Ensuring optimal wine quality through management strategies for Botrytis cinerea

Abstract

This study considered host nutrition as a management option in reducing the potential severity of Botrytis grey mould in vineyards. Levels of nitrogen (as ammonium nitrate), calcium (as calcium sulphate) and potassium (as potassium sulphate) were applied as either soil drenches or foliar sprays to Chardonnay (field) and Chardonnay and Cabernet sauvignon (glasshouse) vines. Applications were made at fruit set, early pre-bunch closure and late bunch closure.
Preliminary results suggest that managers of vineyards with high nitrogen in petioles should avoid further applications and wait for natural depletions to occur. Calcium/potassium additions resulted in less compact bunches although the bunch numbers were higher. Applications of nitrogen, calcium and potassium did not affect winemaking parameters such as pH, Brix or titratable acidity (TA).
In glasshouse trials, increased addition of calcium did correlate with reduced Botrytis leaf blight severity. Lower Botrytis incidence was reported from spur-pruned vines suggesting that light penetration to the bunch zone was greater in spur pruned than in cane-pruned vines.
The results reported relate to induced Botrytis expression through laboratory incubation and do not equate to natural Botrytis expression in the vineyard at harvest.

Summary

Explores vine nutrition as a management option. High N and low Ca seemed to favour Botryits through various mechanisms.