Influence of cover crops and weeds on the epidemiology and pathogenicity of <i>Plasmodiophora brassicae</i>

Abstract

Club-root disease has increased significantly in oilseed rape cultivations in recent years in Germany. The pathogen of the disease, Plasmodiophora brassicae, penetrates the root hairs and root bark of the plant. In the course of the disease, the tissue proliferates and the typical root gall forms.

The soil-borne fungus forms permanent resting spores that can survive for up to 20 years. Short crop rotations with cruciferous plants provide good conditions for propagation of the pathogen. A direct control of the disease is not possible; therefore club-root prevention strategies are essential for minimizing disease losses.

This includes the selection of crops that are not susceptible to club-root and the timely control of various weeds that could be host plants. In a greenhouse experiment at the Julius Kühn-Institut in Braunschweig, weeds and cover crops from different plant families were evaluated with regard to their susceptibility to the club-root. The seedling plants were pricked into raised beds and inoculated with a spore suspension of P. brassicae - type P1. Thirty five days after inoculation, a visual disease assessment of the roots was made with regard to the typical disease symptoms.