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FUZZY PEACHES AND SMOOTH-SKINNED NECTARINES

TWO FRUITS WHICH BEG FOR MORE IMPROVEMENT

"Mr.Burbank," said a visitor, "you have taken the thorns off the blackberry bush and the spines from the cactus. Now why can't you take the fuzz off the peach?" "Most of us don't deal much with blackberry briers or with cactuses, spiny or otherwise; but we all eat peaches, and a good many of us would about as willingly bite into a spiny cactus as a fuzzy peach. If you will only take the wool off this otherwise perfect fruit, we will raise a monument to you by popular subscription." "But nature took the wool off the peach some thousands of years before you and I were born," I answered; "and I have not heard of any monuments being erected in commemoration of the event." "What in the world do you mean? A fuzzless peach-who ever heard of such a thing?" "Everyone has; the fruit that you call a nectarine is precisely that thing-a peach without the fuzz." "But that does not serve the purpose at all," he insisted. "If the nectarine is a peach that has lost its fuzz, it is also a peach that has lost its flavor. What we want is a fuzzless peach with the true peach flavor remaining." "Well, I think I shall be able to satisfy you even there before a very great while," I answered; "for I am on the track of experiments that are likely to meet all your requirements in that direction. Even now I have a fruit that is smooth-skinned and yet is unquestionably a peach-not only that, but a peach of excellent flavor. But it is not yet quite good enough to put on the market, and I shall have to carry the experiment a stage or two farther before I am ready to demand that monument." And then I led the way to a part of the orchard where I was able to show a number of peaches with perfectly smooth skins, some of which are by no means ill-flavored, even though none quite compete with the best peaches now on the market. My visitor assured me that nothing else that he had seen gave him so much satisfaction or aroused such pleasurable anticipations as this smooth-skinned peach. And I suspect that a very large number of persons under the same circumstances would be of the same mind, for I am told that the aversion to the fuzz of the peach is a by no means uncommon form of phobia. It might be of interest to inquire just how this curious antipathy to anything so soft and delicate as the structure of the peach's skin was developed. I know men of perfectly stable nerves who cannot touch a peach without experiencing a disagreeable sensation, and who cannot bite through the fuzzy surface without shuddering. And as there seem to be large numbers who experience more or less the same sensation, it goes without saying that there must be some hereditary basis for this curious and seemingly absurd prejudice. It is somewhat comparable to the fear of the mouse so common with women, or the instinctive dread of the snake that most of us feel. Just how the peculiar antipathy was developed, would, as I say, be a curious matter for speculation. Here, however, we are concerned with the fuzz of the peach not in its direct relation to human psychology, but in its bearing on the heredity of the peach itself. To the plant developer this is a matter of interest, because linked with it is the question of the way in which the superfluous skin-covering can be eliminated. I speak thus of the fuzz of the peach as being superfluous, but on second thought we cannot be too sure that it really serves the fruit no useful function. Indeed, the inference should be rather the other way. At least we may feel sure that unless the woolly coating at some time served a very important purpose, it would never have been developed; or, having been developed, it would not have been retained. That is assuming, however, that the peach developed this unusual fruit covering in a state of nature, and without the aid of man's selective influence, which it certainly did.

HOW THE PEACH GOT ITS COAT

If it could be shown that the fuzz was developed only after the peach came under cultivation, and in response to man's wishes, the case would be altered. In that event it might readily be that the fuzzy covering, appearing first as an accidental "sport," had been retained because it pleased the fancy of some plant experimenter, or met the taste of some influential market man-say of Athens in the olden days, or of Rome in the time of its power. But in all probability the peach had its fuzzy coat at a time vastly more remote than this. It is almost certain that the coat was developed long before the fruit came under cultivation. The fair presumption is, probably, that the ancestor of the peach, wandering from one territory to another as all plants do, found itself at a certain stage of its career in an environment where the conditions of moisture and wind and sunshine were peculiarly trying, or where some insect or fungoid or bacterial pest menaced its immature fruit. And in such a case it may readily have chanced that a peach that tended to produce a skin of exceptionally resistant texture, one in which the bloom assumed a more than usually powdery or fibrous character, was given protection against the enemies, and thus preserved where fruit with smoother skin was destroyed. Under these circumstances, the incipient fuzz on the peach would serve as material for the operation of natural selection, and a race of peaches bearing fuzzy-skinned fruit would presently supplant the tribe of smooth-skinned peaches. Something like this, I suspect, we should find to be the history of evolution of the fuzzy-skinned peach, could we look with some necromantic microscope into the germinal center of the peach seed and translate the marvelous history of endless generations of peaches, back to the beginning, that is therein recorded. There is no such microscope as this, of course. But we can, in a sense, perform the same necromantic feat, and lay bare the mysteries of the history of the evolution of the race of peaches, in a quite different manner. If you have read the earlier chapters of this work, you will know that the method I have in mind is the familiar one of causing the germ plasm of the peach, with its weird record of past events, to blend with the germ plasm of another tribe of plants having a somewhat different history; in order that the conflict of tendencies thus brought about (as we used to say; or the blending of hereditary factors, to use the popular phrase of the moment), shall bring to the surface and make tangible in the hybrids of a new generation, the traits that were submerged and hidden in the individual plant before us. And when this familiar yet no less wonderful test is applied, we learn, among other things, that the peach which now holds to its fuzzy coating so tenaciously, at one time had a cheek as smooth as that of any other fruit. For among the offspring that appear as the result of blending peach strains, there now and again is one that bears smooth fruit. Moreover, the smooth fruit that thus appears is closely similar to another fruit which, from its general appearance, would be declared by any competent observer to be a close relative of the peach, namely, the nectarine. So this bit of evidence from heredity-this freak of atavism-may be taken as furnishing substantial evidence that the ancestor of the nectarine was also the ancestor of the peach. Or, stated otherwise, that the peach is in reality a modified nectarine. It may be added that both are undoubtedly modified from a plum-peach-apricot-almond ancestor. That the nectarine, rather than the peach, represents the ancestral form is witnessed by the fact that the nectarine is rarely observed-at least in my experience-to produce a fuzzy fruit, however closely it may otherwise simulate the peach. And, of course, this evidence is in keeping with the natural inference one would draw from the fact that pulp fruits in general have smooth skins, or skins with at most a delicate bloom quite lacking the texture of the peach's almost woolly covering.

THE MARRIAGE OF COUSINS

In any event, there can be no question that the peach and the nectarine are very closely related; in fact, they are generally classified as a single species, the trees differing very slightly in any respect, the only difference being in the fruit. It is probably but a short time, as compared with the entire stretch of their racial histories, since the two fruits branched from the same stem. And so it is quite to be expected that the two would readily cross. In point of fact, the experiment of cross-pollenizing is so readily performed that it is very often carried out by the bees. The hand pollenizer may make the test successfully without the slightest difficulty. I was led to experiment along this line by the recollection of an old peach tree called a "Melocotoon", four of which stood in our home garden in New England, and one of which, as I well recall, had a single branch high up in the tree that always bore a fruit quite different from the peaches with which its other branches were laden. This anomalous fruit, which appeared as a "bud-sport" was in fact a nectarine. I had learned also that when peaches and nectarines were grown in the same neighborhood, one could never be certain as to which fruit would grow when the seed of either fruit is planted. You may plant a peach seed and grow a nectarine tree; or, far less frequently, you may grow a peach tree from a nectarine seed. The explanation, of course, is that the two tribes are constantly intercrossed when growing side by side, through the agency of the bees. Pondering these facts, I determined to mate some definite experiments in hybridizing. I first selected for the experiment the white nectarine and the Muir peach. In 1895 numerous crosses were made, using principally the white nectarine pollen to fertilize the blossoms of the Muir peach, a very hardy, vigorous, abundantly productive variety of the peach that is largely cultivated in California. The white nectarine has a rich flavor, but it is too acid to eat without cooking. It is of large size, has a large stone, and white flesh, with perfectly smooth white skin. The Muir peach, on the other hand, is very sweet, with firm yellow flesh, and an unusually small, free stone. A tree of this variety is unusually hardy, long-lived, and immune from that pest of the peach orchard, curl-leaf. It may be grown in a large variety of soils in locations where other peaches and nectarines often fail. The offspring of this union of nectarine and peach in due course came to fruiting age, and in some cases the fruit they bore was found to be of a quality superior to that of any peach or nectarine at that time ever seen. In the second and third generation there appeared a varied company, showing remarkable new combinations of qualities, and anomalies of form, size, color and flavor. Many of them combined the sweet yellow flesh of the peach and the acid quality of the nectarine, producing delectable and altogether novel flavors.

SMOOTH-SKINNED PEACH HYBRIDS

There are now large numbers of these crossbred peach-nectarines on my place, some of them being of the fifth and sixth generation from the original crossing, Some have a crimson leaf like that of the crimson-leaved peach. Some that have the characteristic rough stone of the peach, retain the smooth skin of the nectarine. These constitute a smooth-skinned variety of peach such as the visitor with the aversion to fuzzy skin longed for. First and last, these hybrids show almost all possible combinations of a score or so of qualities as to which the two fruits in their divers varieties differ. Among these there are some that are of such desirability as to make the fruits worthy of introduction, notwithstanding the very excellent assortment of peaches already on the market. The first member of the hybrid company to be sent out into the world was named the Opulent. It grew on a vigorous tree that bore abundantly even when quite young, and produced a full crop of superlatively luscious fruit each season, ripening here about July 30th. The fruit has a white skin with numerous beautiful dots and shadings of light and dark crimson, and the flesh is pale lemon yellow, suggesting a blend of the deeper tint of the Muir peach and the white flesh of the nectarine. In flavor the fruit has an indescribably delicious quality that in my estimate surpasses that of all other peaches. But it is too soft for long shipment, although having all the desirable qualities of a home fruit. The Opulent has been acknowledged by all who have tested it to be the best in quality of any peach ever produced. The tree is unusually hardy. It has been cultivated as far north as Canada and has proved able to endure a temperature of 40 degrees below zero, bearing a full crop after other peaches in the same locality were destroyed by the severity of the winter. Among the numerous seedlings from the Opulent, some are white nectarines pure and simple, some are red or pink nectarines, and some closely resemble the Muir peach. Yet here and there one differs from any known variety of peach or nectarine. Similar results have been obtained in a subsequent series of experiments, in which the white nectarine was crossed with the early Crawford and peaches of other varieties. These crosses produced some seedlings of unusual size and good quality. The trees are nearly all resistant to curl-leaf and mildew. As might be expected, the seedlings from succeeding generations differ widely. While nearly all possess one or more desirable qualities, it is rare that any one combines enough good qualities to entitle it to special consideration.

THE UNION OF PEACH AND ALMOND

Another series of hybridizing experiments, begun about eighteen years ago, used for the original cross the purple-leaved peach and the Languedoc almond. In the first and second generations, the four or five thousand seedlings produced had green leaves like the almond. In the succeeding generation, however, there appeared a few seedlings having purple leaves suggestive of those of the peach ancestor. A particularly dark one was saved. As is usual with the peach and almond hybrids, this tree was very fertile. One season I obtained more than 500 fruits from it. In every respect this fruit was intermediate between the peach and the almond. About nine-tenths of the seedlings grown from the fruit of this purple-leaved hybrid had purple leaves like the parent plant; most of the others had leaves of pure green, but a small proportion showed leaves of an intermediate color. Looking at the row of seedlings from a short distance one would hardly perceive anything but a line of deep crimson or purple. Some of the individual seedlings were much darker than the parent, being fully as dark as the original purple-leaved peach. Most of the seedlings resemble the peach in foliage, but some have longer and more pointed leaves like the almond parent, and these grow more rapidly than the others and have a more upright appearance, in this respect also resembling the almond. Although the exact parentage of the hybrids of the later generations of this combination of the almond and the purple-leaved peach was not traceable, and although no close record was kept of precise numbers, it will be obvious that the result of the first cross showed that, as between green leaves and purple leaves, in the relations of these two species, the influence of the green leaf was prepotent or dominant. This is perhaps what one would expect, considering that green is the normal color of leaves, and purple exceptional. The reappearance of the purple leaf in later generations is, of course, precisely what would be expected of a recessive character. In any event the reappearance of the purple leaf, fully pigmented, after its submergence, affords another interesting illustration of the segregation of hereditary characters that we have repeatedly had occasion to note in connection with other experiments.

COUSINS FROM THE ORIENT

Continuing the experiments in peach betterment, I not unnaturally turned to the Orient for the material for further experiments in crossing. There is a double-flowering peach that has long been under cultivation in China and Japan. It is a slender, willowy tree, generally with drooping branches. The blossoms are about an inch and a quarter across, snowy white, or pink, or deep crimson. They are quite double, resembling little roses, and they are produced in great profusion. The trees, however, are dwarfed and ill-shaped; they are also peculiarly subject to mildew and curl-leaf. The fruit of the flowering peach is somewhat almond-shaped and unusually pointed. It has flesh of light color and a large stone. The fruit is hardly edible even when cooked. I have taken particular pains to cross this double flowering exotic with standard and the new cross bred peaches, and have succeeded in producing some fine varieties. The most striking result, up to date, was a tree bearing a rich, rosy, pink blossom, fully two inches in diameter, which is produced in greatest abundance, on trees of strong growth, which show no propensity to droop like the oriental tree, and which appear to be resistant to curl-leaf and mildew. This large, vigorous, healthy tree, bearing a profusion of bright pink flowers, has obvious ornamental value. But in addition to this, this new variety bears an abundance of fruit, large in size, and almond-shaped, which is of fairly good quality when fresh, although scarcely to be compared with standard peaches, but which when cooked is probably unsurpassed by any peach, having a delightful almond flavor. This particular variety is a cross of the crimson flowering oriental peach and the hybrid Muir peach, and is a product of the first generation. Especial interest attaches to the results of crossing the oriental peaches with peaches of the occidental stock because, as in the case of so many other fruits, the peach of the Orient is widely divergent from the European type, although doubtless both have the same remote origin. As in the case of our other chief fruits, the native home of the peach was doubtless southern and central Asia and eastern Europe, and there was a double migration in prehistoric days which resulted in stocking China with peaches of one type and Europe with quite another. The peach most commonly grown in the United States is usually spoken of as belonging to the Persian race. The Chinese type of peach has been variously tested in California, and for the most part found wanting. The chief defect of the Oriental variety is the pointed almond shape of its fruit, and susceptibility to mildew and curl-leaf. It will be recalled that the oriental pear showed precisely the qualities of hardiness and resistance to disease that the oriental peach notably lacks. The difference, in all probability, is to be explained by the different treatment the two fruits have received in their Asiatic home. The pear has been developed for its fruit, and the oriental taste demanded certain qualities of firmness and perhaps slight astringency that might be said to be in keeping with the natural character or propensity of the wild fruit. But in the case of the peach special development has taken place along the line of flower production. Doubtless more attention has been given to this than to the question of fruit. And as with most specialized races of plants, there are incidental defects due to the selective breeding for a single quality, and the overlooking of other qualities. But whatever the explanation, the fact remains that the Chinese peach is not to be looked to as introducing the elements of hardiness and virility. Nevertheless in the southern states the Chinese peach, which seems to be of tropical origin, thrives and is even quite as popular as the Persian strains. Fortunately some of the varieties of the European stock are vigorous and hardy growers. But the development of new varieties that will be absolutely resistant to the diseases to which the peach is peculiarly subject is a task that invites the plant experimenter. I have already referred to the success in this regard that attended some of my hybridizing experiments. My new peaches, named respectively the Leader and the National, both of them crosses of the Muir and Crawford stock, have been entirely free from any suspicion of mildew or curl-leaf. But there is demand for a great variety of peaches, and it is highly desirable that the average stock of this important fruit should be greatly improved in regard to virility. That the peach may under favorable conditions live to an old age and continue in bearing is demonstrated by exceptional trees that are known to be half a century old, yet still retain their vigor and productiveness. When we contrast with this the familiar fact that the average peach orchard bears only for a relatively short term of years, often only ten or fifteen at most, the vast economic importance of this possible improvement will be quite obvious.

A STONELESS PEACH?

As to the fruit itself, there is one opportunity for improvement that is particularly inviting-the possibility of producing a stoneless peach. The desirability of such a development, from the standpoint of the peach consumer, requires no demonstration. From the standpoint of the tree itself, a reduction in the stone would be highly important. It costs a peach tree to produce a pound of stones probably as much as to produce many pounds of pulp. The drain on the vitality of the tree in producing the stone that it no longer needs must take from it in some measure the capacity for production of fruit pulp that it might otherwise have. The hybridizing experiments with the almond have influenced the stone of the fruit in a suggestive way. Some of my hybrid peaches have a kernel that is almost as sweet and edible as the kernel of the almond. As yet I have not secured a peach having really good quality of flesh combined with the edible seed. But that this combination might be effected, if one were to select for it, admits of no question. And a peach retaining its recognized qualities of flesh and having at its center an edible nut like the almond with thin shell would obviously be a desirable acquisition. Such a combination of fruit and nut would be doubly desirable if the stone that surrounds the kernel can be eliminated as it has been eliminated in the stoneless plums. As yet very little has been accomplished in this direction. There is, to be sure, a Bolivian peach which is remarkable in that it has a globular stone very little larger than a good-sized pea. The fruit itself is of intermediate size and poor quality; moreover, it is produced sparsely, and the tree is peculiarly subject to the peach maladies. The fruit has been thought hardly worth crossing with our ordinary peaches on account of its inferior qualities, yet the diminutive stone suggests that it would be possible by such crossing to produce a superior peach having an exceedingly small stone. Time and patience would, of course, be required to carry out such an experiment, but its results could hardly be in doubt. It is possible, however, that the experiment of reducing the size of the peach stone will prove less inviting than the attempt to remove the stone altogether. My success in producing the stoneless plum points the way to a possible development through which the peach also may at some time become stoneless. And it is not unlikely that the Bolivian pea-stone peach, which has shown a propensity to minimize the stone, may be utilized advantageously in the course of these experiments. It is true that no stoneless peach of whatever quality is known, comparable to the original wild bullace of Europe, that gave the opportunity in the development of the stoneless plum. But, fortunately, I have been able to demonstrate that the peach may be hybridized with the plum. I have made the hybridization successfully with both the Japanese plum and the Chickasaw plum. Should it prove impossible to hybridize the peach directly with a stoneless plum, one of these peach-plum hybrids might perhaps be made to bridge the gap. No doubt a vast deal of ingenuity would be required to find the combination that would work out successfully. But it was shown in the case of the stoneless plum that it was possible to reassemble the good qualities of the fruit of one parent and the stoneless condition of the other in the progeny of the hybrids of later generations. There is no obvious reason why the same thing might not be done in the case of the peach. The possibility seems the greater because the peach has been cultivated in so many different regions and for so many different purposes that it is highly variable. Its affinity with other stone fruits has been illustrated over and over in the story of hybridizing experiments already related. So it seems at least within the possibilities that a way may be found to combine the stoneless condition which has now been bred into the germ plasm of one member of the stone-fruit family, with the recognized qualities of the peach, in a hybrid-produced, no doubt, only after a series of experiments extending over many years-that will represent the ideal of a stoneless peach. If the qualities of the almond seed were also bred into the combination, the final product-a fruit having the matchless flavor of the peach, a perfectly smooth skin, and a stoneless seed of delicious edible quality-would assuredly be the paragon of orchard fruits. That such a fruit will ultimately be produced there can be little doubt. When we reflect on the long gap that separates the peach of to-day from its primitive wild ancestor, we need not regard such further development as that just suggested as being very formidable. But, of course, there is a time element that cannot be ignored. So here, as with other orchard fruits, it is only such experimenters as have the gift of patience who can enter the field with prospect of success. Granted that endowment, however, and a reasonable comprehension of the principles of plant breeding already presented, any intelligent amateur may undertake experiments in the further education of the peach that may well lead to results of the highest interest and of notable economic importance.

-The peach with its luscious meat, the nectarine with its smooth skin, the almond with its delightful kernel, and the stoneless plum with its unsheathed seed-who will breed these together and thus produce a unique and valuable fruit-nut?

This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 4 Chapter 5