Leaf-Pulling: A Shady Subject
To pull or not to pull? That is the question.
The Long Island Merlot Alliance was established as a quality alliance. Through the sale of Merliance, we fund research into what it takes to make quality merlot. Our research has included the taste and aroma profiling referenced in earlier blog posts, as well as field trials designed to understand what it takes to improve quality right from the vine. We have, for three years running, commissioned a leaf-pulling study with Cornell’s Long Island Horticultural Research and Extension Center in Riverhead. The study, which had to be suspended in 2009 due to the unusual growing conditions, has begun to yield interesting results. I talked with Rich Olsen-Harbich, winemaker at Raphael, who annually leads the study on the LIMA side, to learn how leaf-pulling can lead to better-quality merlot.
Donnell: First of all, why does leaf-pulling matter?
Rich: We need leaves for carbohydrate (sugar) production but we don’t need all of them—just like we don’t need all of the fruit a vine will want to produce. Removing leaves allows sunlight to penetrate the canopy of the vines to help the grapes get riper. It also allows summer breezes to help keep fruit dry and reduce the incidence of mildew and other fruit rots. It’s important to practice this sort of viticulture in the northeast since we often lack sun and heat. The vines can use all the help they can get.
D: Isn’t this Viticulture 101 stuff? I mean, leaf-pulling seems like one of the routine things vineyards do. Why make a study of it?
R: You would think so, but not all vineyards pull leaves. Many do, but may not be getting the timing right. Leaf-pulling is one of the reasons the wines from Long Island are so much better today than they were, say, 20 years ago when it was not as common. As with any practice, even if it seems to be working, it’s good to look at it from a scientific standpoint, see its cause and effect, and make sure you’re getting the most benefit from your labors.
D: Can you give a brief overview of LIMA ’s leaf-pulling trials?
R: The trials were done with the help of Alice Wise and Libby Tarleton from the Cornell Research Center in Riverhead. We utilized the Pellegrini South Harbor Vineyard as the location for the study. A Cornell protocol laid out three different levels of leaf-pulling, based on the percentage of the leaves present, as well as a control (no leaves pulled). We pulled leaves at these levels at three different times in the growing season-early, middle and late-at four plots within the vineyard. Wine was made from each trial (four wines in all) and LIMA members did the first formal tastings of these wines this past summer.
D: What were the results?
R: The wines were from the 2007 vintage, so of course they were actually all pretty good! We did see some riper flavors, though, with an earlier removal of leaves. I think the results of the 2008 trial will be a little more interesting since it was a more challenging year.
D: What do these results mean in laymen’s terms?
R: We can make better wine if we remove leaves earlier in the season rather than later in the summer or fall. The more time the fruit is exposed, the riper it will get.
D: What do you do with the results? Publish them to LIMA members? Do LIMA members apply them to their own plots of merlot?
R: We hope to get the actual numbers [technical data] up on the website soon to share with the industry. We’ve also supported the work of a Cornell grad student, who looked at the same trial with cabernet franc. His results were presented at the Long Island Agriculture Forum a few weeks ago, and were very similar to our findings for merlot.
D: Will LIMA continue the leaf-pulling research or focus on another aspect of improving quality for Long Island merlot?
R: We’d like to fund this project for at least one more year to make sure our results are consistent and statistically significant. Last year we began a three-year study on the effects of crop load on flavor composition. I think many of us also would like to delve deeper into the question of what makes Long Island merlot special. Not only identifying the flavor characteristics of our local merlots, as we have been, but isolating the reason those flavors express themselves as they do here. Our research is taking our vineyards to the next level. I have no doubt that this and other work being done around Long Island will help us to keep making better and better wines in the future.