PROGRESS IN
APPLE IMPROVEMENT

J. R. MAGNESS, Principal Pomologist,
Division of Fruit and Vegetable Crops and Diseases, Bureau of Plant Industry¹

[Abstract]     APPLE breeding is a task that requires not only great patience but ability to look well into the future. In most sections of the United States at least 10 to 15 years are required to grow an apple from seed to bearing age and to obtain an accurate evaluation of it. To propagate and test a promising kind will require an additional 10 to 12 years. Therefore not less than 25 years are usually required from the time a cross is made until the progeny of that cross can be fully evaluated. Additional years must then elapse before commercial orchards come into fruiting. Thus it usually takes from 30 to 40 years between the planting of the original seed and the production of commercial crops of even a very superior apple. Apples originating from the earliest breeding investigations in the United States, begun as far back as 1880, are just now coming into prominence; those from the breeding work of 20 or 25 years ago are not yet fully tested. It is easy to see, then, why few of our popular commercial varieties have as yet resulted from modern breeding work. However, there is every prospect that varieties superior to those now in use will result from the many thousands of hybrid seedlings now under test at various research centers.

The apple we have today is far removed from the “gift of the gods" which prehistoric man found in roaming the woods of western Asia and temperate Europe. We can judge that apple only by the wild apples that grow today in the area between the Caspian Sea and Europe, which is believed to be the original habitat of the apple. These apples are generally only 1 to 2 inches in diameter, are acid and astringent, and are far inferior to the choice modern horticultural varieties.

The improvement of the apple through the selection of the best types of the wild seedlings goes far back to the very beginning of history. Methods of budding and grafting fruits were known more than 2,000 years ago. According to Unger, Cato (third century, B. C.) knew seven different apple varieties. Pliny (first century, A. D.) knew 36 different kinds. By the time the first settlers from Europe were coming to the shores of North America, hundreds of apple varieties had been named. in European countries.

The superior varieties grown in Europe in the seventeenth century had, so far as is known, all developed as chance seedlings, but gardeners had selected the best of the seedling trees and propagated them vegetatively.

The early American settlers, particularly those from the temperate portions of Europe, who came to the eastern coast of North America, brought with them seeds and in some cases grafted trees of European varieties. Within a few years after the first settlements were made in the temperate portions of North America, bearing apple trees were reported.

From this start, apple trees were rapidly disseminated. The apple was apparently carried by Indians, traders, and missionaries into the wilderness far beyond the white settlements. In the early writings frequent mention is made of Indian villages with apple and peach orchards adjacent to them; apparently the Indians were an important factor in the early dissemination of these fruits. All the Indian orchards consisted, of course, of seedling trees. Since the apple does not come true from seed, wide variations in size, color, and quality of fruit and season of ripening undoubtedly occurred in these early orchards. As the country became more settled, farmers and gardeners were interested in growing the best of these seedlings rather than in planting a miscellaneous assortment that could be secured from seed.

   Certain it is that in 1647 the apple is recorded as grafted upon wild stocks in Virginia, while in 1686 William Fitzhugh, in describing his own plantation, mentions "a large orchard of about 2,500 apple trees, most grafted, well fenced with a locust fence.” * * * Frequent importations of seeds, scions, and grafted trees, together with propagation from those already noticed, both by seeds and grafts, brought the orchards of New England up to such point that Dudley, in 1726, stated in a paper in the Philosophical Transactions, “our Apples are without doubt as good as those of England, and much fairer to look to, and so are the Pears * * * Our People of late years, have run so much upon Orchards, that in a village near Boston, consisting of about forty Families, they made near ten Thousand Barrels [of cider].”

As settlements spread westward to the Mississippi Valley and on to the Pacific, apple planting kept pace. An eccentric missionary, John Chapman, known as “Johnny Appleseed”, roamed the frontier settlements of Ohio and Indiana in the early nineteenth century, planting apple seed and starting orchards wherever he went and encouraging others to do the same. He lived to see bearing trees throughout the area. Thus the apple became more or less naturalized throughout the temperate part of North America.

The apple varieties grown here today are quite largely those that have been developed from the seedling trees that happened to be superior. Only a few of our important commercial varieties have been imported from Europe. During the past century the primary emphasis in the United States has been on varieties with superior dessert and cooking quality, along with good size, a range of ripening from midsummer to late fall, and a storage quality that will carry the fruit through the winter months. Perhaps the greater emphasis in Europe on the use of apples for cider making is partially responsible for the smaller number of really high-quality dessert apples selected there. Table 1, in the appendix, indicates the source of leading American varieties of apples so far as it is known.

Few of the apples that have reached commercial promise to date have been produced as a result of systematic hybridization. The reason for this is readily apparent when certain of the factors involved in apple breeding are considered. Practically no systematic work was started in the United States prior to 1880, and little was carried on prior to 1895. In most sections of the United States at least 10 to 15 years are required to grow an apple tree from seed to bearing age and to give an accurate evaluation of it. To propagate and test a promising kind will require an additional 10 to 12 years. Therefore not less than 25 years is usually required from the time a cross is made until the progeny of that cross can be accurately evaluated. Additional years must then elapse before commercial orchards come into fruiting. Thus from 30 to 40 years will usually elapse between the planting of the original seed and the production of commercial crops of even a very superior apple. Apples originating from the earlier breeding investigations are just now coming into commercial prominence. Since much of the breeding work has been conducted during the last 20 or 25 years, sufficient time has not yet elapsed to give a full evaluation of the offspring of the crosses made.

The apple belongs to the great family of plants termed by botanists the Rosaceae, or rose family. This family is very large and includes many tree fruits of the Temperate Zone, such as plums and prunes, peaches, cherries, apricots, and pears, as well as strawberries, blackberries, and many other forms of cultivated and wild plants. Apples and. pears belong to the pome fruit subfamily Pomoideae, which includes, in addition to these fruits, the hawthorns, cotoneasters, quinces, medlars, mountain-ash, and a number of additional related forms. All of the plants in this subfamily are characterized by having the seeds borne in a fleshy covering and having two to five carpels, or seed cavities, in each fruit. Within the Pomoideae the genus Malus, comprising the apples, makes up one important group. Many botanists have included the apple in the pear genus, Pyrus. The fruits of these two groups are distinguished by the fact that the pears contain grit cells, while the flesh of the apple is free of grit cells. There are also other distinctive differences in the structure of certain flower parts.

The various species that make up the genus Malus can in most cases be hybridized rather readily. Species of Malus apparently do not hybridize readily with species of Pyrus or with those of other genera in the Pomoideae. No such crosses have been reported, although there has been ample opportunity for them to occur naturally in view of the wide distribution and adjacent plantings of many members of these genera.

There is some difference of opinion among botanists as to whether one or more than one species originally entered into the parentage of our cultivated apple. The wide diversity of existing forms has led some students to believe that several species were involved originally. However, this diversity might well be expected in a fruit crop selected and cultivated for thousands of years and propagated largely by vegetative means. Every interesting variation occurring in seedlings could thus be preserved.

In addition to the cultivated apple, Rehder, in his Manual of Cultivated Trees and Shrubs, lists 24 species of apples or crab apples, native mainly in China, Siberia, Japan, and the United States. Bailey in his Manual of Cultivated Plants makes a somewhat different division, listing 25 species of Malus. Knowledge of the close relatives that might be expected to hybridize readily with the cultivated apple is of much interest from the breeding standpoint.

While these species represent basic raw material available to the apple breeder, for most purposes it is not desirable to use the original types in breeding work. The selection of superior varieties through the centuries has given us breeding material that is far more promising than the parent species for the development of superior new kinds by hybridization. Only when special characters, such as extreme hardiness, are needed does it seem more desirable to use original species material. For the production of crab apple types and for ornamental purposes, however, these species are of outstanding value.

Objectives in the apple-breeding work vary, of course, in different sections. Throughout most of the apple belt in the United States increased winter hardiness is highly desirable, and in the colder sections, including the northern Great Plains area and northern New England, it is the all-important factor in apple production. A few varieties such as McIntosh, Wealthy, Oldenburg, and Yellow Transparent are sufficiently hardy for all but the northernmost part of the Plains region. Many important varieties, including Baldwin, Stayman Winesap, Winesap, Grimes Golden, Rome Beauty, Yellow Newtown, and Jonathan, may be severely injured or trees may be killed during severe winters in many sections of the country. Increased hardiness must continually be sought in the apple-breeding program for all but possibly the southeastern districts.

The second most important objective is greater disease resistance. The five diseases that cause the greatest loss of apples in the United States are scab, blotch, bitter rot, fire blight, and apple cedar rust. There are wide degrees of susceptibility to all of these diseases. No commercial variety is immune from scab. However, McIntosh, Delicious, Stayman Winesap, and Rome Beauty are far more subject to the disease than are Grimes Golden, York Imperial, Baldwin, or Jonathan. Similarly, Golden Delicious, Yellow Newtown, Grimes Golden, and Jonathan are extremely subject to bitter rot, and for this reason they are of doubtful value for planting in the far southeastern districts. “On the other hand, Winesap, Baldwin, Delicious, Rome Beauty, Stayman Winesap, and York Imperial are relatively resistant to this disease.

Varieties very susceptible to blotch include Ben Davis, McIntosh, Northwestern Greening, and Oldenburg, while a list of relatively resistant varieties includes Delicious, Grimes Golden, Jonathan, Stayman Winesap, and York Imperial.

Baldwin and Delicious are highly resistant to apple cedar rust, while Jonathan, Rome Beauty, Wealthy, and York Imperial are quite susceptible. Seedlings of resistant parents show a high degree of resistance to this disease, while seedlings of susceptible parents are highly susceptible.

Fire blight is a serious orchard disease of Yellow Transparent, Jonathan, Wealthy, York Imperial, and a number of other varieties. On the other hand, Delicious, Ben Davis, and the Winesap family of varieties are resistant. We know that seedlings of Yellow Transparent tend to be susceptible, but we have little information as to how the characters of susceptibility or resistance to fire blight or other diseases behave in hybridization.

Susceptibility to spray injury also is an important character from the standpoint of evaluating a variety for commercial use. Golden Delicious and Ben Davis are particularly susceptible, while many varieties, including Delicious, McIntosh, Rhode Island Greening, Rome Beauty, Stayman Winesap, and others, show little injury.

The securing of new varieties fairly resistant to all of these diseases and to spray injury is a distinct possibility. It should be a primary objective in breeding, and all new selections should be studied from the standpoint of disease susceptibility.

The third objective, important in many parts of the United States, is the securing of late-blooming varieties that will have a greater possibility of escaping spring frosts and freezes. In most apple sections spring frosts or freezes are likely to reduce the apple crop greatly in certain years. In some sections this may run as high as 2 years in 5, in other sections perhaps not over 1 year in 10. Varieties blooming a week to 10 days later than standard types would have an increasingly better chance to escape such losses. This is particularly important in some of the midwestern areas. The late-blooming character is present in Rome Beauty, Mother, Ralls, and some other varieties, and through the use of such varieties in breeding, late- blooming trees can be obtained.

A fourth objective is the securing of varieties having highly developed, rich flavor combined with desirable tree characters.  Among highly flavored varieties are Delicious, Golden Delicious, Esopus Spitzenburg, Jonathan, Grimes Golden, and McIntosh. Many of these have horticultural weaknesses such as lack of hardiness, disease susceptibility, insufficient tree vigor, and susceptibility to spray injury.

It is desirable to obtain high-quality, attractively colored varieties that will be available throughout the year through the use of cold storage. Improvement in color in our present varieties is being accomplished by selection of attractive, highly colored bud mutations. On the average our long-keeping varieties are inferior in quality to those that are available earlier in the season, such as McIntosh, Grimes Golden, and Jonathan.

Another important objective is the development of varieties adapted to the far South. At present there are no satisfactory varieties for the region within 200 miles of the Gulf of Mexico. Native crab apples might be of value for hybridizing to produce varieties adapted to that region. No active work of this kind is under way, but there is a real need for it. Until apples can be grown locally, many people in that region will never have an adequate supply of the fruit.

The relative importance of these different objectives varies in different regions. In the Southeastern States disease resistance is of major importance. In the northern Plains area winter hardiness becomes the most important single objective. In the Missouri and Ohio Valleys, late blooming to escape the hazards of spring frost assumes major importance. Throughout all of the regions a succession of high-quality varieties available for use throughout the year is highly desirable.

Occasionally cell division in the vegetative tissues fails to reproduce a new cell exactly like the parent. The result is an occasional branch or bud that varies in some respect from the parent tree on which it is borne. Such a mutant branch or bud normally reproduces true when propagated vegetatively, provided the variation is a true mutation and has not been caused by environmental conditions.

The fact that such bud or branch mutations occasionally occur has long been known to plant propagators. It is only in recent years, however, that the importance of these variations, from the standpoint of improving our fruit varieties, has been fully appreciated.

During the past decade an intensive search of American apple orchards has been conducted to locate such mutations as may be of value. Since red-colored apples command a considerable premium on the American markets, mutations carrying a greater amount of red color have been particularly sought. How successful the search has been is indicated by the fact that we now have more than 30 red strains of the Delicious variety. Many of these red strains, however, may prove to be so similar as to be practically indistinguishable. More than 15 red strains of Rome Beauty are known, 20 strains of Winesap, 8 strains of Stayman Winesap, and several strains of McIntosh, York Imperial, Jonathan, and other leading varieties. At the present time, strains believed to color earlier or to have better color are in existence for practically -all of the leading red or blushed apple varieties. In several varieties, namely, Delicious, Rome Beauty, Winesap, Jonathan, and Stayman Winesap, new commercial plantings are largely of the improved strains rather than the standard varietal forms.

It has been assumed by many nurserymen and growers that in general such mutations vary from the parent in only one character. This is not necessarily true. Variations in season of ripening, fruit size, storage quality, dessert quality, or productiveness may accompany color variations. Therefore the various bud mutations should be thoroughly tested before they are widely propagated commercially.

In addition to mutations affecting color, a few have been found that involve season of maturity, size, shape, and flavor of fruit. It is of course obvious that variations in flavor, storage quality, or productiveness are less likely to be located than are variations of color or season of maturity, which are very conspicuous when the fruit is still on the tree.

A search for bud mutations is especially likely to lead to rapid results in the improvement of horticultural varieties. Generally these mutations mean only a slight difference in varieties that have already proved themselves excellent from a commercial standpoint. For example, the Winesap apple is already established as a leading commercial variety. Its greatest weakness is its tendency to rather small fruit size and lack of tree vigor under all but the best soil conditions. Its growing season is too long to permit proper development of the fruit in northern districts. Thus, bud mutations of Winesap that would give an earlier ripening apple would extend the range north- ward. Similarly, a mutation showing larger size of fruit would be of much value. A search for such mutations should be continued in American orchards.

The process of selection, propagation, and testing of bud mutations perhaps offers a possibility for more rapid improvement of our present desirable varieties than does any other method of breeding. Possibly by bud selection we might find a later maturing McIntosh adapted for growing farther south than the present McIntosh belt, or an earlier maturing Stayman Winesap, Rome Beauty, or Winesap, which would mean better adaptation to northern sections. The fact that color can be improved by the use of such selections has already been amply demonstrated. The testing of bud mutations should be an integral part of the variety-improvement program in the years to come. For originating definitely new types of apples, however, or for the incorporation of new characters, such as greatly increased hardiness or vigor, hybridization appears to offer the greater possibilities.

There is no unusual difficulty in the technique of hybridizing apples and pears. Several steps of this technique are illustrated in figure 1. The flower parts of an apple or pear, in order, from the outside of the blossom to the center, are as follows: (1) The calyx, consisting of 5 sepals at the base of the blossom; (2), the corolla, made up of 5 white or pink petals; (3), the stamens or pollen-bearing organs, usually 20 in number, which are borne just inside the petals; (4), the pistil, the central organ that contains the seeds. In-hybridizing most varieties it is desirable to remove the pollen-bearing stamens from the flower before it opens. The best time to do this is at the so-called balloon stage, illustrated in figure 1, A, while the petals still form a complete covering over the inner flower parts. At that stage the stamens have not yet begun to shed pollen and there has previously been no opportunity for either self- or cross-pollination to occur.

Figure 1.—Steps in hybridization of apples and pears: A, Bud in proper stage for emasculation; B, after emasculation, showing petals, sepals, and stamens pinched off and removed; C, an open flower, showing the flower parts that are removed in emasculation; D, the method of protecting emasculated flowers from chance pollination.

Two methods may be employed in removing the pollen-bearing organs. In the method shown in the figure, the thumbnail or a small knife or a laboratory scalpel is used to make a cut just at the base of the sepals. The flower part is then bent sidewise, and the whole flower organ except the pistil can be torn loose, as shown in figure 1, B. If carefully done, this leaves the pistil, consisting of the ovary containing the seeds, with a cluster of styles and stigmas, as shown in B. The tearing loose of the flower parts may result in enough injury to reduce the set of fruit. In the second method, which is somewhat slower but less likely to cause injury, the petals are pulled loose at the stage shown in A, and the anthers are picked out of the blossom with an instrument; an ordinary comb is satisfactory.

If the flowers are within a day or two of opening when emasculated, it is satisfactory to apply the pollen of the selected male parent at the time the emasculation is done; or the application of pollen may be postponed for a day or two. The pollen should be applied, however, before the stigmas begin to turn brown. The emasculated blossoms must be protected from chance pollination for several days. A satisfactory method is shown in figure 1, D.

A higher percentage of set of fruit will usually result if not more than two blossoms are emasculated and pollinated in a cluster. The remaining blossoms should, of course, be picked off at the time the emasculating is done.

To secure pollen, buds in the stage shown in figure 1, A, are picked and the anthers combed out of them as described above, If these anthers are held in a moderately warm, dry place they will ripen rather rapidly and begin to shed pollen within 24 to 48 hours.

Sometimes branches of the desired pollen parent are brought into a room or a greenhouse before the blossoms open, set in water, and allowed to bloom protected from insects. The pollen is removed from the open flowers when it is ripe.

Pollen is usually applied to the stigmas of the emasculated blossoms with a fine camel’s-hair brush, which may be sterilized between pollinations by washing in alcohol or immersing for several seconds in boiling water. After the pollen has been applied, the emasculated blossoms should again be protected (fig. 2). When conditions are favorable, from 30 to 50 percent of the emasculated blossoms should set fruit. After the stigmas have turned completely brown the protecting bags may be removed and labels designating the cross should be carefully adjusted. The fruit may be harvested when slightly immature to prevent undue loss from dropping. Germination of the seed is not affected by such early harvesting.

HANDLING THE FRUIT AND SEEDS

Two or three alternative methods may be used for handling the fruit and seeds after harvest. Since apple and pear seeds must go through certain transformations, often described as “resting” or "after ripening,” before they will germinate, the fruit may be placed in cold or cellar storage and held until spring. The seeds can then be removed and immediately planted in nursery rows. An alternative method of handling is to remove the seed from the fruit after harvest, place it in small labeled bags, and put these in cold storage over winter. It is necessary that the seed be sufficiently well dried and that it be stored in a sufficiently dry place to prevent it from molding, but excessive drying should be avoided. A third method is to stratify or bury the seed and carry it over winter outdoors. If facilities are available, the seed may be planted in flats in the greenhouse or in coldframes and the seedlings allowed to grow 3 or 4 inches high before being transplanted to nursery rows in the field, but this is not necessary.

Figure 2.—Cross-pollinated apple blossoms protected under glassine bags and labeled.

After 2 years in the nursery row the apple seedlings may be transplanted to the orchard, sufficient space being allowed to permit the trees to come into fruit. Pear trees can be planted at somewhat closer distances in the orchard than apple trees; they will usually fruit satisfactorily if planted about 4 feet apart in the row, with the rows about 15 feet apart to facilitate cultivation and spraying. Apple trees should have at least 10 feet of space in the row, with rows 15 feet apart, if the fruiting value of the young trees is to be adequately determined.

To speed up the testing and at the same time conserve space, buds or grafts from young seedling trees may be put into older trees growing in orchard form. Several buds or grafts may be put into an apple tree 4 to 6 years old. Usually it is preferable to have only seedlings of the same parentage worked on one orchard tree. If such a tree is maintained in good vigor and if the budding or grafting is satisfactorily accomplished, fruiting records should be obtained within 3 to 4 years from the date of budding or grafting. Usually budwood or scions from the seedlings can be obtained at the end of the first growing season. Thus, by this method, an indication of fruit value with apples or pears can be obtained in about 5 years from the time of making the cross. If the seedlings themselves are grown to fruiting age in the orchard, 8 to 10 years will usually be required. However, growing the seedling itself to fruiting permits a better evaluation of the tree from the standpoint of vigor, hardiness, disease resistance, and tree form.

In using the budding or grafting method, it is desirable to have trees that are not too old. Young orchard trees 4 to 5 years old are most nearly ideal from the standpoint of top-working, and they are small. enough to facilitate the work of taking records on fruiting branches.

Several steps in apple breeding as carried on at the New York Agricultural Experiment Station at Geneva are illustrated in figures 3, 4, and 5.³

It is only within the last 10 years that we have had definite information on the chromosome numbers of the various apple varieties. This has clarified our understanding of the behavior of varieties, particularly from the standpoint of pollination and breeding. We now understand the reasons for the peculiar behavior of certain varieties long observed in the orchard.

Investigators have known for some years that certain varieties are poor pollinizers for others. They do not form much good pollen, most of the grains being abortive and failing to grow when put in a sugar solution suitable for pollen germination. Usually when these varieties are planted alone or in blocks with others of similar type, poor sets of fruit are secured. Among the varieties known as poor pollinizers are Stayman Winesap, Baldwin, Rhode Island Greening, Gravenstein, Arkansas (Black Twig), TompkinsKing, Stark, and several less important ones.

These varieties have certain other characteristics in common also. All produce large-sized fruit, and all are vigorous growers and develop into large trees. Nursery investigations have indicated that as a rule seed produced by these varieties germinates poorly and the seedling trees are usually weak growers.

Our present knowledge of the number of chromosomes in apple varieties has been contributed by many investigators in many countries, including V. A. Rybin, in the Union of Soviet Socialist Republics; A. A. Moffett, M. B. Crane, W. J. C. Lawrence, and C. D. Darlington, in England; J. S. Shoemaker and B. R. Nebel, in the United States; F. Kobel, in Germany; O. Heilborn, in Sweden; and others. These workers have shown that most of the cultivated varieties of apples have 34 chromosomes (17 pairs) in the vegetative or somatic tissues, and 17 (one member of each pair) in the germ cells. These varieties with 34 diploid chromosomes as a rule produce fertile pollen and they are generally classed as good pollinizers for other varieties. The trees vary in vigor from low to moderately high, and fruit size varies from small to large.

The peculiarity of the second group of varieties, described above as being partially or in some cases almost entirely pollen-sterile and producing large fruit and large vigorous trees, is that they have 51 chromosomes instead of 34 in the somatic tissues. They are termed triploids,⁴ since the chromosome number in the vegetative tissue is three times that of the usual reproductive cells of apples, instead of twice, as in the diploids.

Figure 5.—Second tests of promising hybrid selections. The tree in the foreground is Early McIntosh.

The question arises, How have these triploid varieties developed? Normally the cells of the vegetative tissue have only twice as many chromosomes as the reproductive cells. How can we account for the considerable number of apple varieties that carry three times this basic chromosome number?

It is not known definitely how the triploid forms developed. At long intervals, the frequency varying with different species, a germ cell in either the male or the female organs may be developed with an extra set of chromosomes. Experimentally, cells are occasionally formed with double the normal number of chromosomes as a result of subjecting them during the process of germ-cell formation to unusual environmental conditions, such as high or low temperatures. It may be deduced, therefore, that at rare intervals under natural conditions pollen grains or egg cells are formed that carry 34 rather than 17 chromosomes in the reproductive cells.

Now if an egg cell carrying 34 chromosomes is fertilized by a sperm carrying 17 chromosomes, the resulting fertilized egg will have 51 chromosomes. It will develop into an embryo and ultimately into a plant carrying 51 chromosomes in its vegetative tissues. If such a tree is propagated vegetatively, the result is a horticultural variety with 51 chromosomes instead of the normal 34.

Approximately one-fourth of all commercial apple varieties are these triploid or 51-chromosome forms. Yet it is probable that such forms are rarely produced among seedling apple trees. For example, in all of the controlled breeding work that has been done in the United States, involving crosses of diploid x diploid, diploid triploid, triploid x diploid, and triploid X triploid, no seedling of merit known to be a triploid has been produced. It is apparent, therefore, that in nature triploid forms are produced only rarely as compared to diploids.

How, then, can we account for the fact that at least a fourth of our important varieties are triploids? This is possible only if we assume that the triploids have characteristics that make them of unusual value as commercial varieties, so that an unusually high proportion of the triploid forms have been selected and propagated as varieties. It is probable that in the United States in the last 250 years more than 200,000,000 apple trees of seedling origin have grown and fruited. Even if only 1 in 50,000 of these was a triploid, it would mean that several thousand triploid trees have grown in the United States some time during the past two and a half centuries. If these trees on the average had certain superior characteristics as compared with the hundreds of millions of diploid trees, they could easily have become the source of a relatively large number of improved varieties. Some of their characteristics of unusual value from a commercial standpoint have already been enumerated, namely, large size of fruit and vigorous growth and large size of trees. Heilborn (9) has also pointed out that most of the triploid varieties grown in Europe have relatively long storage quality. This does not apply to all of the American triploid varieties, but many of them are firm-fleshed apples of good storage quality. Thus it seems probable that from the mass of seedling material available in the United States and Europe a relatively high proportion of the rare triploids has been selected and a relatively small proportion of the more common diploids.

These points of superiority of the triploid varieties would indicate that attempts should be made to secure triploids in breeding. It is true that a large portion of the seedlings produced in breeding work tend to run to medium or small fruit size. This tendency could undoubtedly be corrected if triploid varieties could be obtained at will. Unfortunately, however, this cannot be done.

As explained above, crossing of diploid X diploid varieties normally gives only diploids. What occurs when we cross diploids X triploids or triploids X triploids?

The triploid somatic or vegetative cells contain 51 chromosomes— 34 obtained from one parent germ cell and 17 from the other. In the pairing of the chromosomes, which takes place prior to the formation of germ cells, 34 will pair normally into 17 pairs. But the remaining 17 of the 51 chromosomes are not arranged in any special order, and they are unable to pair among themselves. After pairing, the chromosomes again divide, half going to one pole of the nucleus and half to the other pole. But the 17 unpaired chromosomes cannot do this in an orderly fashion. Some of them go to one pole and some to the other at random. Thus, when the cell finally splits in half to form two germ cells, we find that each of these contains 17 chromosomes from the original pairs and an indefinite number of other chromosomes from those that had not paired. This indefinite number varies all the way from none at all to the whole 17 unpaired chromosomes. Such a germ cell may have any number of chromosomes from 17 to 34.

The great majority of these germ cells with an irregular chromosome number are sterile. The addition of chromosomes above the normal number but less than double the number seems to result in sterility to a large extent throughout the plant kingdom. In apples, however, some viable pollen grains are found in most of the triploid forms, and in most varieties enough of the egg cells are sufficiently fertile to give a satisfactory fruit set, particularly if they are pollinated with diploid pollen.

However, when the egg cell containing 17 to 34 chromosomes is fertilized with a nucleus from diploid pollen containing 17 chromosomes, we usually will have neither diploid nor triploid offspring. The number will vary from 34 to 51, that is, 17 from the pollen cell plus 17 to 34 from the egg cell. These are called aneuploids, and the seeds generally germinate poorly. Those that do grow are likely to produce weak seedlings, though occasionally they are fairly vigorous. It is of interest to note, however, that of the varieties that have been introduced as a result of breeding work in the United States to date, none has a parent of known triploid constitution. This is in line with cytological studies on many species of plants, which indicate the slight probability of obtaining promising varieties when one or both of the parents are triploids.

Triploids crossed with triploids also are likely to give aneuploid progeny. Here the possible number of chromosomes will range from 34 to 68 and may be expressed numerically by the formula [17+ (0 to 17)]+[17+(0 to 17)]. Such triploid x triploid progeny are likely to be weak vegetatively if they grow at all.

In order to obtain triploids at will in breeding, it is necessary to have a tetraploid parent (four times the basic number) to cross with a diploid. We do not now have any apple or pear varieties that are known to be tetraploids. There is a possibility that tetraploids resulting from chromosome doubling in some cell in the vegetative tissues originate at rare intervals as bud sports or somatic mutations in normal diploid varieties. One or two mutations that may be of this type have recently been found in pears, though their nature has not yet been definitely determined. If similar mutations can be found in apples, they will be of great interest from the breeding standpoint. Such bud sports will probably be characterized by giant fruits, since the character of giantism is often associated with chromosome doubling. Giant strains of apples, occurring as bud sports, should be carefully preserved until their character can be determined, even though the fruit itself may appear to be of no value.

Aside from diploid and triploid varieties, a word should be said as to the chromosome make-up of the genera Malus and Pyrus. These genera and other closely related forms stand out among the Rosaceae in having 17 chromosomes in the reduced phase (the reproductive cells), whereas the basic number in other genera of the family is mostly 7 and in a few 8 or 9. In Malus and Pyrus the 17 chromosomes are believed to represent multiplication from the simpler base of 7, 8, or 9, either by hybridization or by polyploid mutations. This complex chromosome constitution of apples and pears may account for the fact that there is such wide variation in selected varieties within these species, that mutations both in seed reproduction and vegetative tissues occur fairly frequently, and that most selected varieties are highly heterozygous, failing to reproduce seedlings closely resembling the parent.

Most of our apple varieties are highly heterozygous, or mixed in their inheritance. This fact, coupled with the long time required to grow a generation, the impossibility of successfully selfing most varieties, and the relatively small populations that can be grown, makes the working out of inheritance factors difficult. The following summation is taken mainly from Wellington (17), Auchter (2), Lantz and Bole (12), and Crane and Lawrence (6).

Triploid X triploid or triploid X diploid varieties produce generally weak trees if seeds grow, because of aneuploid chromosome make-up.

Among diploid X diploid crosses, weak growth appears recessive to vigorous growth.

Tree shape—spreading, round, or upright—appears to be due to a number of genes. Forms of hybrids are usually intermediate between parents, with the progeny tending to be more nearly round than a strictly intermediate form would be.

Age of bearing is undoubtedly inherited, but simple segregations have not been obtained. Late-bearing and early-bearing parents tend to transmit these tendencies.

Susceptibility to apple cedar rust, to blight, and to scab appears to be inherited, but little is known of the segregations involved.

Date of fruit ripening follows parent behavior closely. Late- ripening parents give late-ripening progeny; early-ripening parents, early-ripening progeny; and early X late crosses usually ripen between the ripening dates of the two parents. In fruit size, large size seems dominant over small, but the factors are complex. Small crab apples crossed with apples give intermediate sizes. Most large apples carry some factors for small. To secure large size, cross large x large. Large X small fruit sizes yield progenies that are usually intermediate. Crane and Lawrence found the average of the progeny to be somewhat smaller than the average of the two parents.

Yellow or green skin color usually behaves as a recessive, though occasional red apples will appear in yellow X yellow hybrids. Apparently a number off factors are involved in color. Blush X blush parents may occasionally give deeper reds than either parent.

Flesh texture appears to follow parent type to a considerable degree, but some coarse-fleshed progeny are produced by tender-fleshed parents, Several factors appear to be involved in flesh texture, as well as in flesh color.

In flavor, sweet (lack of acidity) appears to be recessive. Some highly acid varieties, as Boiken, Oldenburg, and Montgomery, seem to be homozygous, or “pure” in their inheritance, for acidity. “Mildly acid varieties give some sweet progeny and appear heterozygous for sweetness. Acid X acid gives a considerable proportion of progeny with acidity accentuated beyond either parent.

A relatively large program of apple breeding is now under way in the United States, with active projects at 12 experiment stations and work at two points by the United States Department of Agriculture. The past and present workers in apple breeding are listed in the appendix. (See table 4.) In table 3 are summarized the crosses made at the stations that have fruited to date, together with the number of progeny from each cross considered to have horticultural promise, either as varieties or for further breeding work.

In the following pages, the work at the various stations is briefly summarized.

At the Idaho Agricultural Experiment Station, Moscow, breeding was begun in 1909 by C.C. Vincent, and since then 11,824 hybrid seedlings have been planted in orchard form. Results have indicated that the Jonathan, Wagener, and Esopus Spitzenburg varieties have tended to give highest dessert quality. Ben Davis crosses have the highest percentage of seedlings showing good keeping quality. No varieties have yet been introduced to the trade, but 101 selections have been made for detailed study.

Since the work was started at the Illinois Agricultural Experiment Station, Urbana, in 1908 by C. S. Crandall, approximately 15,000 trees have been fruited in the orchard, and detailed records have been made of the characteristics of the fruit produced. In the earlier work, a large number of crosses were made between cultivated varieties and various species of crab apples. Later, the emphasis has shifted to hybridizing commercial varieties containing the qualities desired. The primary objective in the early breeding work was to secure data on genetic behavior of the apple. This is being continued, but greater emphasis is now placed on the securing of high dessert quality and good keeping quality in new varieties. At the present time, almost 3,000 seedlings representing high-quality parents are being grown. The principal varieties used in this later breeding work include Akin, Delicious, Jonathan, Golden Delicious, Maiden Blush, Fameuse, Winesap, Fanny, Grimes Golden, and Rome Beauty. In breeding for early apples of good quality, Yellow Transparent is being crossed with high-quality standard-season varieties.

From the seedlings that have fruited, 338 promising selections are being held for further observation as to their commercial value. No varieties have been named.

Apple-breeding work in Iowa was begun by C. G. Patten (fig. 6) at Charles City about 1867. Patten began as an independent fruit breeder but later received some financial assistance from the Iowa State Horticultural Society. From 1909 to 1914 the United States Department of Agriculture assisted in the work. In 1916 the State purchased the farm and fruit-breeding materials and the station was operated by the Iowa Agricultural Experiment Station until 1932. Patten introduced several varieties— Patten, Eastman, Brilliant, Silas Wilson, Iowa Beauty, and University. A number of selections from his work are still being used by the Iowa station.

Work in fruit breeding and variety testing was begun at the Iowa Agricultural Experiment Station, Ames, about 1880, by J. L. Budd. The primary objective was to secure varieties of fairly good quality that would be hardy and productive under the severe winter conditions existing in Iowa. A large number of Russian varieties were introduced between 1880 and 1890 and tested at Ames. Most of these were not of desirable quality although many were extremely hardy. The inherent hardiness of this group of apples suggested their value for breeding. That they transmit their hardiness to their seedlings has been amply demonstrated by the work at the Iowa station since 1917. Budd grew seedlings of many open-pollinated fruits during the period from 1882 to 1905. Fruiting records were not made, and the results of this earlier work are not available. In general, results were not sufficiently good to warrant continued work with open-pollinated seedlings.

The cross-breeding work in apples was initiated by S. A. Beach (fig. 7) in 1905, and large numbers of crosses were made between 1906 and 1910. Further breeding work was not attempted until the crosses were fruited. The seedlings began to fruit in 1916 and were described and the results tabulated by H. L. Lantz, T. J. Maney, and others, under the direction of Beach.

Figure 7.—Spencer Ambrose Beach (1862-1922). As head of the horticultural work at the New York (State) Agricultural Experiment Station from 1891 to 1905, and at the Iowa Agricultural Experiment Station from 1905 to 1922, he laid sure foundations for the splendid work of both stations in the breeding of fruit crops.

In an effort to bring the seedling trees into fruiting as early as possible, top-working was practiced, with three to five different seedlings worked on suitable stocks. While top-working was found to promote earlier bearing, several difficulties developed. Some scions failed to make satisfactory growth because they were too heavily shaded by more vigorous neighbors. Records were difficult to make because of confusion as to location of each graft on the tree. The growth habit of the tree could not be satisfactorily determined on top-worked material. In later work, therefore, the practice of top-working was discontinued. The varieties that have been introduced to date as a result of the breeding work at the Iowa station are listed in table 2 in the appendix.

After most of the crosses made by Beach had fruited, additional crossing was started and has been carried on with little interruption. At the present time, about 13,000 seedlings are being grown to fruiting from crosses made since 1917. A considerable number of these are now fruiting. A summary of the parentage of these seedlings is published in the Transactions of the Iowa State Horticultural Society, 1935.

Breeding work was begun at the Maine Agricultural Experiment Station, Orono, in 1911, but no records of the earlier work are available. Approximately 1,000 seedlings of crosses of McIntosh, Golden Delicious, Delicious, Northern Spy, Wealthy, and Cortland are now growing in nursery rows. Additional crosses involving the above varieties and Haralson and Scott Winter have been made during the past year. The objectives in this work are to secure hardy, high-quality varieties adapted to New England.

Chromosome counts have been made on several apple varieties, The following apparently are diploids: Ben Davis, Oldenburg, Early Harvest, Golden Delicious, LaRue, McIntosh, Milden, Northern Spy, Opalescent, Porter, Red Astrachan, Golden Russet, Chenango, Tolman Sweet, Wealthy, Wolf River, and Yellow Transparent. Varieties showing irregular chromosome numbers, probably triploids, include Baldwin, Gravenstein, Rhode Island Greening, Rolfe, and Stark.

Breeding work at the University of Maryland, College Park, was started in 1906. The objective at first was to produce early-ripening red varieties of good quality. A total of 1,073 seedlings were grown prior to 1917. In this group of seedlings, 13 were selected as promising. Since 1929, a limited number of seedlings have been grown as a result of seed produced in pollination work. Three hundred and fifty-eight seedlings, representing crosses of good-quality main-season varieties, are now growing in the experimental orchard. Typical western Maryland apple orchards are shown in figure 8.

Figure 8.—The fruits of breeding: Apple orchards in the Shenandoah-Potomac Valley section.

At the Massachusetts Agricultural Experiment Station, Amherst, a number of cross-pollinated seeds resulting from pollination work have been planted from 1925 to date. These include crosses of Red Astrachan with Cortland, Delicious, and McIntosh; McIntosh with Cortland, Delicious, Northern Spy, and Macoun; Northern Spy with Delicious, McIntosh, and Wealthy; Gravenstein with Wealthy; and Northern Spy selfed.

Apple-breeding work supported by the State of Minnesota was started in 1878, when an annual subsidy administered by the board of regents of the university was granted to Peter Gideon for continuation of his breeding work. Apple breeding organized by and completely under the control of the Minnesota Agricultural Experiment Station was begun about 1890, under the direction of S. B. Green. From 1890 to 1905 several thousand seedlings, largely of Russian varieties, were grown. In 1907 about 4,000 seedlings of Malinda, open pollinated, were planted in the field. About 300 of these have characteristics either of hardiness or fruit quality of sufficient merit to be retained.

From 1907 to 1912 approximately 13,000 seedlings, many from controlled crosses, were grown. In this group of material, 541 trees have been retained for further study. Since 1918, 4,781 seedling trees of hybrid parentage have been grown to fruiting in the breeding plots. The principal crosses are listed in table 3 in the appendix. At the present time, approximately 5,000 trees resulting from crosses made from 1921 to date are being grown to fruiting.

The primary objective in Minnesota is the securing of varieties of good quality that are hardy under the extremely cold winters of that section. Several varieties introduced as a result of the breeding work are listed in table 2, in the appendix.

During the past 100 years a number of individuals have contributed to the list of hardy varieties adapted to this section. The best known of these, Peter Gideon, began planting seed in 1854. He introduced the Wealthy, still one of the leading apple varieties of the United States. Peter, Gideon, and Gideon Sweet were other varieties developed by him. Others in the State who have raised apple seedlings for the specific purpose of developing hardy varieties include G. H. Pond, of Bloomington; John Shaw, of Minnesota City; H. M. Lyman, of Excelsior; Amasa Stewart, of Le Sueur County; Titus Day, of Farmington; Henry Stubbs; and others. A relatively large number of hardy apples have been named as the result of the efforts of these men.

Apple-breeding investigations in Missouri are conducted both at the Missouri State Fruit Experiment Station, Mountain Grove, and at the University of Missouri, Columbia. Work at Mountain Grove was started in 1901. In 1935 the six varieties listed in table 2 were introduced.

The primary objective in the early breeding work at the Mountain Grove station was to obtain good storage varieties well adapted to growing conditions in Missouri. With this objective, the principal varieties used included Ben Davis, Winesap, Jonathan, Ingram, and Delicious.

In the breeding work since 1923, the primary objective has been to produce late-blooming varieties with high quality. The principal varieties used include Ralls, Ingram, Mother, Northern Spy, Jonathan, Delicious, King David, and Golden Delicious. Since 1923, 1,821 seedlings of known parentage have been produced and are now growing in orchard form. Most of these have not yet fruited.

At the University of Missouri, at Columbia, some apple-breeding work has been conducted since 1905. The variety Whitten, from an Ingram X Delicious cross made in 1905 by J. C. Whitten, was introduced in 1925. This is a vigorous tree, a prolific bearer, and has fruit above medium size, yellow blushed with red, and of good quality.

At the present time, 2,732 seedlings resulting from crosses made in 1931 and 1932 at the State Fruit Experiment Station are being grown to fruiting at Columbia. This collection consists mainly of crosses of King David, Wolf River, Ingram, Alexander, Ralls, Twenty Ounce, Rome Beauty, Jonathan, Golden Delicious, Delicious, Mother, Gravenstein, and Northern Spy.

Breeding work with apples at the New York (State) Agricultural Experiment Station, Geneva, was started in 1892, and since that time over 13,000 apple seedlings have been set in the orchard for fruiting, with nearly 2,000 additional now in the nurseries. Over 9,000 of these trees have been set in the orchard since 1922, so the major part of the seedlings have not yet been tested. In producing these 15,000 seedlings, 110 varieties, 10 species, and 63 seedlings have been used as parents. Fifty-five varieties and seedlings have been self-pollinated, but seedlings resulting from these self-pollinations have lacked vigor. Varieties now known to be triploids, including Baldwin, Gravenstein, Rhode Island Greening, and TompkinsKing, have given only weak and worthless progeny. Of the diploid varieties, crosses of McIntosh have given by far the greatest number of desirable seedlings. Crosses of Northern Spy and of Yellow Newtown. generally produce late- maturing fruit. Yellow Transparent has given early-ripening varieties tart in flavor. Delicious and Deacon Jones have given mostly mild-flavored fruits. Results show that if large-fruited seedlings are desired, large-fruited parents must be used. Sweet flavor appears to behave as recessive, but it is usually impossible to predict just how flavors will be transmitted.

Varieties used most extensively in the breeding work are: Baldwin, 23 times; Cortland, 71; Deacon Jones, 26; Delicious, 38; Early McIntosh, 41; Gravenstein, including Red Gravenstein, 27; Kendall, 26; Macoun, 37; McIntosh, 186; Milton, 31; Northern Spy and Red Spy, 76; Oldenburg, including red sports, 39; Rhode Island Greening, 27; Rome Beauty, including red sports, 57; Wealthy, 32; Yellow Newtown, 30; and Yellow Transparent, 35.

The specific objective of the New York station is to obtain hardy, good-quality apples for dessert and cooking that ripen throughout the season. The most important single need is to secure a high-quality, productive, late-keeping red variety that is ‘fully hardy under New York State conditions. Tree characters desired include early bearing, hardiness to cold winters, self-fruitfulness, sufficiently late blooming to resist spring frosts, and resistance to insects and diseases.

A study of the chromosome constitution of varieties and seedlings is an important part of the breeding program. Crossing of triploid varieties or of triploid and diploid varieties has produced no new triploid varieties. Chromosome counts on more than 100 resulting seedlings have been made, and all have been aneuploids; that is, having chromosome numbers other than 34 or 51. More than 1,000 such seedlings have been discarded for lack of vigor and fertility. Table 2, in the appendix, lists the varieties introduced as a result of the breeding work at the Geneva station.

There is no formal breeding project at the New York (Cornell) station, Ithaca. At present, about 100 seedling trees of McIntosh crosses, obtained incidentally in pollination experiments, are being grown to fruiting.

Apple-breeding work was begun at the Ohio Agricultural Experiment Station, Wooster, by J. B. Keil in 1915. During that year and the year following, crosses were made from which 963 seedlings have fruited. Of these, 25 have been selected for further study or for further use in breeding.

Since 1929, some additional crosses have been made each year by F. S. Howlett and C. W. Ellenwood. From these, 2,414 seedlings are now being grown to fruiting. These later crosses are primarily between Delicious, McIntosh, Gallia Beauty, Northern Spy, Golden Delicious, Cox Orange, Jonathan, Esopus Spitzenburg, Ralls, Rome Beauty, Mother, and some of the numbered selections that resulted from the earlier breeding work. Table 2 in the appendix lists five varieties recently introduced as a result of the breeding work in Ohio.

The specific objectives include (1) to obtain late-blooming varieties that will thus tend to escape the hazards of spring frosts and freezes, and (2) to develop late-keeping varieties whose storage season will extend from February until late spring. A considerable number of seedlings that bloom later than Rome Beauty and Northern Spy, but for the most part derived from these two varieties, have been obtained.

Breeding of apples and other hardy fruits has been a leading horticultural project at the South Dakota Agricultural Experiment Station, Brookings, since 1895. The primary objective is to obtain fruits of fair to good quality that are hardy under the extreme winter cold and frequent summer drought of the northern Plains area. Fully 10,000 apple seedlings of various pedigrees have been grown to fruiting. Much of this has been open-pollinated material. Numerous hybrids between selections of wild crab apples and hardy cultivated apple varieties have been made. As a result of this breeding work, about 25 varieties of crab apples and a considerable number of apples have been introduced. The apples, with their parentage and characteristics, are listed in table 2, in the appendix. Crab apples introduced include Alexis, Amur, Cathay, Beauty, Dolgo, Hopa, Ivan, Izo, Kola, Linda, Maga, Mercer, Missouri Pippin, Nocalyx, Olga, Red Tip, Sapinia, Shoko, Sugar, Tipi, Zapta, Red Flesh, Wakonda, Zelma, Zita, Zaza, Bison, Caputa, Wanblee, Waubay, and Amsib.

The apple-breeding program at the Virginia Agricultural Experiment Station, Blacksburg, is not extensive. A number of open- pollinated seedlings have been fruited, of which one from Mother, one from Northern Spy, and three from Delicious appear to have horticultural value. A number of crosses are being made to secure late-blooming, high-quality, and highly colored varieties. Eight hundred fifty-six seedlings of Ralls X Rome Beauty, 622 seedlings of Ralls X Mother, and 1,234 seedlings of York Imperial open-pollinated are now growing in the nursery row.

A limited amount of apple breeding has been done by Department of Agriculture workers. From 1912 to 1920, C. P. Close hybridized early varieties with the objective of securing early good-quality varieties in season with Yellow Transparent, or before, and preferably carrying red color. The varieties used included Yellow Transparent, Early Harvest, Early Ripe, Red June, and Red Astrachan. About 400 seedlings representing hybrids of these varieties have fruited in the orchard.

A number of early-ripening selections have been made. Seven of these selections, carrying red color and ripening with Yellow Transparent or earlier, have been distributed for experimental testing. Yellow Transparent has tended to be an excellent parent in the transmission of shape, size, and season of ripening.

Approximately 500 seedling trees of crosses made from 1927 to 1929 are now coming into fruiting at the National Agricultural Research Center, Beltsville, Md. These represent crosses of long- keeping varieties made with the objective of securing good-quality, long storage-season types. The principal parents include Winesap, Yellow Newtown, Granny Smith, Vandervere, and McIntosh.

Promising bud mutations of possible horticultural value originating in various parts of the United States are being grown for comparative testing at Beltsville. The oldest of these selections have now been planted in the orchard 4 years. Additional plantings have been made each year as additional material has been collected. Four - trees propagated from each mutation are grown in comparison with parent varieties. In the orchard at the present time are the following bud sports: Baldwin 3, Delicious 30, Gravenstein 5, Jonathan 4, McIntosh 4, Northern Spy 3, Oldenburg 5, Rome Beauty 15, Stark 2, Stayman Winesap 9, St. Lawrence 1, Summer Queen 1, Twenty Ounce 1, Willowtwig 1, and Winesap 20.

A considerable amount of hybridizing between the Siberian crab, Malus baccata (L.) Borkh., and standard apple varieties was done in earlier years. These crosses have resulted in seedlings that are hardy and vigorous but have generally small fruits. The varieties being used most largely for hybridizing purposes include Wealthy, Oldenburg, Red Duchess, McIntosh, Delicious, Starking, Yellow Transparent, Haralson, Anoka, and the crab apples Dolgo, Florence, and Whitney.

Beginning in 1889, a major program was started to develop superior apple varieties sufficiently hardy to withstand rigorous weather conditions in all parts of Canada. At the Central Experimental Farm, Ottawa, seed of Russian varieties planted in 1889 gave 3,000 trees. From this work, only one variety worthy of mention developed— the Rupert, an apple a little earlier than Yellow Transparent and equal to it in quality.

The next step was the crossing of the Siberian crab with named Russian and American apple varieties. Fruits of the first-generation progeny were all under 2 inches in diameter. These, recrossed with apple varieties, gave fruits up to 2½ inches in diameter but lost some of the hardiness of the first-generation hybrids. Most of the fruit of the first-generation hybrids retained the crab characters—long, slender stem; thin, tender skin; and firm, crisp, breaking flesh.

Cross-breeding with better varieties was begun in 1898. Since then, 253 different combinations with 66 different varieties have been made. The variety that has been outstanding as a parent is McIntosh. In one block of 159 trees from open-pollinated McIntosh seed saved in 1898, 27 varieties of sufficient promise for naming were developed. Among these are Melba, Joyce, Macross, Hume, and Lobo. In more recent years, McIntosh has been crossed with the finest quality varieties available. Much of this material has not yet fruited.

In addition to this work carried on at the Central Experimental Farm, breeding is also conducted at the Ontario Agricultural College, Guelph, Ontario, and at the Horticultural Experiment Station, Vineland, Ontario. At Guelph, several thousand seedlings, representing mainly crosses of the McIntosh, Northern Spy, Wealthy, Wagener, and several other varieties, have been fruited. At Vineland, more than 8,000 seedlings have been grown since the work was started in 1915. These represent 130 crosses between varieties, and seed of 65 crosses and selections open-pollinated.

In more recent years the attempts to secure extreme hardiness have been centered at experiment stations in the prairie Provinces, namely, the University of Saskatchewan, Saskatoon, Saskatchewan, and the Dominion Experimental Station at Morden, Manitoba. The most extensive project is at the University of Saskatchewan. Prior to 1930, more than a quarter of a million crosses of apples had been made at that place. The female parents used have been the Siberian crab and the hardiest of the hybrid crab apples such as Osman, Columbia, Prince, Charles, Tony, and Magnus. The apple varieties have included McIntosh, Melba, Wealthy, Oldenburg, St. Lawrence, and Yellow Transparent.

The largest collection in Canada of the hardiest varieties of apples and crab apples is at the Dominion Experimental Station at Morden. In 1916 some 27,000 open-pollinated seedlings from the hardiest Russian and other varieties of apples were planted. Several thousand of these have fruited, and many are being tested in the prairie Provinces.

A limited amount of breeding work is under way at the Dominion Experimental Station, Summerland, British Columbia. This work consists of crosses of high-quality and long-storage apples. The principal parents used are McIntosh, Yellow Newtown, Winesap, Delicious, Golden Delicious, Rome Beauty, and Grimes Golden. The earliest of these seedlings are just coming into fruiting. Macoun summarized the first 40 years of apple-breeding work in Canada, with the comment that the time should not be far distant when there will be varieties of Canadian apples suitable for all parts of that country where farm development is possible. Experience with breeding apples in Canada indicates the following conclusions, according to Macoun (13):
   (1) To originate extremely hardy apples:
        (a) Cross the apple with the wild Siberian crab and recross the hardiest F₁ with the apple.
        (b) Sow seeds of apples that are hardy in other sections having severe climatic conditions.
   (2) To originate apples having hardiness, vigor, productiveness of tree, and high quality, good size, and appearance, cross varieties having most of the characteristics desired.
   (3) In cross-breeding, where quality is an important factor, cross two varieties that are both good or very good in quality. In crossing a variety of good quality with one of inferior quality, the F₁ will nearly always bear fruit of mediocre quality.
   (4) Use parents that have been found by other breeders to transmit their desirable characters to a large degree.

The work of European agencies in apple breeding is summarized in the appendix. This summary includes work with the other tree fruits as well as apples, since in most cases several fruits are involved in a single more or less unified breeding program.

(1) ALDERMAN, W. H.
1936. ACCOMPLISHMENTS IN FRUIT BREEDING BY STATE AND FEDERAL EXPERIMENT stations. Amer. Soc. Hort. Sci. Proc. (1935) 33: 13-20.
(2) Auchter, E. C.
1921. PRELIMINARY REPORT ON APPLE AND PEAR BREEDING IN MARYLAND. Amer. Soc. Hort. Sci. Proc. (1920) 17: 19-32.
(3) Beach, S. A., assisted by Booth, N. O., and Taylor, O. M.
1905. THE APPLES OF NEW YORK. 2v., illus. Albany. (N. Y. Agr. Expt. Sta. Rept. 1903, pt. 2.)
(4) Crandall, C.S.
1926. APPLE BREEDING AT THE UNIVERSITY OF ILLINOIS. Ill. Agr. Expt. Sta. Bull. 275, pp. 341-600, illus.
(5) Crane, M. B., and Lawrence, W. J. C.
1930. FERTILITY AND VIGOUR OF APPLES IN RELATION TO CHROMOSOME NUMBER. Jour. Genetics 22: 153-163.
(6) ——— and Lawrence, W. J.C.
1934. THE GENETICS OF GARDEN PLANTS. 236 pp., illus. London.
(7) Einset, O
1930. CROSS-UNFRUITFULNESS IN THE APPLE. N. Y. State Agr. Expt. Sta. Tech. Bull. 159, 24 pp.
(8) Hansen, N. E.
1927. PLANT INTRODUCTIONS (1895-1927). S. Dak. Agr. Expt. Sta. Bull. 224, 4 pp., illus.
(9) Heilborn, O.
1935. REDUCTION DIVISION, POLLEN LETHALITY, AND POLYPLOIDY IN APPLES. Acta Hort. Bergiani Proc. (1930) 27: 406-410, illus.
(10) Howlett, F.S.
1927. APPLE POLLINATION STUDIES IN OHIO. Ohio Agr. Expt. Sta. Bull. 404, 84 pp., illus.
(11) Kimball, D. A.
1931, A STUDY OF THE PROGENY RESULTING FROM CROSSING CERTAIN APPLE varieties. Amer. Soc. Hort. Sci. Proc. (1930) 27: 412-415.
(12) Lantz, H. L., and Bole, S. J.
1935. APPLE BREEDING: INHERITANCE OF TREE SHAPE IN APPLE PROGENIES. Amer. Soc. Hort. Sci. Proc. (1934) 32: 256-260.
(13) Macoun, W. T.
1929. PROGRESS IN APPLE BREEDING IN CANADA. Amer. Soc. Hort. Sci. Proce. (1928) 25: 117-122.
(14) Nebel, B. R.
1931. RECENT FINDINGS IN CYTOLOGY OF FRUITS (CYTOLOGY OF PYRUS III). Amer. Soc. Hort. Sci. Proc. (1930) 27: 406-410, illus.
(15) Taylor, W. A.
1898. THE FRUIT INDUSTRY, AND SUBSTITUTION OF DOMESTIC FOR FOREIGN-GROWN FRUITS. U.S. Dept. Agr. Yearbook, 1897: 305-344, illus.
(16) Vincent, C. C., and Longley, L. E.
1930. APPLE BREEDING IN IDAHO. Idaho Agr. Expt. Sta. Research Bull. 8, 58 pp., illus.
(17) Wellington, R.
1924. AN EXPERIMENT IN BREEDING APPLES. 11. N. Y. State Agr. Expt. Sta. Tech. Bull. 106, 149 pp.

The following summary includes the more important fruit-breeding stations in Europe.

Průhonice; State Institute for Horticultural Research (director, Ing. Fr. Landovský; chief, Division of Fruit Trees and Nurseries, Ing. J. Souček).—Objective: To secure fruits of better quality with good storage and utilization properties.

Lednice, Morava; Fürst Liechtenstein Plant-Breeding Institute (director, Prof. Dr. Fr. Frimmel).—Extensive breeding investigations of apples and peaches are being conducted. Crosses of several apple varieties are at fruiting age and are being tested in comparison with standard varieties.

Long Ashton: Agricultural and Horticultural Research Station, University of Bristol (director, Prof. B. T. P. Barker).—In connection with general fruit investigations, the station conducts breeding investigations on apples, pears, plums, and berries. Several apple varieties, one pear, and four plums have been named and distributed. The objective in the breeding work is to produce high-quality dessert varieties.

East Malling, Kent; Horticultural Research Station (director, R. G. Hatton).— Breeding investigations include the following principal lines:
   (1) Apples.—Production of rootstocks immune to woolly aphis and conferring disease resistance on the scions; production of fruiting varieties resistant to woolly aphis; production of commercial varieties ripening at times when present English varieties are not available.
   (2) Plums.—Production of new varieties of rootstock that propagate readily and confer resistance to silver leaf and to bacterial dieback diseases.
   (3) Pears.—Production of improved varieties of quince stock compatible with pear varieties, and production of commercial pear varieties of high quality.

Merton; John Innes Horticultural Institution (director, Sir Daniel Hall).—The institution is engaged primarily in genetic and cytological research from the standpoint of pure science. When the investigations on inheritance in fruit produce varieties of promise for commercial cultivation, they are selected and given an extended try-out.
   (1) Apples.—Four thousand seedlings and varieties provide data for the study of the inheritance of characters. About 40 are under extended tests as market varieties. Breeding of rootstocks resistant to woolly aphis, carried on in collaboration with the East Malling station, has yielded seedlings of promise now under trial.
   (2) Plums.—A large number of seedling plums are being grown in the study of inheritance of characters, particularly of self-incompatibility. Selected seedlings are under trial for commercial value.
   (3) Cherries.—A large number of varieties of sweet cherry have been raised in the study of cross incompatibility, some of which are now under commercial trial.

Berlin; Institut für_gärtnerischen Pflanzenbau, Friedrich-Wilhelms-Universität (director, Prof. Erich Maurer).—Breeding of tree fruits consists of the selection of vegetatively propagated rootstocks for apples, pears, sweet cherries, and plums. Around 3,000 clons are under observation.

Berlin; Institut für Obstbau, Friedrich-Wilhelms-Universität (director, Prof. Erwin Kemmer).—Investigations on the value of seedlings of varieties and from the wild stocks for stone fruits and pomes.

Geisenheim a.Rh.; Versuchs-und Forschungsanstalt für Wein-, Obst-, und Garten- bau (director, Prof. Dr. Rudlofi).—Breeding of tree fruits has been conducted since 1884. A series of new apple and pear varieties has been developed through growing open-pollinated seedlings of named varieties or through hybridization of named varieties. Twelve varieties of pear and seven varieties of apple have been named.

Müncheberg (Mark); Kaiser Wilhelm-Institut für Züchtungsforschung (director, Prof. Dr. Rudorf).—An intensive program of investigation, particularly to develop disease-resistant varieties of fruits. In the apple work, the important objectives are to secure greater resistance to apple scab and to cold and frost, and to develop high-quality market and table varieties. In the work on scab resistance, mass infection of the seedlings of crosses between cultivated varieties and scab-resistant apples is practiced. Over 16,000 apple seedlings are under observation in this work.
   (1) Pears.—The important objectives are to develop pears resistant to pear scab and to develop high-quality, large-sized summer pears. The testing of resistance to scab is similar to that of apples. Four thousand pear seedlings are under observation.
   (2) Cherries.—One objective is to secure cherries resistant to brown rot. A large number of crosses of sweet X sour varieties have been tested. Tests of the cross- and self-sterility of the F₁ hybrids of sour sweet cherries are also being made.
   (3) Plums.—Testing of strong-growing seedlings of Prunus cerasifera from western Asia for their resistance to unfavorable climatic conditions, their adaptation, vigor, productiveness, and fruit quality. These are being crossed with other types of plums. Observations are made of a large number of seedlings of crosses between Mirabelle and Reine Claude types.
   (4) Apricots—Seedlings of the vigorous wild apricot of Asia are being tested for their resistance to climatic conditions, adaptation, vigor, productiveness, and fruiting value, and are being crossed with cultivated varieties.
   (5) Peaches.—A large quantity of seedling material of varieties and crosses between varieties is being tested for the resistance of the buds against late frosts and winter temperatures and the resistance of the trees against peach leaf curl.

Zweigstelle, Naumburg (Saale); Biologische Reichsanstalt für Land- und Forst- wirtschaft (director, Dr. Borner).—The objectives are the development of high- quality apple varieties and of stocks that are highly resistant to woolly aphis, mildew, and scab. A large number of F, hybrids between resistant wild types and cultivated varieties are under observation.

Pillnitz a. d. Elbe; Staatliche Versuchs- und Forschungsanstalt für Gartenbau (director, Prof. Schindler).—Investigations on understocks for apples, pears, quinces, plums, cherries, and peaches. The objectives are to obtain good congeniality between stock and scion and to obtain cold resistance and good propagation qualities for the production of clon stocks.

Alnarp: Lantbruks-, Mejeri-och Trädgårdsintitut (director) L. Forsberg.—Investigations are conducted with apples, pears, plums and cherries. Specially hardy apple varieties producing large yeilds are crossed with those of fine quality but not hardy in central and northern Sweden. A total of 3,750 seedlings, representing 136 combinations, are being grown. Crosses between triploid and diploid strains have yielded some trees that show promise. Crosses have been made between pear varieties for quality and productiveness, involving 41 combinations and 570 individual trees.
In plum and cherry breeding, difficulty has been experienced in obtaining satisfactory germination. Only one promising type of plum has been secured to date. A small number of crosses between soft-fleshed, high-yielding, early-bearing cherry varieties and the hard-fleshed, sweet varieties have been made.

During the past decade plant explorers from the Soviet Union gathered at central breeding stations in that country much of the available material of the world that may be of promise for production there or for breeding purposes. Under the direction of the Institute of Plant Industry, 14 plant-breeding centers have been set up in different parts of the Union. At these centers, fruit breeding to develop varieties adapted to the different parts of the Union constitutes a major line of investigation. Genetic and cytological studies are being made.

Information from the USDA 1937 Yearbook. Reorganized for consistency and potentially export into a future database. Maga
Breeder(s): South Dakota Agricultural Experiment Station in Brookings.
History: Originated as a cross of McIntosh X Virginia Crab?. Introduced in 1922, the same year that the New York Times wrote their first article about Hitler, wherein they described his followers as, "potentially dangerous, though not for the immediate future." Also introduced that year was the Spineless raspberry.
Fruit quality: good
Fruit size: Small.
Fruit appearance: Flattened, bright-red stripes.
Culinary characteristics: No information. [redacted by Bill Barr?)
Storage characteristics: No information.
Harvest season: late.