Suppression of soil borne fungal pathogens associated with apple replant disease by cyclic application of native strains of Pseudomonas aeruginosa

Abstract

Plant growth promoting fluorescent Pseudomonas aeruginosa strains An-E and An- F were used for the suppression of replant disease organisms which were isolated from replant site of apple in Shimla district of Hima-chal Pradesh. Full and half concentration of individual and consortial strains were used for the experiment. Among all the treatments, full concentration of compatible consortial strains were quite effective in decreasing the deleterious rhizobacterial (197-99 cfu/g) and fungal population (7-0 cfu/g). Total rhizobacterial count starts decreasing after each cyclic application of fluorescent P. aeruginosa strains An-E and An-F due to root colonization property of these plant growth promoting strains in the replant site of apple. Establishment of Pseudomonas aeruginosa strains at replant site was inversely correlated with decreasing deleterious bacterial and fungal population in the replant site. 70 per cent survival of apple rootstocks was recorded in full concentration of consortial treatment (An-E and An- F) as compared to control after three years of plantation. Four major fungal pathogens viz. Dematophor anecatrix, Phytophthora cactorum, Pythium ultimum and Fusarium oxysporum were isolated and identified from National centre for fungal taxonomy, New Delhi. These strains can be further exploited and recommended for the management of replant problem of apple