Systemic Effect of Ganoderma lucidum Filtrate on Septoria Leaf Spot and Pycnidia Formation by Septoria lycopersici

This study aimed to evaluate the potential of the mycelial growth filtrate (MGF) from Ganoderma lucidum in providing systemic protection to tomato plants against Septoria lycopersici ‐induced leaf spot and inhibiting the production of reproductive structures by the phytopathogen. In greenhouse experiments, foliar application of MGF at 40% ( v / v ) two days before fungal inoculation reduced disease severity by 76% at 21 days post‐inoculation. Significant reductions were observed in both the rate of colonised stomata and the formation of pycnidia in the mesophyll of treated leaves, with only 10 pycnidia/lesion compared to 22 pycnidia/lesion in control plants. A systemic effect was observed through both root irrigation and foliar spraying with MGF, resulting in an average 60% reduction in disease severity. In vitro assays demonstrated the direct antifungal activity of MGF and its fractions against the pathogen. These results suggest that the cultivation of G. lucidum in liquid medium produces preparations with antimicrobial activity, effectively controlling Septoria leaf spot both locally and systemically. The bioactive compounds released during the submerged cultivation of G. lucidum show potential for use in managing tomato diseases.