Effects of ethephon, methanol, ethanol and girdling treatments on berry maturity and colour development in Cardinal table grapes

Abstract

To hasten berry maturity and improve skin colour, the early-season table grape variety Cardinal was treated (post veraison) with a bunch + foliar spray using either 240 or 480 mg/L ethephon, as well as with 30% methanol, 30% ethanol (v/v); or by girdling. Treatment effects were evaluated in a randomised experimental design, with 10 replications of one plant per plot, down a single row. Ethephon at 480 mg/L applied twice, on July 2 when 5% of the berries showed colouring and on July 9 when 20% of the berries developed partial colour, increased total soluble solids, °Brix/titratable acidity and skin colour. Girdling, methanol and ethanol also increased total soluble solids and berry colouration and caused faster ripening. Ethephon at 480 mg/L was generally the most effective means of hastening ripening and improving colour.