Influence Of Stilbenoids On The Propagation Of Gray Mold(botrytis Cinerea) On Grape Berries Under Lab And Vineyard Conditions

The impact of vine stilbenoids on the propagation of gray mold (Botrytis cinerea) in grape berries under lab and vineyard conditions, was studied. As concerning the lab experiment, healthy berries of 3 red wine-grape varieties were sampled, as follows: a) Alexandrouli, from a 12-year-old vineyard located in western Georgia (Racha-Lechkhumi) grown on Brown forest acid-Dystric cambisols type; b) Mujuretuli, from an 8-year-old vineyard cultivated in the same location on the same type of soil; c) Saperavi, from a 15-year-old vineyard grown on Eutric Cambisoil in Eastern Georgia (Gurjaani district). The experimental design included the following treatments: 1) berry pre-treatment with 1 mg/100mL, 3 mg/100mL, 5 mg/100 mL of a stilbenoid mixture, and then fungal infection; 2) berry pre-treatment with 1 mg/100ml, and 5 mg/100 mL of ε-viniferin, and then fungal infection; 3) berry pre-treatment with 1 mg/100mL, and 5 mg/100 mL of transresveratrol, and then fungal infection; 4) control berries with fungal infection but without pre-treatments. The pretreatments 1), 2) and 3) also included freshly prepared or one-week-old stilbenoid mixture, ε-viniferin and transresveratrol solutions. As concerning the vineyard trial, healthy clusters of Saperavi (red wine-grape variety) from a 15-
year-old vineyard cultivated on Eutric Cambisols type in Eastern Georgia (Gurjaani district), were selected. The experimental design was as follows: 1) cluster pre-treatment with 5 mg/100 mL of stilbenoid mixture and then fungal infection; 2) cluster pre-treatment with Bordeaux mixture and then fungal infection; 3) control vines with fungal infection but without any pre-treatment. The stilbenoid mixture included a mix of trans-resveratrol and its derivatives. The degree of fungal infection at berry level was checked. Under lab conditions the pre-treatment with 5 mg/100 mL of stilbenoid mixture, ε-viniferin and trans-resveratrol completely inhibited Botrytis cinerea growth. Under vineyard conditions Bordeaux mixture showed a better fungal control than the stilbenoid mixture (97% versus 84%).