Impact of chemical, biological and cultural treatments on the growth and yield of apple in replant-disease soil

An orchard experiment was established to determine the long-term (six year) effects of chemical (sodium methyldithiocarbonate-metam sodium), fertilise r (monoammonium phosphate) and biological agents [strain B8 of Enterobacter agglomerans, strain EBW-4 of Bacillus subtilis and Glomus intraradices (GI )] alone and in selected combinations on tree growth, fruit production and root rot incidence of apple trees in apple-replant-disease soil that was co nducive to replant disease over six years. The response was measured by inc reases in trunk cross-sectional area, fruit yield and percent root rot of G ala apple trees on M.9 rootstock. The application of E. agglomerans (B8), B . subtilis (EBW-4), G. intraradices (GI), metam sodium (MS), MS + B8, MS CI and B8 + EBW-4 significantly increased fruit yield, tree trunk growth an d reduced infection by Phytophthora cactorum and Pythium ultimum. These res ults suggest the potential use of E. aerogenes (B8), B, subtilis (EBW-4) an d G. intraradices to increase growth and fruit production of apple trees pl anted in soil conducive to replant disease.