Field Evaluation of Winegrape Rootstocks
Data on rootstock performance is presented for 13 trials, ranging from Ukiah to Amador to Bakersfield. Rootstock recommendations tend to be site specific so readers are urged to obtain a copy of the complete report. In general, the rootstock 110R is performing well in the dry-farmed site while Teleki 5C and Kober 5BB tend to do well in heavier soils well supplied with water. The rootstocks 3309C and 101-14 Mgt tend to be moderate vigor rootstocks in some situations but can be vigorous when used in fertile sites with plenty of water. The 420A is a lower vigor rootstock. These experiments point up the interaction between rootstock performance and grower management practice. Two of the VR rootstocks trials have been concluded and have supported the hypothesis that VR 039-16 is the only recommended rootstock for sites with fanleaf degeneration complex. This recommendation is holding as well for plots in the northern, central and southern San Joaquin Valley, although more data are needed in those sites. Future trials will focus on interactive effects of rootstocks with other cultural practices such as vineyard floor management, water availability and vineyard spacing.