1Department of Plant Pathology, Rajasthan College of Agriculture, Udaipur-313 001, Rajasthan, India
2Department of Botany, University of Rajasthan, Jaipur-302 004, Rajasthan, India
Research Centre, Godrej Agrovet Limited, Pirojshanagar, Eastern Express Highway, Vikhroli (East), Mumbai-400 079, Maharastra, India
Online published on 30 November, 2019.
Local isolates of 18 fungal and 19 bacterial biocontrol agents and five neem based formulations were evaluated at first in vitro, and then in green house to find the most effective ones for suppression guar root rot complex caused by Fusarium solani and Rhizoctonia solani. Maximum inhibition of F. solani and complete inhibition of R. solani was recorded in T. viride (S) and T. harzianum Gn1. The 17 Bacillus subtilis isolates and two Streptomyces isolates were highly effective against F. solani and R. solani in dual culture studies. Kernel extract and oil based neem formulations (0.2%) caused maximum growth inhibition of both F. solani and R. solani. Among the fungicides, Carbendazim, Mancozeb and Captan were effective. The biocontrol agents, neem formulations and fungicides found promising in vitro were then evaluated as seed treatments in greenhouse experiment. The highest seed germination and dry biomass and lowest disease incidence was recorded in T. harzianum Gn1 followed by B. subtilis isolate Ch-Kp-b-1. Among the neem based formulations tested, neem oil as seed treatment + soil drench resulted in good seed germination, reduced disease incidence and higher dry biomass. Among the fungicides Captan was found most effective in suppressing root rot of guar followed by carbendazim. The BCAs could establish and multiply well in the guar rhizosphere and significantly lowered the density of the both pathogens. The population density of F. solani and R. solani was lowest in T. harzianum Gn1and B. subtilis isolate Ch-Kp-b-1.
Guar, root-rot, Fusarium solani, Rhizoctonia solani, integrated management
