Production of the phytoalexins trans-resveratrol and delta-viniferin in two economy-relevant grape cultivars upon infection with Botrytis cinerea in field conditions

► Merlot and Cabernet Sauvignon are differently susceptible to B. cinerea infection. ► Leaves, shoots and flowers were examined for stilbene levels upon inoculation. ► Analyses were performed at pre-bloom, bloom and post-bloom stages. ► Differences in resveratrol and viniferin levels were observed through HPLC-MS. ► Their levels were proportional to plant response to fungal infection.