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August 2016 WINES&VINES 21 WINE INDUSTRY NEWS Researchers Study Colored Shade Nets to Improve Grape Chemistry O akville, Calif.—Research- ers from the University of California, Davis, began a trial this year at the Oakville Ex- perimental Station in Napa Valley to evaluate the use of different colors of commercially available shade netting and its effects on grape cluster temperature and light exposure in relation to chemi- cal and phenolic development and composition in grape berries. The trial is being conducted by viticulture extension specialist Dr. Kaan Kurtural and enology exten- sion specialist Dr. Anita Oberhol- ster (both of UC Davis). The researchers discussed the trial during a recent field day held at the Oakville Station vineyard. "As the climate is getting warmer, we're seeing potentially different responses from plants to tempera- ture and light," Kurtural said. The Oakville vineyard study is using colored shade nets, known as ChromatiNets, available from Ginegar Plastic Products Ltd., based in Israel, with a California sales office in Santa Maria. Chro- matiNets are also available from Green-Tek West in Dinuba, Calif. These shade nets can diffuse light, potentially filter different parts of the light spectrum or filter light by wavelength, based on the color and density of each net. Available net colors are black, grey, pearl (white), red, blue and yellow. The Oakville trial is in a block of Cabernet Sauvignon planted in 2012 with five replicate trials with shade netting on both sides of the vine row shading clusters on three adjacent vines for each replicate. The netting was applied this spring at berry set, a period when some chemical compounds start to synthesize, according to Kur- tural. The netting simply is at- tached near the top of the grape canopy and hangs down on each side of the vine row to shade the cluster zone. Net colors being used in the Oakville trial are pearl, black, red, blue and grey. Measurements are being taken during the growing season for each shading treatment and control vines for temperature, relative hu- midity, and light intensity, includ- ing photosynthetically active radiation (PAR), in the grape clus- ter zone. Berry samples will be analyzed at véraison and harvest from vines with each type of net- ting treatment along with berries from control vines to compare chemical and phenolic differences. Oberholster will be making wine from the different grape shading treatments for both chemical and sensory analysis. Physical data will also be collected and compared on berry and cluster sizes and weights, overall yields and vine pruning weights after harvest. —Ted Rieger A research trial at the University of California Oakville Experimental Station is using colored shade nets to study the effects of light and temperature on grape berry chemistry and phenolic composition during ripening. by