Antifungal action of chitosan in combination with fungicides in vitro and chitosan conjugate with gallic acid on tomatoes against Botrytis cinerea.

In the present work, a positive effect was obtained by using low molecular weight chitosan compounds in combination with synthetic fungicides. Antifungal activity against Botrytis cinerea, determined by the radial growth method, was more than 75%, with a 25 × 10 g/L concentration of fludioxonil or difenoconazole in compounds. Metabolic activity of B. cinerea fungus was about 15% when using a chitosan compound containing fludioxonil at a concentration of 25 × 10 g/L. The combined action of chitosan with difenoconazole at a fungicide concentration of 25 × 10 g/L is 2-3 times more effective than the action of each component separately. Results of studies for artificially inoculated B. cinerea tomato fruit when treated with low molecular chitosan and chitosan conjugate with gallic acid reduced the frequency of rotting fruit by 50 and 83%, respectively. Chitosan-gallic acid conjugate were obtained from chitosans with Mw of 28 kDa (Ch28GA) was proved to be effective as a preventive treatment for 3 days and can potentially be used as a biofungicide against B. cinerea on tomatoes in the post-harvest period.