Enhancement of grape berry weight induced by an ethanol spray four weeks before harvest and effects of a night spray at an earlier date

Spraying aqueous solutions of ethanol (between 2.5 and 10%, v/v) 1 month before harvest has been shown to increase berry weight of Cabernet Sauvignon by about 10% at harvest compared with controls sprayed with water. These observations were made in France and in Australia. The increase in berry weight was not associated with significant changes in total soluble solids. Additional measurements showed that spraying aqueous solutions of ethanol onto the berry surface 1 month before harvest had only small effects on the colour of berry skin extracts. In another trial, spraying ethanol at night 1 month earlier than other trials lead to a slight increase in the colour of the skin extracts. Optimisation of the spraying conditions is discussed.