Rain detachment and catch

Splash-borne spores are detached from the sporulating lesions by rain-splashes and carried by splashing droplets as far as they are caught on the host surface or moved away from the crop canopy.

The rain dispersal of the spores (Drain, 0-1) is simulated on a daily basis according to Waggoner and Horsfall (1969):

where Rain is the daily rainfall (mm), LAI is the leaf area index (m2 m-2) and Rain50 is the daily rainfall (mm) able to cause the detachment of the 50% of the spores produced by the sporulating lesions.

The function is plotted in the figure below, with different values of Rain50 to show the flexibility of the function to compute the efficiency of rain spore dispersal according to specific pathosystems.

Spores detachment as a function of daily rainfall. The functions obtained

with three Rain50 values are plotted (LAI = 2)

The decrease in the caught of the spores as a function of rainfall (CRain, %) is simulated according to Waggoner and Horsfall (1969):

where CRainmax is the maximum proportion of spores that can be caught by 1mm of precipitation(%).

Decrease of percentage of spores caught as a function of daily rainfall. The functions obtained

using three CRainmax values (Cmax) are plotted

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