Decay on plums caused by Alternaria rot is generally firm. The surface of the fruit is covered by dark green / black spore masses. The fungal growth initially appears dark, grey-black, with a dark green colour settling as decay progresses. Early infections on green fruit appear as red, sunken areas, turning brown, with signs of fungal, as the fruit matures. Alternaria rot is regarded as a ‘slow-developer’ during storage. Alternaria alternata and other species are causal pathogens.
Alternaria in cracks / wounds during storage - plum example.