Untersuchungen von Leindotter (Camelina sativa (L.) Crtz.) auf Krankheiten unter besonderer Berücksichtigung von Falschem Mehltau (Peronospora parasitica (Pers.) Fr.)

Abstract

Investigations on diseases of false flax (Camelina sativa (L.) Crtz.) with special regard to downy mildew (Peronospora parasitica (Pers.) Fr.)

During the study presented here, one bacterial and seven fungal/fungal like diseases on false flax were diagnosed. These were the bacterial blight (Pseudomonas syringae pv. spec.), downy mildew (P. parasitica), grey mould (Botryotinia fuckeliana), stem rot (Sclerotinia sclerotiorum), white rust (Albugo candida), white leaf spot (Pseudocercosporella capsellae), stem and root rot (Rhizoctonia solani) and powdery mildew (Erysiphe spec.). Of these diseases, downy mildew and grey mould, followed by stem rot were the most important.

Currently available varieties showed distinct differences with regard to their susceptibility to downy mildew. Two Danish varieties showed a distinct resistance to downy mildew. The registered German varieties (Lindo, Bavaria, Soledo, Licalla, Limaga and Ligena) showed high infestation levels with downy mildew. For the differentiation of the susceptibility of the varieties against downy mildew, the inoculation at the seed-leaf stage proved to be the most efficient method, as described for various Brassica species. During this examination, virulence differences between the downy mildew isolates of false flax were established.

For our studies on downy mildew (P. parasitica), we had to establish a method to store the pathogen. Three different methods were tested. The most efficient method was to store downy mildew on infested leaves at -25 °C. With this method we were able to maintain the germination capacity and the infectivity of the conidia for a period of 10 months.

Concerning the epidemiology of downy mildew of false flax, the seed-born nature was proven. Cross-infection of different brassicaceae by downy mildew from false flax was not possible. Conversely, false flax could not be infected with downy mildew isolates from the different brassicaceae. Furthermore, it was not possible to infect false flax with downy mildew-isolates of other weeds.

The usage of BION^® provoked a systemic acquired resistance (SAR) in false flax. Seven false flax-cultivars were treated with 10 respectively 20 ppm of a watery solution of BION^®. Later inoculations of these plants with downy mildew showed that infection was very strongly reduced or even prevented.