43" Of Rain: The Good, The Bad, and What It Means for the 2017 Vintage
June 15, 2017
By Jordan Lonborg
As of now I am sure you are all aware of the phenomenal winter we experienced in California. The snow pack in the Sierras is record setting. Lakes and reservoirs are at capacity in the northern two-thirds of the state. Mammoth Mountain is expecting to be open through July (and possibly the entire year). Lastly, our beloved Senior Assistant Winemaker, Chelsea Franchi, will reach her personal goal of skiing 40 days this season (you read that right) even as a weekend warrior.
At Tablas Creek, we received close to 43" of rain this year. There are reservoirs that are still full in our Adelaida region that I didn't even know existed. Until April, there were spots in the vineyard where water was literally bubbling out of ground squirrel burrows. Las Tablas Creek, the seasonal watershed from which we get our name, hadn't flowed since 2012, but started in December and didn't stop until three weeks ago. It was a rain season that will be remembered by those who live and work in the Adelaida for years come. After 5 years of intense drought, what does this mean for our vineyard?
Amazing Vigor in the Vineyard
This is only my second summer as Tablas Creek's Viticulturist, so my history here is limited. That said, vigor is vigor. It is unmistakable. Schooled or not, novice or expert, anyone could walk into the glorious property that I am fortunate enough to call my office and recognize the extreme growth that is occurring at this moment. If you were to stretch out some of the shoots in our Viognier, Syrah, and even our head trained Grenache, they may remind you of NBA Finals hero and the Warriors' own Kevin Durant and his wingspan (if you are unfamiliar with my line of reasoning, I urge you to look him up. He defies human anatomy). Some canes are easily ten feet long. We have pulled wires up twice in some blocks and still it feels as if you are walking in downtown NYC and its endless sky scrapers. This is true even with varieties (like Viognier, pictured right) where you're normally thrilled with modest vigor.
One of my favorite quotes is from a local vineyard consultant: "as vineyard managers we aren't farming vines or even fruit, to be successful, we farm leaves." Forty-three inches of rain makes growing leaves easy. During the growing season, the canopy acts like a solar panel. As the vines go into dormancy post harvest, the chlorophyll within those leaves is drawn back into the plant and is stored as energy for the following season. But until harvest, these leaves are the engine that drives the vines' ability to ripen fruit.
Fruit Set Looks Good
I was worried that the cool spring we've had would mean that the fruit clusters wouldn't develop properly. Physiologically, a grapevine relies on many factors to develop the pollen tube required for proper fertilization of each berry. But in general, cold weather is bad news. A chilly May -- when most of our early grapes are in bloom -- in 2015 produced painfully low fields in some varietals. Pollen tubes were not able to develop quickly enough, and the result was widespread shatter: berries that were not fertilized and therefore fell off the rachis (stems). But it looks like we largely avoided shatter this year, as we apparently tiptoed above the temperature line that can be so disastrous during that crucial period in May. Fruit set looks good.
Unusually High Mildew Pressures
So, vine vigor is through the roof, we have had had a great fruit set, all is good right? If only farming was that easy! With the good comes the bad. Extreme vigor in a vine means extra shoots and leaves (canopy), and all this growth can create the perfect environment for a fungal disease known as powdery mildew. Mildew isn't usually a huge problem for us, because by the time we have significant canopy growth, our daily high temperatures are above the range (70-85F) where mildew thrives, and it's usually so dry that all fungal diseases struggle to get established. Unfortunately, these are the exact temperatures that we have seen in the Adelaida since bud break, and all the moisture in the ground has meant that evaporation has given the mildew spores enough moisture to get established.
Powdery mildew can affect both leaves and fruit. Some varieties such as Syrah, Tannat, and Mourvèdre are fairly resistant. Others like Grenache Blanc, Marsanne, and Grenache Noir are fairly susceptible. Heavy infestations require fruit drop to prevent the disease from spreading. Realizing the conditions were perfect, we knew the threat of powdery mildew was on our doorstep and we have been diligent in protection. As a certified organic property, we have used all available tools allowed (various oils and forms of sulfur) to protect and have been extremely successful in doing so.
As of now, we have found only a couple of very small pockets of of the fungus and have treated accordingly. Here's an area where the longevity of the team at Tablas Creek pays off. David Maduena, Vineyard Manager at Tablas Creek since the 1990's, has such a deep understanding of where the outbreaks occur, literally to the vine, that he can know with confidence where to look. It's an amazing asset.
More Shoot (and Cluster) Thinning Required
Just because the vine has lots of vigor and wants to set lots of crop doesn't mean that we will let it. If we were to just let the vines go, we would be allowing a micro-climate to form within the canopy creating a breeding ground for the aforementioned fungus. Vines will always push non-count buds that are in between positioned spurs. More often than not, the shoots will not have fruit on them. It is imperative that we go back through the vineyard as early as possible to remove these shoots to create space and airflow through the canopy. There has been so much vigor this year (read: so many extra shoots) that the removal of this growth is taking twice as long as it should in some blocks. This sets off a chain reaction. By spending more time in one block, we are delayed from entering another block that needs to be thinned. The longer you wait to thin, the more energy each vine wastes on shoots that will be removed. In another year, we could have hired extra crew to supplement our full-time team. Unfortunately, with this year's labor shortage in California, our ability to do so has been limited, and we're still playing catch-up.
Shoots are not all we are removing. We will have to thin more fruit this year as well, in order to make sure the grapes the vines produce have good concentration, and in order that vineyard blocks ripen as evenly as possible. (A vine with 20 clusters will ripen them more slowly than a vine with 10 clusters, which makes picking decisions difficult.) Typically, we like to limit our vines to two clusters for each shoot, or 12 clusters per vine for most of our trellissed blocks. For vines that may be diseased and have shorter shoots, we may thin to 1 cluster per shoot. This year, there are blocks on the ranch that are carrying three clusters per shoot! We are in the process of removing the clusters, which is easily one of the hardest decisions for any farmer.
The Future: Groundwater
Up until this point, the vines are largely working with the water that's in the topsoil. And that's been plentiful. But as the summer progresses, what will be important will be how well the water has made it down into deeper layers. This is our own small reflection on the importance of groundwater, which is hands-down the biggest ongoing water issue in California. Are the basins recharging? I cannot speak for California or our neighbors, but as far as Tablas Creek is concerned, our water table has jumped from 48 ft. when we first dug one of our wells in the middle of the drought to 27 ft. as of today. That is a considerable jump. Water has clearly percolated.
We are excited about the prospects of an extremely wet year. Yes, it has its challenges. We will need to be more diligent in controlling our yields, and in watching for mildew. We are a bit behind in getting the cover crop turned under and the vineyard looking manicured. But it's a pleasure to have these be the challenges we're facing, instead of the challenges of the last five years, where we were wondering how to keep the vines going until they can finish ripening their grapes. With three months to go until harvest, we have every expectation that it will be an excellent vintage.