Comparison of Four Methods of Variety Conversion in Established Vineyards

Abstract

Four vine conversion treatments were imposed on two mature California North Coast vineyards. The treatments were: 1) ground (low) level wedge graft, 2) high level wedge graft, 3) chip-bud, and 4) T-bud. Conversion was performed by skilled vineyard employees.

Of the four methods used, the high wedge graft treatments yielded significantly lower bud take and fewer vines growing than did the others for both locations. Low wedge grafting yielded excellent results in one location with an 81% bud take and 97% of the vines growing; however, bud take and vines growing were both poor at 63% in the other location. The chip- and T-budding treatments resulted in an excellent percentage of vines growing in both experimental plots. The percentage bud take ranged from a low of 66% to a high of 77%, but because two buds per vine were used on some vines, the number of vines growing ranged from a low of 88% to a high of 96%.

Pruning weights were taken in one location. The low wedge graft pruning weights were significantly higher than those of the other treatments. Pruning weights for the high wedge graft, chip-bud, and T-bud were not significantly different.

It was concluded that chip- and T-budding were the best conversion techniques in these trials, owing to the high percentage of vines growing and ease of conversion.