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

The aetiology of blight of chickpea in South Australia was studied followin g sporadic disease outbreaks over several years that had been tentatively i dentified as Phoma blight. Nine fungal isolates from diseased chickpeas wer e tested for pathogenicity in the glasshouse, of which two caused symptoms resembling those of Ascochyta blight. The two aggressive isolates were iden tified as Ascochyta rabiei based on morphological characteristics of cultur es and RAPD analysis. This was further confirmed by successful mating to in ternational standard isolates, which showed that the two Australian isolate s were MAT1-1. These isolates are accessioned as DAR 71767 and DAR 71768, N ew South Wales Agriculture, Australia. This is the first time that A. rabie i has been positively identified in commercial chickpeas in the southern he misphere. The pathogen was found (in 1992) in only one of 59 seed samples h arvested throughout Australia between 1992 and 1996 and tested using Intern ational Seed Testing Association methods. The teleomorph has not been found in Australia and results to date suggest that only one mating type is pres ent. This suggests that quarantine restrictions on imported chickpea seed s hould be retained to prevent the introduction of the opposite mating type.