<i>In Vitro</i> Fungistatic Bioactivity of a Biostimulant Based on Pine Bark Extract Against Phytopathogenic Fungi

The use of biostimulants and corroborants is increasing worldwide. Laboratory and field assays show their effectiveness in improving the vegetative performance of plants and their tolerance to abiotic stresses. This study aims to evaluate the <i>in vitro</i> activity of a biostimulant, based on pine bark extract, against some fungal phytopathogens. This research was carried out at the Laboratory of Plant Pathology (SAAF Department, University of Palermo, Italy), employing the poison food technique. Artificial agar media (Potato Dextrose Agar, PDA), simple or added with different concentrations of the biostimulant, were used to evaluate the differences in diametral growth of the fungi <i>Aspergillus niger</i>, <i>Aspergillus tubingensis</i>, <i>Botrytis cinerea</i>, <i>Coriolopsis gallica</i>, <i>Fomitiporia mediterranea</i>, <i>Fusarium oxysporum</i>, <i>Pleurostoma richardsiae</i> and <i>Pleurotus ostreatus</i>. The biostimulant was shown to contain the growth of most of the tested fungi, with the greatest effectiveness on <i>A. tubingensis</i>, <i>C. gallica</i>, <i>F. mediterranea</i> and <i>P. richardsiae</i> at the highest concentration, moderate effects on <i>A. niger</i>, <i>F. oxysporum</i> and <i>P. ostreatus</i> and no effect on <i>B. cinerea</i>. The observed fungistatic effects suggest that this biostimulant could contribute to integrated disease management while supporting more sustainable crop protection practices. In vivo tests aimed at evaluating the efficacy of these products on the evolution of different diseases in the field are ongoing, and preliminary results are promising but they are part of future work.