Field performance of red and white “pilzwiderstandsfähige” (PIWI) cultivars in the south of Uruguay

Abstract

As knowledge about the oenological potential of disease-tolerant grape varieties (PIWI) continues to grow and consumer demand for product safety and sustainable production increases, more governments worldwide are permitting the cultivation of these varieties [1]. The Uruguayan wine sector is deeply engaged in this evolving landscape, where the country’s wine regulatory body, the National Institute of Vitiviniculture (INAVI), is now considering amending the law that currently prohibits the production of wines from hybrid varieties. This growing interest is primarily due to the substantial reduction in the use of fungicides, fuel, machinery, and labor required for controlling Peronospora (Plasmopara viticola) and Oidium (Erysiphe necator). Additional advantages include the effectiveness of biological treatments, the ease of producing low-intervention wines, and the alignment with internationally recognized certification standards [2].

This study aims to evaluate the vegetative and productive performance, as well as the maturation process, of PIWI varieties cultivated in Uruguay. The experiment was conducted in an experimental vineyard at the INIA-Las Brujas Research Station (Canelones, Uruguay; 34°40’ S, 56°20’ W; 32 m.a.s.l.), where advanced selections and cultivars with resistance to fungal diseases are being assessed. The varieties studied—Fleurtai, Sauvignon Kretos, Sauvignon Nepis, Sauvignon Rytos, Soreli, Cabernet Volos, and Julius—were introduced through an agreement between Vivai Cooperativi Rauscedo (VCR) and INIA Las Brujas. Productive performance was evaluated based on the number of clusters per plant, average cluster weight, total production per plant, yield, and the Ravaz index. Technological and phenolic maturation parameters included pH, soluble solids, total acidity, and total polyphenols.

Microvinifications were carried out, followed by both sensory and chemical analyses to assess the presence of undesirable compounds. The results indicated that certain white varieties demonstrated strong oenological potential for young wines under Uruguayan conditions. Additionally, the anthocyanin profile of the red varieties was analysed to establish criteria for distinguishing PIWI varieties with winemaking potential from other hybrids lacking quality attributes.

References

[1] PIWI International. http://www.piwiinternational.de. Accessed February 2025.

[2] ANII FMV. Project FMV_1_2023_1_176176: Is it reasonable to re-enable the production of wine from hybrid varieties in Uruguay?