Assessment of antifungal potential of biocontrol agents and fungicides against Fusarium wilt of cotton

Abstract

Fusarium wilt disease is a most common disease of cotton in Pakistan. Antifungal potential of fungal biocontrol agents, PGPRs and fungicides was assessed for the management of Fusarium oxysporum f. sp. vasinfectum, cause of cotton wilt disease. The antifungal properties of three species of Trichoderma, i.e., Trichoderma harzianum, Trichoderma viride, and Trichoderma aureoviride were investigated by employing the dual culture method. T. aureoviride showed maximum inhibition (81.17%) followed by T. viride (69.41%) and T. harzianum (38.21%) after 9 days. Four PGPRs were evaluated against F. oxysporum alone and in different combinations. In case of PGPRs, the best inhibition (68.13%) was observed when the Bacillus subtilis, Rhizobacter strains, Pseudomonas putida and Enterobacter strains were applied in combination after 9 days with minimum colony diameter (1.98cm).  Six different fungicides were tested i.e. Score® 250EC (Difenoconizole), Amistar Top 325 SC (Azoxystrobin + Difenoconazole), Nanok® 25% SC (Azoxystrobin + Flutriafol), Nativo® 75% WG (Tebuconazole + Trifloxystrobin), Vangard® 25% EC (Triadimenol) and Triger® 25% EC (Tebuconazole) at 40, 50, and 60ppm concentrations against F. oxysporum.  Score exhibited maximum pathogen inhibition (40.95%) followed by Nanok (40.63%) at 60ppm after a period of 9 days. Similarly, minimum colony diameter (3.83cm) and (3.87cm) of F. oxysporum f. sp. vasinfectum was recorded in Score and Nanok treated plates, respectively.