The Relation Between Rate of Reproduction and Average Number of Eggs Per Cyst in Globodera Rostochiensis and G. Pallida

Abstract

Pooled rates of reproduction of Globodera rostochiensis (five pathotypes) and of G. pallida (three pathotypes) from several pot experiments in four years on potato cv. Irene at initial population densities of 1 egg and 5 eggs/g soil were, per nematode species, proportional to average number of eggs per cyst and per pot and, per initial egg density, not correlated with number of cysts produced per egg in the inoculum. This also applied to rates of reproduction of pathotype Ro 1 on cvs Bintje and Mentor in four field experiments at initially 1 egg/g soil. The average number of cysts produced per egg in an inoculum of 5 eggs/g soil by G. rostochiensis in pots was 1.7 times that produced by G. pallida. At initially I egg/g soil the ratio was 1.5. Numbers of cysts of G. rostochiensis pathotype Ro 1 produced per egg in an inoculum of 5 eggs/g soil were proportional to dry haulm weight per pot. At initially 1 egg/g soil pathotype Ro 1 produced more cysts per egg in the inoculum than pathotype Ro 3 but not at initially 5 eggs/g soil. This indicates that the maximum cyst density per g dry haulms of the latter pathotype on cv. Irene was larger than that of the first. No differences between G. pallida pathotypes were apparent.