2007 Annual Report 1a.Objectives (from AD-416) Build and install "bridge" units in a well-watered juice grape vineyard trained on a single-curtain trellis; compare bridge-load cell system with open-ended load cell measurements; collect continuous data to monitor the crop and estimate yield; and collect intensive supplemental data on vegetative and reproductive growth. Build and install "bridge" units in a deficit-irrigated wine grape vineyard on a modified sprawl trellis; compare bridge-load cell system with openended load cell measurements; collect continuous data to monitor the crop and estimate yield; and collect intensive supplemental data on vegetative and reproductive growth. In ten commercial juice grape vineyards, couple a local processor's sentinel vine system for yield estimation via hand sampling, with measurements of trellis wire tension using the bridge-load cell system; and compare processor's 10-site yield estimate with that derived from the tension measurements. 1b.Approach (from AD-416) A set of bridges will be installed in a research block of 20-year old, well-watered juice grapes trained to a single curtain on a cordon wire at six feet above the soil. Initial wire tensions will be set before bud break. Each bridge-load cell unit will be paired with an open-ended load cell installation. The load cell installations will be monitored continuously from bud break in 2005 through dormant pruning in 2006. Intensive periodic measurements of vegetation will be recorded to add to our growing database that will supply information for models of vegetative mass in this system. Another set of bridge-load cell units will be installed in a research vineyard of six-year old, deficit irrigated wine grapes trained to a modified sprawl with a single cordon wire at 42" and two foliage catch wires at 60". Portions of the existing sprawl trellis either will be left intact or modified to reduce the number of load-bearing elements (e.g., some vine stakes removed). All fruit will be harvested by hand. Intensive periodic measurements of vegetative growth will be recorded from fruit set until harvest. The load cell installations will be monitored continuously from bud break through dormant pruning in 2006. Documents Reimbursable with UC Davis. Log #32745. 3.Progress Report This report serves to document research conducted under a reimbursable agreement between ARS and the University of California, Davis. Additional details of research can be found in the report for the parent project 5358-21000-034-00D, Production Systems to Promote Yield and Quality of Grapes in the Pacific Northwest. Dr. Tarara and collaborators conducted the following research towards the agreements objectives: During 2006, progress was made in three main areas. First, in a research vineyard, continuous estimates of yield were made with an empirical model that used the tension record and final yield from preceding years. This approach also was pursued for a "bridge" system paired with an "open" system within the same row. The "open" systems significantly underestimated actual yield while the "bridge" estimate came within ~10%. The predictions derived from this simple approach became fairly stable in early July, well before the onset of ripening (mid-August). The second area of progress was the second complete season of tension measurement using paired "bridge" and "open" systems in 10 commercial juice grape vineyards. The 2005 data were used to test yield prediction during 2006. The tension records from these vineyards demonstrated the sensitivity of the load cells to overhead irrigation. Other management practices like mechanical thinning also were detected in the wire tension. There are some transient fluctuations in the tensions for which we have no hypothesis to date. The third area that we pursued was to modify the "bridge" system for wine grapes in a research vineyard with a single cordon wire and two foliage wires. Five pairs of "bridge" and "open" load cells were installed and tension measured continuously from before budbreak through harvest. During 2007, the 52 trellis tension monitors in our 13 sites will continue to operate. The continuous stream of data will be used to track vine growth during the season and to predict yield. With the additional year added to the database, yield predictions should become more robust. Collaborating with WSU Extension, we posted graphic depictions of the tension records to the web (http://www.fruit.wsu.edu/Grapeweb/cropload.htm) weekly. During 2006, this included estimation of yields at each load cell installation. USDA-ARS holds a U.S. patent (no. 6,854,337) on this technology. A major U.S. winery and a major Australian winery are working with a small number of trellis tension monitors on an experimental basis, beginning in 2006 (Australia) and 2007 (U.S.). Widespread commercial application on farms requires a private sector engineering-manufacturing partner to commercialize the load cell and datalogging equipment, and to write robust software for data processing with a suitable graphical user interface. ADODR Statement: The ADODR met with the cooperating PI and project personnel at meetings during the year and discussed results through phone calls, e-mail, and in person.