The Relationship in Field Experiments Between Population Density of Globodera Rostochiensis Before Planting Potatoes and Yield of Potato Tubers

Curves according to the equation y = m + (1-m) 0.95(P/T)-1 (= m + (1-m) zP-T with z-T = 0.95) for P T and y = 1 for P T could be fitted to the relation between relative yield of potato tubers y and population density of Globodera rostochiensis P in five field experiments in the Netherlands, four experiments in England and one (with Solanum tuberosum subsp. andigena) in Ecuador. Estimations of T varied between 1.8 and 2.7 eggs/g soil and of m between 0.25 and 0.6.