CONTROL OF ROOT-KNOT NEMATODE WITH FORMULATIONS OF THE NEMATODE-TRAPPING FUNGUS ARTHROBOTRYS DACTYLOIDES

Arthrobotrys dactyloides grew readily in shaken flasks containing gluc ose corn steep powder and 8-10 g dry wt of fungal biomass/liter medium was usually produced in 5-6 days. However, it was difficult to conver t this biomass into a viable, granulated product suitable for commerci al use in biological control. Formulations prepared using kaolin and v ermiculite as carriers and gum arabic as a binder showed poor viabilit y when biomass was harvested from Liquid culture, mixed with formulati on ingredients, granulated, and then dried to a moisture content of le ss than 5%. Inclusion of a solid-phase incubation step following granu lation and prior to drying (incubation of moist granules for 3 days at 25 degrees C in a sterile plastic bag aerated with sterile air) marke dly improved biological activity. When granules produced in this manne r were placed on a glass slide in held soil, hyphae proliferated from granules and always produced traps. Seven experiments in soil microcos ms showed that formulations which had been subjected to solid phase in cubation prior to drying consistently reduced numbers of Meloidogyne j avanica juveniles by more than 90%. In seven glasshouse experiments in which field soils were treated with granules (10 g/liter) and planted to tomatoes, the number of galls induced by the nematode was reduced by 57-96%. (C) 1998 Academic Press.