Harvest pruning of young Sultana vines under various training systems

Trellis drying of Sultana grapes necessitates the severing of the fruit bearing canes from the vine at harvest time (Harvest pruning, HP). Two experiments have shown that HP of young vines, from the beginning of cropping onwards, caused no greater yield losses than those reported for mature vines, viz 10 per cent. In one experiment, HP gave significant yield reductions over six seasons, amounting to about 7 per cent, apparently due to fewer berries per bunch. Vines harvest pruned only every second year suffered losses mainly in the season following HP. In the other experiment, HP did not cause any loss of yield over four seasons. With or without HP, vines on a 0.9 m and 1.2 m wide T-trellis yielded about 20 per cent more than vines on a 0.3 m trellis, apparently because of better bud burst. Providing vines with two trunks, each producing the crop or replacement shoots only in alternate seasons, did not prevent HP losses. Such vines yielded similarly to one-trunk vines while vines with one trunk and planted in pairs yielded less. A 'split system' of training was used where each vine had all fruiting canes placed on one trellis wire whilst spurs producing all replacement shoots were trained on the other wire, the arrangement alternating down the row from vine to vine. HP of such vines was more than twice as fast as that of conventionally trained vines; other management advantages are discussed.