Wind detachment and catch

Air-borne spores are carried by wind currents and are dispersed as far as they impact or deposit onto the host surfaces, or blow away from the crop canopy.

The wind dispersal of the spores is simulated on a daily basis according to Aylor (1982), as a function of daily wind speed. The approach is the same of the one adopted within the InoculumPressure component, and it is described in the 'Spore dispersal' topic.

The proportion of spores caught by wind speed (CWind, 0-1) is simulated basing on the evidence that shearing stress at the surface is often proportional to the square of wind velocity:

where GLAI is the green leaf area index (m2 m-2), LAI is the total leaf area index (m2 m-2) and Wind is the wind speed (m s-1). The function is plotted below, with different values of GLAI LAI ratio.

Spores caught as a function of daily wind speed. The functions obtained

using three GLAI LAI ratio values are plotted

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