Mycosphaerella pyri

A parasite affecting living leaves of the common pear (Pyrus communis), causing brown leaf spots 3 to 5 mm across, paler in the center; in the center of these spots, several globose, ostiolate, black pycnidia appear, up to 150 µm in diameter.

This study corresponds to the anamorph (asexual or conidial stage) of the species.

Inside these pycnidia are the conidiogenous hyphae or cells; these are hyaline, subcylindrical to ampulliform (bottle-shaped), 6 to 12 µm long and 2.5 to 4 µm wide.

The upper part of the pycnidia opens to discharge the conidia; these conidia are cylindrical, strongly curved, with one or two septa, olive-brown under the microscope, 45 to 75 µm long, 3 to 5 µm wide, and without any apparent reaction in Melzer's reagent.