Issue link: http://winesandvines.uberflip.com/i/789891
42 WINES&VINES March 2017 GRAPEGROWING although the turnaround is just a few days, it would be nice if we could do a comprehensive test in the vineyard and get immediate informa- tion. Field tests would allow us to test more vines, too, and better understand whether the virus is spreading. Most vineyards are pulled due to virus, and most vines are rogued (pulling individual diseased vines) due to virus. The University of California system has put a lot of energy into providing nurseries with clean plant material, and nurseries are doing their best to provide growers with clean material. An in-field test would allow growers to take virus and disease control to the next level, which would ultimately extend the life of our vineyards. Currently we use NDVIs (normalized differ- ence vegetation index) from a service called VineView to help pinpoint virused vines and to detect strong and weak areas in vineyards. These are helpful to view over time. We can do a less technical and more immediate version of this with a drone, so we're experimenting with this. I'm learning to fly my DJI Phantom 3 now and, thankfully, no living creatures are aboard my test flights. I've purchased a lot of extra blades the past few months. The drone can also look for things like irrigation leaks, pest or dis- ease pockets and water stress. Q Water is likely to continue to be a huge issue in California. How are you man- aging water use in the vineyards you farm? Barbour: Our farming clients are producing wines for the ultra-premium and luxury mar- kets, so irrigations are always intentional and far less than someone who's trying to set 6 tons to the acre, for example. We'll continue to tightly manage water for all our clients and help them put into place any new regulations, which we expect to see in the coming months and years. We use several tools to trigger an irriga- tion. One is to measure water stress by looking at the leaf water potential. Another is analyz- ing weekly neutron probe reports. We've ex- perimented with sap flow sensors and evapotranspiration sensors. At the end of the day, our most valuable tool is walking the vineyard and irrigating at the right time dur- ing the growing season. The timing of rain periods plays a huge role in canopy growth and development. If we receive all our rain in December, we may start irrigating two months earlier than if we have a wet March. We've also gotten better at identifying areas within the vineyard blocks that might need CHOOSING ORGANIC SOLUTIONS V ineyard manager Jim Barbour says he's farming mostly organically, wheth- er or not his clients decide to get certified. "We know better fruit is grown in healthy soils with populations of microbes, which play an important role in nutrient exchange and water retention," he says. "Synthetic products tend to destroy that. We also farm organically because the organic materials usually work better than synthetics.… "Also, we just want to make sure we're taking care of the places we farm. A lot of people live on their vineyards, and you also might have neighbors." Barbour adds that logistics figure into farming practices, too. "Our equipment is down at our office in south Napa, and most of the vineyards we farm are up valley. So we can't run down to change material in a spray rig from vineyard to vineyard." As for certification, he says, "Most clients who want to certify organic or farm Biody- namically tell us their preference. For them, it's usually a philosophical decision."