Tel Button

It’s Pruning Time in the Vineyard

by David on January 4, 2010

A vineyard update from Goosecross, Napa Valley, Winemaker Geoff Gorsuch:

I always look forward to pruning season every year because it’s great quiet time out there, just me and the vines. We get a lot of questions this time of year because some vineyards in the valley are already completely pruned, others look quite wild and untamed and still others, like ours, are sort of half pruned. So, let’s talk about timing.

mustard_dormantvines 005

When: The big picture answer is any time from December through February – maybe even into early March. Once we’re sure the vines are dormant, we can start and it’s important to finish before the growing season begins again (bud-break), usually mid-March. Growers and wineries with lots of acreage will start as early as possible in order to get done on time. For the small grower, like Goosecross, there are a couple of reasons we like to prune at the last minute when we can.

One is to protect the vines from a fungus called eutypa die back (common name: “dead-arm disease”). During the rainy season, the spores are everywhere and will infect fresh pruning wounds. If we prune late, often the worst of the rain is behind us, plus the wounds develop resistance faster. But now, in the height of the rainy season our partially-pruned vines are still OK because eutypa moves so slowly. There’s no way it can travel all the way down these foot-long shoots to the cordon before March so the damaged plant material, if any, will be pruned off later.

The other reason to prune late is that it may delay the onset of bud-break, slightly, and spare us some of the lost sleep and expense of protecting the new growth from frost.

M_E_pruning 027

So, what about these half-pruned vines? In order to make quick work of our last-minute pruning, we get the worst of it done in advance. Last year’s shoots were a tangled mess, clinging to the trellis wires, so we got that cleaned up so we can finish the job quickly and easily later.

How: The vines need to be severely pruned, kind of like roses. From a wild tangle of shoots that are 3-5 feet long, I bring it down to what looks like almost nothing — just the vine skeleton.

Our vines are trained into what is called a bi-lateral cordon (two permanent arms) and we use what is called vertical shoot positioning (VSP), which means the shoots are trained up vertically, through the trellis wires. VSP maximizes light exposure to the leaves, which helps heighten fruitiness, and provides filtered light to the clusters.

M_E_pruning 031

I leave several small protrusions on the cordons, called spurs. The spurs contain the buds (growing points) for the next season’s shoots. The theory is that for each bud, I’ll get a new shoot in the spring. From each new shoot, I can expect about two clusters.

The problem is that the vines don’t read the textbook, and I’m bound to have some surprises. So, I’ll go through in April, to see what actually happened, and inevitably do some shoot thinning. If there are too many shoots and the canopy is dense, it blocks the light and increases mildew and mold problems. Plus the extra shoots produce excess clusters, which can compromise quality.

In late May, after flowering, I’ll make cluster counts to see if I need to do any thinning. There’s nothing I can do about too few, but if there are more clusters than I anticipated, the grapes may not ripen properly and could lack flavor intensity.

Every year is a new ballgame, but one thing we know for sure: Quantity and quality hardly ever go together, when it comes to wine, so careful winter pruning and thinning, later, during the growing season is critical to the quality of the vintage.

So, we’ve already done our “pre-pruning” and we’ll finish up in late February. Happy New Year!

Previous post:

Next post: