Untersuchungen zur Schadwirkung von Ramularia beticola in Zuckerrüben und Möglichkeiten zur Differenzierung der Sortenanfälligkeit nach künstlicher Inokulation

In 1998 and 1999 field trials were designed to measure the effects of Ramularia beticola (R. b.) to sugar beet in general and especially for different fungus isolates. Furthermore different sugar beet genotypes were tested for tolerance to Ramularia beticola with an inoculation method. It could be shown that a R. b. infection can reduce white sugar yield up to 24 %. Additionally to the reduction of root yield sugar content was significantly reduced. However, sodium and α-amino-N contents were higher after inoculation with Ramularia beticola. In 1998 and 1999 the climatic conditions were more favourable to Cercospora beticola. Consequently the development of Cercospora leaf spots were much quicker compared to Ramularia. Due to the higher severity of C. b. the damage was higher. Inoculation with various isolates of R. b. caused different extents of reduction in white sugar yield. The maximum difference between two isolates was larger than 10 %. With the inoculation method used different reactions of the sugar beet genotypes could be observed. There were Ramularia tolerant and very susceptible genotypes. However, interactions between Ramularia and Cercospora tolerance could not be observed.