This is a guess, but perhaps the result of an infection by a fungal plant pathogen related to [*Taphrina deformans*](https://en.wikipedia.org/wiki/Taphrina_deformans). *T deformans* infects species of the genus *Prunus* (i.e. the genus of prunes and apricots), but is is best known for causing peach leaf curl in another *Prunus* species, peaches. For example, see this image of *T. deformans* infecting a leaf in Catalonia, Spain: [![enter image description here][1]][1] <sup> Source: [flickriver](https://www.flickriver.com/photos/11299883@N08/5676229830/); Credit: [esat_ahi](https://www.flickr.com/photos/11299883@N08/) </sup> From [Wikipedia](https://en.wikipedia.org/wiki/Taphrina_deformans): > trees infected with *T. deformans* will experience leaf puckering and distortion, acquiring a characteristic downward and inward curl. Leaves will also undergo chlorosis, turning a pale green or yellow, and later show a red or purple tint Are yo usure your infected plant part is a fruit and not a grossly infected leaf? (Did you cut open the infected fruit to examine it closer)? [1]: https://i.sstatic.net/Rnxyw.png