Larry Bettiga*
*University of California Cooperative Extension, 1432 Abbott Street, Salinas, CA 93901 (lbettiga@ucanr.edu)

Improper planting techniques that result in a distortion of the downward distribution of the roots of grapevine planting stock can increase the potential for poor growth and root disease. This upward curling of the root system is often referred to as “J” rooting. Reducing root length during planting may reduce the potential for “J” rooting. A field trial was established in a Pinot noir vineyard site west of Soledad, CA (Santa Lucia Highlands Viticultural Area) to evaluate (1) root trimming of dormant benchgraft roots to either 4 or 15 cm; and (2) planting method, by either digging a traditional hole or using a planting spade to dig a slot in which the benchgraft was inserted. The experimental design was a randomized complete block with 12 replications of the four treatment combinations. The bench grafts were planted in 2013 using SO4 rootstock and were trained as bilateral cordons on a vertically shoot-positioned trellis, then spur-pruned. Vine spacing was 1.8 × 1.8 m. Planting method and root length of dormant benchgrafts were observed to influence initial vine growth. Both trimming of roots to 4 cm and spade planting reduced vine growth in the first year. Of the two factors tested, only reducing root length resulted in less vine growth in the second year. In years three, four, and five, there were no significant differences in vine canopy growth as measured by pruning weight. Although there was some loss of initial vine growth by root trimming in the first two years after planting, initial yield in years three to five was not affected. Root trimming of dormant benchgrafts prior to planting could be an effective practice to reduce the incidence of “J” rooting, especially for high-risk methods such as spade planting.

Funding Support: No external funding