Butterfield, H. M. : Agriculturist Emeritus

' Spaller Or D1IWarled WIIIO 01l • • or S Oil ' R ' R . , . , . ' ' " NATURE OF ESPALIER FRUIT TREES H . M . Butterfield * A dwarf tree is one which is naturally dwarf , while a dwarfed tree is one made so by special treatment . The term - espalier " commonly refers to the trellis on which dwarfed trees are grown or to a dwarfed tree grown flat on a trellis . The dwarfed fruit trees occasionally grown in California and rather extensively in parts of Europe are made to retain their small stature by grafting on a dwarfing rootstock , by restricting the roots , or by severe pruning of the top to suppress growth . There is an opinion among some nurserymen who grow espalier fruit trees that only by se . lecting varieties which have been long grown as espaliers and working these on suit­ able rootstocks can the dwarf habit be fully maintained . It is also claimed that the standard or common orchard trees worked on dwarfing stock will soon get out of hand and grow rank in'both limbs and trunk . and in time bear fruit only on the top later­ als . Such opinions or claims may be true to some extent ~ at least certain varieties of fruit trees seem to be much easier to dwarf and keep in good condition than oth­ ers , but there is little sound experimental evidence to show that continued dwarfing of a variety will cause it to acquire a natural dwarf habit which can be transmitted through the scion . Actual cases are known where scions from standard trees have been used successfully for producing dwarfed fruit trees when the right kinds of rootstocks were selected at . t.he outset and the trees were properly pruned and man­ aged over a period of years . Those varieties which are extremely vigorous or make a large annual growth may be hard to manage as espalier trees . Peaches are usually considered more difficult to dwarf than apples or pears . It may also be demonstrated that certain vaTieties of apples or pears grown on the same root will differ a great deal in respect to ease of dwarfing and in maintaining good bearing condition . Dwarfed apples are grown on either the Paradise or the Doucin stock . There are several varieties of dwarfing storks in each of these two general classes . These dwarfing apple stocks may not be readily a ~ ailable in California . Dwarfed pear trees are usually grown on the Angers quince stock . Since many Va ~ rieties of pears do not unite readily with the Angers quince , it is the common prac­ tice to first graft the Hardy variety of pear on the quince and then topwork the n Hardy to the desired variety , such as the Bartlett . This is called - double - working . of the dwarfed pear trees sold by nurserymen have been double - worked in this Some fashion . In most cases it will be desirable to double - work the stock while it is fairly young so that the framework of the tree will consist of the desired variety . Wherever pear blight is serious , it may be more satisfactory to build the framework of the tree on a resistant pear variety such as Old Home and later topwork this to the Bartlett or other variety which , although susceptible to pear blight , is de­ manded because of higher quality . In the case of cherries , the Mahaleb stock is sometimes used for dwarfing pur­ poses , but the cherry is not very satisfactory as a dwarfed fruit tree . Plum trees that are to be dwarfed are worked on the Damson or St . Julien stock . The last - mentioned stock is especially suitable for the European varieties of plums . Still other plum stocks , such as Prunus pumila and prunus besseyi , have been used for the European varieties of plums and are also best for t ~ e Japanese varieties of plums for dwarfing purposes . * Agriculturist Emeritus 2 The peach , apricot and nectarine may be dwarfed by using prunus pumila or Prunus besseyi stock or by topworking on Prunus ins ~ itia stock . SELECTION OF VARIETIES Varieties of fruits popular in the locality should be selected as far as they are available on dwarfing rootstocks . Considerable publicity has been given to cer­ tain so - called dwarf fruit trees selected primarily for very cold climates in other states . In most cases these trees have not proved very satisfactory in California , and some of them have not proved to be very dwarf . Almost any nursery catalog in California will list popular fruit varieties . California Agricultural Extension Service Circular 117 on Home Fruit Growing in California lists varieties of fruits for different areas and also briefly discusses dwarf fruit trees on pages 18 - 26 of the 1947 edition . TRAINING DWARFED FRUIT TREES The most difficult task in producing dwarfed trees is shaping the young trees according to the desired form . This shaping should normally cover a period of sev­ eral years . Some of the dwarf trees which have been produced in California nurseries have been hurried along too rapidly to give the greatest strength to the young trees . Patience will be needed in trellising the young branches so that they will ultim­ ately make a strong healthy tree and at the same time be properly shaped . Pruning is usually much more severe on dwarfed fruit trees than on standard ; consequently , no one should attempt to grow espalier trees who does not have the time and patience to suppress the growth and maintain a desirable form , Since the more elaborate forms require longer training and additional expense , it is not likely that these espal­ iers will be popular . Even the ordinary forms have retailed for as much as $ 15 to $ 20 fOT the larger specimen trees . Dwarfed trees may be trained according to anyone of several forms . The sket­ ches given in figs . 1 to 12 show some of the more common basic espalier forms . It is to be understood that the framework indicated in the sketches will be covered with fruit spurs or fruiting laterals . All excess growth is rigidly removed each year . The more popular forms include the single - U ( fig.l ) , the double - U ( figs . 2 and 3 ) , the multiple - U ( fig . 4 ) , the palmate ( figs . 3 and 5 ) , the single - cordon ( fig . 6 ) , the double cordon ( figs . 7 , 8 , and 9 ) , and the pyramid forms ( figs . 10 , 11 , and 12 ) . Numerous modifications and combinations of these forms may be made for special pur­ poses , as for covering pergolas . 3 Fig . 1 . U Form Fig . 2 . Double - U Form Fig . 3 . Palmate or Double - U Form ~ . J . / . A " " " " ~ ~ Fig . 4 . Multiple - U or Palmate Forms 4 a b Fig . 5 . Palmate For ~ s Fig . 6 . Single or One - Arm Cordon • I Fig . 7 . Double or Two - Arm Cordon Fig . 8 . Double - stemmed Two - Arm Cordon 5 Fig . 9 . Multiple Cordon Fig.IO . Leader - type Pyramid Fig.II . Pyramid - open center Fig . 12 . Combination Palmate and Half Pyramid 6 Fig . 13 . Design for Small Trees Trained to a Three - Wire Trellis The dwarfed fruit trees grown in Europe are very frequently trained on stone walls , which absorb considerable heat , and this heat aids in early maturity of the fruit . Since very few stone walls are to be found in California , it will be neces­sary to provide substitutes for suppor ~ s . Various kinds of trellises may be used , and galvanized wire trellises are common . Wire has also been used to help train the dwarfed trees growing against stucco walls . In the open garden a wire trellis is satisfactory in the early years , but a more gubstantial trellis is desirable where the trees are to become a permanent fixture . Redwood posts treated with pentachloro­phenol or creosote at the base may be used for supports , and wire may be stretched between these upright supports as needed to give the desired shape . An & anchor arm " on the bottom end of the posts will permit wire tightening when pulling against end braces . ( See fig . 13 . ) The pruning of dwarfed fruit trees consists of summer and winter pruning , and after maturity some root pruning may be needed . Summer p ~ uning is usually needed af­ter the new growth begins to harden , which will be in late June or early July in many districts . New shoots are either cut back or pinched back to 2 or 3 inches ; this favors the development of fruiting wood near the main stem . This summer pruning is especially important for those varieties which tend to bear their fruit far out on the branches . Pruning too early in the summer , before ~ he wood has begun to har­den , favors further vegetative growth and requires additional pruning to maintain the desired form . When cuts are made , avoid leaving long stubs . Winter pruning is necessary to shorten all length growth to just a few buds of the current season's growth . Dead spurs and all water - sprouts or suckers should be removed entirely . In some cases it may be possible to leave small laterals which can be developed into replacing spurs for old spurs that are no longer fruitful . On the younger trees it may be possible to force out a dormant bud by notching the stem just beyond the bud . Branches and laterals being trained are tied with raffia or similar binding material which will not cut into the growing wood . If stakes or posts are placed at the proper intervals on a wire trellis , tying will be easy . Ne ~ growth may be bent downward while it is still pliable ; after the wood hardens , it may break rather than bend . The proper time to tie in the summer is just before the new growth begins to harden . Start tying near the main framework branches . After the wood has fully rip­ened , it may be tied more securely . Laterals held in a horizontal position tend to grow more slowly than the upright branches . Raising a weak lateral to an upright po­sition for a few weeks may fav « more vigorous growth . Where a framework branch shows a lack of vigor , it may be improved by inarching a vigorous lateral into it . In cases where a missing bud or lateral injures the shape of the espalier , a bud or side graft may be inserted and the desired form thus restored . Grafting is done just before new growth pushes out in the spring . Budding is done from June to August . t 7 Each grower will have to decide for himself just how high above the ground the framework of the tree should be . In some cases the double - U form of dwarfed tree is started within 6 inches or 1 foot of the ground , while in other cases the bottom part of the framework is at least 2 fe ~ t from the ground . Local conditions will usually determine at what ~ eight to start the framework . As far as the health and fruitfulness of the tree are concerned , it will normally be best to head the tree fairly low , in most cases not more than 24 inches from the ground . PLANTING AND MANAGEMENT Most fruit varieties grown as espaliers will fruit best 1n a south or east ex­posure or in the open garden . Espalier trees may sunburn , however , when planted along walls in the hotter valleys . Very few fruit trees thrive in a shady location , although some sour cherries have been used where there is mild shade . Trees planted in the open are usually located near a path or near the edge of the property but far enough away from the path or property line to keep all growth within the limited area . An allowance of 2 fe ~ t for the new growth will be sufficient . The length of the arms in the cordon or T - shaped pruning may be as much as 5 to 10 feet , and in the doubleU or multiple - U forms the maximum spread will probably be from 5 to 8 feet . A similar spread may be anticipated in the palmate or fan·shaped form of tree . Extreme spread of the arms should be avoided . for fear th ~ t the growth may be weak far out on laterals or arms . If several trees are necessary to fill a given space , the tips of the outermost laterals should barely touch each other at the end of the growing season after the trees are mature . Jt is also desirable to anticipate the ~ aximum height of the trees when grown against buildings where the eaves might inter­fere as the trees grow taller fhe roots of an espalier tree should be spread out in the hole dug so that they will not be cramped A hole 18 inches square and 18 inches deep should be large e­nough . Fertile soil should be sifted about the roots after they are spread out and gently firmed with the foot . Water is later given to wet and settle the soil thor oughly . Once a tree ha ~ covered all the space allotted to it further length growth or spread must be limited . This may be accomplished by pruning as already described an ~ if necessary by root pruning Root pruning is done by means of a spade . the spade being inserted out a distance of about 2 feet from the main stem or trunk and only on one side . If this does not check growth sufficiently , then further root pruning may be done on the opposite side the next season . Such root pruning is best done just before new root growth commences in the late winter . Over - stimulation with fer­tilizers should also be avoided in such B case , but in order for the tree to remain fruitful it must have a reasonable amount of feeding roots and must be able to form new fruiting wood each year . Dwarfed fruit trees will need the usual care given other fruit trees , such as fertilizing and watering , as well as spraying to control insect pests . A miscible oil spray in the dormant season will control scale insects . The codling moth on apples requires at least three applications of lead - arsenate spray , using 2 pounds to 50 gallons of water ) the first spray being applied when the petals fall , the second when the apples are about the size of a pea . and the third when they are the 8 sIze of a waLnut . The pear or cherry slug is easily controlled ~ ith a 40 % nicotine­sulfate spray . using 1 part to 600 parts of water . Regular attention should be given to the matter of systematic pruning and fertilizing , because the dwarfed trees must make some growth each year to remain in a healthy condition . Publications dealing with important pests , such as the codling moth , the oyster - shell scale and other scales . the mealy plum louse , or any of the other pests found on fruit trees in California , may be consulted for further details in control . It is not likely that dwarfed fruit trees will ever be as profitable under com­mercial conditions as the standard trees , and yet in some gardens where space is lim­ited dwarfed fruit trees may be very fruitful and beautiful . Co - operative Extension work in Agriculture and Home Economics , College of Agriculture , University of California . and United States Department of Agriculture co - operating . Distributed in furtherance of the Acts of Congress of May 8 , and June 30 , 19 [ 4 . I . Earl Coke , Director , California Agricultural Extension Service . Rerun 2 / 61 . · 1000