Nematode-resistant varieties are specified to reduce the beet cyst nematodes (Heterodera schachtii). With an active hatching stimulus the catch crops attract the larvae inside cysts lying in the soil to move into the roots of mustard and oil radish. Within the nematode-resistant mustard and radish varieties the nematodes are not able to develop to females: the immigrated larvae die or become male.
Depending on the degree of control, the varieties are classified according to their resistance level. Level 1 means that more than 90 per cent of all beet cyst nematodes have been reduced in official testing, varieties which have reduced these nematodes by 70 to 90 per cent are awarded a level 2 in resistance against beet cyst nematodes.