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3 8 V I N E YA R D & W I N E RY M A N A G E M E N T | J a n - F e b 2 016 w w w. v w m m e d i a . c o m all the work that has been done, however, I think the best thing to do is start your vineyard with healthy stock from a nursery you know and trust. Start preventive practices, i.e. double pruning, once you have the vines trained up. In a mature vineyard with esca, drop fruit from symptomatic shoots and flag those shoots, so next year even if they do not show symptoms, you know where they are. "Some fruit testing can give you a good sense of how the symptom- atic vines, or vines that have previ- ously showed symptoms, compare to healthy ones, and this can help you decide which fruit to drop. If your yields, quality and vine vigor are going down each year, getting to the low points where you are barely offsetting your management costs, you might want to pick a future date to replant. "Although I'm not a fan of retraining cordons and trunks, we probably should do some studies on the efficacy of this practice against esca, as well as continuing research on other preventive methods." Remi Cohen is the vice president and general manager of Lede Fam- ily Wines in Napa Valley. Her primary areas of expertise include viticulture, sustainable vineyard management, winemaking, grower and winery relations, and strategic business development. Comments? Please e-mail us at feedback@vwmmedia.com. the process from ordering through inspection of the vines and plant- ing. "Since you can see the wood s y m p t o m s i n d o r m a n t b e n c h grafts, it may be worth sacrificing a few," Baumgartner said. "With- out the black streaking of the wood, diagnosis of infection by an esca pathogen is a challenge." She also noted that it is assumed that practices found to be effective in a commercial vineyard also will be effective in the nursery; there- fore, late-pruning, double pruning, and fungicide treatments may be effective. Discuss the nursery's practices with them and ask about their experiences and preventive practices for esca. Unfortunately, there is no guar- anteed way to eradicate esca in an infected vine. "There hasn't been any testing that I know of for the efficacy of vine surgery (i.e., cutting out symptomatic cordons / trunks and retraining) against anything but Eutypa," Baumgartner said. "I would assume that the esca infec- tions are localized, like Eutypa, but this is a guess." Most management practices for esca focus on preventive practices and dropping symptomatic fruit. It also is useful to flag infected shoots to track the appearance of symptoms over several years to learn more about the etiology of the disease in your particular vineyard. "There are a lot of things we still do not know about the esca patho- gens and the trunk pathogens, in general," Baumgartner said. "From against botryosphaeria and Eutypa diebacks. Preliminary results sug- gest that Rally may be more effec- tive against the esca pathogens. Regardless, you need good, thor- ough coverage of pruning wounds for fungicides and other protectants to be effective barriers against the spores. Use the highest spray vol- ume you can if you apply by tractor. Don't use the lowest labeled rate or lowest spray volume." As with the pre-pruning process, she recom- mends starting with vines that are young and asymptomatic. Sealing pruning wounds with sealants also seems to be an effective practice. "Vitiseal, I hear from Dr. Doug Gubler, seems to be effective based on preliminary results," Baumgartner said. Gubler, a professor of plant pathology at UC Davis, is a leading expert on the epidemiology and control of grape- vine pathogens, and his lab has tested all of the materials currently labeled as protectants against trunk diseases. R e m o v a l o f p r u n i n g s f r o m the vineyard can be considered, Baumgartner said, although it is labor intensive. "Infected wood can be a source of spores within the vine- yard, so it is a good idea to cut out dead spurs/cordons and to not stack them up on the edge of the vineyard, where rain can hit them and splash the spores onto your vines." SOURCING PLANT MATERIAL Since propagated vines can be a source of esca and young esca, we turned our discussion toward the practices of nurseries and the sourcing of good plant material during the planting phase of vine- yard development. Esca pathogens have been isolated from nursery stock all over the world, although we certainly have many vineyards in California that never show esca symptoms. Certified stock is only certified free of certain graft-trans- missible agents, but it is not certi- fied free of the trunk pathogens or any other fungal pathogens. It is important to work with a nursery that you trust to pur- chase the vines and to be part of SOIL & CELLAR REMI COHEN