Primordial Clusters and the Fractal Geometry of Nature

Thanks to temperatures that were pushing 90 degrees last weekend, vines in Napa Valley experienced a whopping four inches of growth according to the Napa Valley Grapegrowers, whose members gathered at Round Pound Estate on Wednesday to discuss the 2012 vintage. Yield, as usual, was a hot topic. Jon Ruel, Director of Viticulture & Winemaking at Trefethen Vineyards in Oak Knoll, says that while fruit set is the most important factor in determining ultimate yield (meaning at this stage it is simply too soon to tell) we can predict the number of clusters each vine is capable of producing because they were actually formed last year.

The inchoate clusters form inside the vines long before we ever see them. It’s crazy but true: This year’s clusters were formed inside last year’s shoots. In looking at the elongation of flower clusters (pictured above), Ruel can estimate the number of eventual grape clusters, which won’t develop until after flowering (mid-May). “Before flowering,” says Ruel “the ‘cluster’ shows up on the side of the young shoot and the rachis (stem) of the cluster elongates to spread out the flowers (or what will be flowers at bloom, and then grapes).”

“Only after elongation can we really see how big the clusters might be. Right now, you can see where there are clusters and where there aren’t — which is one clue about yield. You can even see if there are lots of branches or wings on the cluster.  But, elongation helps you see how big the clusters might be eventually — how many potential flowers or grapes are on each cluster.”

Ruel continues to explain, essentially, how the fractal geometry of nature (as pioneered by Benoît Mandelbrot) applies to the grapevine: “This year’s clusters began as primordial clusters inside last year’s shoots. Each dormant bud along a shoot made last year had, inside of it, a tiny compressed version of a shoot ready for 2012.  As the buds break, the tiny shoot expands. Tendrils grow on the shoot, opposite each leaf — except where those tendrils have undergone differentiation to become clusters. Grape clusters are really just modified tendrils. This is usually opposite the first 1-3 basal leaves and then all tendrils up the rest of the shoot. Sometimes you see a funny one that really looks like a tendril but will have a couple flowers stuck on it — hinting at the physiological origin of clusters. Anyhow, right now, it’s all growing out there. The shoots are growing, rapidly, the young leaves are expanding and the tendrils and clusters are elongating.”