Abstract: Fungal activities of food additives, potassium sorbate, methylparaben, sodium benzoate, propylparaben, sorbic acid and plant activators harpin-protein and potassium dioxide were comparatively examined with ipradion in vitro conditions on two isolates of Botrytis cinerea obtained from strawberry fruits. Food additives and plant activators showed inhibitory effect at different levels on the mycelial growth of fungus isolates. According to the Minimum Inhibition Concentration (MIC), sorbic acid (300 μg mL-1 for each isolate) and comparison fungicide ipradion (10 μg mL-1 for each isolate) displayed the highest inhibition effect on the radial mycelial growth of fungal isolates. Similar efficacy was obtained at the highest dose (1000 μg mL-1) from other additives propylparaben (for both isolates), potassium sorbet and methylparaben (for isolate 1) and from plant activator potassium oxide. It was detected that all alternative substances has high inhibition activity according to ED50 values. Methylparaben, harpin-protein and potassium oxide revealed efficacies similar to ipradion. While harpin-protein did not have any effect on B. Cinerea germination, other alternative substances excluding potassium sorbate inhibited germination completely at differing doses. Potassium oxide and food additives except potassium sorbate inhibited the spore germination of isolates by 50% at doses between 25-345 μg mL-1. MIC value of ipradion on spore germination of isolate-1 and isolate-2 was determined as 10 and 30 μg mL-1, while ED50 values were determined as 2.9 and 12.5 μg mL-1, respectively. Data obtained from the research verified that food additives may be used in traditional and organic agriculture individually, or in appropriate combination with each other or with fungicides. Moreover, the study put forth that harpin-protein and potassium oxide not only activate plants against pathogens, but they may also have toxic effect on different growth periods of fungus. Although ipradion works only with two isolates, its MIC and ED50 values were considered noteworthy in terms of the resistance risk of B. cinerea.