RETENTION OF LEAF AREA INFLUENCES FIELD GRAFTING OF CONCORD GRAPEVINES

Abstract

Field grafting of the Concord variety (V. labruscana) when using t-bud, chip bud or sidewhip grafting is typically less successful than when these grafting methods are applied to several European (V. vinifera) and European-American hybrid varieties. Sap flooding is one cause of failure of field grafts. Although trunk slashing basal to field grafts is used to control such sap flooding, it was not effective on Concord vines. Therefore, a strategy to reduce sap flooding of graft unions on Concord vines by increasing transpiration was evaluated. Additional leaf area was retained at the time of field grafting by using the following approaches either alone or in combination: (a) delaying trunk decapitation until several weeks after grafting, (b) retaining a trunk renewal cane and (c) retention of a second, ungrafted trunk. All treatments significantly increased the success rate for the t-bud (88% vs. 63%), chip bud (85% vs. 36%) and sidewhip (90% vs. 48%) grafting methods. Concord vines develop modest leaf area from base buds at the time of field grafting when compared to many other grape varieties. These results suggest that this factor influences the application of certain field grafting methods to this variety.