Updated: Jul 9
Veraison is one of the most exciting moments in grapes season and a critical phase affecting the quality of the harvest. It's a tipping point in the vines' lifecycle, when energy is pushed from the roots and stored in the grapes as sugar and other nutrients. Prior, grapes are small and have low amounts of sugar while post-veraison some varieties will increase by 50% in size, with nearly a quarter of the grape consisting of sugar. As a result, acidity decreases, grapes are becoming sweeter, and their colors break.
Gold rush? Sugar rush!
To help optimize this "sugar rush" process, growers who up until now were applying regular irrigation to avoid stress and keep a positive growth rate of the vines will switch to regulated deficit irrigation. The result: growth slows down, and more energy is transported to the grapes and stored as sugar. Timing is everything. Identifying the start of Veraison and reducing irrigation accordingly becomes critical.
Trees don't have to write for growers to read them
Sure, it would have been great if vines could text their growers "just started Veraison". and in some sense, it's a sound metaphor to what happens as our trunk-sensors translate the vines' hidden internal processes (contractions, trunk growth, water demand) into a visual language. Growers don't just get data readings, they are reading the story of their vines and can know when the "veraison chapter" begins.
As they say, a good graphic tells the story.
In the following example, high MDS on July 15th 2019 was the signal for the grower to switch to "veraison mode" followed by deficit irrigation/controlled stress tactics to reduce vines' growth and maximize grapes' sugar level.
It is also worth mentioning that by carefully following the growth/MDS graphs and plant status growers are able to avoid severe stress (red status) and negative growth which might harm the vines' health and future productivity.