Some new equipment for routine assessment of levels of soil infestation by the potato‐root eelworm, Heterodera rostochiensis Woll

SUMMARY In the examination of a soil sample for the cysts of potato‐root eelworm subjective errors are liable to occur at three particular stages of the technique, especially when large numbers of samples are being examined as a routine. Three pieces of equipment have been developed to mechanise these stages as far as practicable: (1) A centrifugal divider was adapted to obtain mechanically a uniform aliquot subsample from the full soil sample taken from the field; (2) A turntable was developed so that if cyst numbers are large the total may be estimated without picking off all the cysts present; (3) A magnetic stirrer was used to ensure that a reliable aliquot subsample is taken from the suspension of eggs for counting in the Fenwick slide. The inherent errors associated with each of these stages of the technique are examined.