How to use sugar loading to support harvest decision ?

Dyostem® results

Fruition Sciences will provide you the Dyostem® results directly on 360viti, our vineyard intelligence platform. Results will be presented in two ways.
  1. One sugar loading curve per sampled blocks. Measurements will start at veraison. The sampling frequency should be once a week for red varietals and twice for whites. A minimum of 4 sampling dates will be needed, and the average number of sampling dates to get a good sugar loading curve is 6.
  2.  Four Dyostem® maps describing your vineyard. Those maps are based on the analysis of four distinct indices: the sugar loading dynamic, the berry volume, the aromatic potential and the sugar balance (more detail on those maps here)
What is a sugar loading curve?

Sugar loading

Figure 1: The sugar loading concept (source: Vivelys)

The sugar loading profile (Figure 1) reflects the time variations of a fruit ripening index integrating the effect of vine physiology and environmental stresses. See our previous article about sugar loading here.

Analysis of sugar loading profile requires to distinguish two periods (as discussed in this article).

  • The first period during which berries are actively accumulating sugar. This period starts at véraison and ends typically before harvest (but not always depending on vintage conditions and winemaker decisions).
  • The second period during which the sugar quantity per berry is more or less constant. During this “plateau” period, Brix can increase or decrease, as a consequence of berry volume variations (dilution or concentration) but no longer as a consequence of active sugar accumulation.
What can you learn from a sugar loading profile?

You can see below in Figure 2, a typical sugar loading curve measured on 250 blocks of Cabernet Sauvignon in California for one season. Statistically, a plateau is observed starting on August 26th and the quantity of sugars per berry stabilizes around 190 mg/berry.


Dyostem® results

Figure 2: Seasonal profile of sugar loading per berry in Californian Cabernet Sauvignon (source)

Additionally, you can also observe that the average rate of sugar loading during the first phase is 5 mg/berry/day and that the duration of active sugar loading is about 36 days. By tracking precisely what else is happening in your vineyard during those 36 days  (vine water status, climatic events, operations, etc..) you deepen your understanding on how vineyard indices variations directly affect sugar accumulation profile.

How can you use sugar loading analysis to support harvest decisions?

After sugar loading stops (day “0” in Figure 3), the fruit flavor profile keeps evolving. Figure 3 below illustrates the path from vegetal flavor to over-ripe flavor following sugar loading stops. Thus, your picking decisions can be supported by an analysis of the number of days observed since sugar loading has stopped.

Dyostem® results

Figure 3: illustration of berry typical flavors after sugar loading stops (source)

Take home in practice:

 By integrating sugar loading profiles into 360viti you can support your harvest decision with data and connect:

  • the current trends of berry ripening across different blocks, different regions or even different seasons.
  • plant physiological indexes variations (ie. water status, nitrogen, etc…) and climatic variations (ie. minimal or maximal temperature) with their effects on berry ripening. If you want to know more about uncovering the relationship between vine water use and berry sugar accumulation, we recommend reading this article.

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