Growth of Arthrobotrys superba from a birch wood resource base into soil determined by radioactive tracing

The ability of a nematode‐trapping fungus to establish in field soil is an important characteristic when considering its use as a biological control agent. The outgrowth of the nematode‐trapping fungus Arthrobotrys superba from wood was recorded by labelling the fungus with [ 14 C]3‐ O ‐methylglucose and [ 32 P]orthophosphoric acid and by using the soil sprinkling method. The fungus reached a distance of 7–8 cm during 25 days in heat‐treated (60°C) soil, detected by either radioactive tracing or the soil sprinkling technique. The two labelled compounds were co‐distributed at all sampling times ( r 2 =0.946) which indicates that the glucose pool (as methylglucose) and phosphorus content were correlated throughout the mycelium. In natural, non‐heat‐treated soil the fungus reached a distance of 1.5 cm from one disc of birch wood after 30 days, while it reached 3.2 cm during the same period when the food base was a pile of five inoculated discs. The experiments showed, for the first time, that a nematophagous fungus, A. superba , can grow out into soil from a piece of wood and supported by nutrients translocated from the resource base to the edge of the mycelium.