Aeromycology of Cercospora arachidicola on peanut

A diurnal periodicity of conidium release by Cercospora arachidicola was observed with peak catches at 12.00 h. Temperature of 20–24 °C with periods of r.h. > 90% favoured production and release. Few conidia were trapped following periods of high r.h. when temperatures were lower than 17°. Fewer conidia were trapped following rain than under similar temperature and r.h. conditions without rain. Quantitative estimates of lesion numbers per field area permitted analysis of release under different environmental conditions, independent of lesion density. Multiple regression analysis was used to relate conidium release to temperature, r.h. and rainfall. A sporulation prediction model based on a 3-day running average of duration of humidity above 90%, of mean temperature during the high r.h. duration, and rainfall was derived.