Ascochyta blight of chickpea in Australia: identification, pathogenicity and mating type

The aetiology of blight of chickpea in South Australia was studied following sporadic disease outbreaks over several years that had been tentatively identified as Phoma blight. Nine fungal isolates from diseased chickpeas were tested for pathogenicity in the glasshouse, of which two caused symptoms resembling those of Ascochyta blight. The two aggressive isolates were identified as Ascochyta rabiei based on morphological characteristics of cultures and RAPD analysis. This was further confirmed by successful mating to international standard isolates, which showed that the two Australian isolates were MAT1-1. These isolates are accessioned as DAR 71767 and DAR 71768, New South Wales Agriculture, Australia. This is the first time that A. rabiei has been positively identified in commercial chickpeas in the southern bemisphere. The pathogen was found (in 1992) in only one of 59 seed samples harvested throughout Australia between 1992 and 1996 and tested using International Seed Testing Association methods. The teleomorph has not been found in Australia and results to date suggest that only one mating type is present. This suggests that quarantine restrictions on imported chickpea seed should be retained to prevent the introduction of the opposite mating type.