### EFFECT OF GLOBODERA ROSTOCHIENSIS ON THE YIELD OF POTATO IN VENEZUELA

#### Abstract

The relationship between initial densities (Pi) of Globodera rostochiensis pathotype Ro2 and yield of the susceptible potato cultivar Andinita was investigated in 30 dm³ microplots at Cubiro, Lara State. Pi used were 0, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128 or 256 eggs/cm³ soil. Yield response to Pi fitted the model y=m+(lm)z[supPû[supT]; in which y is the relative yield, m is the minimum relative yield and Tis the tolerance limit. A tolerance limit of the potato cultivar Andinita to G. rostochiensis of 1.5 eggs/cm³ soil was derived with the model. Maximum yield suppression was 73% and occurred at Pi= 256 eggs/cm³ soil. Maximum nematode reproduction was 20-fold and occurred at Pi= 0.25 eggs/cm³ soil. Nematode equilibrium density was 40 eggs/cm³ soil.