Efficacy of the Nematophagous Fungus ARF18 in Alginate-clay Pellet Formulations Against Heterodera glycines.

Dry alginate-clay pellets containing mycelium of ARF18 were added to sandy soil in greenhouse tests to determine the formulation's efficacy in the suppression of Heterodera glycines. Pellet formulation variables included quantity of mycelium per pellet (0.0-3.9%), pellet size (2.3 or 8.3 mg), pellet application rate per unit soil (0.4 or 1.0% based on dry soil weight), and pellet storage (0 or 90 days). All of these variables affected efficacy. Nematode suppression was greatest (95%) with 8.3 mg pellets containing 3.9% mycelium that were not stored and applied at the rate of 1.0% of dry soil weight. Storage for 90 days reduced the efficacy of the pellets. The soybean cultivars tested were not equally good hosts of H. glycines, but reproduction of the nematode was reduced equally on all. The average suppression was 96% (range 86-99%). Similar suppression of reproduction occurred in tests with six races of H. glycines. ARF18 appeared to be nonspecific with regard to soybean cultivar and H. glycines race.