Epidemiology and control of leaf and awn spot of barley caused by Ramularia collocygni

Abstract

Leaf and awn spot of barley caused by the fungus Ramularia collocygni (Ovularia hordei) has been prevalent in crops in Canterbury New Zealand over the last few seasons causing rapid leaf senescence late in the season Control can readily be achieved with a single triazole and strobilurin fungicide application but timing of application at late booting is important A rate response to a triazole fungicide was noted but there was no response to the rates of the strobilurin fungicides tested Good control is achieved at both high and low application rates with strobilurins The correlation between disease severity and grain yield shows a nonlinear relationship with low levels of disease having a major influence on grain yield Seed infection has also been noted but the significance has not been evaluated