallow root system. For this reason they should not be placed where they are subject to heavy winds. What may be called air drainage is sometimes quite as important as water drainage. Cold air flows down the hillsides and settles in the valleys. [64] o'o*1 ^S^^S » *^5 ! *f filter * «• a «• *2 i-»T «*»• 2J« ;». S-a a.§ Early-Bearing Peaches The peaches here shown illustrate the possibility of remodeling an old peach orchard by grafting. This bunch of luscious fruit was borne on a don only two years old, grafted on a tree that otherwise would have borne fruit of inferior qual- ity or no fruit at all. There are thousands of aban- doned peach orchards that might be rejuve- nated by proper grafting. ON PRACTICAL PLANS So the bottom of a valley is a very poor place to plant fruit; except, indeed, in certain canyons or gulches where there is a steady current of air in motion throughout the night. In general, the or- chard site should be on a hilltop or hillside, or at least at an elevation above the lowest land sur- face in the neighborhood, unless the valleys are either naturally or artificially well drained. Without attempting further details in this place, enough has been said to show that there are almost numberless points to be considered by the up-to-date fruit grower in the development of a new orchard. What has been said will supply clues that the thoughtful orchardist may readily follow up. As to the specific fruits, further details, with particular reference to the practical aspects of the subject, will be given in succeeding chap- ters. — "7n several cases" says the Ohio report, "a net profit of $bOO per acre has been secured from an abandoned orchard." Mr. Burbank's 400 The picture gives a direct glimpse into the foliage of the large cherry tree at Sebastopol on which Mr. Burbank has grafted more than four hundred different varieties of cherries. Prac- tically every branch here shown bears a different kind of cherry, and nearly all are of superlative quality. A single tree thus treated becomes in itself an orchard. DOUBLING THE PRODUCTIVENESS OF THE CHERRY MORE AND BETTER CHERRIES WHEN I chance to see mention in the newspaper headings of the doings of New York's celebrated Four Hundred I am sometimes reminded of the Four Hundred of Sebastopol. The particular Sebastopol that I have in mind is the place where my fruit farm is located, about seven miles from Santa Rosa. By the Four Hun- dred of Sebastopol I mean a very aristocratic colony, comprising four hundred families of pedi- greed cherries, that are colonized on a single big tree in my cherry orchard. I could speak only from vaguest hearsay as to the lineage of New York's aristocratic coterie, but may claim to discuss the pedigrees of the Four Hundred of Sebastopol with final authority. And I can vouch for the blueness of blood, so to speak, of every one of them. [VOLUME IV — CHAPTER III] LUTHER BURBANK That there are about four hundred families in my patrician cherry colony is a matter of acci- dent, quite uninfluenced by any thought of imita- tion. It chances that year by year the process of elimination about balances the process of addition to the family, and the census of the colony is not greatly altered. Reference has been made in various earlier chapters to the origin and development of the patrician cherries. They are closely related as to their remote ancestry, as I suppose is the case with the members of every other aristocracy. Yet, as we have seen, the ancestral traits are variously blended in the different families, and there is notable diversity among them as to individual traits. Some of them bear fruit that is vividly red in color, others fruit that is pallid; and there are corresponding divergences as to flavor, free- dom of stone, sugar content, and all the rest of the complex characteristics of a well-bred cherry. Of course these qualities are variously re- combined in the progeny of each new generation. So I can never tell what surprise is in store for me when I raise seedlings from the fruit. And there are always new additions to the colony that will only come into bearing next sea- son or the season after and reveal what they hold in store. [70] Some of the 400 Come to Judgment This picture shows a few of the several hundred varieties of cherries plucked on the same day from the same tree, and laid out for Mr. Burbank's examination and selection. As new com- binations are effected each season through cross-pollenization, there are alwai;s unique varieties to be found on the tree each June-time, and these new varieties, may, of course, be perpetuated by grafting. LUTHER BURBANK Thus it chanced that in the season of 1908 I found among the cherries one that bore quite the largest fruit I have ever seen; fruit, moreover, of the most inviting color and having qualities of flesh to match. Cions from this new stock will be sent out and will in due course colonize many an orchard with a new variety of fruit that is sure to find great favor. But if I thus from time to time have pleasant surprises, I am also too often chagrined to find among my patrician cherries offspring that seem unworthy. But of course one hears of black sheep among the scions of even the noblest families, so it is not surprising that the blueblood cherries of Sebastopol offer no exception. And as the black member of any human family is always held up as a warning example, I have thought that I might in the same way make the black sheep of my cherry colony serve a useful purpose by explaining somewhat in detail the rea- son for their appearance. In so doing I shall be able, perhaps, to make a somewhat clearer exposition than has hitherto been attempted of certain aspects of heredity that are peculiarly important from the standpoint of the practical plant developer. UPPER CASE QUALITIES We have learned something in earlier chapters [72] South American Cherries Much of Mr. Burbank's success has been due, as the reader is aware, to the hybridizing of plants brought from different geographical localities. This picture shows a South American cherry that has been used in the course of the crossbreeding and hybridizing experiments through which Mr. Burbank's many varieties of perfected cherries have been developed. It will be seen that the South American cherry differs quite widely in appearance as well as in the foliage from the ordinary cherry of the northern hemisphere. LUTHER BURBANK about unit characters and the way in which they are Wended or mosaiced together to make up the personality of any individual plant. It will be recalled that where the two parents of a given individual have opposing qualities as regards a given characteristic — where one, let us say, is black and the other white — it is quite the rule for one quality to dominate the other in such a way that the offspring precisely resembles, as regards that quality, the dominant parent — in this case the black one — and resembles the other par- ent seemingly not at all. And we have learned also that the latent or recessive character that is thus subordinated — in this case whiteness — will reappear in a certain proportion of the offspring of the succeeding generation. Now, it has been found convenient by recent experimenters to adopt a graphic method that will make the printed accounts of their experiments more readily comprehensible. The expedient in question is the simple one of using a capital letter to designate the dominant factor of any pair of unit characters, and a corresponding lower case or small letter to designate the recessive factor. Letting "JD," for example, stand for the domi- nant trait of blackness in the illustration just given, and "d" for the recessive trait of white- ness, we may concisely state the facts of inher- [74] LUTHER BURBANK itance as just noted in the following formula: Parent "D" being mated with parent "d" the offspring, whether few or many, bear in each in- dividual case in their germ plasm the factors "D" and "d" in combination. But if two of these off- spring are interbred, there will be a splitting up of the factors and re-combination in such wise that in any average group of four of their progeny the result will be this : One member that is pure dom- inant (DD), two members that are mixed dom- inants (Dd), and one member that is pure re- cessive (dd) . The DD individual is "homozygous" for dominant factors and will breed true to black- ness. The dd individual is homozygous for the recessive factors and will breed true to whiteness. The two Dd individuals are heterozygous for the color factors, and whereas they are individually black their offspring will repeat the formala 1 DD + 2 Dd + 1 dd; they will reproduce, in other words, the conditions of the second filial genera- tion itself as just analyzed. Let me re-state all this, using only the letters, to show the convenience of the formula and at the same time to fix it in memory: D mated with d in the first generation gives us Dd + Dd + Dd, etc., in the second generation. Dd mated with Dd gives us in the third generation 1DD + 2Dd + Idd. [76] Some Curious Short-Stemmed Hybrids These black cherries, it will be observed, have the pecu- liarity of growing on exceedingly short stems. Such variations a» this are observed in many hybrids, and of course they give oppor- tunity for selection, through which permanent varieties are developed. Shortness of stem, however, in the cote of the cherry is a merit that must not be carried too far, lest the cherries crowd each other too much in the bunches. LUTHER BURBANK If this is not absolutely clear, you will do well to re-read the above paragraphs, and it is quite worth your while to consider the matter somewhat attentively. If you have only theoretical interest in plant breeding you should be concerned in the matter no less personally, because the same laws of hered- ity that are about to be illustrated apply with full force to all life, including human offspring. If, on the other hand, you have thought of un- dertaking some experiments in plant developing, which I hope is the case, it is doubly important that you should get the full significance of these simple formulae. Like other formulae, they are devised solely for convenience in promulgating ideas. As used in the following illustration, they will make it possible to present vividly the case of our black-sheep cherry, and through this to clarify a large number of obscure cases that must prove very puzzling to the novitiate in plant develop- ment. EXPLAINING THE BLACK SHEEP Let us now stake our way, as it were, with the aid of the upper-case and lower-case letters, along the line of a series of plant experiments through which a certain patrician cherry was developed. To avoid complications and to escape getting into a tangle of ideas and a maze of letters, let us con- [78] ON THE CHERRY sider only a single quality in detail, keeping in the background of our minds the idea that the actual experimenter is at all times considering almost innumerable other qualities as well. The one quality that we will consider at the moment is, let us say, the matter of size. We wish, for some special purpose, to develop a cherry that shall be a giant among cherries, yet which of course shall combine size with quality. Now we have at hand a cherry that bears very large fruit of poor quality. We have also at hand a tree that bears small fruit of delicious quality. Our first step will be to transfer pollen from the stamens of one of these to the pistils of the other. We carefully mark the limbs bearing the hybrid- ized flowers; and subsequently we gather the fruit and save the seed and in due course plant it and nurture the seedlings by methods hitherto fully explained. So when a year and a half has passed from the inauguration of our experiment we have a row of hybrid seedlings ready for grafting. The one thought that is uppermost in our mind, for purposes of the present exposition, is that of securing a plant that will bear fruit of large size. Now we have learned that there are certain cor- relations of parts that will enable the plant ex- perimenter to predict, from the quality of the [79] LUTHER BURBANK seedling, a good many things about the quality of the fruit it will subsequently bear. Utilizing this knowledge, we pass along the row of seedlings and select from among the thousand or five thou- sand individuals the ten or twelve that seem to us to give greatest promise. Nor at this particular stage of the development is the selection very diffi- cult, for the first generation hybrids usually show no very great tendency to variation. That ten- dency is revealed in subsequent generations, as we have seen. In point of fact, as a moment's reflection will tell us, the seedlings before us are really all of one quality as regards the particular characteristic of their innate tendency to bear large or small fruit. One of their parents bore large fruit; the other bore small fruit. If, then, we assume that here, as in many other cases of plant breeding, the quality of largeness is dominant to the quality of small- ness, it may be expected that all the hybrids of the first generation will tend to bear large fruit. If, introducing our convenient system of sym- bols, we designate the dominant quality of big- ness with the letter B, and the recessive quality of smallness with b, we may designate the mem- bers of the hybrid generation as all being mixed dominants, each bearing the factors Bb. This means that the factor B dominates the factor b, [80] Botan and Black Giants, Side by Side The two types of cherries are shown here together, that their similarities and differences may be seen at a glance. The Black Giants represent one of the newest varieties developed bg Mr. Burbank in his famous colony of four hundred. LUTHER BURBANK and that the individuals in question will all bear large fruit. So we may expect (on this assumption), having grafted our selected seedlings, that each of them will show, two or three years hence, fruit of large size. But of course the other qualities of this fruit will not be all that we could desire, so it will be necessary to continue the experiment. Suppose we do this by cross-pollenizing differ- ent members of the same group. We shall thus mate Bb with Bb. And the result of this mating, as we know, will be to produce, in each group of four, one BB individual, two Bb individuals, and one bb individual. Being interpreted in terms of our actual row of seedlings, as they stand in our orchard in this, the fourth or fifth year of our ex- periment, this means that in every lot of four thousand seedlings one thousand are pure domi- nants as regards large fruit, two thousand are mixed dominants, and one thousand are pure re- cessives. But now comes a very tangible and very prac- tical complication. As regards their external traits, and as regards the fruit that they will indi- vidually bear, the one thousand pure dominants (BB) and the two thousand mixed dominants (Bb) are identical. There is nothing in their exterior [82] ON THE CHERRY appearance, and there will be nothing in the ap- pearance of their fruit, to indicate which of them contain only the factors of dominance (BB)9 and which contain the recessive factor combined with the other (Bb). Yet for the purpose of future ex- perimentation, in which we shall be obliged to call on succeeding generations, it makes a vast differ- ence which individuals are selected. We are well aware of this as we walk along the row of our seedlings, but we are also aware that there is no method by which we can fathom the secrets of the germ plasm of our seedlings, to determine which are BB and which are Bb stock — save only the method of future breeding. In spite of our best endeavors it may very well happen that the ten or twelve seedlings that we now select, to be grafted for the continuance of our experiment, include not a single pure domi- nant (BB), but are made up exclusively of mixed dominants (Bb). We have seen that the latter are twice as numerous as the others, and that the two look just alike; therefore the chances are two to one that they will be chosen in the majority, and it will not be strange if they are inadvertently chosen to the exclusion of the others. Yet this choice will insure that the factor of smallness which we are striving to eliminate was carefully preserved in the germ plasm of the [83] LUTHER BURBANK cions of this second generation that we now graft into membership in the aristocratic cherry colony. And when, after another interval of two years, these cions come into flower and are mutually cross-pollenized, the seeds they bear, being the off- spring of mixed dominants (Bb xBb), will pro- duce a generation of seedlings precisely repeating, as regards the quality under consideration, the formula of their parent generation. In a given lot of four thousand, let us say, one thousand will be BB, two thousand will be Bb, and one thousand will be b b. And precisely the same difficulty in selection confronts the experimenter that confronted him before. If he could only know which are the pure domi- nants and which the mixed one, all would be well. But not only is it impossible for him to know this, but he may not be able even to determine with certainty, from examination of the foliage of the seedlings, which ones belong to the group of three thousand that bear the dominant factor (either BB or Bb), and which to the group of one thousand that bear only recessive factors (bb). It must be borne in mind that the experimenter is really considering a large number of qualities, and it must be understood also that there may not be any clearly established point of correlation [84] Mr. Burbank's Abundance Cherry This is another of the comparatively recent developments in the famous cherry colony. It is often difficult to find names for the many new varieties that are developed at Sebastopol, but in the present case the word "Abundance" seems almost to suggest itself. It may be added that the cherries taste as delicious as they look. LUTHER BURBANK between the foliage or stem or buds of the seedling and the qualities of its future fruit as regards the matter of size. So it may quite conceivably happen that the experimenter, using his best endeavors to make right selection, picks out for preservation, among the ten or twelve chosen out of the thousands, in- dividuals that (though they have only large-fruited ancestors in the two generations back of them), yet themselves are pure recessives (bb) as regards that quality, bearing no factor of large fruit what- ever. And in that event the experimenter will be con- fronted, after another two-year or three-year in- terval of waiting, with an array of fruit, borne on the branches of his long-nurtured and carefully selected cions, not a single specimen of which is other than insignificant in size. Other good qualities the fruit may have. But in the essential quality that we are keeping under consideration it is utterly lacking. In the matter of size it reverts to the recessive member of its great-grandparental ancestry. And so its telltale progeny, hanging there among the luscious fruits of surrounding branches (of other lineage), are like the black sheep in a patrician family. Not an enheartening experiment, thus far, for the would-be developer of a colossal cherry. [86] Branch of 1909 Cherries The number 1909 here refers not to the actual number of cherries, but to the season in which they were first developed. They appeared that year on one of the branches of the famous tree, and they were at once seen to have such qualities as to merit further attention. The branch was therefore multiplied by grafting, and the new variety assured perma- nence. As yet, however, it has not been named. LUTHER BURBANK Yet the case is not really quite so bad as it seems. There is an old familiar saying that "blood will tell," and our new formula, if properly ap- plied, gives full support to the saying. Making application of it, we may say that the dwarf cherry which we have developed as the re- sult of about nine or ten years' efforts at the pro- duction of a giant, is after all a thing of quality, even though it lacks one of the qualities that we are seeking. It is a scrub as to size, but it is none the less a thoroughbred as regards a number of other qualities. In the matter of color, let us say, it is a vivid red; it is sweet and appetizing; it is resistant to disease; it will bear shipping, and so on. NOT so BAD AS IT SEEMS Indeed, it is not unlikely that, as regards all desirable characteristics but one, our cherries are of such quality that, even in the patrician ranks in which they find themselves, they must be ad- mitted to be "upper crust," to use a phrase that is said sometimes to pass current in human patrician circles. Or upon reverting to our formulae, and therefore to the terminology of the printer, we may say that they are "upper case" as regards all qualities other than size. As to bigness, to be sure, they are pure reces- sives and must be labeled bb; but as to juiciness [88] Other Nameless Seedlings This picture shows some extra early seedlings thai are now being given particular attention by Mr. Burbank. They have not as yet reached the stage of development when they will be named and sent forth into the world, but their present appear- ance gives assurance that this is only a matter of time. The reader is aware that Mr. Burbank develops hundreds of varieties of fruit that are in many ways valuable, but they do not meet his tests in all directions, and hence are never in- troduced. LUTHER BURBANK they are JJ; for shipping qualities they are SS; for resistance to disease RR; for hardiness HH; and for productivity PP. That is to say, they are pure dominants for each of these qualities. Their germ plasm requires only an infusion of the dominant factor for bigness and their progeny will prove that breeding does tell. There is a tradition that passes current among dog breeders which I do not vouch for but which suggests a condition so comparable to that of our cherry that I cite it by way of illustration. It is said that the greyhound had been bred so exclu- sively for speed that it developed all the desired speed qualities of a hunting dog, able to overtake any quarry, but lacked the courage to seize the quarry once it had been overhauled. To over- come this defect, so the story goes, some one crossed the greyhound with the bulldog, thus breeding in a strain of courage; and in subsequent generations eliminated all the bulldog traits ex- cept courage by selective breeding; and so gave us a race of greyhounds in which the one missing quality had been supplied. This greyhound legend seems much more plausible to-day, now that attention has been so generally called to the segregation of unit charac- ters, than it formerly seemed. But whatever its truth, the case of the hypothetical greyhound [90] ON THE CHERRY strongly suggests the case of our black-sheep cherry. This also lacks but a single quality. Can we not then breed this quality into our cherry and by remedying the one defect attain our ideal? SOLVING THE DILEMMA Fortunately, yes. This is precisely what we can do, and what the wise plant experimenter will do. We have but to look about in our cherry col- ony and we shall find another family, habiting perhaps a neighboring branch, the fruit of which exhibits in imposing measure the quality of size that our protege of the moment so notably lacks. This big cherry may even be the original domi- nant parent with which our experiment started. But it is a fruit which, although being everything that could be desired in size, is unfortunately quite lacking in color. In spite of its inviting big- ness, it cannot make its way in the market be- cause, even at full maturity, it has the appearance of unripeness. But it is big, and bigness is the thing we are seeking. So we cross-fertilize the flowers of our little cherry with those of this big one. The result is readily foretold. Bigness, as we have seen all along, is dominant, and so the off- spring of this union are individually big. They [91] LUTHER BURBANK are mixed dominants (Bb), to be sure, but that, as we have seen, is something that concerns their descendants rather than themselves. Individu- ally, they will bear big cherries, and that is all that we demand. But what as to the color of our new fruit? Here fortune again favors us. For it is very commonly observed that color of flower or fruit is likely to be dominant over lack of color. So our little red cherry, pure dominant as to color (CC) will stamp its influence in this regard on the progeny; the recessive color factor of the other parent (cc) being subordinated or made latent. In regard to color, as in regard to size, the progeny will be mixed dominants only (Cc). But here again the fact that they have the re- cessive factor (c) is of no consequence, since as we have seen the mixed dominant tangibly pre- sents the quality as markedly as if it were a pure dominant. So when we have raised seedlings of this union of our little red cherry with the big white one, and when we have waited yet another pair of years, we shall finally be rewarded with the appearance on the cions, of fruit that meets our original ideal as to size, is as red as could be desired, and ex- hibits the other good qualities that entitle it to a permanent place in our patrician colony. [92] Some That Have Proved Worthy Here are cherries that have proved themselves of superior quality, yet which have not been named, and which perhaps will never be introduced. They have admirable flavor, but they lack something of the aboundant production that characterizes other of the cherries shown in earlier pictures. This fault will probably be remedied in their descendants, and these cherries will be rep- resented in their progeny. The story of the combination of qualities of different parent forms to produce the ideal cherry is told in detail in the text. LUTHER BURBANK It has taken us about twelve years to accom- plish this result. And even now our new fruit must be propagated by grafting and budding, for it cannot be depended upon to breed absolutely true from the seed. The recessive factors for size and for color, as we have seen, are in its germ plasm; and these will make themselves manifest in the progeny. But so long as we confine ourselves to the method of grafting, we may hold the type of the new variety and spread broadcast our big red cherry with its combination of desirable qualities, with full assurance that, given reasonable condi- tions as to soil and climate, it will reproduce for- ever the qualities of the patrician fruit, the ances- tral history of which we have just traced. INVITING OPPORTUNITIES I have thought that by thus tracing in detail the history of a single experiment, paying heed chiefly to a single quality, but reminding the reader from time to time that other qualities can- not be ignored, we could perhaps gain a clearer notion than would otherwise be possible of the practical steps through which a new form of fruit is developed. It is through such series of experiments, lead- ing sometimes forward and sometimes backward in successive generations, that the four hundred [94] ON THE CHERRY families of cherries of my patrician colony have been developed. No two among the four hundred show precisely the same combination of qualities, but all of them show one combination or another of good qualities. Those that reverted to undesirable ancestral traits have been weeded out. And this is equivalent to saying that the se- lected varieties of cherries represent a fixed stock as regards many of their good qualities. We can- not expect that any given one will reproduce its kind precisely from the seed, for reasons that have been fully explained. But we can expect that there will be a goodly proportion among any company of seedlings from this stock that would produce fruit of excellent quality. In a word, then, these perfected varieties of cherries repre- sent stock that is immediately available for the purposes of further experimentation. What they have accomplished is an augury of still better things that may be expected of their descendants. And so the practical question arises as to what, specifically, are the qualities that the improved cherry still lacks; and as to what particular ex- periments in hybridizing should be undertaken to remedy the defects. The first and perhaps the most important de- [95] LUTHER BURBANK feet that suggests itself is that the newly devel- oped cherries, particularly the sweet ones, lack something of hardiness. They grow to perfection in California, but as yet they are little grown in the eastern United States, and not at all in regions north of Ohio and Missouri. Yet the race of cher- ries, taken as a whole, constitutes a very hardy stock. The wild cherries of the eastern United States grow far to the north and are able to with- stand the winters even in regions where the mer- cury sometimes freezes. It should be possible, and doubtless it will prove possible, to combine the best existing vari- eties of cherry with some of the wild cherries, and thus to develop a race of cherries that will retain the present qualities and introduce additional qualities of hardiness fitting them for growth anywhere in the United States; in fact this is a work in which I am now engaged. The common choke cherry (Prunus Virgini- ana) is a very hardy tree, unusually productive, and almost indifferent as to soil and climatic con- ditions. I have made experiments in the cultivation of this tree, raising thousands of seedlings from fruit of a large, handsome specimen that grew by the roadside near Westfield, Massachusetts. The ex- periments as far as conducted have been satisfac- [96] ON THE CHERRY tory. Of course the fruit of this tree is astringent and almost as bitter as a green persimmon. But the little beach plum from which one of my finest plums was developed, was scarcely of better quality. Perhaps it is not unreasonable to hope that it may be possible to make some such improvement in the cherry, through combination with the choke cherry, as I produced by hybridizing the beach plum with the Japanese plum. In that event, we shall in all probability have a cherry surpassing any existing one in size (be- cause of the virility that the cross with the wild species has given it), retaining the good qualities of the present Burbank cherries, and in addition being so hardy that it would thrive in any soil and in almost any climate. If the choke cherry should fail to prove a sat- isfactory parent, there are numerous other wild species from which to choose. The black cherry of the eastern United States (Prunus serotina), is a tree that grows from Nova Scotia to Florida and westward to Dakota and Texas. It is of large size, and bears a fruit resembling that of a choke cherry in color and appearance, but of less astrin- gent flavor. Then there is a small red cherry, commonly called the bird cherry (Prunus Penn- sylvanica), the fruit of which is sour and astrin- [97J I i|'HJJ|f|-f|^| i ON THE CHERRY gent, but which is not without qualities of virility and hardiness that might make it a valuable hybridizing agent. This is perhaps the hardiest of all cherries. I have seen it growing wild nearly as far north as Hudson Bay, in regions where it is not uncommon for the mercury to fall sixty degrees below zero. The California holly-leaf cherry and the Cata- lina cherry are species that may be available for the development of other desirable qualities — for it is not in hardiness alone that the best varieties sometimes are found wanting; though the species just named are so far separated biologically and physiologically that it may be impossible to com- bine them. Many cultivated cherries, for example, are unable to withstand the warm spring rains with- out serious loss from cracking of the fruit. Some- times almost an entire crop will thus be ruined. Again many cherries are susceptible to blight. A bulletin issued by the State Commission of Hor- ticulture of California lists more than twenty in- sects— leaf hoppers, scales, mites, caterpillars, and borers — that prey more or less upon root or bark or leaf of the cherry tree, or that attack its fruit. Then there are inherent maladies, such as the tendency to overflow and condensation of sap, forming an injurious gum that may induce decay [99] LUTHER BURBANK of bark and wood (called gummosis), to which the cherry is peculiarly liable. Hybridizing with wild species, intelligently and systematically carried out, might produce vari- eties of cherry that would show exceptional re- sistance to insect pests as well as inherent vitality that makes for healthiness in the tree. It has long been my belief that a solution of the problem of protecting our fruit trees from both insect and fungus pests must eventually be found in the development of the qualities that make for immunity of the trees themselves, rather than in the resort to such expedients as spraying and "gasing." In this regard the plant experimenter may well take a leaf from the note- book of the physician, who has learned that im- munity to disease often depends more upon the condition of the patient than upon the presence or absence of disease germs. It is possible, furthermore, that the cherry may be hybridized even more widely, and that a fruit differing markedly from any cherry hitherto pro- duced may thus be developed. An inkling of the possibilities in this direction is given by some ex- periments made recently by Professor N. E. Han- sen, of the South Dakota Experiment Station, who has cultivated a variety of wild fruit, called the Sand Cherry, Prunus Besseyi, which is a dwarfed, [100] ON THE CHERRY compact grower, of heavy form and good foliage, and which had previously been put upon the mar- ket as the Improved Dwarf Rocky Mountain Cherry. This native tree has a fruit nearly as large as the Richmond cherry and sometimes of fairly good flavor. The Prunus Besseyi has al- ways been considered a cherry by horticultural and botanical writers. My experiments, however, seem quite clearly to demonstrate that it is more truly a plum. I have had the tree under cultivation for more than sixteen years. The fruits of the original plant were black and bitter, almost as astringent as a persimmon. By combining this plant with various other American and Japanese plums, I produced abundant seedlings, and in 1904 had de- veloped one especially promising variety. The fruit of this hybrid seedling ripens in California about August 10th, and is extremely large for this type. It is globular, and about one inch and a quarter in diameter. The color is pure, deep crimson, with a semi-transparent amber flesh, firm, juicy, and of a rich, sweet flavor, resembling that of the American plum. The tree is intensely productive, even breaking with its own weight of fruit. It has been suggested that this tree gives great promise as an aid in the production of a hardy [101] LUTHER BURBANK type of fruit that will withstand the rigorous climate and conditions of the cold northern plains of Nebraska, Minnesota, and the Dakotas. What has just been said suggests that the fruit is not truly a cherry, yet the botanists seem to feel that it occupies an intermediate station, and is more closely related to the cherry than any other fruit. Such being the case, it should be possible to hybridize this dwarf hardy species with the cherry. The tree has the further valuable prop- erty of being able to grow on dry, barren sands. A hybrid cherry having this characteristic from one of its ancestors might be expected to constitute a fruit that would grow in regions too arid for the existing cherry as well as in regions that are too cold. And this is but one of several lines of pos- sible development that invite the plant experi- menter who will give attention to this type of cherry. To suggest one other line of improvement, it is sufficient to call attention to the familiar fact that the cherry has a very brief season. The Burbank cherry fruits two or three weeks earlier than others, as we have learned in another chap- ter. But even so the total period during which cherries of different varieties are in fruit is very limited. One hears reports of an exceptional cherry tree that fruits a second time in the au- [102] A Large, Late-Bearing Red Seedling The cherry here shown, developed like the others prev- iously shown, in Mr. Burbank's celebrated colong, differs from the one specifically called the Embank, in that it is a very late bearer. The Burbank bears particularly early. It is desirable to extend the cherry season, and this variety has been preserved chiefly because of its lateness, although it has many other desirable qualities, as the picture suggests. LUTHER BURBANK tumn. By the usual process of raising numerous seedlings, or by crossing and selection, a variety having this fall-bearing habit might be produced. The value of such a variety is obvious, — though the early ripening of the cherry is at present what gives it greatest value, — and it is well worth the while of the amateur to attempt experiments in this direction. The fact that cherry trees of one kind or another grow throughout the United States makes it possible for almost anyone to experiment with this fruit. And the opportunities for improve- ment are especially inviting. — In cherry trees, as in the human plant, "blood will tell" THE RESPONSIVENESS OF THE PEAR WHAT HAS BEEN DONE Is BUT THE BEGINNING A CORRESPONDENT who is seemingly prone to personify inanimate objects writes to ask which tree among our cultivated ones I regard as the most "human." And then, without awaiting reply, my corre- spondent supplies the answer: "The pear, of course,'* he says with full assur- ance. But when he goes on to state the reasons for this decision, I am not quite sure that his argument carries conviction. Perhaps the most striking bit of analogy that he offers is the fact that a pear tree sometimes fails to reach maturity until it is from fifteen to twenty years old, coupled with the cognate fact that the tree may continue to thrive for three score years and ten or even longer. He cites a good many other analogies, or sup- [VOLUME IV— CHAPTER IV] LUTHER BURBANK posed analogies, to be sure, — the fact that the pear over-rides adversity, as it were, bearing abund- antly in bad soils and when totally neglected; the fact that it grows by roadsides and in dooryards showing a domestic habit and as it were a friendly spirit toward man; and finally, the fact that it responds to attention and proves as receptive and responsive to good treatment as it is resistant to bad. But I am by no means sure that as to most of these traits, and for that matter in regard to any others that might be mentioned, the apple tree is not to be given a place quite on a par with that which the pear can claim. There is no occasion to dispute about the matter, however, for at best such comparisons have no great significance. Let it suffice that the pear and the apple, close cousins as they are, may very well be considered the two orchard trees that are friendliest to man, in the broad use of the word. They have been his associates probably almost from the earliest times when he learned that plants would respond to cultivation. They have gone with him on his chief migra- tions throughout the temperate zone and even well into sub-arctic regions. They have proved themselves adaptable to all soils and nearly all climates; and they jointly pro- [106] Seedling Pears The pear is a fruit that has been very long under cultiva- tion, and it has developed certain familiar and very individual characteristics. A comparatively few types have become popular and are raised everywhere. But nothing more is necessary than to plant the seeds, to secure seedlings showing the greatest variety as to their fruit. Two aber- rant types are here shown, and nu- merous others are shown in succeeding pictures. LUTHER BURBANK duce a variety of pulpy fruits that stand in a class by themselves and are quite without competitors— or were until the quince came under the hand of the plant developer in very recent times. EARLY MIGRATIONS Which of the twain, pear or apple, was first adopted, no one can say, but it is certain that both were friendly with man even in prehistoric times. There is evidence from the ruins of remote civilization of the Lake Dwellers of Switzerland that the pear was known even in that day. Of course it was familiar to the Greeks and Romans from the earliest recorded periods of history. Long before that it had come out of its central Asian home — if, as is almost certain, that was its original habitat — and had become thoroughly do- mesticated about the Mediterranean. Other branches of the same race had migrated eastward until they found a home in China and Japan. And in these widely separated regions, at the extremes of the largest continent, the two descend- ants of the primitive stock developed, each in its own way, in response to soil, climate, and the di- verse temperaments of the peoples, until the pear of Europe was in many ways a different fruit from the pear of the Far East. But there was one migration made by prehis- toric man in which the pear, apparently, did not [108] The Long and the Short of It No one unfamiliar with practical horticulture would sus- pect that these two pears were grown from seeds of the same fruit. They illustrate the strangely varied hereditary factors that find lodgment in the germ cells of a cultivated fruit. And of course they furnish material for selective breeding through which new varieties may be developed. LUTHER BURBANK accompany him. This was the final stage of the eastward journey of our remote ancestors which carried them across a land bridge, now no longer in existence, between northeastern Asia and the present Alaska, and thus brought them to America. It seems a fair presumption that when prehis- toric man made this final migration he brought the apple with him. At all events, with or without man's aid, the apple made its way across the bridge that joined the continents. Probably the fact that the seeds of the pear will not germinate when once dried may explain the failure of that tree to come with the forerun- ners of the Indian to the new continent. The seeds of all orchard fruits germinate far better if they have not been too thoroughly dried. But the seed of the pear is peculiarly susceptible to destruction through drying; and if the ancestral pear had the same quality, which we need not doubt, this fact may in itself have been instru- mental in restricting the spread of a tree which, when introduced in America in modern times, proved thoroughly adapted to our soil and climate. We must not press this point too far, however, for the plum seed also dies if dried; yet the plum came to America in prehistoric times along with [110] ON THE PEAR the apple. And, for that matter, we shall see else- where that there is another possible interpreta- tion of the story of the prehistoric migrations of the trees. Be all that as it may, the pear retains to this day evidence of the inherent need, in the interest of its race, that the seeds borne at the heart of its fruit shall be preserved in a moist condition. The skin of the pear, except in the most re- cently modified varieties, is firm and thick. It is of a green or mottled yellow color calculated to protect it from the observant eyes of birds and animals rather than to attract them. It has been assumed that the eatable pulp that surrounds the seed was designed by nature — that is to say, de- veloped through natural selection — for the pur- pose of attracting animals and birds, that these creatures may aid in disseminating the seed. But the case of the pear, in common with that of the wild crab apple, suggests that the chief purpose of the fruit-pulp is to keep the seeds moist through the winter. As a further aid to this, and in token of the moisture-loving quality of its seeds, the skin of the pear is fortified by a deposit of woody cells at its inner surface that give it a gran- ular or even gritty texture. This unique quality of the fruit may even ex- tend to the pulp itself, especially with the more LUTHER BURBANK primeval forms, giving the pear a texture different from that of any other fruit. This unusual habit of depositing wood cells in the fruits, aside from the seed case itself, is no longer of use to the cultivated pear; but the fact that it tends to be retained shows how important a part it bore in the struggle for existence of the pear's remote ancestors. But let us put aside theories as to the remote history of the pear and consider the fruit in its modern relations. The significant thing to bear in mind is that in our day the pear is represented by two races, obviously related, yet quite as obviously long sep- arated, one of them finding its home in Europe and (since the Discovery) in America and the other being indigenous to eastern Asia, the two having thus migrated in opposite directions, circling the earth, and finally meeting on the Pacific Coast of America. And the fact that these two races of pears have thus diverged, yet still retain the capacity to hy- bridize, is an all-important one from the stand- point of the fruit developer. This fact is, indeed, the basis of the newest progress in the development of the pear, and it gives the augury of still more important develop- ments probably to take place in the near future. [112] 2 «"o 2 ? I LUTHER BURBANK It is only fair to recall, however, that the new beginnings in the development of the pear took place in western Europe independently of an ori- ental alliance. NEW BEGINNINGS IN EUROPE The pears of to-day, as known in the eastern United States, and for that matter most of the finest Californian varieties, are the bearers of an impulse to development that was given by a French horticulturist, Jean Baptiste Van Mons, and Andrew Knight of England about a century ago. Van Mons acted on a theory, now aban- doned, that young plants produce the best prog- eny. But this led him "to sow, to re-sow, to sow again, to sow perpetually." And he selected his seeds with such care as to develop many improved varieties. In particular, he taught some pears to bear fruit in three years from the seed. Van Mons produced by selection about four hundred new varieties of pears, among others a dwarf variety that was a prolific bearer. Meantime, however, the pear was making its way in America, and one of the most famous va- rieties, the Seckel, originated in the early part of the nineteenth century on the farm of a man whose name it bears near Philadelphia. This was a "spontaneous" variant or mutant, the precise origin of which is unknown. [114] ~fs*tpf$tiM LUTHER BURBANK At the time of its origin the Seckel was pro- nounced by the conservative London Horticultur- ist Society to be superior to any European variety of fall pear then known. Rather curiously it chanced that the next very notable step in the progress of the pear also took place on a farm near Philadelphia. The owner of the farm was Mr. Peter Kieffer. The thing for which he was responsible was the introduction of a pear bearing his name, which originated through the chance hybridization of a pear of European strain with the Chinese sand pear, which had been introduced as an ornamental garden tree not long after relations were established between America and the Far East. The oriental pear which thus at last came to mingle its racial strains with those of this remote relative, after the two had traveled around the world in opposite directions, was a graceful tree having large and attractive flowers and bearing fruit of a pleasing fragrance but of such consist- ency as to be almost uneatable except when cooked. In spite of the defects of its fruit, how- ever, the oriental pear had certain qualities of hardiness and resistance to disease that made it a valuable mate for its European cousin. So the Kieffer pair soon gained popularity. So also did a number of other hybrid pears of [116] ;i»fi>B *&***M* n o s- 2 LUTHER BURBANK similar origin, including the Le Conte, the Garber, and the Smith. These hybrids soon became stand- ard pears in the Gulf States, where the European pears do not thrive. MAMMOTH PEARS IN CALIFORNIA The hybrid pears did not gain popularity in California, because the climate and soil of this state seemed to be peculiarly hospitable to the European pears, notably the Bartlett. By crossbreeding and selection these have been so developed, without hybridization with the oriental species, as to assume almost colossal pro- portions, and while differing widely in flavor from the original stock, to retain enough characteristics of the original to constitute a most valuable mar- ket fruit. The California pears, indeed, have quite out- done themselves. They have been described as "grand in size, delicate in color and aroma, and of unsurpassed richness." A specimen has been re- ported that was "nine inches high, sixteen inches around the base, and five pounds in weight." Pears of allied varieties show scarcely less notable tendency to grow to unprecedented size; for example, five Vicar of Winkfields are reported as weighing four pounds, eight ounces; nine Easter Beurre as weighing 24% pounds, the heaviest sin- gle specimen weighing 2% pounds, and the like. [118] ON THE PEAR In the mere matter of size, then, there remains little to be desired; but there are other qualities as to which not so much can be said. In particu- lar the pear is often susceptible to disease, and in general the extreme development of productivity has been more or less associated with a tendency to lose vigor, rapidity of growth and general vitality. For this and sundry other reasons it seemed to me that it might be desirable to make further experiments in the blending of the oriental and occidental heredities. So as early as 1884 I made importations of the seeds of the Japanese pear. In a shipment containing loquats, plums, chest- nuts, persimmons, gooseberries, blackberries, peaches and raspberries, I received also twenty pounds of pear seeds. The seedlings were grown, but at first little use was made of them except as grafting stocks. The valuable developments that ultimately came from the introduction of the oriental hered- ities were not secured at the outset. TRAITS OF THE ORIENTAL PEAR About 1890 I imported from Japan large quan- tities of the seeds of the Chinese sand pear. The seedlings proved extremely variable. Some of them grew six or seven feet the first year, while others from the same lot of seed, under exactly [119] LUTHER BURBANK the same conditions, grew only a few inches; and a corresponding rate of growth characterizes the seedlings as long as they live. But, although the seedlings themselves proved so variable, their fruit was singularly uniform in size and quality. As to shape, the fruit of the oriental pear is usually oblate, approaching the globular. This raises a rather curious, if not very important, question as to whether the European pear owes its very characteristic shape to artificial selection. The ordinary pear, as everyone knows, has a form that is so individual and so little duplicated, that no single word of familiar usage describes it. In this regard, as in a good many others, the pear is unique. One would not commonly think of describing anything as "apple-shaped," or "peach-shaped," or "plum-shaped," but "pear-shaped" is a cogno- men that is at once convenient and definitive. So, as I said, the fact that the oriental pear has not assumed this shape has a certain interest and suggestiveness. The hybridizing experiments that were begun as soon as I was in possession of the oriental seedlings called for more patience, perhaps, than almost any other tests that the fruit experimenter can make, for the very obvious reason that the pear is the slowest to mature of all the fruits grown [120] A Patrician This seedling pear has qualities of form that entitle it to a special consideration. It has also good qualities of flesh, but, as will be seen, it is quite lacking in richness of color, except just about the stem, where there is a splash of red that suggests submerged hereditary color factors that might be brought to the surface by selective breeding. LUTHER BURBANK in temperate climates. It often requires from ten to twenty years for seedlings of the pear to come to their first fruiting. The matter may be forced a little by grafting the pear cions on quince stock, but while this makes them fruit earlier, it also tends to dwarf them, and I do not recommend this as a general practice, though highly desirable for special purposes. Whoever has not patience to wait had best not undertake experiments with the pear. With a tree of such slow development, it is peculiarly desirable to make no mistakes in select- ing seedlings for preservation. Judgment as to the future tree must be based, as with other fruit, largely on its growth, and the appearance of the foliage. Pear seedlings that have an abundance of large leaves, and strong, thick, short-jointed wood, and thick, fat buds, are those to be selected. But this is not by any means as sure an indication of superior fruit in the pear as in most of our cul- tivated fruit, for the reason that Van Mons and other workers in this line have mostly sought early-bearing and fine quality of fruit, neglecting the foliage and growth of the tree almost fully. THE EFFECT OF NEW BLOOD I grew great quantities of pear seedlings from seed imported in 1884 from Japan. The selected seedlings of this original stock have enormous, [122] ON THE PEAR glossy leaves, some of which for weeks after the first frost show varied and brilliant colors almost like the autumn foliage of oaks and maples of the Northeast. Many of the best of these were dis- tributed for planting as ornamental trees. Very early in the experiments I found among many seedlings of a cross between the Bartlett and the hybrid Le Gonte one that seemed to have exceptional qualities. This proved to be aston- ishingly productive of fruit of the largest size and best quality, and the tree had extraordinary vigor of growth and was apparently immune to the blight. But only one was selected as showing good promise as a fruit bearer. Through further hy- bridization and selection, during a period of near- ly a quarter of a century, the hybrid progeny of this Japanese pear developed a variety that was introduced in 1911 as the 'Test." Year after year it had produced two or three times as much as any other pear that I had ever grown. The fruit averages rather larger than that of the Bartlett, and it appears about four weeks later. The flesh is similar to that of the Le Conte but superior to it in quality, although hardly comparable to that of the Bartlett except when cooked. Although I have raised and fruited number- [123] LUTHER BURBANK less seedlings from a great variety of crosses, and have noted many variations, the Test is the only one that I have thus far thought worthy of intro- duction. Several hundred three-year-old seed- lings of this new pear, grafted on quince stocks, give great promise by their vigorous, compact growth, heavy foliage and full, round buds. Among those that have fruited are some mam- moth pears of exquisite quality when cooked; and a few are good when fresh. There is unusual variation in growth of wood, foliage, season of ripening, form, size, and quality of fruit. Some of the hybrids have a smooth, pol- ished skin with red cheeks; others are russet throughout. The varying qualities of the hybrids are doubtless due to the releasing of latent char- acters brought about by the commingling of the two widely diverse strains. It was necessary thus to hybridize and select through successive generations, because the ori- ental pear brought to the combination very unde- sirable qualities of fruit as to texture and flavor. Only when these were eliminated from later gen- erations, and the qualities of the Bartlett and its allies substituted, did the hybrid pear become a commercial possibility. But, along with its undesirable qualities of fruit, the oriental pear brought other qualities [124] Unhandsome but Luscious This seedling pear shows a tendency to depart from the typical pear shape, being much broader at the base, and corre- spondingly less graceful, than the favorite varieties. It h*zs, however, qualities of flesh that commend it, but these were not considered by Mr. Burbank to be sufficiently exceptional to war- rant the introduction of the fruit. LUTHER BURBANK that were pre-eminently desirable. First and fore- most it had fundamental vigor of constitution that promised to supply precisely what the European pear most lacked. This was manifested not only in the vigor of its growth, but in its seemingly al- most entire immunity to the attacks of the disease that has been the scourge of the pear growers of America for more than a century, and which made its appearance in California about ten years ago, the disease known as the pear blight. THE PEAR TREE SCOURGE To appreciate the importance of this element of resistance to disease, as manifested by the ori- ental pear, it must be understood that the blight is a malady of such virulent nature that when it attacks the pear tree it very commonly results in killing it outright. This suggests, obviously, a pe- culiar susceptibility on the part of the pear. Such susceptibility is manifested, unfortunately, in ex- ceptional measure by the best European varieties, including the Flemish Beauty and the Bartlett. This, presumably, is the penalty of over-specializa- tion in a certain direction, or unbalanced selection. Until very recently the cause of pear blight was much disputed, but the agricultural experiment stations have now furnished conclusive proof that it is a bacterial disease, due to the presence of a germ that has been named Bacillus amolovorus. [126] ON THE PEAR This germ has close cousinship with the vari- ous tribes of bacilli that cause the contagious human maladies. And there is a curious resem- blance between the assault of the microbes on the pear tree and the corresponding assaults of cer- tain bacilli, for example the diphtheria bacillus, on the human organism. In one case as in the other, the bacilli, once they find a lodging place, multiply inordinately and give out excretions that are virulently poisonous. Located on the flowers and fruit of the pear, or finding their way to the inner bark or cambium layer of the tree, they multiply prodigiously and exert a malignant in- fluence that withers blossoms, blights the fruit, and causes the leaves to take on a bronzed red hue that is often premonitory of the death of the tree. If they find lodgment in the cambium layer of the trunk, they may spread rapidly in every di- rection, until they girdle the tree, shutting off its supply of sap as effectively as if it had been girdled with an axe. Wherever lodged, the colonies of bacilli may be located by the oozing out of a milky or dirty brown sticky liquid when the spring rains come. This liquid is attractive to insects, and as the feet and bodies of these marauders become covered with the germ-laden fluid, the transfer of the [127] LUTHER BURBANK germs to other trees and to flowers and fruit even fairly remote is thus assured. Not merely flies and gnats, but the bee itself may have a share in thus transporting the contagion from one tree to another till it infects every tree in the orchard. The nectary of a pear, which the bee may in- advertently inoculate, furnishes a most favorable medium for the multiplication of the bacilli. Thence they work their way from the fruit buds to the limbs. Once they gain access, through the links in the tree's armor furnished by the buds, to the cambium layer of the inner bark, there is nothing to prevent the indefinite extension of their colony. A tree thus inoculated may soon take on the appearance of a tree scourged by fire. Indeed, the malady is sometimes spoken of as "fire blight." ANTISEPTIC SURGERY IN THE ORCHARD The measures taken by the horticulturist to save his tree when thus attacked are curiously suggestive of the methods of the modern surgeon. Infected limbs must be amputated; local areas of infection in the bark or trunk or large branches must be thoroughly excised, including a goodly portion of healthy wood and bark to make sure of the removal of every microbe. Large wounds are then carefully disinfected with a sponge or bunch of waste soaked in kerosene or in a solu- [128] Wit! LUTHER BURBANK tion of corrosive sublimate, one part to the thou- sand. It is merely antiseptic surgery applied to the tree to combat a microbe closely similar to the ones that are man's most malignant enemies. But, of course, such measures as these, how- ever necessary, can by no means be regarded as solving the problem of the pear blight. Just as the surgeon of to-day attempts to prevent the in- trusion of the germs, rather than to depend on killing them after they appear, so the orchardist must hope to find a means of preventing the blight instead of being obliged to practice such heroic and wasteful curative measures. One measure looking to this end that has been suggested is the destruction of old hawthorne and wild crab apple trees and of abandoned pear and apple trees in the neighborhood of the orchard, since a single infected tree would prove a source of danger to every tree within a radius of a mile or more. Such measures are important; but they do not go to the root of the matter. The real solution must come through making the tree immune to the attacks of the germ. This is the keynote of preventive medicine with the human subject to-day, as illustrated by the vaccine treatment, of which the most familiar example is [130] LUTHER BURBANK Sir Almroth Wright's inoculation for the preven- tion of typhoid fever. It is at least within the pos- sibilities that a not dissimilar inoculation may give the tree immunity by developing its powers of re- sistance, quite as the human subject is given immunity. Of course the tree has no arterial system that can be inoculated with hypodermic syringe as the human subject is inoculated. But the life of the tree is dependent on the circulation of fluids with- in its tissues none the less. These fluids are taken in by the roots, and they find their way to the ut- termost leaf. So it is conceivable that by proper treatment of the soil about the tree, the tissues of the tree itself might be so altered as to become resistant to the attacks of the bacterial enemies. IMMUNITY THROUGH TREATMENT AND BREEDING Nor is this idea altogether theoretical. Experi- ments have already been made that look to the checking of the growth of the tree by withholding fertilizers and water, that the development of the tender buds and shoots, which are the usual points of attack of the enemy, may be made to take place slowly and thus to present tissue of a less succu- lent order. Such hardening of the wood by withholding water has proved effective in the case of some pear orchards in Colorado, where it appears that the [132] A Seedling Pear This is a seedling pear that departs from the ideal shape, but which has many other qualities that highly commend it. It is large, and of luscious quality of flesh. Owing to its form, ana to its lack of color, however, it has not been introduced, but has been used in further breeding experiments in the attempt to develop an ideal pear. LUTHER BURBANK pear does not really need so much water as it or- dinarily receives. But the effort to give the tree immunity must go even deeper. Induced immunity is valuable, but the ideal condition is that of inherent resist- ance, bred in the tissues. Physicians tell us that the all-important thing in warding off bacterial infections in the human subject is the inherent vitality and resistance of the patient himself. In the last analysis, this is the prime essential. A thoroughly rugged organ- ism may be immune to almost every type of bac- terial disease. We are told that almost no one escapes infection with the germs of tuberculosis. The ones who show no evidence of the disease are simply those whose tissues are so resistant that the attacks of the bacilli are thwarted. The horticulturist must take a lesson from the experience of the physician, in particular with regard to the malady we are now considering; for, as we have just seen, the analogy between the pear blight and human infections is almost perfect. So the ideal at which the plant experimenter must aim is the development of a tree that will be im- mune to the attacks of the bacillus, however freely the germ finds access to it. My new hybrid pear, thanks to its Oriental heritage, seems to fulfil this condition. The same [134] ON THE PEAR thing appears to be true, at least in some measure, of the other hybrids that have the Oriental strain. So there is every reason to hope that we shall be able to develop races of pears, having all desirable qualities of fruit for the different markets, that will be free from the pest that hitherto has made the raising of this fruit a more or less precarious industry. IDEALS AND POSSIBILITIES As to the other needs and possibilities of pear development, not much need be said. Reference has elsewhere been made to the desirability of giving the pear a brilliant color; but this can doubtless be accomplished without great difficulty. It has also been noted that as to size of fruit, as well as in the matter of form, there is little to be desired by way of change. There is, however, one quality that the special- ized pears have markedly lacked. They will keep for a time if plucked while green, and will ripen off the tree. But if allowed to ripen on the tree they decay very quickly after picking. It is ob- viously desirable that the pear should be given keeping qualities. But here, as in case of im- munity to the blight, the solution is already in sight. Among the varied fruits of my hybrid seed- lings, there are some that produce winter pears [135] LUTHER BURBANK that keep quite as well as ordinary winter apples. These furnish the foundation for future hy- bridizing and selecting experiments, through which, without question, it will be possible to produce races of pear having all the qualities of flesh that have hitherto made the fruit popular, and with the added property of keeping over winter. Other possibilities of pear development lying a little farther in the future and therefore some- what more vaguely outlined, have to do with the hybridization of the pear with the allied fruits of related species. It is well-known that the pear shows, in this regard, a strong disinclination for entering into such an alliance. The pear may be grafted on the quince but it is usually considered impossible to graft it on the apple. I successfully carried out such a grafting ex- periment, however, when I was a boy in Massa- chusetts, the cion being a Seckel pear. But al- though this grafted cion bore fruit for two sea- sons, it then died, probably because of the uncon- geniality of the alliance. This experiment shows that there is not com- plete antagonism between the two species; and the same thing is further demonstrated by the well-known fact that the apple may be grafted on the pear stock; although here also the alliance is [136] q;itafii»-:i irflc SSs1sif