NATURAL DEPOSITION 



Measurement of deposits on leaves in the field are few, but Rishbeth 

 (1959) has used surface microflora of conifer needles and leaves of birch, 

 etc., as a measure of infection-potential of forest contamination with 

 spores of Fomes annosus and Peniophora gigantea. Studies on the rate at 

 which spores accumulate and disappear in East Anglia, showed that there 

 was no continued increase, and that the rate of deposition was roughly 

 equivalent to the rate of disappearance. 



Rain-washing of air, when it occurs, rapidly ends the process of spore 

 dispersal, and seems to be effective with small spores which are deposited 

 only slowly and ineffectively by other processes. 



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