Biomanagement of Root Rot of Pine Seedlings

Abstract

Studies were conducted on biomanagement of root rot of pine (Pinus wallichiana) seedlings during 2008-2009 at Shalimar campus, Srinagar, Kashmir. The pathogens associated with the disease were isolated, morphologically characterized and identified as Fusarium oxysporum f. sp. pini (Schlecht.) Synd. and Hans. and Rhizoctonia solani Kuhn, and F. oxysporum proved more pathogenic. In bioassays all the biocontrol agents tested inhibited the mycelial growth of F. oxysporum and R. solani in dual culture, however, Trichoderma harzianum and T. viride were more effective. Pseudomonas fluorescens showed strong antibiosis and developed zone of inhibition against both the pathogens in vitro. Laccaria laccata caused hyphal lysis of the pathogens in dual culture. In vitro evaluation of the culture filtrate of test antagonists revealed that culture filtrate of P. fluorescens had maximum inhibitory effect on mycelial growth and spore/sclerotial germination of test pathogens followed by T. harzianum, T. viride and L. laccata. Inoculation of T. harzianum, P. fluorescens and L. laccata individually or in combination significantly improved the growth and biomass of Kail pine seedlings in vivo. Combined inoculations of biocontrol agents showed synergistic growth promoting action. Seed germination was improved by the biocontrol agents with drastic reduction by pathogenic microorganisms. Biocontrol agents inoculated individually or in combination reduced the pathogenic effect (root rot) as compared to the control.