SPLASH DISPERSAL OF PSEUDOCERCOSPORELLA-HERPOTRICHOIDES SPORES IN WHEAT MONOCROP AND WHEAT-CLOVER BICROP CANOPIES FROM SIMULATED RAIN

Simulated rain was allowed to fall onto spore suspensions of Pseudocer cosporella herpotrichoides. The resulting splash droplets were collect ed on horizontal traps at the bottom of a canopy and at 12 cm above tr eatments comprising no-crop, wheat monocrop and a wheat-clover bicrop. The number of conidia collected on horizontal traps declined exponent ially with distance from the inoculum source. The mean number of spore s collected in the absence of any crop was twice that in a monocrop; i n the monocrop it was twice that in the bicrop. Both splash droplet an d spore deposition gradients were steeper in the monocrop treatment th an in no-crop, and shallower in bicrop than in monocrop. Evidence is p resented that suggests the clover canopy acts as a secondary source fo r the redistribution of previously dispersed droplets and spores.