Lingonberry extracting leaves antifungal activity against the strawberry rot agent Rhizopus stolonifer

The aim of research is to study the antifungal properties of the water extract of the leaves of the lingonberry Vaccinium vitis-idaea L. against the causative agent of flowing strawberry rot Rhizopus stolonifer Vuillemin (1902). The decrease in spore germination of R. stolonifer in the presence of extract of lingonberry leaves relative to control was used as an indicator of antifungal activity. The concentration range of the extract was from 0.53 to 67.5 g/l in terms of dry lingonberry leaf; the total number of options for extract concentrations was 8. It was found that the extract of lingonberry leaves statistically significantly reduces the germination of R. stolonifer spores already at a concentration of 0.53 g/l in terms of dry leaf. The dependence of the antifungal effect on the extract concentration has the character of a curve with saturation, reaching a plateau at a concentration of 17 g/l in terms of dry leaf. This curve can be adequately (coefficient of determination R2 = 0.997) described by the sum of two logistic functions. The first function corresponds to the substance responsible for the death of more than 60 % of the spores of the fungus. The theoretical concentration of the extract, at which the death of half of the indicated number of spores occurs, for a given substance is 0.54 g/l in terms of dry leaf. The second function corresponds to the substance responsible for the death of more than 20 % of the spores of the fungus. The theoretical given substance is 8.23 g/l in terms of dry leaf. Despite the pronounced antifungal effect of the lingonberry leaf drawing, even the maximum tested concentration (67.5 g/l in terms of dry leaf) did not ensure 100 % death of R. stolonifer spores. Based on the results of the study, it is possible to recommend an aqueous extract of lingonberry leaves as an additional component of preparations for the control of R. stolonifer.