Cultural Control of Phylloxera in Root System Conversion Treatments

Root system conversion methods were evaluated at the White Hills Vineyard near Santa Maria, Ca. This study consisted of two experiments which utilized Gewurztraminer and Chardonnay in separate locations. Root system conversion treatments included inverted side grafting using cuttings, approach grafting using rootings and an ungrafted control for Gewurztraminer. The Chardonnay experiment investigated the suitability of selected rootstocks for root system conversion using the inverted side graft and approach grafting. Freedom, Harmony, Teleki 5C, Teleki 5A, Kober 5BB, and Couderc 1613 were the rootstocks used in this experiment. Yield data were collected for Chardonnay on October 6, 1994. The Gewurztraminer experiment was harvested and yield data collected on October 13, 1994. Berry samples were collected at harvest and fruit composition determined for both experiments. Vine growth and graft union assessment data were collected for Chardonnay on January 27, 1995. Graft union assessment data for Gewurztraminer were collected on January 27, 1995. As in previous seasons, the type of rootstock used was not an important factor in the response of Chardonnay vines to rootsystem conversion. Rootstock treatment had little effect on growth, yield or fruit composition. Gewurztraminer vines displayed a positive response to root system conversion in 1994. Vines which had been converted using approach grafting or inverted side grafting produced significantly higher yield than control vines.