and allowing the potatoes to develop in the dark. Ten
replicates for each cultivar and nematode species were
used. Three weeks after planting, when the tubers of the
different cultivars had developed roots, each container
was inoculated with 200 J2 of M. minor, M. fallax or
M. chitwoodi. Ten weeks after inoculation, the roots were
screened for egg masses. The root systems were washed
carefully with tap water and then soaked into a Phloxine
B solution (0.15-0.20 g per 1 l water; Sigma-Aldrich).
Phloxine B stains the gelatinous matrix of egg masses and
facilitates counting (Daykin & Hussey, 1985). The roots
were left for 15-20 min in the solution and the stained
egg masses were counted with the aid of a binocular
microscope