(1926) Taphrina padi is a fungal plant pathogen that induces the form of pocket plum gall that occurs on bird cherry (Prunus padus).

The gall is a chemically induced distortion of the fruits, which are swollen, hollow, curved and greatly elongated,[1] without a seed or stone, but retaining the style.

The surface of the gall eventually becomes corrugate and coated with the fungus, showing as a white bloom of ascospore producing hyphae.

[1] The fungus may also cause dense clusters of live and dead twig, called "witches' brooms".

[6] The fungus infects the ovaries causing a pseudo-pollination and an enhanced cell division, resulting in the infested fruit being larger than the healthy one.