Issue link: http://read.dmtmag.com/i/111102
SOIL REMI COHEN & CELLAR tant to take cluster weights at lag phase and harvest each year and record the findings. Variety, rootstock, irrigation, Brix at harvest and the weather during the growing season impact final berry weight. I usually use a multiplier of 1.5-1.7 for pinot noir, 1.31.5 for cabernet sauvignon and 2.0 for sauvignon blanc and chardonnay. These are based on averages of several seasons. I continue to take cluster weights as the season progresses through veraison and as the blocks approach maturity, in order to factor in the influence of the current vintage's weather and practices. I use cluster sampling for maturity evaluation, and use these same samples to take cluster weights as harvest approaches to compare to the estimate that I generated at lag phase. Usually, cluster weight peaks around 22 °Brix, so if the weights are much higher or much 6 lower than the estimated weight at this time, adjust the estimated final cluster weight based on this data. It is important to understand the target Brix at harvest and consider that hang time and dehydration may cause the cluster weight at harvest to be lower than the peak cluster weight. It is not uncommon for cluster weights at harvest to be 10% lower than the peak cluster weight, so accounting for target ripeness and possibly dehydration will lower the multiplication factor that should be used. Another useful technique for double-checking estimates is to harvest one or more individual vines. By choosing a representative vine or a few vines, and counting and weighing all of the clusters on the vine, you can get the number of clusters per vine and the average yield per vine. If this is done at lag phase, the same multiplier you choose for that block should be 5 4 used. If it is done closer to harvest, use a lower multiplier, or perhaps no multiplier. I don't suggest this as your primary method, but it's a helpful backup. All of this data collection can help provide a reasonable estimate, but the most important rule of crop estimation is to spend time in the vineyard. The more time spent walking the rows, the more reliable visual estimates will become. Remi Cohen is the director of wine- making & viticulture for Cliff Lede Vineyards in Napa Valley. Her primary areas of expertise include viticulture, sustainable vineyard management, winemaking, grower and winery relations, and strategic business development. She also writes a wine industry blog, which can be found at blog.vinestowine.com. Comments? Please e-mail us at feedback@vwmmedia.com. 3 2 1 TOP-SELLING TRELLISING SYSTEM D IN EUROPE profilalsace.us.com C D The EuroPost ® 5° 15 ° B ( 4 :1 ) Maintenance Free 2 ,3 3 Cost-Efficient Installation B C Patented CLICK LOCK Cross Arm System 9 ,6 3 B +0 0,5 8,65 6,35 75 Now available in the U.S. Exclusive Distributors: A 6,35 19,5 12,7 28 - No Clips, Bolts or Nuts Necessary ° R4 Mechanical Harvester Approved R1 CALIFORNIA - cvbsupply.com OREGON - ovs.com 2 A info@cvbsupply.com 6 w w w. v w m media.com 5 4 3 2 M a r - A p r 2 0 13 | 60° 8,4 1 V I N E YA R D & W I N E RY M A N A G E M E N T 37