Evaluation of Root System Conversion

Root system conversion methods were evaluated in three vineyards using Cabernet Sauvignon grafted on Chenin blanc, Semillon grafted on Napa Gamay, and own-rooted Sauvignon blanc, respectively. The root system conversion methods included in this study were approach grafting 1992 (rootstock rooting planted next to vine and grafted in 1992), approach grafting 1993 (rootstock rooting planted next to vine and grafted in 1993 when canes had sufficient diameter for grafting), interplanting (rootstock rooting planted between vines in the row and budded in 1993), and an ungrafted control. Freedom rootstock were used in all experiments. Vines from the approach grafting 1992 and 1993 treatments which failed to take were regrafted in June 1994. The interplant/field bud treatments were not rebudded in 1994. Growth and percent take of the interplants was limited due to shading by existing vines. Yield data for Semillon and Sauvignon blanc were collected at harvest on August 22 and September 2, 1994, respectively. Cabernet Sauvignon vines were harvested and yield data collected on October 4, 1994. Berry samples were collected at harvest and fruit composition determined for all experiments. Growth data were collected at the time of pruning on January 20, 1995. Pruning weights were unavailable for Semillion. Percent conversion was also determined on January 20, 1995. Root system conversion method had little effect on yield, fruit composition, or growth during 1994. Based on previous research, we anticipate treatment effects, if present, would be detected during the next two seasons. The number of vines successfully converted has declined in most plots due to mechanical damage, shading, etc. This result demonstrates the difficulty in managing young and mature vines planted together in the same vine row.