Plant tolerance for managing plant parasitic nematodes

The crops potential to tolerante damage caused by plant parasitic nematodes and still produce high yields is an important economic feature and can be used as cultural practice within integrated pest management. This is especially the case when no nematode control mechanisms are available. However, its use is still restricted to few cropping systems due to our limited understanding regarding occurrence and functioning of tolerance. In field experiments a broad spectrum of sugar beet cultivars and hybrids was tested for its tolerance towards the beet cyst nematode Heterodera schachtti. Three cultivars/hybrids were then selected for further field and greenhouse studies on the mechanisms of tolerance: 'Penta' (intolerant-susceptible) Strul915 (tolerant-susceptible) and 'Nematop' (tolerant-resistant). In field experiments the degree of tolerance varied between years and was most pronounced under dry summer conditions, mainly due to the fact that tolerant plants suffered less from water stress, In greenhouse experiments, tolerant plants showed higher compensatory growth and rooting depth. Especially root length and shoot fresh weight were positively correlated with tolerance and therefore should be considered as early indicators for tolerance.