Cluster Counts and Fruit Set Evaluation: Taking a Guess
Wednesday, June 16th, 2010June has arrived and with that comes the ending of bloom and fruit set, which means that we have reached the second stage in evaluating the size and quality of the upcoming harvest.
If you remember, we first counted tiny clusters in April (before bloom) which gave us an idea of our cluster counts and our potential cluster size. I say potential because we never know what effect the environmental and growing conditions during bloom will have on the eventual set of the fruit.
The individual berries are “set” when successful fertilization occurs of the ovules. Wind, rain, temperature, disease, and genetics are some of the major factors that can hamper the pollen from successfully germinating and fertilizing all ovules present. So, even though we may see a large cluster with lots of berries before bloom, it’s very possible that a significant percentage of potential berries never develop, especially in sensitive varieties like Merlot.
These undeveloped berries are called “shot berries“, and as winegrape growers, we generally do not like to see them!
However, a “shattered” bunch can be a benefit to some varieties that have extremely large or dense clusters, allowing the bunch to be looser and therefore decreasing the chance of berries rubbing and splitting.
In the pictures below, you can see a Chardonnay bunch which set a couple of weeks ago and this is evident by the larger size of the berries. The cluster looks a little smaller than normal years.
The other picture is a Cabernet Sauvignon cluster which is still finishing set, as you can see by the presence of the old flowers. Notice the cluster is looser (but still not as developed) as the Chardonnay.
- Chardonnay
- Cabernet Sauvignon
So, long story short: We are evaluating the fruit set now to make predictions on the crop size. This is very important to not only regulate our crop and canopy correctly with proper fruit thinning, irrigation, leaf pulling, and trimming techniques, but also for winery tank management for the 2010 crush: do we have enough tank space for the grapes?
At the end of the day, it is nothing more than an educated guess, because the harvest always has a way of throwing unpredictable curveballs at us!















