Dr. Patty Skinkis, Viticulture Extension Specialist & Associate Professor, OSU
Dr. R. Paul Schreiner, Research Plant Physiologist, USDA-ARS
Véraison marks the start of fruit ripening in the vineyard, and it is one of the two main time points to consider evaluating vine nutrient status. Sampling petioles at bloom was the long-time standard recommendation for measuring grapevine nutrient status. However, more recently we have been suggesting that growers consider sampling vine tissues at véraison for macronutrient assessment, particularly nitrogen (N), phosphorous (P), potassium (K), and magnesium (Mg). Sampling should be conducted at approximately 50% véraison (50% color change/softening), and leaf blade or petiole samples can be taken. However, leaf blades are better for diagnosing many nutrients compared to petioles (Schreiner and Scagel 2017). Recent studies conducted in Oregon by both of our labs show that leaf blade samples at véraison serve as a good indicator of vine N status and fruit N levels (yeast assimilable N). To learn more about research into leaf and petiole nutrient guidelines and to learn about how to collect tissue samples and interpret results, see the articles listed below.
Schreiner RP and Scagel CF. 2017. Leaf blade versus petiole nutrient tests as predictors of nitrogen, phosphorus, and potassium status of ‘Pinot Noir’ grapevines. HortScience. 52: 174-184.
Schreiner P. and Skinkis P. 2014. Monitoring grapevine nutrition. eXtension.org.