UNIVERSITY OF CALIFORNIA AGRICULTURAL EXPERIMENT STATION 
 COLLEGE OF AGRICULTURE " NJ - ' DE WHEELER " '■«'"■" 
 
 THOMAS FORSYTH HUNT, Dean an d Director 
 
 BERKELEY 
 
 E. VAN NORMAN, Vice-Director and Dean 
 University Farm School 
 
 CIRCULAR No. 191 
 January, 1918 
 
 PRUNING THE SEEDLESS GRAPES 
 
 By FREDERIC T. BIOLETTI 
 
 The general principles of vine pruning; are the same for all 
 varieties. These and the general practice of pruning have been quite 
 
 Fig. 1. — Forms of cuttings. 
 
 fully discussed in Bulletins 241 and 246 of this Station. In this 
 circular will be given simply specific directions for the methods of 
 pruning which have given the best results with seedless raisin grapes. 
 
1. TREATMENT OF YOUNG VINES 
 
 First Year. — Cuttings are made 12, 15, or 18 inches long; the 
 shorter for nursery planting or moist soil ; the longer for planting in 
 the vineyard and where the soil lacks moisture (see Fig. 1). Well- 
 grown and well-ripened laterals make better cuttings than over-grown, 
 long- join ted canes. 
 
 Fig. 2. — Pruning of rooted vine before planting. 
 
 One-year-old rooted vines are pruned to one cane, which is 
 shortened to one or two buds. Surface roots are cut off entirely and 
 the lower roots shortened to 1 to 4 inches, according to size (see 
 Fig. 2). When planted, only the buds at the top are left above 
 ground. 
 
 During the first growing-season (see Fig. 3), little pruning is 
 done. With vines on resistant stocks, the stock suckers and scion 
 roots must be carefully cut off clean. The removal of surface roots 
 is also advisable in irrigated land. 
 
In the first winter following planting, the vines (see Fig. 4a) are 
 pruned to one cane, and this cane is shortened to two buds, exactly 
 as was done with the young vine before planting (see Fig. 4b). The 
 vines are then staked. The stakes used are only temporary and need 
 not be more than three feet long and an inch and a half in diameter. 
 
 
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 Fig. 3. — Growth during the first summer. 
 
 They should be driven about two inches from the vine on the leeward 
 side so that the prevailing winds will press the growing vine against 
 the stake. 
 
 Second Year. — During the second growing-season, the vines need 
 careful and continual attention. Though only two well-defined buds 
 have been left, many shoots will start. All but one or at most two 
 of these are removed as soon as they have grown one or two inches. 
 
This throws the energies of the vine into those left, which will there- 
 fore grow rapidly (see Fig. 5a). 
 
 As soon as one of the shoots has grown six to ten inches, it is tied 
 loosely to the stake, and the other, together with any new shoots 
 
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 Fig. 4. — Vine at end of first growing season. A, before pruning; c, c, Places for 
 making cuts; B, after pruning and staking. 
 
 Fig. 5. — Growth and treatment of the vine during the second season, c, c, Place 
 where shoots are removed; L, L, laterals. 
 
 which have started, are removed at the same time (see Fig. 56). 
 
 The single shoot will then grow rapidly and must be tied again 
 higher (see Fig. 5c.) 
 
 When the shoot has grown one or two feet above the top of 
 the short stake, it is topped at about three feet from the ground 
 (see Fig. 5c). 
 
This will force a growth of laterals (see Fig. od). If these laterals 
 grow so large that they are in danger of being broken by the wind, 
 they should be topped or pinched. All snckers from below ground 
 should be carefully removed as soon as they appear. 
 
 
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 1 
 
 
 A. Average vine. B. Very vigorous vine. 
 
 Fig. 6. — Winter pruning second year. 
 
 The second winter pruning will be very simple if the summer 
 work has been done properly. It consists in cutting back the single 
 cane to a height of about eighteen inches (see Fig. 6a), leaving a full 
 joint above the top bud. Where strong laterals have been produced, 
 those on the upper part of the cane should be cut back to one 
 
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or two buds and the rest removed (see Fig. 6b). All the buds on 
 the vine at this stage may be fruit buds and a good crop should be 
 produced in the following autumn. Vines which have not made 
 eighteen inches of vigorous, well-ripened cane should be cut back to 
 two buds and treated as during the previous year. If any vines 
 have been allowed to grow more than one cane, all should be removed 
 entirely, except the strongest and best placed. 
 
 After pruning, the vines are carefully tied to the stake as shown 
 in figure 6. Extra heavy binding twine is good for this purpose. 
 The cane is tied firmly to the stake by passing a ' ' half -hitch ' ' around 
 
 Fig. 7. — Growth and treatment of the vine during the third season. T, T, places 
 where the vine is tied; c, c, shoots and tips removed; B, B, blossom branches. 
 
 the joint above the top bud. One or two ties are then made near the 
 middle of the cane. These should be moderately loose to allow for 
 growth of the cane and should not pass around the cane, or it will 
 be choked. 
 
 Third Year. — As the buds start in the spring, the vines should be 
 gone over several times and all shoots within six to ten inches of the 
 ground rubbed off before they are more than two or three inches long 
 (see Fig. la). This rubbing off of low buds will have to be repeated 
 two or three times (see Fig. lb). This will force all the growth into 
 the upper shoots which will bear the crop and form the ultimate arms 
 of the vine. When these upper shoots are fifteen to twenty inches 
 
long, their extreme tips should be pinched off (see Fig. 7c). This 
 will delay their lengthening and protect them from wind injury. 
 All suckers from below ground and shoots on the lower part of *the 
 trunk should be carefully removed as soon as they appear. 
 
 a. Before pruning. b. After pruning. 
 
 Fig. 8. — Winter pruning third year — one fruit cane and two spurs. 
 
 An example of the winter pruning at the end of the third year 
 is shown in figure 8. It consists in leaving one or more fruit canes 
 and two or more wood spurs. The number of canes and spurs is 
 determined by the size and vigor of the individual vine. No invar- 
 iable rule can be given. In the example shown, there are five 
 well-developed canes on the unpruned vine. A vine having ten well- 
 
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 developed canes should be allowed two fruit canes and four spurs. 
 This is about the maximum for vines of this age. The most vigorous 
 fruit canes should not be more than four feet long and those less 
 vigorous should be from two to three feet. The spurs should all have 
 two well-developed buds, not counting the base bud. 
 
 The spurs should always, whenever possible, be below the fruit 
 canes, as shown in the figure. They should be so placed as to give 
 the vine the required shape. The position of the fruit canes is less 
 important, as they are removed the following year. The spurs should 
 be arranged as much as possible in the plane of the trellis to be 
 erected, that is, spread out like the ribs of a fan in the direction of 
 the rows. This is very important as on the perfection with which 
 this form is obtained depends the ease and cheapness of cultivation 
 and the protection of the vine from cultivation injuries. 
 
 2. TRELLISING 
 
 As soon as the pruning is finished, the brush should be removed 
 and the trellis erected. 
 
 The trellis consists of two wires stretched along the rows in the 
 direction where the vines are closest together. The bottom wire is 
 placed at twenty-four inches from the ground and the upper eighteen 
 inches higher. A straining post is placed at each end of the row 
 and a supporting stake at intervals in the row. 
 
 The stretch between posts should not be much more than 200 feet 
 and less is better. A supporting stake every fifteen or twenty feet 
 is sufficient. These stakes should be placed half way between two 
 vines. 
 
 For straining posts, ordinary fence posts may be used, or 4x4 
 pieces of sawn redwood seven feet long. They may be set in concrete 
 or held by a stone or concrete anchor or by a diagonal brace of 2 x 4" 
 redwood. For intermediate stakes, the ordinary six-foot split red- 
 wood stakes are best. No. 12 galvanized iron fencing wire is most 
 commonly used. No. 14 is a little too light, especially for the lower 
 wire. No. 11 for the bottom wire and No. 13 for the upper are good 
 sizes. 
 
 The general plan of the trellis is shown in figure 9. The trellis 
 should be erected and the vines attached to it before the buds com- 
 mence to swell in the spring. It is best to leave the temporary stakes 
 to support the vine for a year or two longer, as it is very important 
 that the trunks should be straight and perfectly upright. Crooked, 
 irregular, spreading vines interfere with cultivation, require a large 
 
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 amount of hoeing and other expensive hand work, and are subject 
 to injuries from the cultivating implements, which result in smaller 
 crops and shorter lived vines. 
 
 All the fruit canes are tied to the lower wire. The use of the 
 upper wire is to support the growing shoots during the summer to 
 protect them from wind injury and' to keep the grapes off the ground. 
 
 The canes should be looped over the wire or turned once around 
 it. This will prevent the weight of the fruit from breaking the twine 
 with which they are tied to the wire. They should not be twisted 
 around the wire, for if this is done, they are very troublesome to 
 remove at the following winter pruning (see Fig. 9, A). 
 
 3. PRUNING BEARING VINES 
 
 In the fourth year, the vines should be practically in full bearing, 
 and the regular form of pruning for mature vines commences. This 
 consists in leaving two to four fruit canes averaging four feet in 
 length, and four to six renewal spurs of one to two buds each (see 
 Fig. 9, B). 
 
 Fruit Canes. — A fruit cane should be of well-ripened wood, of 
 good thickness, but not over-grown. Any laterals with well-matured 
 buds, which it may have, should be left and cut back to short spurs 
 of one or two buds, if not over a third of an inch thick and to three 
 or four if thicker (see Fig. 9). 
 
 The length of the fruit canes should be from two to five feet. The 
 thicker and more vigorous they are, the longer they should be. They 
 should not extend beyond the ends of the canes of the next vine. 
 
 These rules will give a maximum length of fruit wood for a single 
 vine of about sixteen feet. This is ample for the largest crop for a 
 vine in vineyard form. Many vines in the experiment vineyard with 
 less than this length of fruit wood have borne 80, 90, and over 100 
 pounds of grapes. Nothing is to be gained by making the canes 
 longer or more numerous and excess in this respect tends to weaken 
 the vine and to prevent the production of good fruit wood for the 
 following year. 
 
 It is usually supposed that water sprouts, that is, canes from the 
 old wood, are not suitable for fruit canes and that a fruit cane should 
 grow out of two-year-old wood. Some limited tests with the Sultanina 
 indicate that for this variety at least, there is little difference. How- 
 ever, properly pruned vines produce few water sprouts and it is 
 nearly always possible to obtain all the fruit canes required without, 
 using them. 
 
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 Renewal Spurs. — The renewal spurs are intended to produce canes 
 for the following year. As some of them may fail to produce suitable 
 canes, a few more are left than the number of canes needed. They 
 should, where possible, be chosen nearer the head of the vine than 
 the fruit canes, in order to prevent the vine from spreading too 
 rapidly. No spurs should be left which project out into the avenues 
 at right angles to the wire of the trellis. The narrow, fan-shape of 
 the vine should be carefully preserved. Where spurs at right angles 
 to the trellis must be left they should be cut short to the base bud. 
 
 Fig. 10. — Unit of long pruning. 
 
 Summer Pruning. — All the seedless raisin grapes are very vigorous 
 and summer pruning may be used more freely than with weaker 
 vines. 
 
 All suckers below the ground and water sprouts from the trunk 
 below the head should be carefully removed before they become tough. 
 
 Pinching the growing tips of the shoots on the fruit canes when 
 they are eighteen to twenty-four inches long and the blossom bunch 
 is well formed helps the setting of the fruit and increases the size of 
 the berries. Topping or cutting off about twelve inches of the shoots 
 from the renewal spurs when they are three or four feet long promotes 
 the growth of laterals which give excellent fruit buds for the following 
 year. 
 
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 The pruning of a bearing vine, in short, consists in leaving a 
 sufficient number of fruit canes to bear as large a crop of grapes as 
 the vine can bring to perfection without being weakened; in leaving 
 enough spurs to provide fruiting wood for the following season ; and 
 in having these so placed that the form of the vine will be maintained 
 or improved. 
 
 To do this properly requires some care and experience. Each 
 arm, of which there should be from three to four on each vine, is 
 treated according to the same principles, which are those indicated 
 in figure 10. 
 
 This figure represents a single well-developed arm ready for the 
 winter pruning. F2 is the fruit cane which has just borne its crop. 
 Si is the accompanying renewal spur. In pruning, the old fruit 
 cane is removed at g. A new fruit cane (C) is formed from the 
 upper cane on the old spur and cut back to / or fl or to some inter- 
 mediate point, according to its vigor. A lower shoot on the same 
 spur is cut back to a or lower to form the new spur S. 
 
 This is the normal treatment for a properly developed arm. 
 Many arms have, however, defects which make modifications of this 
 treatment necessary. If no good fruit cane has developed on the 
 old spur Si, a fruit cane can be made from one of the canes on the 
 old fruit cane F2 as, for example, B or D. If the arm is weak and 
 has no good canes, a fruit cane should not be left, but only one or 
 two spurs as Rp and S. These will produce little or no crop, but 
 the arm will be invigorated and a good crop will be produced the 
 following season. If the arm is becoming too long, like the arm 
 in the figure, the renewal spur should be left as near the head of the 
 vine as possible as at RP. 
 
 This method is suited to all the seedless raisin grapes, Sultanina, 
 Sultana, Black Corinth, and White Corinth. It is also suitable for 
 any vigorous variety which requires long pruning, but must be used 
 with discretion, as the vines will otherwise be weakened and after 
 one or two good crops, they may cease to bear or even die. Any 
 signs of weakening should be followed by shorter pruning, shorter 
 and fewer fruit canes or even no fruit canes at all for one vear.