Failure of a Mycelial Formulation of the Nematophagous FungusHirsutella rhossiliensisto Suppress the NematodeHeterodera schachtii

Abstract

Abstract Research was conducted to determine whether pelletized hyphae of Hirsutella rhossiliensis suppressed invasion of roots by the sugarbeet cyst nematode Heterodera schachtii in field microplots. The loamy sand in the microplots was infested with H. schachtii but not with H. rhossiliensis. Alginate pellets, with or without hyphae of H. rhossiliensis, were mixed into soil removed from the microplots (1 pellet/cm 3 of soil). The soil was placed in cylinders positioned vertically in microplots; cylinders (6/microplot) were 10.1 cm wide and 15.3 cm deep and contained 1200 cm 3 of soil. Pellets and soil also were placed in soil observation chambers, which were buried in the cylinders or kept at 20°C in moisture chambers in the laboratory. After 12 days, cabbage seeds were planted in each cylinder, and after 10 days of growth, the seedlings were removed from the soil and H. schachtii in the roots were counted. The number of H. schachtii in roots was large and was unaffected by addition of H. rhossiliensis. In soil observation chambers, H. rhossiliensis grew vigorously from the pellets in heat-treated soil but not in nonheated soil, and enchytraeids and collembolans were observed near damaged pellets. We suspect that organisms, possibly including enchytraeids and collembolans, fed upon or otherwise inhibited H. rhossil- iensis.