Records of airborne Mycocentrospora acerina conidia in and near carrot plots.

The occurrence of Mycocentrospora acerina conidia in the air, in or close to carrot plots, was examined by the use of volumetric spore traps at three locations, in connection with crop-rotation experiments in Norway. The traps were operated during the late summers of 1985-1987 and in 1995. At two locations, 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 conidia were observed. The highest conidial record, 47 conida per m3 air, was observed inside the carrot plot, during 1 h in September 1985 at one location. Only one or two conida were trapped on most of the other days. The conidial records in relation to climatic parameters are discussed. Aerial spread of M. acerina conidia appears to be insignificant in the climatic conditions of Norway.