Rabbit Anti-Pssy polyclonal antibody for ELISA. The bacteria Pseudomonas syringae pv. syringae is a member of a large genus of plant-pathogenic bacteria. The bacteria exist as surface dwellers (epiphytes) on leaves and, during wet weather in spring or early summer, can enter through the leaf pores (stomata), causing infections to develop in the young leaves. As the leaf matures these infections cease to expand and are revealed as small patches of dead tissue. As the leaf expands fully, the live tissues pull away from the dead patch, which drops out, leaving a 'shothole'.