Cluster Thinning!

August 17, 2012

Veraison is pretty much finished in the basaltic section of the Montana Vista block, which as you may remember is a block of Cabernet Sauvignon near the top of the property. Once veraison is over, it becomes possible for us to start trying to figure out exactly how much fruit we can get from a given area when we eventually harvest it. This is called ‘estimating yield’, and once it’s been done it becomes possible for us to start adjusting crop load to maximize the quality of our grapes and, by extension, our wine.

What we found this week is that Montana Vista is cropped a little heavily for our purposes. This is actually not surprising, because this block (especially the basaltic section, with its’ deep, clay-rich soil) is pretty vigorous. When a vine has too much crop on it, the grapes tend to lack the concentration of flavor that leads to an excellent bottle of wine. To correct the situation, we cut the extra clusters loose and leave behind the amount of fruit that is appropriate for the size of the vine.

This is a common sight in years that the vines bear heavily. Excess fruit is dropped in the vine row, where it will eventually be incorporated back into the soil.

Deciding which clusters to remove takes a fair amount of specialized knowledge about how the canopy of the grapevine impacts the maturation of high-quality winegrapes.

There are a number of factors that go into deciding which grapes will stay and which will leave. One is how well a given cluster is exposed to light. A cluster that is tucked up in the middle of the canopy receives less light, and will generally be more likely to have unappealing vegetal characters than clusters out towards the edges.

Another factor is how much a given cluster crowds its’ neighbors, clusters that are too close together have a tendency to shade each other and restrict airflow through the fruiting zone, which can result in delayed maturation and increased risk of disease.

As you can see in comparing this picture with the one just above, we chose to remove the cluster that was tucked in between the other two, both because it was somewhat shaded and it blocked the airflow around its’ neighbors.

In the end, we are trying to create a vine where each cluster is able hang freely in the sun and air, and that has the right number of clusters on it. It’s important not to remove too many, because a vine that has too little fruit on it will develop distinct flavors bell pepper, asparagus, and other vegetables that you would not want to smell in a Cabernet Sauvignon.

This is what we would like the vines in this block to look like, the clusters evenly spaced and the whole plant carrying about six pounds of fruit.

Things are picking up, and we have a lot more great information to share about how we do what we do! Be sure to check back soon!

Amapola Creek is Richard Arrowoods’ latest winemaking project, to visit the Amapola Creek Winery main site, please click here.



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