Field Evaluation of Winegrape Rootstocks

Rootstock performance is, to some degree, dependent on site and/or culture. For example, 039-16 was highest yielding in MEN1 but lowest in AMA2. AFV supporters are urged to obtain and closely examine a copy of the entire report. In the M0N1 site, 110R, 3309C and AXR#1 are showing the highest yield with cluster weight contributing more than cluster number. °Brix readings at harvest indicate that vines were well balanced. The exception was 3309 which was delayed by about 1 °Brix. Pruning wt differences were significant with 1202, AXR#1 and St. George having higher wts. In M0N2 and M0N3 sites, additional data will be necessary to establish a pattern of yield components. Thus far showing the greatest growth are 043-43, 5BB and Harmony in MON2, and 5BB and Freedom in M0N3. In NAP2, 039-16 is showing the greatest yield, while 101-14 has the least. This is the site of the apparent collapse of Harmony to phylloxera. In AMA1, a dry-farmed Zinfandel trial, 110R and St George and performing best and visually have the least stress, while 420A and 5C are showing the greatest visual signs of stress. In LAK1, a heavy clay soil, 5C and 5BB are showing the greatest growth, greatest yield and best maturity. These two rootstocks are also exhibiting the least visual symptoms of K deficiency. In SAC2, Chardonnay yielded most on SaltCreek, Freedom and 1103P, while in SAC1 Cab Sauv was relatively high yielding (10+ tons/ac) on all rootstocks. LAK1 and SNJ1 were concluded in 1994 and will be submitted for publication in 1995, in both scientific and trade publications.