Quantitative studies on dispersal of Pseudocercosporella herpotrichoides spores from infected wheat straw by simulated rain

Splash dispersal ofPseudocercosporella herpotrichoides spores from infected wheat straw was investigated using simulated rainfall (rate 13.8l h−1 m−2, volume mean diameter 2.9 mm) and wind (2 m sec−1) in a raintower/wind tunnel complex. Spores were deposited on the floor of the wind tunnel up to 1 m upwind and 2.5 m downwind from the centre of the straw and impacted on vertical surfaces at heights up to 36 cm above it. Fewer spores were collected with increasing distance from the straw and with increasing height. Most spore-carrying splash droplets were in the size range 400–600 μm and very few were less than 200 μm. Our results show that these spores are generally dispersed over short distance, which is consistent with field observations.