The investigation was conducted during the period 2020-2022 in an organic orchard of the Institute of Agriculture – Kyustendil, Bulgaria with plum (Prunus domestica L.) cv. Stanley. The following fertilization variants were applied: V1 – unfertilized – (control), V2 – Ecofol program (Amino Expert® Balans, Helasol (B), GO! BIO Total, GO! BIO (K) and GO! BIO (Ca)), V3 – Humustim, V4 – chicken manure Vita organic 2,5 kg/ tree, V5 – chicken manure Vita organic 5,0 kg/tree. The percentage of brown rot in the Stanley plum variety was 2,8 times less with Humustim foliar treatment, 3,1 times less with the application of organic fertilizers according to the Ecofol scheme, and the soil application of Vita organic with rates 2,5 and 5,0 kg/tree with 2.5 and 3 times, respectively, compared to the control, the results being statistically proven. Organic fertilizers application of plum reduced the density of the European cherry webspinning sawfly – Vita organic 5,0 kg/tree – by 18,3%, Ecofol program – by 31,7%, Vita organic with 2,5 kg/tree – by 41,5% and Humustim – 53,7%.