Biocontrol and organic management strategies against Alternaria brassicae using native Trichoderma spp. in mustard crop

Abstract

Trichoderma spp. were isolated from soils of Chhattisgarh and screened for antagonistic activity against Alternaria brassicae using dual culture and inverted plate methods. Among the isolates, Trichoderma harzianum (T6) showed the strongest inhibition of A. brassicae, with 53.80% inhibition in dual culture and 42.83% through volatile compounds. For mass application, T. harzianum was multiplied and combined with organic amendments (Karanj, Mahua, and Mustard cakes at 3% w/w) and applied to both pot and field soils. The effectiveness of treatments was evaluated by assessing percent disease index (PDI) on mustard at 75 and 90 days after sowing (DAS). The integrated treatment of Trichoderma with organic amendments significantly reduced disease severity compared to Trichoderma alone, demonstrating a synergistic effect. The native isolates T6 and T4 exhibited strong antagonism via mycoparasitism and volatile compounds, highlighting their potential as effective biocontrol agents. Overall, the integrated use of Trichoderma and organic amendments offers a promising strategy for managing Alternaria leaf spot in mustard.