Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
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Spring 2011
Figure 4. A hand-held ceptometer was used to evaluate the amount of light filtering through the fruit zone of the canopy, to measure the microclimate of grapevines being tested.
Crop load and leaf area had significant effects on ripening. Mechanically box-pruned vines were slower to ripen grapes than spur-pruned canopies, especially in Pinot Grigio, but there were no adverse effects on fruit composition at harvest.
The only adverse effect of mechanical canopy management was delayed ripening of Pinot Grigio with leaf removal, attributed to the reduced leaf area to fruit ratio achieved by this practice.
Overall, control of yield was achieved by integrating mechanized canopy management. Winegrapes are said to be in-balance when the vine can grow its fruit from flowering to a target °Brix within a given summation of degree days.
The leaf area to fruit ratio of Syrah fell between 1.2 m2/kg for Syrah, and 1.0 m2/kg for Pinot Grigio when these vines were boxpruned, adjusted to medium shoot density, and had leaf removal on the east (morning) side of the fruit zone. These leaf area to fruit ratios are in line with the 0.8 to 1.2 m2 leaf area per kg of fruit needed to mature fruit trained to singlecanopy trellis systems in the San Joaquin Valley.16
Read this and more viticulture/enology studies by Fresno State University on their website.
The authors would like to acknowledge American Vineyard Foundation for partial funding, Bronco Wine Company for in-kind labor and land, and Oxbo International Corp. for use of the equipment and in-kind labor during the execution of the research.
Oxbo de-leafer with two heads to remove leaves from the morning side of a vine row where only one head is in operation, depending on the direction of travel in the vineyard.
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