As you tour Dry Creek Valley, you'll notice some vineyards appear neat and tidy with vines that grow vertically through sets of wires. You'll also see other vineyards with rows of shorter, gnarled old vines that have survived for decades and look like something out of a Tim Burton film. It's the difference between Vertical Shoot Positioning (VSP) vines and head-pruned vines, aka old vines.
There are plenty of growers and winemakers who swear by the wines produced from old vines. And in Dry Creek Valley, I encourage you to try some of the delicious Old Vine Zinfandel that's out there. These vines are masters at self-regulating their yields, and there is something to be said for the history in a glass of wine from 50 or even 100 year old grapevines. However, newer plantings are almost always trained to grow through a VSP system as opposed to head-pruned because of the inherent advantages of farming using this more modern practice. At Collier Falls, the original 8 acres of Zinfandel vines planted in 1982 were converted from head-pruned to VSP, and now we farm all 20 acres of our fruit using this method.
While a head-pruned vine produces fruiting canes that drape all around the trunk like an umbrella, the VSP system allows for two cordons (or arms) to extend horizontally from the trunk, with each producing 12-16 fruiting shoots that are trained vertically through the course of a growing season. The VSP allows more sunlight to reach the leaves and helps the vine achieve greater efficiency of photosynthesis. Another benefit from the VSP system is the increased air circulation around the vine, which reduces the risk of mold and mildew on the clusters. VSP also lets us tailor our leaf pulling and canopy management to control the microclimate around the fruiting zone, and can even give us the ability to customize sun exposure around specific clusters.
There are benefits to the VSP when it comes time to harvest as well. All the fruit on a head-pruned vine is hidden beneath the canopy just a foot or two off the ground. This makes for a much more difficult and labor intensive harvest than a VSP system where our fruiting zone is at waist height and exposed for easy picking. And while the steep slopes of our property make mechanical harvesting impossible, many larger vineyards on flat ground can make use of mechanical harvesters with VSP systems. But head-pruned vineyards, no matter how flat or how vast must always be hand picked.
No matter whether a vineyard has old vines or a VSP system, the pruning of last year's growth needs to be completed before spring arrives and bud break starts the next growth cycle. And that's just what we're finishing up now at Collier Falls. Pruning in the rain is a big risk though, since the fresh cuts make the vine susceptible to a disease called Eutypa dieback. It's just as scary as it sounds, and can infect shoots and eventually kill an entire cordon. I'm happy to report a beautiful sunny start to 2013 in Dry Creek Valley with lots of great pruning weather. My dad and our vineyard manager, Salvador Acavedo, prune daily from January 1st through March 1st, and between the two of them they trim all 16,000 vines at Collier Falls!