Terence R. Bates

Sampling and Estimating Average Pruning Weights in Concord Grapes

Pruning weights are a useful indication for growers of vine size within their production systems. However, pruning weights are rarely collected in commercial situations, as there is little information to help growers determine how many samples to measure. An intensive study of individual vine pruning weights was undertaken over three years in a Concord (Vitis lambruscana Bailey) block at the Lake Erie Research and Extension Laboratory, New York. The population variances associated with individual and aggregated neighboring vine measurements were used to determine random sampling schemes to assist growers. A sampling scheme based on 23 random interpost samples (3-vine sampling) is suggested as a good compromise to minimize the time associated with sampling and to maximize the accuracy of measurement and the value of the information. A spatial analysis of the variance indicates that the same sampling scheme could be extrapolated to block sizes larger than the survey area (0.93 ha), provided that the management and environmental conditions can be considered uniform over the larger block.

Effect of Cane Length on Concord and Niagara Grapevines

Concord and Niagara grapevines in Fredonia, NY, were studied from 2001 to 2005 to evaluate the impact of cane length on yield, vine size, crop load, and juice soluble solids (JSS). Concord grapevines were manually pruned to 100 buds using three configurations: two-node spurs or five- or 10-node canes. Niagara grapes were manually pruned to 80 buds using three configurations: two-node spurs or five- or 10-node canes. In addition to standard viticulture measurements, yield was measured separately at each node position along the spur or cane in 2004 to 2005. There was a pattern in bud fruitfulness along the length of the cane, with the greatest yield originating from node positions three to six in Concord and two to six in Niagara; this did not change with pruning treatment. Since all vines were pruned to a constant total node number, five- and 10-node cane treatments had a greater proportion of more-fruitful buds and higher final yield than the two-node spurs in two out of five years. The higher yield on longer canes also led to greater crop load values indicative of overcropped vines, which decreased vine size. In contrast, two-node spur-pruning maintained balanced crop load values and adequate vine size. In the final two years of the study, there was no difference in final yield or JSS among pruning treatments because the longer cane treatments were starting the season with lower vine capacity.

A Protocol to Map Vine Size in Commercial Single High-Wire Trellis Vineyards Using “Off-the-Shelf” Proximal Canopy Sensing Systems

Summary Goals: This report aims to present a clear protocol for (a) deploying proximal canopy sensors into single high-wire trellis Concord (Vitis labruscana cv. Bailey) vineyards and (b) converting the canopy sensor response into an indication of vine size (pruning weight). The protocol is designed to be robust and practical for easy adoption in commercial systems. Evidence will be presented of the efficacy of vine size prediction using the protocol in multiple research and commercial vineyards. Key Findings: Using different vineyards and pruning crews, the protocol performed well in >80% of vineyards and permitted growers to generate maps of actual vine size within vineyards. These maps provide a valuable indication of current site-specific production potential and a baseline to assess changes in vine size over time. In a few vineyards, the proposed simplified calibration process did not generate a clear relationship between canopy response and vine size, which may be due to changes in vine shape in highly mechanized systems. Impact and Significance: Managing vine size is critical to the long-term sustainability of cool climate viticulture and to managing quality in all viticulture systems. However, convincing growers to routinely measure vine size for more effective management has been difficult historically because of the time involved and the difficulty of translating the data into a decision process. The proposed protocol uses technology and targeted sampling to minimize the effort required, and presents more coherent information that allows fast grower responses. Grower adoption of this protocol should promote continual vine size measurement, with the goal of decreasing vine size variation within vineyards.