The cuticle and epicuticular wax layer of grape berries provides a first line of defense against fungal pathogens. A relatively thick cuticle and wax layer may result in enhanced resistance to Botrytis cinerea Pers. The structure of epicuticular wax also has been postulated to play a role in Botryris resistance.
To examine the role of cuticle and wax in disease resistance, berries of diverse grape cultivars were sampled to quantify the cuticle and wax layers. Wax surface structure was examined by scanning electron microscopy. Significant differences among cultivars were found for both cuticle and wax measurements. Environmental conditions may influence development of these layers, some cultivars had significantly greater cuticle and wax layers in berries that developed in full sunlight. Visual differences in surface wax appearance were apparent among cultivars. Size, density and orientation of wax platelets varied among cultivars.