Issue link: http://winesandvines.uberflip.com/i/116287
grapegrowing LR1 RB2 Photos: M.R. Sudarshana, US DA- ARS Davis, CA RB1 RB3 LR2 RB4 RB1 and RB3: The underside of a Cabernet franc leaf with red blotch disease shows pink veins; LR1: Leafroll has leaf margins that roll downward (Cabernet franc); RB2: Leaf margin on red blotch diseased Cabernet franc grapevines remains flat, and blotches may develop from the margin while veins turn red; LR2: Leafroll has green veins on the underside of a Cabernet franc leaf; RB4: Coalesced red blotches cover most of a Cabernet franc leaf. teamed up in an effort to identify the virus causing red blotch disease. Al Rwahnih is an early user of next-generation, or high-throughput DNA sequencing technology since 2007. Sudarshana reports that one block of Cabernet Sauvignon on 101-14 rootstock planted in 2001 at the Oakville Station Experimental Vineyard has GRBaV in 46% of the vines. Presence of the virus in a vine can be confirmed using an extremely sensitive laboratory test known as polymerase chain reaction, or PCR, to detect small amounts of genetic material. This analytical process uses an amplification technique that multiplies the existing DNA and similar genetic material to identify the virus. Analysis of the genomic nucleotide sequence indicates a new circular, monopartite DNA virus that is tentatively assigned to the family Geminiviridae. Several labs offer a test for GRBaV. In October 2012, Agri-Analysis VINEGUARD testing service, which screens for up to 19 viral and bacterial pathogens, added GRBaV. AL&L Crop Solutions began offering testing for GRFaV in November 2012. CSP Labs Inc. offers a virus Multi-Scan PCR Synchronizing Wine with Wood 52 p r acti c al w i ne ry & v i n e yard APRIL 20 13