In vitro bio efficacy of biocontrol agents against Colletotrichum truncatum associated with leaf blight disease of Linseed in India

Abstract

Leaf blight caused by Colletotrichum truncatum is an important fungal disease of linseed (Linum usitatissimum L.) that can reduce crop growth and productivity. Considering the ecological concerns associated with excessive fungicide use, the present study evaluated the in vitro efficacy of Trichoderma asperellum and Pseudomonas fluorescens against C. truncatum using the dual culture technique. Among T. asperellum treatments, T₁ showed the greatest antagonistic activity, restricting pathogen growth to 25.40 ± 0.52 mm with 70.80% inhibition, followed by T₂ (26.80 ± 0.63 mm; 69.20%) and T₃ (27.65 ± 0.58 mm; 68.22%), compared with 87.00 ± 0.00 mm in the control. Among P. fluorescens treatments, T₂ was most effective, limiting mycelial growth to 29.10 ± 0.56 mm and achieving 66.65% inhibition, followed by T₁ (31.25 ± 0.78 mm; 64.18%) and T₃ (32.53 ± 0.75 mm; 62.72%), against 87.25 ± 0.73 mm in the control. Overall, T. asperellum exhibited superior antagonistic activity. This study demonstrates that promising biocontrol agents identified through in vitro screening could serve as environmentally compatible components of an integrated disease management strategy for the management of C. truncatum-induced leaf blight in linseed.