This week we present to you a new, unique plastic cover concept, developed and produced by Retilplast Srl, Italy: www.retilplast.it.

Those of you who visited last year’s August field day in California saw an example of this covering. In the past, the concept was that in order to gain earliness, a vineyard greenhouse should be designed like a closed vegetable greenhouse. Mr. Franco Ruggia of Retilplast Srl. refuted this concept with a specially designed polyethylene cover – PolyFilm-Plus – that diffuses sunlight and allows the passage of beneficial UV-A and UV-B light. In combination with the innovative installation system used, growers have a covering that is more user-friendly, has lower maintenance costs and reduces the temperature on hot days, compared to the traditional greenhouse systems adopted in the past.

Retiplast Open Corridor
Permanently open air ventilation corridor in middle of rows.
Retiplast corridor

Variable air corridor system:
Almost total closure in middle of rows.
 (Early Sweet Vineyard, Borquez Farm – Mexico)

Variable air corridor system:
Partial opening in middle of rows.
(Early Sweet Vineyard, Borquez Farm – Mexico)

Furthermore, vineyard growth under the PolyFilm-Plus cover is faster, healthier and stronger and when looking at the grapes’ quality under the cover, we discover that berry uniformity, size and shape are by far superior to non-covered blocks.

Pablo Borquez and his sons from Borquez Farm in Obregon, Sonora State, Mexico visited our field day last year and were very excited to see the unique plastic cover which advances the crop by 7-10 days and cools the vines in the summer heat. Pictured below is the Borquez’s Early Sweet vineyard in Obregon.

Sergio Borquez says, “This is in the south part of the state of Sonora. Campos Borquez is the only one to produce grapes in this region which has the advantage of being vast in resources like water and land, while also being very early – as early as any other region in Sonora.”

Early Sweet is known for its berry size variability and shot berry sensitivity. When grown under the PolyFilm-Plus covering, the berries grow to be uniform and clean.

Sergio Borquez carried out a comparative study at the Borquez Farm on the production of Early Sweet in an uncovered environment compared to Early Sweet production under Retilplast’s PolyFilm-Plus covering. The clear results of which can be seen in the graphs below.

The following conclusion is drawn from the aforementioned comparative study:

Conclusion on Harvesting Date

  • According to the data and phenological observations, so far it appears that we are starting around 8 days earlier on covered fields than those uncovered.
  • It is also important to note that as the graph presenting Phenological Stages shows, plastic coverage was installed a few weeks after pruning. Since the greatest impact of plastic coverage occurs at the beginning of the cycle, we believe that there is potential for significantly stronger effect if the plastic is installed on time.

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