INVESTIGATIONS ON HETERODERA SCHACHTII, SCHMIDT. IN LANCASHIRE AND CHESHIRE: PART III. CERTAIN CORRELATIONS BETWEEN CROP YIELDS AND DEGREE OF INFESTATION

Data concerning infestation of H. schachtii, certain soil properties and crop yield, from a series of plots at four centres affected with disease, have been collected and examined. Limitations imposed on the design of the plots have prevented a complete analysis of the variates, but the results obtained lead to the conclusion that eelworm infestation is not of primary importance in determining the yield of potatoes and that the cysts tend to increase in number only on a crop which is not a failure but which has been adversely influenced by some other factor. The authors would like to express their thanks to Messrs I. S. Macdonald, J. Orr, B. Holmes Smith and I. Thomas of the Advisory Department at Manchester for their willing co‐operation and assistance, and to Mr L. H. C. Tippett for his helpful criticism of the statistical treatment of the results.