Forecasting oilseed rape diseases from airborne inoculum

Most fungal diseases of oilseed rape are initiated by airborne spores. The seasonal timing of spore release of each species changes in response to weather with maturation and release of spores typically driven by moisture (rain, dew and relative humidity) and temperature. The dispersal of airborne spores from a source and deposition onto crops at different distances from the source under different atmospheric conditions has been described by numerous mathematical functions. Spore deposition results in individual disease foci when occurrence of viable inoculum and infection conditions are rare; as a gradient in a crop when a large number of spores are produced from a nearby source; or as a uniform infection when there is a large but distant source or multiple local sources of inoculum