Issue link: http://winesandvines.uberflip.com/i/658375
16 WINES&VINES April 2016 WINE INDUSTRY NEWS S an Rafael, Calif.—A team of research- ers with the University of California, Davis, identified the three-cornered alfalfa treehopper (Spissistilus festi- nus) as the first confirmed vector of red blotch- associated virus in greenhouse tests. The researchers cautioned that the treehop- per might not be the only vector. "It's important to note we're not specifically saying this is the only vector out there," said UC Davis entomol- ogy post-doctorate researcher Brian Bahder during a Feb. 26 webinar presentation about his work. The webinar, which features several other updates about current red blotch re- search, is available online. Bahder has been studying California vine- yards with evidence of the virus spreading through them starting with the UC Davis Oakville research vineyard. Researchers, how- ever, also have found vineyards in California's Amador and Santa Barbara counties that ex- hibit the telltale signs of how it's spreading, such as a cluster of infection on the edge of a vineyard that spreads to other vines. Bahder has been surveying the insect popu- lations of these vineyards to see which critters are present in all of them. "I've been able to come up with a short list of species that I be- lieve are likely going to be the vector of this virus," he said. That short list is comprised of one tree- hopper (Membracidae), two leafhoppers (Ci- cadellidae), one jumping plant lice (Psyllidae) and one planthopper (Cixiidae). Bahder took one insect from each of these species and placed it in a greenhouse with infected vines for 48 hours, and then placed it with clean plants for another 48 hours. During the we- binar he discussed the results after five months since the trials. To test for the presence of the virus, Bahder used digital PCR analysis that he said is far more sensitive than quantitative PCR, and which can detect the virus at levels of much lower concentration. Of Bahder's short list of suspects, he only was able to reproduce transmission of the virus with the three-cornered alfalfa treehopper. Grapevines are not the insect's preferred host, which are grasses, legumes and its namesake alfalfa. Bahder said such plants could often be on the edges of vineyards in riparian areas, so that could explain the pattern of the spread of the disease in some vineyards. Bahder and the other members of the re- search team are working on a paper about TOP STORY Researchers Confirm Red Blotch Vector Start with the right toolS. Western Square is Barrel Racks. Since 1988 we have been the world leader in Barrel Racks. Regardless of size, when it comes to Barrel Racks, Western Square is your best partner. Photo couRteSy of allagaSh BReWing comPany, PoRtland, me. one of ouR PaRtneRS Since 2005. westernsquare.com n 209.944.0921 WESTERN SQUARE I N D U S T R I E S Brian Bahder (left) and Frank Zalom with the Uni- versity of California, Davis, look for insects at a red blotch-infected vineyard in Amador County. LYNN WUNDERLICH / UCCE