Spring is keeping us on our toes this year, the uneven weather that we experienced in April continued into May. Sonoma County experienced further challenges – mainly from late season frost and storm conditions coinciding with bloom or flowering. Bloom or flowering is when bunches of tiny flowers bloom from the new vine shoots. Grape vines are self-pollinating, so each of these flowers has the potential to turn into a single berry. During bloom the delicate grape flowers are extremely vulnerable to damage from wind, rain and or unexpected late frost. On May 10th, we were subjected to scattered thunderstorms that brought rain, lighting, and hail to some areas. This mix of conditions during bloom can affect the grape vines pollination success rate, potentially reducing the number of grapes per cluster.
In terms of our Estate vineyard, we were spared severe changes in weather, but did experience close to freezing temperatures eight nights in May – though we were able to use our frost protection system to avoid any damage. With all these fluctuations in weather during a pivotal time in the growing season, it could result in poor fruit set in various vineyards around Sonoma County. We won’t know the full impact of the challenging conditions for a while still. However, we welcomed temperatures in high 90 degrees Fahrenheit and this heat is what was needed to get back on track in the vineyard. Our Estate vineyard is now in full bloom and the smell of the small blossoms is fantastic!
Blossoms in the Pinot Noir block of the Estate Vineyard
Canopy and Groundcover Management
With the latest heat up we are seeing very rapid canopy growth in our vineyard. One key task that was just completed is shoot thinning. Shoot thinning is important in being able to manage the crop level of each vine and to keep each vine in balance.
Shoot thinning in the Estate vineyard
By removing the smaller, shorter shoots and reducing the overall number of them we are also reducing the number of grape clusters which will prevent over cropping. An ideal number of shoots on our Pinot Noir vines is twenty-four with each one having two grape clusters. A balanced vine will average forty-eight clusters per season. As the shoots grow taller it is important to give them support and to guide them. We do this with trellis wires. After the shoot thinning is complete it is followed by moving the trellis wires up which will hold the remaining shoots vertical, and it also provides the tendrils something to garb on to. The trellis system in a vineyard is designed to capture maximum sunlight while at the same time protect the clusters from direct sunlight. It’s also designed to allow airflow around the grape clusters to prevent mildew. It requires this amount of work to ensure our vines have the best conditions to grow the best grapes.
Example of the trellis system
The warming temperatures not only push the vines to grow, but also the cover crop in the vineyard as well. Vineyard Manager, Alvaro Zamora, is spending time this month on the tractor mowing the cover crop and cultivating the soil between the vine rows.
Vineyard Manager, Alvaro Zamora, mowing cover crop between vine rows
Some benefits of having a cover crop are that it contributes to better soil structure, increases organic content with nutrients and greatly improves the water-holding capacity of the soil. We also need to keep the cover crop trimmed otherwise it makes getting in between the rows difficult. Directly underneath the vines canopy, along the length of each row, the goal for soil management is different than between the rows. By removing the grasses and legumes directly under the vines we limit the competition between the vines and grasses for available water and nutrients. Adhering to our substantiality ethics we eliminated the use of herbicides in the vineyard, and we use a special cultivation tool that “scrubs” the grasses from underneath vines. It gives us the best of both worlds – removing the under-vine grasses and legumes without the use of chemicals.
On behalf of the entire team here at Ron Rubin Winery, we wish you all continued good health!