Effect of chemicals and antagonists on growth and sporulation of Fusarium oxysporum causing wilt of chilli (Capsicum annuum L.)

Abstract

Efficacy of fungicides and antagonists was tested under in vitro conditions for the mycelial growth inhibition and reduction in sporulation of Fusarium oxysporum (i.e., Isolate Fo8). The fungicides carbendazim 50% and carbendazim 12%+mancozeb 63% were quite effective which completely inhibited the mycelial growth and the sporulation at all the concentrations (50 ppm to 1000 ppm); other fungicides viz., propiconazole 25%, captan 70%+hexaconazole 5%, carboxin 37.5%+thiram 37.5% showed effectiveness relatively at higher concentrations (i.e., 1000 ppm), whereas, captan 50% was least effective. The rate of sporulation decreased linearly with an increase in fungicides concentration and with the type of fungicidal treatment. The statistical analysis (P ≥ 0.05) showed that rate of sporulation measured at 100 ppm was significantly affected with the fungicides. Complete inhibition in sporulation was revealed by carbendazim 50% and carbendazim 12% + mancozeb 63% that was statistically at par with rest of the fungicides. However, the minimum inhibition in sporulation was recorded in captan 50% (i.e., 20.01%) that was significantly lower than rest of the treatments. Among the four antagonists, Trichoderma harzianum was better which inhibited 45.9 per cent mycelial growth, followed by T. viride (31.9%), whereas, the bacterial antagonist viz., Pseudomonas fluorescens and Bacillus subtilis were ineffective. The maximum reduction in sporulation (92.66%) was exhibited by T. harzianum and T. viride (86.85%), whereas, P. fluorescens and B. subtilis were least effective with 49.85 and 34.86% reduction in sporulation, respectively. The effective chemicals and antagonists may form a part of integrated management of the disease.