DIFFUSION AND EFFECTIVENESS OF THE NEMATOPHAGOUS FUNGUS HIRSUTELLA RHOSSILIENSIS IN CONTROL OF THE CYST NEMATODE HETERODERA DAVERTI UNDER FIELD CONDITIONS

An epidemiological survey on 176 soil samples, collected from carnation fields in the Vesuvius area (Naples, Italy) revealed, in more than 90% of samples, the occurrence of second stage juveniles of the cyst nematode Heterodera daverti parasitized by the nematophagous fungus Hirsutella rhossiliensis. The diffusion of the fungus over the area of cultivation of carnation could account for the substantial decrease in severity of nematode attacks, which were observed over the last five years. The influence of various factors on H. rhossiliensis-mediated suppressiveness in soils subjected to repeated treatments with fumigants is discussed.