Screening of fungicides, biocontrol agents, and PGPR for in vitro Suppression of cotton wilt pathogen Fusarium oxysporum f. sp. vasinfectum

Abstract

Fusarium wilt, caused by Fusarium oxysporum f. sp. vasinfectum (FOV), poses a significant threat to cotton production. In this study, the efficacy of five biocontrol agents and ten fungicides was evaluated under in vitro conditions against FOV isolate FOV-5. Antagonistic potential of three fungal biocontrol agents Trichoderma viride (SKDTV-22), T. harzianum (SKDTH-8), T. asperellum (SKDTA-1) and two bacterial isolates Pseudomonas fluorescens (SKDPF-6) and Bacillus subtilis (SKDBS-19)—was assessed using the dual culture technique. Among these, T. viride showed the highest inhibition (54.76%) of FOV growth, followed by T. harzianum (51.46%) and T. asperellum (49.84%). P. fluorescens also displayed strong antagonism with 69% inhibition. Fungicidal efficacy was tested using the poisoned food technique at four concentrations (100, 250, 750 and 1000 ppm). Complete inhibition of mycelial growth at 1000 ppm was observed with Carbendazim, Zineb, Chlorothalonil, Copper oxychloride, and Azoxystrobin, indicating their high potency. Other fungicides such as Propiconazole, Thiophanate methyl, Captan, and Mancozeb showed significant dose-dependent suppression. The study highlights the potential of specific BCAs and fungicides as effective tools for managing Fusarium wilt of cotton, warranting further validation under greenhouse and field conditions for integrated disease management strategies.