Evaluation of Trichoderma spp and pseudomonas fluorescens for suppression of phytophthora capsici infecting black pepper

Abstract

Foot rot caused by Phytophthora capsici is a serious disease of black pepper in India. A filed experiment was conducted at Thamarassery, Kozhikode district, Kerala, India to study the effect of eight Trichoderma, Four P.Fluorescens and four combinations of Trichoderma +P.fluorescens in order to establish their potential for disease suppression. These isolates were short-listed based on their antagonistic potential in in-vitro (pot culture) tests. Biocontrol inoculums was applied to black pepper vines twice a year in june (pre-monsoon) and September (during monsoon break) and disease incidence and growth parameters were recorded. After two years of experimentation T.harzianum IISR 1369 + P.fluorescens IISR 41 combination showed maximum plant height followed by T.harzianum IISR 1369+P fluorescens IISR 6 and T. virens IISR 1370 + P. fluorescens IISR 1l. External manifestation of symptoms was not noticed in any of the treatments. Since destructive sampling was not undertaken to score the root rot their exact role on the disease suppression could not be studied. However, population of P. capsid was monitored and detected in different treatments at periods of interval by soil baiting using Albizzia leaves. Pooled analysis of population of Trichoderma over the years showed that it was able to survive maintaining a population level of about 104 cfu / g of soil. A similar trend was observed in the case of P. fluorescens also. However the population of P. fluorescens was higher than Trichoderma. Since there was no natmal incidence of disease in the field, treatments were repeated in pot culture taking large amount of soil (4 kg / pot). When challenge inoculated with P. capsid, treatments applied with P. fluoreoscens IISR 13 and P. fluorescens IISR 41 were highly disease suppressive showing only 10% disease incidence as compared to 90% in the control. Combination of T. harzianum IISR 1369 + P. fluorescens IISR 41, T. harzianum IISR 1369 + P. fluorescens IISR 6 and T. virens IISR 1370 + P. fluorescens IISR 13 were also on par with the above treatments. Hence it is inferred that P. fluorescensIISR 41 and P. fluorescens IISR 13 can be utilized for the suppression of P. capsici. Combination of T. harzianum IISR 1369 + P. fluorescens IISR 41 and T. harzianum IISR 1369 + P. fluorescens IISR 6 are disease suppressive and promote growth of black pepper