When farmers consider how a variety may be affected or which varieties to use to manage nematodes, they need first to understand the terms resistance and tolerance as applied to disease and pests.
Resistance and tolerance are two different mechanisms.
Resistance or susceptibility of a variety will affect future crops through either the suppression or buildup of nematode numbers in the paddock.
Tolerance or intolerance affects the current crop and refers to the ability of a variety to yield despite nematode attack. However, where a variety is intolerant, the level of resistance will also have an impact on yield in the current crop, particularly with species such as Pratylenchus which go through more than one generation a year.
Where available, resistant varieties hold the promise of long-term advantage.