Distinguishing between Viable and Nonviable Heterodera glycines Eggs.

Greenhouse tests were conducted to determine the persistence of nonviable Heterodera glycines eggs in soil. Laboratory and greenhouse tests were conducted to determine the usefulness of the vital stains acridine orange and tetrazolium red for differentiating viable and nonviable eggs of H. glycines. Nonviable (boiled) egg preparations were compared with preparations that were not boiled for their persistence in methyl bromide-fumigated soil. Boiled eggs persisted longer (>200 days) than untreated eggs, perhaps due to disinfestation of the egg suspensions by boiling. Neither stain was a good indicator of egg viability as inferred from infectivity of juveniles in a bioassay of the same egg preparations exposed to the stains.