Epidemiologie, Bedeutung und integrierte Bekämpfungsmöglichkeiten von Leptosphaeria maculans (Phoma lingam) sowie weiterer pilzlicher Krankheitserreger im schleswig-holsteinischen Winterrapsanbau (Brassica napus L. var. napus)
The aim of this investigation was to record the appearance and epidemiology of Leptosphaeria maculans (Phoma lingam) and other winter oilseed rape pathogens over the years 2000-2003 under the production and weather conditions of Schleswig-Holstein. The studies included the recording of weather data, the determination of L. maculans ascospore flight by using a Burkhard spore trap and epidemiological studies in untreated plots and in plots with different fungicide treatments. Under the aspect of integrated pest management additional fungicide applications which were more orientated on the epidemiology of P. lingam were also tested in these trials regarding their potential for optimal pest and yield control. Two stem-rot (Sclerotinia sclerotiorum (Lib.) de Bary) forecast systems were examined and a winter oilseed rape cultivar was tested regarding genetic effects on pathogen progressions. The results emphasised close relationship between precipitation and ascospore release from L. maculans, ascospore flight and leaf infection by P. lingam and also between the autumn infection of the leaves and root collar infection. Leaf infection by P. lingam was reduced after a fungicide application in autumn as well as in spring. An effective control of P. lingam on the root collar resulted only through autumn treatment. The highest yield effects resulted of the application at flowering and spring while an increased yield after autumn treatment could only be measured in the presence of high Phoma lingam infection incidences and severities. A higher incidence of Sclerotinia stem rot could only be detected in the trial year 2001. The appearance of Verticillium dahliae was observed at every trial site and every year, while pathogen incidence increased with increasing proportions of oilseed rape in the rotation.
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