Diaporthe perniciosa a species of fungus in the family Diaporthaceae.

The names Phoma prunorum Cooke, Phomopsis prunorum (Cooke) Grove, and Phomopsis mali Roberts have been used for its asexual (anamorph) form.

[1] It causes bark cankers on trees in the genera Malus (apples), Pyrus (pears) and Prunus (plums, cherries, peaches and other similar fruits).

One study in the late 1980s was able to isolate the fungus from several trees with die-back symptoms but inoculation of healthy trees with the fungus did not result in disease.

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