Issue link: http://read.dmtmag.com/i/51841
VINEYARD More than 55% of these insects tested positive for GLRaV- 1, GLRaV-3 or both. The original source of vine infection in these vineyards and its primary mode of spread were through infected propagation wood. However, in vineyards with insect vectors, the vectors were important in subse- quent disease spread within these vineyards. LEAFROLL ECONOMIC STUDIES Researcher Shadi Atallah of Cor- nell University presented results from economic case studies of leafroll disease in the Finger Lakes region, based on surveys of 10 ver- tically integrated vineyard-winery operations with a history of leafroll. More than 30 cultivars are planted in the Finger Lakes area. The stud- ies focused on cabernet franc that is at higher risk for loss and lower- quality fruit production from leafroll. Researchers looked at six sce- narios reflecting the cash flow of an acre of cabernet franc over 25 years, a typical vineyard lifespan. Factors considered were percent- ages of yield reductions due to lea- froll, penalties incurred (up to 10%) due to lower-quality fruit, level of vineyard infection with leafroll, and level of control/management of lea- froll by vineyard managers. A base- line price of $1,700 per ton was used. The findings provide vine- yard managers with estimates of the economic impacts of leafroll on the profitability of their businesses, with suggested responses based on different impact levels. Atal- lah said, "Management of leafroll is highly variable among vineyard managers, ranging from no control to vineyard replacement." The estimated impact of leafroll, if no control measures are taken, on a vineyard over its lifetime ranges from $10,000/acre (given a 30% yield reduction and no quality penalty) up to $17,000/acre (given a 50% yield reduction and a 10% quality penalty). The best scenario and results were based on disease prevention through the use of cer- tified, virus-free vines when first planted, which reduces the eco- nomic impact to $740/acre. Roguing (replacement of individ- ual infected vines) is cost-effective for vineyards with disease preva- lence below 25% and reduces lea- froll impact to a range of $1,300/ acre up to $9,400/acre depending on initial leafroll prevalence. Rogu- ing may be cost-effective even when infection occurs at a later stage in the vineyard's lifespan due to the introduction of insect vec- tors. However, Atallah observed, "It is not economical to rogue if the vineyard is five years or less from the end of its lifespan." When leafroll affects more than 25% of the vineyard, full replace- ment is usually the best response, limiting impact to $10,000/acre. Respect the true character of your wine. NO BRETT INSIDE: AN EFFECTIVE NEW PREVENTATIVE TOOL AGAINST BRETTANOMYCES NATURAL NON-ALLERGENIC GRAS-APPROVED BRETT-KILLER 72 VINEYARD & WINERY MANAGEMENT JAN - FEB 2012 WWW.VWM-ONLINE.COM