|- 2 Bud Spur||14 spurs/vine|
|- 2 Bud Spur||14 spurs/vine|
|- Cane||14 buds/cane (2 canes/vine)|
|- Basal Buds||No spurs|
The above pruning methods were utilized in ‘Merlot' trial. The basal bud treatment was not utilized in the ‘Sauvignon Blanc' trial, and the cane pruned treatment consisted of 4 or 5 canes with 12-14 buds per cane. The experimental design was a completely random design with four reps consisting of one vine per plot. Data collected included pruning weight, yield per vine, clusters per vine, cluster weight, and berry quality characteristics which included a must analysis consisting of pH, Brix and acid expressed as per cent tartaric.
The data were collected for only one year for each trial due to vine loss in the Terra Rosa Vineyard and frost damage and deer depredation in the Dos Cabezas Vineyard.
For the ‘Merlot' trial, the amount of wood removed during pruning (pruning weights) (Table 1), was less for the 4 bud spur pruning method when compared to the other methods. This was to be expected. Also, the four bud method resulted in the greatest yield and the most clusters per vine which is directly related to the number of buds retained during pruning. There was very little difference in yield for the 2 bud spur, cane or basal bud pruning methods. The largest clusters accrued on vines from the two bud spur method (normal method) while the smallest clusters were from the 4 bud spur treatment.
Most analysis indicated the fruit produced solely from basal buds had a high pH and acid content when compared to fruit produced from primary buds on a cane (other treatments) (Table 2).
The ‘Sauvignon Blanc' trial produced similar results with the exception that the cane pruning method produced the highest yields with the 2 bud spur treatment producing the lowest (Table 3). In addition, the 2 bud spur method resulted in the lowest number and smallest clusters. There were no significant difference in Brix content of the grapes (Table 4) from any pruning method.
The ‘Merlot' pruning trial resulted in expected results in that the greater number of primary buds left for fruit production (4 bud spur method) the greater the yield. Surprisingly this heavy yield did not affect cluster size (weight) or berry chemical content. However, in all probability this was the first true crop from these vines which means that the vines contained enough stored carbohydrates from previous years to properly mature a large crop. Subsequent yearly observations indicated that these vines were drained of carbohydrates resulting in poor crops or vine death.
This condition was not observed with the other pruning methods. The 4 bud spur treatment is currently being used in several vineyards in the Elgin area. Based on these results it should not be used due to overcropping and vine weaking. The 2 bud spur method was superior to cane pruning in terms of yield and quality of clusters. The basal bud treatment revealed some very interesting information from a fruit quality standpoint in that grapes were high in pH and acid. This would explain why young vines would have some inferior quality fruit and should alert growers that basal buds should not be left for fruiting. There should be a balance between fruit produced and shoot growth.
The ‘Sauvignon Blanc' trials showed that cane pruning is the preferred method to maximize production. This is to be expected due to the small cluster characteristic of the cultivar.