Two methods for the prediction of Mycocentrospora acerina infection on stored carrots

Carrot plants were collected from 26 fields located in different districts in Norway during 1985, 1986 and 1987. Leaves were sampled in the first two years, and roots were sampled in all years. Incidence of Mycocentrospora acerina on the leaves at harvest was correlated (r = 0.82) to the incidence of M. acerina on the roots after storage at 0–1°C for six months (long term storage). Incidence of M. acerina on roots sampled about six weeks before harvest (date c) and placed at 10°C for six weeks (test storage) was correlated (r = 0.84) to incidence of the pathogen after long term storage on roots sampled at harvest (date d). Test storage and long term storage data from parallel samples taken at date d was more strongly correlated (r = 0.90).