Tannins-lignin mixed nanoformulations for improving the potential of neem oil as fungicide agent

Abstract

Sustainability and circular economy are increasingly pushing for the search of natural materials to foster antiparasitic treatments, especially in the case of economically relevant agricultural cultivations, such as grapevine. In this work, we propose to deliver neem oil, a natural biopesticide loaded into novel nanovectors (nanocapsules) which were fabricated with a scalable procedure starting from Kraft lignin and grapeseed tannins. The ensuing formulations were characterized in terms of size and Zeta potential, showing that almost all the nanocapsules had size in the suitable range for delivery purposes (mean diameter 150-300 nm), with low polydispersity and su cient stability to ensure long shelf life. The target microorganisms were three reference fungal pathogens of grapevine (Botrytis cinerea, Phaeoacremonium minimum, Phaeomoniella chlamydospora), responsible for recurrent diseases on this crop: grey mold or berry rot by B. cinerea and diseases of grapevine wood within the Esca complex of diseases. Results showed that grapeseed tannins did not promote inhibitory effects, nor alone nor in combination with Kraft lignin. On the contrary, the e cacy of neem oil against P. minimum was boosted by more than 1-2 orders of magnitude and the parasite growth inhibition was higher with respect to a widely used commercial pesticide, while no additional activity was detected against P. chlamydospora and B. cinerea. HighlightsNeem Oil was loaded into novel nanocapsules formed by tannins and lignin; Nanocapsules had mean diameter of 150-300 nm with low polydispersity.Nanocapsules had a negative surface charge which guarantees good stability;Lignin-based nanocapsules enhance the e cacy of neem oil by more than 1-2 order of magnitude on Phaeoacremonium minimum.