Good Fruit Grower

April 1

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cultivars had significantly lower soluble solids (12 percent in Merlot, 14 percent in Cab Franc), higher titratable acidity (9 percent in Merlot, 16 percent in Cab Franc), and lower extractable anthocyanins (Merlot 4 percent, Cab Franc 9 percent) when compared to berries from nonsymptomatic vines. In contrast, there was no difference in the pH of juice extracted from berries of symptomatic and nonsymptomatic grapevines of both cultivars. Taken together, these results clearly showed significant negative impacts of grapevine redleaf disease on vine vigor, fruit yield, and berry quality attributes in ownrooted wine grape cultivars of Merlot and Cabernet Franc, under commercial growing conditions. Preliminary surveys conducted last year by Rayapati���s team indicated the new disease is prevalent in other red-berried varieties, in addition to Merlot and Cab Franc. It���s unknown if the disease causes symptoms in white grape varieties. Additionally, WSU does not know if the new disease was originally introduced into Washington State through cuttings imported from outside sources. In California, the disease has been observed primarily in vineyards planted with red varieties, with some detected in Chardonnay, according to the U.S. Department of Agriculture and University of California, Davis. Red varieties infected, thus far, include Cabernet Franc, Cabernet Sauvignon, Merlot, Malbec, Mourv��dre, Petite Sirah, Petit Verdot, Pinot Noir, and Zinfandel. ��� A Merlot leaf shows symptoms of the newly detected disease���red blotches and red veins. WAKE-UP call T " ' %& " " %' ! " ) %' # " " - ' *" %'! " ) %'# (%" ( & ' ) "$ #%*$) %$ $- + " " '*$$ $ $ " "! '%() $ %$%#- ) % $) %'!( % $) ) %, %) )%' %, *))" %* " %'! '%*$ % # ! " ! %$+ -%'( ' ) ) *' $ -" $ &' - '( ;;; 4,-0&63;2;)0(-2+ '31 ' % $ $"% $ > )77 8,%2 -2',)7 ;-() *36 2%663; 86)) 63; 74%'-2+7 > !6%'836 13928)( :%0:) -7 %:%-0%&0) > =(6%90-' (6-:)2 6300)6 ',%-2 *36 032+ 71338, 34)6%8-32 > "7)7 )<-78-2+ 86%'836 ,=(6%90-' 7=78)1 > (.978%&0) ,-8', *36 (-**)6)28 (6%;&%6 ,)-+,87 > )%6 13928)( %9831%8-' &3< 7834 83 46):)28 70-(-2+ Building the Best Since 1964 PHIL BROWN WELDING CORP. ,32) ��� %< ��� ? -0) ( $ 32/0-2 -',-+%2 Contact Vine Tech Equipment your Northwest Phil Brown Dealer ;;; :-2)8)',)59-41)28 '31 46 April 1, 2013 GOOD FRUIT GROWER he newly detected grapevine redleaf disease is a wake up call to Washington���s wine industry. Growers and winemakers have been grappling with grapevine leafroll disease, but now with the emergence of redleaf disease, the industry has to deal with two of the most serious virus diseases affecting wine grape vineyards. With increased sourcing by growers and wineries of plant materials from different grape growing regions to meet the growing demand for new plantings, there is potential for viruses alien to Washington State vineyards to be introduced through contaminated cuttings and propagative material. The perennial and long-term nature of vineyards means that infected vines can serve as a ���Typhoid Mary��� and provide constant infection sources for secondary spread by leafhoppers. Washington State University���s grape virology research team, headed by Dr. Naidu Rayapati, is working to learn more about the new disease. Immediate research priorities for the coming year include identifying the extent of redleaf presence in Washington vineyards; learning if the disease is present in white varieties; and learning more about disease behavior and how it spreads through vineyards. Other questions that need answers are: ��� Is redleaf disease from a recent introduction or has it been here for many years? ��� What are the ages of infected vineyards? ��� Is there commonality in the locations of infections? (shared plant material sources or region) ��� Are some cultivars more susceptible than others? ��� Is the geminivirus present in Concords or other juice grape varieties? ��� Field confirmation of suspected vectors and other potential species is needed. Besides their negative impacts on fruit yield and quality of grapes, the introduction of alien viruses is of great concern for sanitation and grapevine certification programs in Washington and the nation. Thus, it is imperative that a concerted approach among stakeholders, researchers, and regulatory agencies may be to strengthen our clean plant campaign efforts to ensure sustainable growth of Washington���s grape and wine industry. ���N. Rayapati and M. Hansen www.goodfruit.com

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