Dispersal of Pseudocercosporella herpotrichoides and Pyrenopeziza brassicae spores in splash droplets

Abstract

Splash dispersal of conidia which differ in shape and size, those of Pseudocercosporella herpo ichoides (needle‐shaped, 52×2 μm) and Pyrenopeziza hrassicae (cylindrical, 12×3 μm), was studisd by allowing 5 mm drops to fall 13 m on to suspensions (depth 0.5 mm, concentration 120, 000 spores/ml) of each. The resulting splash droplets were collected on photographic film. The pattern of spore dispersal with distance and the distribution of spore‐carrying droplets and spores within droplet‐size categories were similar for both fungi. Regressions of square root spore number) on droplet diameter gave lines with slopes of 0.0138 for P. herpotrichoides and 0.0167 for P. brassicae.