Distribution and dissemination of Mycosphaerella graminicola (Fuckel) Schroeter in relation to the epidemiology of speckled leaf blotch of wheat

Abstract

The distribution of M. graminicola and the dissemination of ascospores in relation to the epidemiology of speckled leaf blotch of wheat in Victoria was studied. The fungus was present on wheat stubble throughout the Victorian wheat-belt and ascospores were discharged from stubble following periods of leaf wetness caused by rain or dew. Fertile perithecia were found on 1-year-old but not 2-year-old stubble. The viability of freshly ejected ascospores remained high throughout the growing season, and when shaded from direct sunlight ascospores remained viable for 1–2 weeks after release. The main period of ascospore discharge was late autumn to early spring, during which time the daily mean number of ascospores trapped 0.3 m above a commercial wheat stubble frequently exceeded 1000/m3 air.