Utility of dormant season pruning wood to predict nutrient status of grapevines

Authors: Schreiner, Roger - Paul

Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2020
Publication Date: 1/15/2021
Citation: Schreiner, R.P. 2021. Utility of dormant season pruning wood to predict nutrient status of grapevines. Journal of Plant Nutrition. 44(2):238-251. https://doi.org/10.1080/01904167.2020.1806311.
DOI: https://doi.org/10.1080/01904167.2020.1806311

Interpretive Summary: Growers rely on tissue tests of leaf blades or petioles collected during the growing season to monitor and manage grapevine nutrition, but an earlier test will allow growers to adjust nutrient inputs early enough to coincide with peak times of nutrient uptake. Nutrient tests on dormant stems collected in the winter were examined as a potential diagnostic tool to indicate grapevine nutrient status. Nutrient levels in dormant stems were evaluated based on their response to varying nutrient supply, and as predictors of leaf or petiole nutrient status in the upcoming growing season. The data used for this work came from a pot-in-pot vineyard where varying rates of nitrogen (N), phosphorus (P), and potassium (K) were provided to Pinot noir grapevines over four years. Results from this analysis showed that dormant stems are useful for diagnosing P and K status of grapevines, but not for diagnosing N. Further research to test the broader utility of dormant stem nutrient tests for practical nutrient management in production vineyards is required to validate these findings.

Technical Abstract: Grape growers utilize leaf blades or petioles collected during the growing season to monitor vine nutrition. However, an earlier indicator of vine nutrient status is desirable. The pruning wood derived from last season’s fruiting shoots (dormant stems) collected in winter may be a useful tissue to assess vine nutrition before the growing season. The utility of dormant stems to indicate grapevine nitrogen (N), phosphorus (P), and potassium (K) status was tested in Pinot noir grapevines from a microplot vineyard where varying levels of N, P, or K were provided over four years. Dormant stem nutrients were evaluated based on their response to varying nutrient supply, and as predictors of vine nutrient status in the upcoming growing season. Concentrations of P and K in dormant stems reflected the rate of P and K supplied to vines and effects grew larger over time. The concentrations of P and K in dormant stems also correlated well with next season P and K levels in leaf blades and petioles. Relationships between leaf blade and petiole tests and dormant stems were more consistent across years for P than for K. Nitrogen concentrations in dormant stems did not consistently reflect N inputs and were only weakly correlated to leaf blade and petiole N tests during the growing season. These findings indicate that dormant stems can be useful for diagnosing P and K status of grapevines, but further work is required to test their utility in production vineyards and to expand testing to other mineral nutrients.