In-vitro Analysis of Antifungal Plant Extracts against Late Blight Disease Causing Phytophthora infestans

Abstract

Late blight, caused by Phytophthora infestans, is a devastating disease affecting solanaceous crops viz., potato and tomato, leading to significant economic losses globally. The increasing resistance of P. infestans to synthetic fungicides and the associated environmental concerns have necessitated the search for eco-friendly alternatives. In this study, an in vitro evaluation was conducted to assess the antifungal efficacy of selected plant extracts against P. infestans, employing five different formulations. The present in-vitro study evaluated the antifungal efficacy of aqueous leaf extracts from three plants viz., Carica papaya, Syzygium cumini, and Lantana camara which had formulated into five different treatments (T1 to T5). The combination of the used plant extract in each treatment in the order of Carica papaya, Lantana camara, Syzygium cumini is as follows, T1 (6:3:4), T2 (3:5:6), T3 (2:6:8), T4 (4:4:4) and T5 (4:8:2) and 10% W/V of chemical fungicide (Carbendazim) is served as control. The antifungal activity was assessed using the agar well diffusion method, with the zone of inhibition serving as an indicator of efficacy. The control showed a mean inhibition zone of 1.15 ± 0.17 cm. Among the treatments, T5 exhibited the highest antifungal activity with a zone of inhibition of 1.925 ± 0.70 cm, followed by T2 (1.700 ± 0.24 cm), T4 (1.200 ± 0.53 cm), T3 (1.125 ± 0.09 cm), and T1 (1.075 ± 0.32 cm). The enhanced performance of T5 and T2 indicates that certain combinations or concentrations of these aqueous extracts may contain bioactive phytochemicals capable of inhibiting the mycelial growth of P. infestans. These findings demonstrate the potential of water-extracted botanicals as effective, eco-friendly, and affordable biocontrol agents. The use of such natural products can significantly contribute to sustainable plant disease management. Further phytochemical characterization and field-based trials are warranted to validate the efficacy and scalability of these formulations for practical agricultural applications.