Records of airborne Mycocentrospora acerina conidia in and near carrot plots

The occurrence of Mycocentrospora acerina conidia in the air, in or close t o carrot plots, was examined by the use of volumetric spore traps at three locations, in connection with crop-rotation experiments in Norway. The tray s were operated during the late summers of 1985-1987 and in 1995. At two lo cations, M. acerina conidia were recorded on a limited number of days. Only a few conidia were trapped outside the plot. At one of the locations, no c onidia were observed. The highest conidial record, 47 conida per m(3) air, was observed inside the carrot plot, during 1 h in September 1985 at one lo cation. Only one or two conida were trapped on most of the other days. The conidial records in relation to climatic parameters are discussed. Aerial s pread of M. acerina conidia appears to be insignificant in the climatic con ditions of Norway.