Phyllachora graminis is a fungal plant pathogen that affects many grass species, including some of our most common grasses.  The upperside or underside of the leaves develop numerous elongated black blisters. Inside the grass tissue are cavities with either conidia or asci. 

microscopy

Please provide photographs and state the host grass species. Specimen should be microscopically examined, and we recommend that it is verified by an expert before submission to NatureSpot.

Late summer and autumn.

See 'Plant Parasites of Europe' website