Efficacy of various antagonistic isolates and species of Trichoderma against Sclerotinia sclerotiorum causing white stem rot of mustard.

摘要

The study was conducted to evaluate the efficacy of various antagonists against Sclerotinia sclerotiorum, the white stem rot pathogen of mustard. Of the eight isolates and species of antagonists tested in vitro, isolates of Trichoderma harzianum - 3 and T. harzianum - 4 were significantly better and most potent in reducing the growth of S. sclerotiorum. Similarly, antagonists T. harzianum - 4, T. harzianum - 3, and T. virens reduced sclerotia formation. Isolates found most potent in vitro were tested in pot soil to evaluate their efficacy on disease reduction when antagonists and pathogen were applied simultaneously or, T. viride was added 7 days after the pathogen, minimum pre-emergence damping off (15.7%) was recorded. However, T. harzianum was superior in checking lesion length and post-emergence damping-off when applied 7 d after or simultaneously with the pathogen. Soil application of T. harzianum resulted in less disease intensity as compared to control (54%) when applied simultaneously or 7 d prior to the pathogen. The antagonists applied @ 15 g kg-1 soil irrespective of time of application were superior than lower doses. Correlation matrix for mycelial growth inhibition by Trichoderma strains in relation to number of sclerotia formation had negative and high correlation (R2=0.976).