Biocontrol activity of Trichoderma viride and Pseudomonas fluorescens against Phytophthora infestans under greenhouse conditions

The biocontrol potential of Trichoderma viride-ES1 and Pseudomonas fluorescens-Bak150 against potato late blight pathogen, Phytophthora infestans, were studied in vitro and under greenhouse conditions. In vitro antagonism test carried out between T. viride and P. infestans showed a radial growth inhibition of the pathogen by 36.7% and a complete overgrowth of T. viride on P. infestans later, whereas P. fluorescens inhibited the radial growth of the pathogen by 88%. Foliar spray method used in the greenhouse trials involved foliar spray of healthy potato plants with suspensions of (i) T. viride only, (ii) P. fluorescens only, (iii) mixed culture of T. viride and P. fluorescens, and (iv) Mancozeb, followed by spraying the pathogen inoculum three days later. The infected leaf area was measured weekly and area under the disease progress curve (AUDPC) was calculated and compared among the treatments. The result showed that T. viride (AUDPC=260) and P. fluorescens (AUDPC=765.1) significantly (P<0.05) reduced the disease compared to the untreated check (AUDPC=1045). T. viride was found to be more efficient than P. fluorescens and mixed culture. No significant difference was observed between the mixed culture and the inoculated/untreated check. This study revealed that the foliar application of T. viride-ES1 has good potential in controlling the late blight disease of potato.