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58 WINES&VINES September 2015 GRAPEGROWING discolored nerves and mottling on the leaf sur- face, which remains during vegetative growth. The symptoms often diminish as the grow- ing season progresses, giving the impression that the plants are recovering. In fact, the new canes and leaves that develop after fruit set appear normal. The following year, however, the symptoms go through the same stages as described above, proving recovery is only illusory and temporary. In more serious cases—especially for Gewürztraminer—cane development remains limited throughout the growing season to the extent that no cane is able to lignify. As for production, in some cases there is a desiccation of the inflorescence and bunch shatter. Bunches of symptomatic plants are generally smaller at harvest, with millerandage and delayed ripening—especially on the worse- affected plants. The depressive effects of the disease on production parameters seem more serious for Pinot Gris, where the weight of grapes at harvest may be reduced up to 80% on symptomatic plants (see "Harvest 2014"). The Glera grape, on the other hand, shows less serious production losses, with an average of about 35%, according to data gathered in 2014. From the point of view of quality, symp- tomatic vines are prone to higher acidity, while the concentration of sugars does not seem to vary significantly between symptomatic and non-symptomatic vines. Incidence of the disease in Veneto In 2014, a voluntary territorial-monitoring network was set up in Veneto by research bod- ies (CRA-VIT and the University of Padua), the Regional Plant Health Service, producers' as- sociations, wineries and grapegrowers includ- ing both consultants and sellers. A single monitoring sheet and online database have been adopted by the Plant Health Service and distributed to technicians working in the Veneto region to collect data. About 290 vineyards were monitored—es- pecially the cultivars Glera and Pinot Gris—and the symptoms were observed for each indi- vidual vine (about 500-1,000 vines per vine- yard). Only 29% of the vineyards observed had no symptomatic plants. Of the total vineyards with symptoms, most currently show a very low incidence of the disease (less than 1%). In about 10% of the vineyards, the presence of symptomatic vines ranges from 1% to 10%. In nine vineyards (3% of the total), the incidence of symptomatic plants is higher than 10%, reaching peaks of 40% (see "Presence of Symp- tomatic Vines"). Processing data collected through the monitoring sheet has shown no correlation between vineyard age and the presence of symptomatic vines. High levels of the disease ColloPack Solutions • Napa CA • 707.258.3940 • www.collopack.com Direct Flow Filtration The gentle alternative to cross flow • Extremely low transmembrane pressure. Less stress means better quality • Minimal product loss • Low energy consumption • Suitable for still or sparkling wine • Automated process control by Diemme's InteliFlex software • Uses 30" code 7 cartridges 091402 ColloPack DiemmeAd_4C_4.5x7.5_final_v2.indd 1 9/25/14 5:03 PM PRESENCE OF SYMPTOMATIC VINES The presence of symptomatic vines in the vine- yards monitored in Veneto in 2014. The data have been organized into four classes of incidence. No Symptoms Incidence 1%-10% Incidence >10% Incidence < 1%