What management strategies are most effective in minimising sunburn damage in Chardonnay vineyards around Orange

Sunburn damage manifests as a browning of the berry skin, and depending on the severity of the damage can lead to cracking and shrivelling of the grapes which reduces the visual and aromatic quality of the grapes causing economic losses to grape and wine producers as a result losses in yield and wine quality. In areas where leaf removal is a common practice, better understanding of the best moment to conduct this practice could help mitigate this problem. During the 2018-19 season the effect of leaf removal timing on sunburn incidence and on the accumulation of photoprotective compounds was evaluated on Chardonnay grapes from 2 vineyards located at different altitudes in the Orange region. Leaf removal led to higher final concentrations of all photoprotective compounds when compared to the non-defoliated control. Marked differences were observed in the accumulation patterns between berries defoliated early (end of flowering) and those defoliated later (véraison), with earlier accumulation, and thus better acclimation in those that were exposed early. Ultimately, sunburn damage was higher in grapes defoliated at véraison. There were no significant differences between yield, total soluble sugars, pH, titratable acidity and YAN between treatments within each vineyard.