In recent years, leaf mold has caused problems in greenhouse cultivation in organic farming and has been responsible for high economic loss. Therefore, it is important to implement pest management strategies to protect plant health. There are a few preparations approved for use in organic production and there is a necessity to estimate and analyse the efficacy of these preparations against leaf mold. In the present study, laboratory experiments were conducted to elucidate the effects of several fungicides, plant strengtheners, fertilizers and surfactants on the parameters mycelial growth, sporulation and spore germination. Altogether, ten substances in 15 treatments (single or in combination) were analysed. Two isolates of P. fulva, which were isolated from different plant populations, were tested. Mycelium growth, sporulation and spore germination were strongly inhibited by Myco-Sin and Sergomil L60. Additionally, the two mix variants Sergomil L60, Netzschwefel Stulln, PREV-B2, Resistance and Myco-Sin, Netzschwefel Stulln, PREV-B2, Resistance showed also strong effects against leaf mold. Apart from these treatments, no others did exhibit such a strong reduction in all three parameters. Moreover, deformations on fungal structures caused by some further substances were observed. This study is an important first step for the future control of tomato leaf mold. However, additional greenhouse studies are urgently needed.