Investigation on Heterodera Schachtii in Lancashire and Cheshire Part I. The Infestation in Certain Areas as Revealed by Cyst Counts; An Estimation of the Errors Involved in the Technique and a Correlation With Intensity of Disease

SUMMARY. Heterodera schacJitii has been identified in many parts of Lancashire and Cheshíre where severe losses have resulted from failure of the potato crop. A detailed study of the errors involved in the technique of a method for estimating the infestation has been made. The degree of infestation, as determined by cyst counts, has been compared with records of crop failure. The conclusions that have been drawn are to the effect that: (a) where “eelworm disease” has been noted recently there is a positive association of intensity of disease and cyst content of the soil; b) where the disease was observed three or four years ago, disease and crop failure are always associated with a high cyst content of the soil, but there may be a moderately high infestation without apparent diminution of crop yield.