Untersuchungen zur Lagerung und Aggressivität von Peronospora parasitica und Ergebnisse im Hinblick auf die Sortenanfälligkeit des Erregers an Winterraps

Abstract

Abstract Results on preservation and aggressiveness of Peronospora parasitica and results with regard to the disease reistance of the paAogen on winter oilseed rape Laboratory‐tests showed, that a long‐time preservation of Peronospora parasitica‐coiaia in a freezer at ‐ 21° C for a period of 1 year was possible using glycerine, poiyethylenglycol (PEG) 400 or PEG 1000 as cryoprotective agents. Glycerine in a concentration of 20% was ascertained as most suitable additive with germination‐rates of 21% after a storage of 1 year.Using a cotyledon‐test a simple and non‐time‐consuming method could be established to find out differences in winter oilseed rape varieties and differences in the aggressiveness of different P. parasitica isolates. Of 32 winter‐oilseed rape varieties Synra was the least susceptible variety to the pathogen; Diadem, Doublol and Accord were the most susceptible varieties. The research on aggressiveness of different isolates gave evidence, that only the British isolate P003. differed in aggressiveness from the other isolates.