Introduction

Susceptibility to Globodera rostochiensis Ro1 and Globodera pallida Pa1 and 2/3 is assessed by planting seed tubers in artificially infested compost. Standard populations of the pathotypes of G. rostochiensis and G. pallida are maintained at 2 centres on plants of cvs. Desiree and Maris Piper respectively. The virulence of all populations is checked regularly on selected clones. Eggs are extracted and the inoculum mixed and standardised to give a soil infestation of 10-15 eggs g-1 compost.

Plot Size and Trial Design

For each pathotype, the pots are laid out in a randomised block design with 3 or 5 replicates.

Cultivations

Seed tubers or seed pieces are planted in pots of c. 1 litre capacity which are plunged in peat beds. Water is applied regularly to the pots to maintain adequate growth. Plants are allowed to senesce naturally before lifting and storing the pots in a dry environment.

Disease Assessment

The number of brown cysts is counted in the float which is extracted from each individual pot.