During investigations on the Eelworm of Potatoes in south Lincolnshire during the summer of 1925 it was found that fields shewing great variation in the extent of damage done to the crop did not have a corresponding variation in the number of eelworm cysts present. It was often observed that patches where plants were doing well shewed as many cysts in the soil and on the roots as those areas where damage was most pronounced. This seemed to suggest that eelworms might not be the primary cause of the failure but a contributory factor.

Owing to the fact that other pests, chiefly fungoid, were invariably present in addition to eelworm it seemed that one might either attribute the failure of the crop to various pests, or to some factor or factors connected with soil fertility which inhibited the proper growth of the plants and reduced their resistance to disease. In order to obtain data which might throw some light on this latter suggestion, a number of fields reported to have failing potato crops were visited and as far as possible the history of the cropping, manuring and general cultivation was obtained. Soil samples from different parts of the fields were brought back to the Laboratory at the Kirton Agricultural Institute for the estimation of the cyst content.