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Causal organism - Various Ascochyta
spp .
Primarily: A. tritici (Didymella exitialis)
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The disease is known to infect wheat, barley, oats, rye and many grass species.
Symptoms are usually found on lower leaves initially but later in the season
symptoms can be found on upper leaves. Lesions
are usually elliptical and although chlorotic
at first, soon become buff to brown in colour, often splitting longitudinally. Initially lesions have a dark brown margin with papery white centre.
Symptoms become less distinct with time and become very similar to those caused
by S. nodorum. 
Pycnidia within the lesions
are generally black, distinguishing the disease from S. nodorum which
tends to have light coloured pycnidia.
