2019 ASHS Annual Conference

Recurring winter freeze events over the years can result in gradual vine decline and reduced yields, prompting growers to consider vine renewal or replanting strategies. Unlike vineyard replanting, successful cordon renewal may result in a full crop within 1 to 2 years. This study evaluated the potential of four different cordon renewal strategies to revive an aging and declining, cordon-trained Merlot (Vitis vinifera) vineyard in southeastern WA. Cordon renewal treatments, applied in March 2014, were: 1) standard spur pruning (control) – existing spur positions were pruned to 2-bud spurs; 2) short canes – three sequential, non-overlapping canes pruned to 5 to 8 buds each were trained onto the cordon while the remainder of the cordon was disbudded; 3) complete disbudding – all visible buds were removed from the cordon; 4) cordon removal – the trunk was cut ~13 cm below the cordon wire, and one strong sucker was retained the following winter and trained onto the wire to reestablish the cordon. Vegetative growth, yield and pruning components as well as fruit quality was measured for three years. None of the cordon renewal strategies tested succeeded in restoring adequate vigor in these vines. However, retaining three short canes (5 to 8 buds each) per cordon increased 3-year average and cumulative yields compared with cordon removal, disbudding, and standard spur pruning. Cordon removal and retraining led to more uniform recovery than other treatments. Complete disbudding of the cordon to encourage renewal of spur positions resulted in yields that were no better than those obtained with continued standard spur pruning. Fruit composition was similar in all four pruning treatments, and the slight differences that were occasionally observed were within the expected range of technological maturity for high quality fruit.