Integration of biocontrol agents with fungicide, weedicide and plant growth regulator for management of stem and root rot of jute

Abstract

Combination of chemical fungicides (viz., Carbendazim 50 WP and Tebuconazole 250 EC) and biocontrol agents (viz., Pseudomonas fluorescens Psfl1, P. striata Pst1, Azotobacter chrococcum Azbc3, Bradyrhizobium japonicum Brj4, Trichoderma aureoviridae S12, T. harzianum JTV2, T. virens JPG1, Aspergillus niger AN15 strains respectively either singly or in consortium) were used to counteract Macrophomina phaseolina, the causal organism of stem and root rot of jute. In addition, suitable plant growth regulator viz., Indole-3-acetic acid (100-1.0 µg/ppm) and herbicide Quizalofop ethyl 5 % EC were used to augment the activity of Trichoderma. T. aureoviridae strain S12 was found to be the best among the eight isolates screened for tolerance against the two fungicides and herbicide at a concentration of 10000 - 500 µg respectively as well as against M. phaseolina (Inhibition=72.33 %) in-vitro. This strain showed best compatibility with other strains and highest tolerance to fungicide i.e., Carbendazim 50 % (up to 500 ?g). Highest number (13.7×106) of active spores was recorded at a concentration of 25 ppm of IAA under in-vitro condition. S12 recorded a biocontrol efficiency of 61.8 % against stem rot of jute along with significant plant growth promotion and fibre production. Plant biomass also increased up to 7.5-12.1 % and fibre production 37.0-39.9 % with fungal and bacterial consortium + carbendazim seed dressing and soil drenching. These biocontrol fungi and PGPR consortium with high tolerance to fungicide, weedicide and plant growth regulator up to certain extent may be potentially exploited in IDM which may be a low cost technology in jute and allied fibre crops.