Effect of root injury on lesion development of caraway roots infected by Mycocentrospora acerina

Abstract

The effect of injury on disease incidence, incubation period and lesion development rate on caraway roots by Mycocentrospora acerina was studied in three laboratory experiments. After inoculation with M. acerina, disease incidence of injured roots was significantly (P< 0.001) higher than of non-injured roots. The incubation period of M. acerina was significantly (P < 0.001) shorter on injured roots than on non-injured roots. The incubation period shortened with increasing root injury level. Younger injured roots tended to be more resistant to M. acerina infection than older injured roots, expressed by longer incubation periods. The lesion development rate was, on average, higher on heavily injured roots than on non- or slightly injured roots. The lesion development rate remained fairly constant after the first emergence of the symptoms on the caraway root, until the whole root was colonized. Caraway roots carefully dug up in autumn frequently showed injuries enabling M. acerina to penetrate the roots. However, the correlation between root injury and root rot after cold storage was weak. Injury of roots had a stimulating effect on infection and development of M. acerina, but roots without wounds could be infected too. Some relevant field observations are discussed.