UNIVERSITY OF CAIIFOR PROPAGATIO of temperate - zone fruit plants C.J.HANSEN • H.T, HARTMAN CALIFORNIA AGRICULTURAL Experiment Station CIRCULAR 471 REVISED The commercial fruit grower who wishes to apply the principles of propagation by budding and grafting in his orchards will find the necessary instructions in this circular. He will also find infor- mation on the propagation of fruit plants by cuttings, layering, suckers, and runners. The material should also be of interest to the nurseryman and to the home gardener. B L E O Rootstocks for Fruit Plants 5 Selecting rootstocks 5 Almonds 5 Apples 5 Apricots 6 Cherries 6 Figs 6 Grapes 6 Olives 7 Peaches and nectarines 7 Pears 7 Pecans 8 Persimmons 8 Plums and prunes 8 Walnuts 9 Stratification of rootstock seeds 9 Planting rootstock seeds 11 Vegetative Methods of Propagation 11 Budding 12 Late-summer or fall budding in the nursery 12 June budding in the nursery 12 Spring budding in the nursery 13 Selection of budwood 14 Position of buds in nursery practice 14 T, or shield, budding 16 Patch, or flute, budding 17 Hinge, i , or modified H budding 19 Chip budding 1° Top budding 1° Grafting 21 Selection and storage of scion wood 21 Root grafting 22 Whip, or tongue, grafting 22 Crown grafting 23 Fruits and nuts grown in California may be divided into two general groups: 1) temperate-zone fruits, chiefly deciduous, produced in both the northern and southern parts of the state; and 2) subtropical fruits which, while not limited to the southern area, are better suited to its warmer climate. This circular is concerned only with the propagation of temperate-zone fruits. O N T E N Top grafting 23 Cleft grafting 24 Bark grafting 26 Saw-kerf, or notch, grafting 30 Whip, or tongue, grafting 31 Side grafting 31 Subsequent treatment of top-worked trees 32 Bridge grafting 34 Inarching 36 Grades of nursery trees 36 Waxes and other grafting materials 37 Layering 37 Simple layering 38 Tip layering 38 Mound, or stool, layering 38 Trench layering 38 Air layering 39 Runners 40 Cuttings 40 Hardwood cuttings 40 Semihardwood cuttings 43 Softwood cuttings 44 Root cuttings 44 Leaf-bud cuttings 44 Rooting media 44 Sand 45 Sand-peat moss mixture 45 Vermiculite 45 Perlite 45 Mist propagation for leafy cuttings 45 Use of growth regulators in rooting cuttings 47 Powder dip method 47 Dilute solution, 24-hour soaking method 47 Concentrated-solution dip method 49 Suckers 49 Methods of Propagating Various Fruit Plants 49 PROPAGATION OF TEMPERATE-ZONE FRUIT PLANTS C. J. HANSEN H. T. HARTMANN JTlants may be propagated in two gen- eral ways: by seeds and by vegetative propagation. As a rule, the use of seeds in the propagation of fruit varieties, although simple and economical, is not satisfactory; the seedlings produced are usually different from the parents, espe- cially in size, shape, and quality of the fruit. In addition, the various seedlings are likely to differ from one another. This great variation, although undesirable to the plant propagator, is a valuable aid to the breeder who is trying to produce better plants. Fruit varieties that would come reasonably true from seed could be obtained by selection and breeding over several plant generations, but as each generation requires a number of years the time necessary would be prohibitive. The fruit-plant propagator must therefore use a vegetative method — that is, he must root some part of the parent plant, such as stem or root (cuttings, layering, and similar processes), or must place a part of one plant on another in such a way that it will grow (grafting and budding) . In vegetative propagation a portion of the parent plant is simply growing in a different location, and therefore a plant so propagated will ordinarily be identical with the parent. Placing a piece of branch — a section a few inches long — in soil or in sand so that it will form roots and new branches is not difficult or expensive. This method — propagation by cuttings — is used for quince, fig, promegranate, grape, olive, currant, gooseberry, and certain other fruits. Unfortunately, some of the prin- cipal tree fruits (for example, pears, apples, cherries, peaches, apricots, al- monds, walnuts, and most plums) are so difficult to propagate by cuttings or simi- lar methods that these procedures usually cannot be followed economically; such plants are generally propagated by grow- ing seedlings and budding or grafting the desired variety upon them. The plants upon which fruit varieties are budded or grafted are called rootstocks. Seedlings are usually uniform enough for this pur- pose, but vegetatively-propagated plants are sometimes used to secure such benefits as disease resistance and uniform vigor. Many additional varieties would be propagated on their own roots by cuttings or similar methods if this were possible or profitable. Sometimes, however, it would not be desirable. For example, cer- tain rootstocks now available are more resistant to nematodes, diseases, or ad- verse soil conditions than are the varieties growing on their own roots. FEBRUARY, 1966 THE AUTHORS: C. J. Hansen is Professor of Pomology and Pomologist in the Experiment Station, Davis. H. T. Hartmann is Professor of Pomology and Pomologist in the Experiment Station, Davis. [4] ROOTSTOCKS FOR FRUIT PLANTS SELECTING ROOTSTOCKS Rootstocks in use are discussed be- low, and some information is given con- cerning the source of seed. Almonds. The principal rootstocks for almond are almond and peach seedlings. Almond seed is sometimes obtained from bitter almond seedlings, but usu- ally from commercial sweet almond va- rieties, such as the Texas. The choice between peach and almond rootstocks depends upon the experience of growers in the district where the trees will be planted, but if root-knot nematodes are present in the soil a nematode-resistant peach rootstock should be selected. (Ad- ditional information concerning peach rootstocks will be found in the section on peaches and nectarines.) Myrobalan plum (Prunus cerasifera) has been tried as a rootstock for almonds, but it is not commercially satisfactory. Marianna 2624, a clonal selection of Marianna plum (P. cerasifera x P. mun- soniana [ ? ] ) , has been used to a limited extent as a rootstock for almonds in heavy, wet soils and in areas infected with oak root fungus {Armillaria mellea) . It is propagated by means of hardwood cut- tings. Ne Plus Ultra, Texas (Mission), Peerless, Jordanolo, and, in most cases, IXL are making satisfactory growth on this stock although considerable over- growth usually occurs at the union. After 7 years growth in the orchard, trees of Ballico, Thompson and Merced on Mari- anna 2624 also seemed satisfactory. Non- pareil, Drake, Davey, Kapareil and Pro- fuse, make unsatisfactory growth on Marianna 2624. The ultimate size of almond varieties on plum roots is not known, but observations made during 21 years indicate that they will be relatively smaller than trees on almond or peach roots. Marianna 2624 is more resistant to oak root fungus than other rootstocks which may be used for almond, but it should not be considered immune. Growing almond trees on Mari- anna 2624 is probably justified if the use of this rootstock is restricted to wet areas in orchards or to areas infected with oak root fungus. Apples. In the past, rootstocks for apples have been grown to a great extent from "French crab" seed, imported mostly from France. The French crab trees are principally seedlings whose fruit is used for cider. In recent years, however, seed of domestic commercial apple varieties has been used in large quantities, and now accounts for a considerable part of the United States supply of rootstocks for apples. Nurseries growing most of the apple rootstocks for California, Oregon, and Washington obtain the seed chiefly from such varieties as Winesap, Rome Beauty, Delicious, Mcintosh, and Yellow Newtown. Jonathan seed is also used, although some nurserymen think that the seedlings obtained are not completely satisfactory. Various agricultural experi- ment stations have tested the ability of the seed of many commercial varieties to germinate and to produce desirable seed- lings. Most of the stations are satisfied with the seed of Rome Beauty, Delicious, Ben Davis, Whitney, and Winesap, but they do not recommend Baldwin, Rhode Island Greening, or Gravenstein seed. If dwarf trees are desired, certain vegetatively-propagated rootstocks should be used. Two groups of such stocks are available: the EM (East Mailing) series, and the MM (Malling-Merton) series; both were developed in England. Root- stocks in the MM series are resistant to wooly apple aphid. The most important stocks in these two groups are listed at the top of next page, classified into four levels of vigor as determined by the size of mature trees worked on such stocks. (Trees on seedling rootstocks are classed as "Standard" in vigor.) [5] Vigor Rootstocks Standard (very vigorous) EM XVI, EM XXV, MM 109 Semi-standard (vigorous) EM II, MM 104, MM 111 Semi-dwarf EM VII, MM 106 Dwarf EM IX, EM 26 Dwarf trees can also be produced by using a strong-growing seedling rootstock with an intermediate stem piece of a dwarfing variety, such as EM IX or EM VIII (Clark Dwarf). Although much research has been con- ducted with these clonal rootstocks in other parts of the world, studies in Cali- fornia have been limited to small trial plantings of some growers. Further eval- uations are necessary before definite recommendations on the use of these stocks in California can be made. Apricots. The chief rootstocks for apri- cot are apricot and peach seedlings. Blenheim or Royal apricot seeds, easily obtained from drying yards and can- neries, are commonly used. If root-knot nematodes are present, the grower may use apricot root or a root-knot nematode resistant peach rootstock (see section on peaches and nectarines). Apricot roots tolerate the root-lesion nematode (Praty- lenchus vulnus) better than other root- stocks that may be used, but are more subject to gopher injury than peach roots are. Plum roots, although not used exten- sively, should be chosen for heavy soils tending to be wet. Seedlings of myro- balan plum (Prunus cerasifera) and hardwood cuttings of Myrobalan 29C and Marianna 2624 (P. cerasifera x P. mun- soniana[?]) are the plum rootstocks usually used. However, apricot trees on myrobalan seedling roots have not been wholly satisfactory; a small percentage has been broken at the graft union by heavy winds, and dieback has sometimes occurred. The trees on Marianna 2624 and Myrobalan 29C roots have made fair growth, but most of the trees growing on these rootstocks are less than 24 years old. Marianna 2624 is more resistant to oak root fungus than are other rootstocks used for apricot, but it should not be con- sidered immune. (Additional informa- tion on these plum rootstocks may be found in the section on plums and prunes.) Cherries. Mazzard and mahaleb seed- lings are common rootstocks for sweet cherries. Mahaleb gives the trees more re- sistance to buckskin disease, root-lesion nematode and drought, but it is more sub- ject to root-knot nematode and gopher injury. A sour cherry, the Stockton Morello, has occasionally been used for adapting sweet cherries to heavy, wet soils; al- though it is considered commercially sat- isfactory, Chapman and a few of the less important varieties sometimes do not do well on it. The most noticeable effect of this rootstock is a definite dwarfing of the sweet cherry top. It is propagated by means of softwood cuttings under mist, or by suckers. Seedlings of Stockton Morello should not be used, because of their vari- ability. Figs. No special rootstocks are used for the fig. The trees are propagated by means of hardwood cuttings, and are therefore on their own roots. Grapes. If neither root-knot nematodes nor phylloxera are present in the soil, grape vines may be propagated by hard- wood cuttings and thus be on their own roots. Where soil is infested with root- knot nematodes, the usual rootstock used is Solonis x Othello 1613. In very sandy soils of very low fertility where 1613 does not grow well the two Vitis champini root- stocks, Salt Creek and Dog Ridge, are [6] used. These stocks are extremely vigorous and should be used only in the poorest soils. Both are resistant to nematodes and have moderate resistance to phylloxera as well. Salt Creek is preferred to Dog Ridge, as the latter has extreme vigor and gives poor fruit set with varieties grafted on it. If phylloxera is the principal problem, V . rupestris St. George is the recom- mended rootstock, especially on hillside and rocky soils where there is no irriga- tion. On irrigated lands and those having deep loamy texture, Aramon x V. rupes- tris Ganzin No. 1 (A. x R. #1) is recom- mended. These resistant rootstocks are all propagated by hardwood cuttings. Olives. Because olive varieties can be propagated by cuttings the trees are often grown on their own roots; they are also budded or grafted on various root- stocks. In California, Mission, Ascolano and Manzanillo produce strong, fruitful trees on their own roots. Sevillano trees started from cuttings are somewhat smaller than grafted trees. Cuttings of Sevillano are difficult to root; those of Mission, Ascolano, and Manzanillo root readily. Seedlings of the Mission and Redding Picholine varieties are some- times used as rootstocks for the major varieties, especially Sevillano, but the re- sulting trees are often variable in vigor and growth habit. Rooted cuttings of a strong-growing variety, such as Mission, are more suitable than seedlings as root- stocks and give more uniform trees. Peaches and Nectarines. Peach and the nectarine are propagated almost en- tirely on peach seedlings grown from seed of commerical varieties, principally Lovell, and from seed of special rootstock selections such as Nemaguard, S-37, and Rancho Resistant. Apricot seedlings are occasionally used in sandy soils to re- sist root-knot nematode injury, but the union is not always successful. Lovell seedlings are seriously injured by both species of root-knot nematodes known to cause trouble in California or- chards, and should be used only where nematodes are not a problem. Seedlings of S-37 and Rancho Resistant are immune to one of the species of root-knot nema- todes (Meloidogyne incognita) com- monly found in California peach or- chards, but are susceptible to the other (M. javanica) . In some cases S-37 has not been as well anchored as other peach rootstocks. Nemaguard, a promising new rootstock, is immune or highly resistant to M. incognita and M. javanica. Pears. The French pear, Pyrus com- munis, is the usual rootstock for pears. Most of the seed is from the Bartlett variety, the principal canning pear, but much Winter Nelis seed is also used. Rootstocks developed from Bartlett and Winter Nelis seed are referred to as either "domestic" or "French" seedlings. Trees on such seedlings apparently are resistant to pear decline. Old Home (a blight-resistant variety) may be used for the framework branches, with French pear seedlings as the root- stock. Even a severe blight infection would not affect the resistant framework, on which a new top could later be built. Pears on own-rooted Old Home as a root- stock are vigorous, have the advantage of a blight-resistant root system, and are re- sistant to pear decline and black-end. Self- rooted Old Home rootstocks can be ob- tained by rooting hardwood cuttings, or by rooting leafy softwood cuttings under mist. They can also be obtained by graft- ing Old Home scions on rooted quince cuttings as a nurse root, with the graft union planted 2 to 4 inches below ground so that the Old Home stem will become rooted. The Japanese pear, Pyrus pyri folia (P. serotina) is an unsatisfactory rootstock because of black-end trouble and because of its susceptibility to pear decline. Pyrus ussuriensis, another Oriental species, is also susceptible to black-end and to pear decline. Only a slight amount of black- end has been found in orchards on P. calleryana roots, and the trees showing [7] the trouble are possibly replants and not on true P. calleryana roots. P. calleryana rootstocks are more resistant to rodents than are P. communis rootstocks, and more resistant to blight than are P. com- munis or quince. Where good pear psylla control has been practiced, trees on P. calleryana roots have shown resistance to pear decline. If dwarf trees are desired, quince (Cy- donia oblonga) roots are used. Because Bartlett variety does not make a good union directly with quince, it is necessary to double-work with a compatible inter- stock, such as Hardy (Beurre Hardy) — ■ that is, to use a short piece of the com- patible interstock stem between the quince root and the Bartlett top. The blight-re- sistant Old Home can also be used suc- cessfully as a compatible interstock be- tween Bartlett and the quince root. Trees worked on some quince clones as rootstocks are susceptible to pear de- cline. Pecans. Seedlings grown from nuts taken either from seedling trees or from commercial pecan varieties are used as rootstocks. Persimmons. Seedlings of three Dio- spyros species — D. lotus, D. kaki, and D. virginiana — can be used as rootstocks for varieties of the Oriental persimmon, D. kaki. D. lotus seedlings are vigorous, drought-resistant, and produce a rather fibrous root which transplants easily. This stock is quite susceptible to crown gall, and does not tolerate poorly-drained soils. Hachiya variety does not produce well on D. lotus stock because of excessive fruit shedding. Scions of Fuyu variety are reported to make a poor union with this stock, although Fuyu top-worked on a D. kaki variety which has been estab- lished on D. lotus roots makes a satisfac- tory tree. D. kaki is probably the best stock for general use, although the seedlings are difficult to transplant because they have a long taproot with few laterals. This stock makes a good union with all varie- ties; the trees grow well and yield satis- factory commercial crops. Seeds for root- stock use may be obtained from any of the Oriental persimmon varieties that produce seeds. D. virginiana seedlings are utilized as a rootstock in the southern part of the United States. Most Oriental persimmon varieties make a good union with this stock, which is tolerant of excess soil moisture and produces a desirable fibrous root. In California, Hachiya variety on this stock is dwarfed and yields poorly because of sparse bloom. Plums and Prunes. The important rootstocks for plums and prunes are my- robalan plum (Prunus cerasijera) and peach seedlings, and Marianna 2624 (P. cerasijera x P. munsoniana[?]) and Myrobalan 29C, which are propagated by means of hardwood cuttings. Most varieties do well on these rootstocks. Myrobalan 29C and Marianna 2624 are not injured by root-knot nematodes, but many of the myrobalan seedlings are susceptible. (Resistance to root-knot nematodes of the peach rootstocks is dis- cussed in the section on peaches and nec- tarines.) The roots of Marianna 2624 and Myro- balan 29C may be more shallow the first 3 or 4 years than are the roots of myro- balan plum seedlings and peach seedlings. Because of this, there is a tendency for young trees on Marianna 2624 and Myro- balan 29C roots to be blown over by heavy winds. Plum or prune trees on peach roots are less susceptible to bacterial canker than are trees on plum roots. However, plum roots should be used in soil that is heavy and tends to be wet during part of the year. The use of peach roots for prunes in the interior valleys of California should generally be avoided, because it contributes in some years to excessively heavy crops and a resultant dieback con- dition of the trees. Marianna 2624 is more resistant to oak [8 root fungus than are other rootstocks used for plums and prunes. Since some Marianna 2624 roots have been killed by oak root fungus, it will require a number of years to determine whether this root- stock has enough resistance to justify its continued use for this purpose. Almond, which is occasionally used as a rootstock for plums and prunes, is satis- factory with many varieties provided soil conditions are suitable. However, it is probably best not to use this rootstock except in soils high in lime or boron. Trees on almond roots show some resist- ance to an excess of these substances. Many varieties do well on apricot root, which is sometimes used in soils infested with root-knot nematodes, but Marianna 2624, Myrobalan 29C or a root-knot nem- atode resistant peach are now preferred. Walnuts. Northern California black walnut (Juglans hindsii) seedlings have been the standard rootstock for Persian (English) (/. regia) walnut plantings in California for many years. They are vig- orous enough in good valley soils suitable for walnut production. The seedlings are highly resistant to oak root fungus, but are not immune. They are susceptible to crown root, root-lesion nematode (Pra- tylenchus vulnus) , and black-line. Paradox hybrid seedlings resulting from natural crosses of northern Cali- fornia black and Persian walnuts have been used increasingly during the past few years. They have usually shown greater vigor than northern California black walnut in foothill soils, in valley soils not of the best quality, and as re- plants. They will withstand fluctuating water table conditions better than north- ern California black walnut, are highly resistant to crown rot, and are partially resistant to root-lesion nematode. How- ever, they are susceptible to black-line. Persian walnut seedlings have been used in a few instances where crown rot and black-line are serious problems but where oak root fungus is not present. STRATIFICATION OF ROOTSTOCK SEEDS When removed from the plant, seeds of most deciduous fruit trees ordinarily will not germinate, even under ideal con- ditions of moisture and temperature. This is caused partially by the fact that the seed embryos are in a rest which must be broken by cold. In addition, the seeds of many plants are covered with a stony layer which must be softened before ger- mination begins. The usual method of breaking the rest and softening the hard coat is to put the seed in a cool place be- tween alternate layers of moist sand or other materials, such as vermiculite or a mixture of sand and peat moss. This treat- ment, called stratification, is begun in fall or winter, depending upon the kind of tree. The seeds remain in the stratifying medium until planted in the nursery. As a general rule, stratification should con- tinue until the embryonic root is seen starting to push through the seed cover- ing. The seeds should then be planted im- mediately. Some species do not require a stratification period for germination. It is advisable, with most seeds, to soak them in water for about 24 hours before they are put into the stratification ma- terial. The size of container (figs. 1 and 2) used for stratification depends upon the quantity of seed to be treated, and may vary from that of a polyethylene bag to a fairly large box or can. The seeds illus- trated (fig. 1) are in layers because that is the easiest way to place them in the box. Slightly better results might be ob- tained by mixing the seeds and sand thoroughly so that each seed would be surrounded by a maximum amount of sand, but most nurserymen do not con- sider this step necessary. The stratifying medium must be kept moist; it is desir- able to check the seeds at intervals during this period and add water if necessary, taking care to avoid excessive moisture. [9] Fig. 1. Side of box removed to show seeds of deciduous fruits being stratified in moist sand. Airtight containers must not be used, as aeration is necessary during the stratifi- cation process. If necessary, cover the containers with wire screen for protec- tion against birds or rodents. If the winters are not too warm, seeds will receive enough cold in a shady, out- door location. However, better germina- tion may be expected with some seeds if they are stratified in cold storage at 33° Fig. 2. Seeds being stratified in moist vermiculite in polyethylene bags. [10] to 40° F. The following are suggested stratification periods at 33° to 40° F: 30 days: 90 to 120 days: Almond Cherry Apricot Peach 60 to 90 days: Plum Apple Walnut Pear PLANTING ROOTSTOCK SEEDS There are two methods of planting fruit tree seeds: (1) directly in the nur- sery row after the stratification period is complete, with the resulting seedlings budded the same year; or (2) thickly in a seedbed, with the seedlings moved to the nursery row the following winter or early spring. The second method pro- duces trees with roots 1 year older than those produced by the first method. For either method, planting is usually done in February or early March. Rootstock seeds planted directly in the nursery row after stratification are apri- cot, almond, peach, walnut, pecan, and sometimes myrobalan plum and mahaleb and mazzard cherry. (Because the tops of pecan seedlings grow rather slowly, it is usually necessary to delay budding or grafting until the second year.) Rows are usually 4 to 6 feet apart, with seeds about 4 inches apart in the row. If experience has shown that certain kinds of seed tend to germinate poorly, the grower may de- cide to plant them much closer than 4 inches and to thin later if necessary. The large walnut seeds are usually placed 4 to 5 inches deep; the medium-sized apri- cot, almond, peach, and pecan, about 3 inches; and the smaller myrobalan plum about 1% inches. To prevent drying out, seeds are usually planted deeper in light than in heavy soils, but this may not be necessary if irrigation water is always available. Occasionally, seeds have been planted directly in the nursery row in the fall without stratification. However, with this method it is difficult to maintain favorable moisture conditions in the field, rodents may destroy many seeds, and weeds growing in winter may be difficult to remove without disturbing the seeds. Rootstock seeds grown one season in a seedbed and then transplanted to the nursery row are apple, pear, and some- times myrobalan plum and mahaleb and mazzard cherry. The type of seedbed varies considerably, but commercial pro- ducers of seedling trees generally plant in rows far enough apart for convenient use of tractor-drawn cultivators. A stand of 10 to 15 seedlings per foot is usually needed to keep the trees from growing too large for satisfactory transplanting. If large numbers of seedlings are not re- quired, the seed may be broadcast or planted in rows in beds of convenient size. Apple and pear seeds are planted about 1 inch deep, and cherry and myro- balan plum seeds about 1% inches. Im- mediately after being transplanted to the nursery row, larger seedlings should be cut back to approximately 8 to 10 inches above ground. It is usually not necessary to prune those with tops less than 8 or 10 inches long. To expedite planting, lateral roots are usually cut back to stubs a few inches long. VEGETATIVE METHODS OF PROPAGATION The chief vegetative methods of propa- gation for deciduous fruits are budding, grafting, layering, and the use of cut- tings, suckers, and runners. Often plants may be propagated by more than one of these methods. The nurseryman knows how to secure the most plants for the least outlay in cost and materials, but a grower may sometimes use a method that would not be practical on a large scale. [in BUDDING Budding is the placing of a single de- tached bud upon a plant called the stock. This method is used by the nurseryman to propagate his plants and sometimes by the grower to change trees over to an- other variety. Some of the names given to methods of budding are based on the time of year in which the work is done. Spring budding is usually done in March or April, June budding in May or the first half of June, and late-summer or fall budding in July and August or a little later. Other names used are based on the method of cutting and inserting the bud, such as shield budding, patch budding, IT budding, chip budding, and other, less important methods. In all these proc- cesses, success depends upon joining the cambiums of the stock and the bud. The cambium, or growing layer, is found be- tween the wood and the bark. Late-summer or fall budding in the nursery. Budding, although usually done in July and August, may be con- tinued into September and October until the bark cannot be lifted. The budwood is collected from the current season's growth at the time the work is done, but may be stored a short while if kept cool and moist. The buds are either placed in trees grown from seeds planted in the spring of the same year, or (with apples, pears, and sometimes cherries and myrobalan plums) in trees lined out in the nursery row in the spring. In a few cases, vegeta- tively-propagated rootstocks are budded. About the time growth starts in the spring after budding, cut back the top of the rootstock to about % inch above the bud (that is, just above the crosscut of the T, or top of the patch). Usually this cut slopes downward from the side where the bud is located. Remove all water sprouts appearing below the bud. The trees are dug in the winter after the buds have grown one season. Trees thus produced will have either 2- or 3-year-old roots and 1 year-old tops. They are, however, called 1-year-old, or yearling, trees; the age of the roo^ ' ^ not considered. In California, 2-year-old de- ciduous fruit trees (that is, trees with 2- year-old tops) are not usually offered for sale. Late-summer or fall budding is the most important method used for decidu- ous fruit trees, although in recent years June budding has been used consider- ably to propagate some kinds of fruit trees. June budding in the nursery. If ad- vance orders and inquiries indicate that the supply of fall-budded trees will not meet the demand, and if the seedling trees have grown sufficiently in the three or four months since planting, June bud- ding may be done in May or in the first half of June. Some nurseries have made it a regular practice to propagate a con- siderable number of trees by this method. The usual procedure is to cut off the seedling top 2 to 5 inches above the bud 3 or 4 days after budding. Leave at least one leaf above the bud, and several below. It may be necessary to bud as much as 8 inches above ground in order to have a sufficient number of leaves below the bud. These rootstock leaves help to manufac- ture food for the tree until the leaves pro- duced by the bud are large enough to take over this function. Make a cut back to the bud 10 to 16 days after budding. Thereafter, any shoots other than those from the bud should be shortened, and when the bud has grown into a shoot 6 to 8 inches high and has enough leaves of its own, remove all other leaves and shoots. Budwood is collected from the current season's growth at the time of budding. As a rule, all wood is removed from the bud shield except a small core in the bud. The easiest way to do this is to make a long cut (fig. 3, A) , and then, at the upper end, to make a cut through the bark only, rather than through both bark and wood. The shield may then be removed with a sliding motion, and the wood remains [12] : Fig. 3. T, or shield, budding. A, bud stick with some buds removed (cuts should be started below buds); B, making crosscut at top of vertical slit; C, bud partly inserted; D, bud in place; E, bud tied with budding rubber. Moderate tension of the rubber gives best results. attached to the bud stick. If the shield is pulled rather than slid from the bud stick, the small core of wood may become sepa- rated from the bud itself, and the result often is failure. Given ideal growing con- ditions, a medium-sized tree suitable for the orchard will be obtained by the time growth stops in the fall, and thus a year will be gained. Though the method de- scribed is relatively simple, heavy losses are likely to occur unless the work is carefully done. Seedlings must grow rapidly in order to be large enough for budding in May or in the first half of June. Because the peach best meets this requirement, most June-budded trees offered for sale are on this rootstock. Nurserymen list various varieties of June-budded peaches, nec- tarines, almonds, apricots, and plums. June budding generally is feasible only in regions which have a long growing season. Spring budding in the nursery. This is begun early in spring, as soon as the bark of the stock slips easily from the wood and allows the buds to be inserted, and should be completed before trees have made much new growth. This will usually be in March or April, depending on the kinds of trees and the season. As a rule, the bud sticks are collected in late winter, while dormant, and are stored in moist sphagnum moss or peat moss in a [13 cool place. They can be used for T, or shield, budding without further treat- ment. For patch budding, however, the bud sticks must be transferred to a warm lo- cation and kept there until the bark will slip from the wood. By that time a few buds will have started to grow; these cannot be used, but others will be in good condition. Bud sticks for patch budding may also be cut directly from the tree at the time of budding, a practice thought by many to be the best. When this method is used, bud sticks on which part of the buds have started to grow are cut from the trees. Some buds will be in the right condition, that is, they will still be almost completely dormant, and yet the bark of the patches can be separated from the wood of the bud sticks — a requirement of patch budding. About 2 weeks after budding, the tops of the stocks are cut off to force the buds into growth. The next winter, after the buds have grown one season, the trees are dug and sold. They are then essentially the same as the 1-year-old trees produced by late-summer or fall budding. This method is usually less satisfactory than late-summer or fall budding, and should be used only for trees not success- fully budded during the fall, or in some other special cases. Selection of budwood. Buds for late- summer or fall budding and June bud- ding should be taken from the current season's growth of the specified tree at time of budding, but for work in the spring dormant branches are usually se- lected and stored until needed. Although it is probably best to choose bud sticks having leaf buds (wood buds) only, many propagators use clusters contain- ing both leaf and flower (fruit) buds. Do not use flower buds exclusively, because these blossom and die. Leaf buds are usually smaller and sharper pointed than flower buds. In plums, apricots, peaches, and wal- nuts, a leaf bud usually occurs at each node or joint, either alone or associated with one or more flower buds. A single flower bud is occasionally found on the bud sticks of these species, but not often enough to cause the propagator much concern. Pear, apple, and almond bud sticks often have a number of single flower buds near the apical end. (In the pear and apple, these are really mixed buds, but usually respond the same as ordinary flower buds.) Since the apical end is customarily discarded because of its small size, the danger of using these undesir- able buds is minimized. The sweet cherry is most likely to cause trouble because its flower buds are lo- cated on the basal part of the shoots (fig. 4), a part which the propagator is likely to use if he does not know the posi- tion of the buds. The matter is further complicated by the fact that cherry flower buds are essentially the same size and shape as the leaf buds. In all fruit tree species discussed above, more leaf buds will generally be found on the most vigorous shoots. The danger of using flower buds can be greatly re- duced by avoiding the shorter, less vigor- ous type of growth. Position of buds in nursery prac- tice. Budding is usually done as near the ground as convenient, but northern Cali- fornia black walnut stock, which is re- sistant to oak root fungus, is often allowed to extend a foot or more above the surface of the ground. Other kinds of resistant rootstocks are commonly budded 4 to 5 inches above the soil surface. Buds are usually inserted on the north side of the seedlings for protection against the sun during healing. In the hot interior valleys of California, however, where summer north winds are common, some propagators prefer to bud on the south side of the tree to prevent drying out of the bud, even though this practice may increase the possibility that the growing bud may be broken off by wind. There is another point in favor of the south side: [14 Fig. 4. Sweet-cherry shoots, showing basal position of flower buds. The lower few inches of cherry bud sticks should be discarded. Less vigorous shoots have more flower buds; more vig- orous shoots have fewer flower buds. The possibility of using flower buds can be greatly reduced by avoiding shorter, less vigorous type of growth. [15] I ABC D E Fig. 5. Patch, or flute, budding. A, bud stick with patch cut, but not removed; B, patches with buds, removed from bud stick; C, patch of bark removed to receive bud; D, bud in place; E, wrapping completed. Notice that bud itself is not covered. after the bud has started growth, the short section of seedling trunk on the side below the bud is less subject to sunburn than is the side opposite the bud. There- fore, less injury will occur if this more resistant side is placed on the south. Not only is sunburn in itself serious, but the damage caused by it is often followed by the entrance of flat-headed borers. T, or shield, budding. This is the method most commonly used for decidu- ous fruits, except the walnut, pecan, and grape. A bud with some bark and a thin layer of wood 1 to l1/^ inches long is sliced from the bud stick with a sharp knife and placed beneath the bark of the stock (fig. 3) . The blade has the rounded point commonly found in budding knives. Leaves have been removed from the bud stick by severing leaf stems, or petioles, about Vi inch from the buds. Beginners often use the leaf stem as a handle to aid in inserting the bud, but experts gener- ally hold the bud between the knife blade and the thumb. If the bud cannot be easily pushed into place in the T cut, it may be necessary to pull it into position with the point of the knife. This can be done with little injury to the bud by inserting the end of the knife a short dis- tance into the shield just below the stub of the petiole. When doing this, hold the blade of the knife perpendicular to the length of the shield. The details so far discussed refer par- ticularly to late-summer or fall budding. They also apply to spring and June bud- ding, except that no petioles are present on the bud sticks used for spring budding because the sticks are collected in winter when leaves are not on the trees. In June budding, the wood is usually removed from the buds by some method such as the one described on page 12. The T cut in the stock that will receive the bud is generally upright, although sometimes an inverted T is used. Most budders make the vertical cut of the T first, then with a single movement they make the crosscut and throw open the bark to receive the bud. Some, however, make the vertical slit last. By whatever method the T is cut, the bud is inserted [16] Fig. 6. Patch, or flute, budding tools. Left, type with four blades; center, budding tool with two parallel blades, suitable for a limited amount of work; right, two-bladed budding knife of the type commonly used by commercial budders. far enough so that its top does not project above the crosscut of the T. The vertical slit should not be longer than necessary to accommodate the bud. If it is too long, the lower part of the shield may not be adequately covered. Although raffia and string have been used to tie the bud, such materials have been practically replaced by budding rubbers, which need not be cut to avoid constricting the stem. These will stretch as the tree grows, and after a few weeks they rot and fall off. Rama or string, if used, should be cut in 10 days to 2 weeks. Wrapping should begin at the top of the T and proceed downward so that the bud will not be forced upward. The budding rubber is held in place by inserting the end back under the last turn. The bud itself is not covered by the wrapping material (fig. 3). With some plants, better results have been reported when the wood has been removed from the buds, but with decidu- ous fruits this is done only when June budding is practiced and when (in a few instances) T budding is used for walnuts and persimmons. In order to force the bud into growth, it is necessary to cut back the top of the rootstock to about % inch above the bud (that is, just above the crosscut of the T) . The time to do this depends on whether the trees are being fall, June, or spring budded. Patch, or flute, budding. This is com- monly used in propagating thick-barked trees, such as walnut and pecan. A square or rectangular patch of bark is removed from the seedling and replaced with a similar one that includes the bud desired. This latter patch is slid rather than pulled from the bud stick so that the small core of wood in the bud itself will be retained. Figure 5 illustrates the steps taken. Be- [17] Fig. 7. Patch, or flute, budding stock branches which have bark thicker than that of the budwood. Left, patch removed and stock bark pared down; right, bud in place and ready for wrapping. cause a good fit at the top and bottom of the patch is necessary, most tools used have two parallel blades 1 to 1% inches apart, for the horizontal cuts. The vertical cuts are made with an ordinary budding knife. The tool in figure 6, center, may easily be made from a small piece of wood, two safety-razor blades, two bolts, and two metal strips, one on the outside of each blade to hold it in place. If con- siderable work is to be done, a stronger knife (fig. 6, right), consisting of two budding-knife blades rigidly attached to each other, is preferable. This is the type usually used by commerical budders. Some tools have vertical knives in addi- tion (fig. 6, left), but this type of bud- ding knife has not been entirely satisfac- tory. If the bark of the stock is thicker than that of the budwood, the stock bark must be pared down as shown in figure 7, so that the patch can be tied firmly in place. The usual wrapping material is waxed cloth or budding tape. String and rubber bands are not recommended be- cause they are less effective in preventing drying out. Waxed cloth, budding tape, or string should usually be cut in 2 or 3 weeks. If the stock is making very vigor- out growth, however, it may be necessary to cut the wrapping material in about 10 days to prevent constriction. In cutting these materials it is best to make the cut on the side opposite the bud. Because the leaf bases of trees com- monly T-budded are not large, they do not interfere with wrapping the bud. Walnut and pecan leaf bases, on the other hand, are rather large and make wrapping diffi- cult. Most propagators cut the leaves off the budwood, except for short stubs, 2 or 3 weeks before budding. Leaves on the terminal ends of bud sticks should be left uncut. By the time the bud sticks are re- moved from the tree the short stub of the leaf stem, or petiole has dropped off or may be easily removed. Ring, or annular, budding is the same as patch budding except that a complete ring of bark is removed around the stem. This method is slower and has no pai- ticular advantage. In order to force the bud into growth, it is necessary to cut back the top of the rootstock to about % inch above the bud (that is, just above the top of the patch) . [18] \ ] Fig. 8. Steps in chip budding grapes. Left to right: bud removed from bud stick; notch made in stock to receive bud; bud in place; bud tied, ready to be covered with soil. Chip budding is seldom used for deciduous fruits other than grapes. The time to do this depends on whether the trees are being fall or spring budded. Many nurserymen whip-graft (see p. 22) seedlings whose buds fail to unite. This is done in the winter after the bud- ding. Hinge, x , or modified H, budding. This method is sometimes used in place of the patch bud when the bark of the stock is considerably thicker than that of the budwood. It eliminates the need for paring down the bark of the stock to hold the patch firmly in place. The cut in the stock is made in the form of an x (like an H on its side) . A patch containing a bud cut as for patch budding is inserted under the flaps of the x . Wrapping is done as in patch bud- ding. This method is reasonably satisfac- tory, but unless care is taken the patch may buckle slightly and not touch the stock under the bud. Chip budding. In budding small grapevines, more consistent results have been obtained with chip budding (fig. 8) than with other common methods. Root- stock rootings, resistant to phylloxera or root-knot nematode are planted in the vineyard in the spring, and are budded the following August in nonirrigated vine- [ yards and in September in irrigated ones. For good results, buds must be taken from mature canes in which bark color has changed to brown. The stock must be growing actively at the time of budding. Figure 8 shows how a chip is removed from the stock and replaced with a chip of similar size and shape carrying a bud of the desired variety. To facilitate the removal of the bud from the bud stick, the first cut is made at the base of the chip deep into the stick, at an angle of about 45 degrees. Buds are placed just above ground level and tied with bud- ding-rubber strips. They are covered im- mediately with about 6 inches of pulver- ized soil. The rubber must be cut and re- moved the following spring but only after the bud on the chip has grown out at least % inch. At that time the top of the vine is cut off about % inch above the bud union. Chip budding is seldom used for deciduous fruits other than grapes. Top budding. Budding is done mostly by nurserymen to propagate their plants, but also by the fruit grower who wishes to change his trees over to another variety. The only differences between or- chard procedure and that followed in nursery work are that the buds are in- 19] o o a o o 3 i. lk «n 3 O 3 T[ *w O Q c o E E o u a> E o < TO c £ o «.2 .. cd £.* 3 :§ s gj 1 >i 3 "S 3 1 1 1 1 1 1 I 1 to J3+» OT 3 S 3 1 1 1 1 1 1 11° 11 1 1 1 1 1 1 1 1 CO W* CD H — 3 1 £ 1 1 1 w 1 O 1 '3 1 t> 1 1 1 to 1 CO 1 a •og| CO I O 1 CO 1 Oil ilS 3 P 1 CO 1 p 1 CO 1 1 3 1 CO 1 1 1 O 1 CO 1 a) 1 p 1 1 1 CO 1 p 1 .3 * u c8 O 1 U 1 O | Oil v CO 1 CO 1 CO 1 CO 1 1 ft ■M § w M» S p t 111*11 III O fc CD 1 1 1 CO 1 1 III T3 *- >> 83 n 1 1 1 O 1 1 III N 05 1 1 1 CO 1 1 III §° X) £ >» "3 t; 1 1 1 O 1 1 III X! 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Top left, Fay Elberta peach; top right, Santa Rosa plum. Lower left, Tilton apricot; lower right, Bartlett pear. To prepare 1 gallon of an approxi- mate 100 ppm solution of indole- butyric acid, measure a level Va teaspoon of the chemical, dissolve it in a small amount of alcohol (ethyl or isopropyl, and add to the water, strirring thoroughly. should be immersed in the solution to a depth of % to 1 inch. The concentrations used vary from 15 to 200 ppm (parts per million) depending upon the species. A strength of 50 to 100 ppm of indolebuty- ric acid is effective in promoting rooting of softwood, semihardwood, and hard- wood cuttings of many plants. [48] f\"^V Fig. 38. Suckers of red raspberry. A, parent plant; B, suckers in different stages of development. Concentrated-solution dip method. A rather concentrated solution — 500 to 10,000 ppm — is prepared in which the basal % inch of the cutting is immersed for about 5 seconds. Large bundles of cuttings can be dipped at one time and then set immediately in the rooting bed. It is always advisable to have fresh basal cuts at the time the cuttings are dipped. For hardwood cuttings, a concentration of about 2,000 ppm is recommended, but for softwood and semihardwood cuttings, higher concentrations (4,000 to 6,000 ppm) are generally more effective. SUCKERS Red raspberries, upright blackberries, filberts, and the Stockton Morello cherry (a rootstock for cherries), can be propa- gated by suckers. The suckers, together with some roots, are removed from the parent plant during the winter (fig. 38). To prepare a 4,000-ppm solution of indolebutyric acid, dissolve a level Va teaspoon of the pure crystals in 3V3 fluid ounces of 50 per cent alco- hol (ethyl or isopropyl). METHODS OF PROPAGATING VARIOUS FRUIT PLANTS Quince, fig, grape, currant, goose- also be propagated by semihardwood berry, olive, and pomegranate, and cer- tain plum rootstocks, such as Myrobalan 29C and Marianna 2624, are propagated by hardwood cuttings. Mound, or stool, layering may also be used for quince, currant, and gooseberry. The olive can Trailing blackberries, dewberries, and black raspberries are commonly propa- gated by tip layering, although they can also be started by leaf-bud cuttings. Red raspberries and upright black- [49] berries are usually propagated by suckers or, if these are not plentiful enough, by root cuttings. The common varieties of strawberries are easily propagated by runners. Pear, apple, cherry, peach, nectarine, apricot, almond, and plum are usually budded on either clonal or seedling root- stocks, using the T, or shield, method. This is generally done in late summer or in the fall, but June or spring budding may also be practiced. Walnut and pecan are budded on seed- ling rootstocks by the patch or flute method, or they may be crown grafted. Fruit trees are top-worked (that is, top grafted or top budded) for various reasons. Sometimes the variety planted may not find a satisfactory market even though the trees are growing well ; some- times seedling trees in orchards or yards may be worked over to established vari- eties; and sometimes the home orchardist desires to graft or bud a number of varieties or kinds of fruit on one tree (table 1, page 20, shows combinations possible). Small branches of pear, cherry, apple, peach, nectarine, apricot, almond, plum, and fig may be budded in the summer by the T, or shield, method. For walnut and pecan, the patch or flute method should be used. Small branches of any common deciduous fruit plant may also be whip- or tongue-grafted — usually in January, February, or March. For branches about 1 inch in diameter, side grafting is reasonably satisfactory. Cleft graft, bark graft, and saw-kerf, or notch, graft are suitable for larger branches up to 3 or 4 inches in diameter. All these methods have given good re- sults with apple, pear, cherry, apricot, almond, plum, persimmon, and fig. Each has advantages and disadvantages which should be considered before making a final selection. Some propagators have successfully cleft- and saw-kerf-grafted walnuts and pecans, but the average worker has better results year after year with the bark graft. The third method of bark grafting described in this circular (page 28) is recommended for the walnut and pecan. Good results cannot be expected when grafting old, weak trees, or trees in which growth has been seriously hampered by lack of water, nitrogen, or other essen- tials; this statement applies especially to the peach and nectarine. Young, vigor- ous peach and nectarine trees may be successfully cleft-, bark-, or saw-kerf- grafted; but on old, weak trees the grafts will often fail to grow. In general, T, or shield, budding and bark and saw-kerf grafting have given better results with peach and nectarine than has cleft graft- ing. Bark grafting can be used in top-graft- ing grapes. It is also the most suitable method for top-grafting olives. Simple layering is the most common way of propagating filberts. Grapes are propagated by hardwood cuttings. If there are root-knot nematodes or phylloxera in the soil, desired varieties may be whip- or machine-bench-grafted before planting in the nursery, or chip- budded or field grafted in the vineyard on resistant rootstocks. Bridge grafting and inarching are ex- cellent methods which can be recom- mended for saving apple and pear trees and, to a lesser extent, other species whose trunks or roots have been injured. To simplify the information, it is sometimes necessary to use trade names of products or equip- ment. No endorsement of named products is intended nor is criticism implied of similar products not mentioned. [50] Co-operative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United Slates Department of Agriculture ^operating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. Ceorge B. Alcorn, D.rector, Cal.forn.a Agricultural Extens.on Serv.ce. 25w-2,'66(F8663)V.L. REVISED ME! A FARM 0 PRODUCT £ Well, not exactly — you can't grow auto- mobiles on farms, but farm products are essential in manufacturing them. Consider the annual agricultural needs of just one major automobile company. | or, in terms of approximate acreage: . 900,000 bushels of corn 736,000 bushels of flax- seed 74,000 bales of cotton 1 5,000 acres of corn 80,000 acres of flax 78,000 acres of cotton During the same period this company used products derived from 364,000 sheep and 36,000 cattle — plus many other items such as hog bristles and beeswax. In all, produce equivalent to the output of 1,000 good-sized farms is needed yearly. No wonder a top executive in the automotive industry has said: "Our plants, here and throughout the world, would have to close their doors in a few days if their flow of agricultural materials were to stop/' Supplying America's countless industries — and feeding the nation bountifully — makes agriculture America's biggest and perhaps most important business. That is one reason why anything which affects agriculture affects everybody.