Stegophora ulmea infects all Ulmus species and Japanese zelkova.

Other elms it is known to infect include:[1] Stegophora ulmea is characterized by chlorotic yellow spots 1 millimeter in diameter with a black center that develop early in the spring.

[1][2] In the spring, new leaves are infected with ascospores which develop from the survival structure, perithecia, found in leaf debris.

[1] A period of wetness and dryness with a temperature over 7 degrees Celsius is required before ascospores are released.

[1] The ascospores disperse through the air and have the potential to travel over long distances.

[1] During spring and early summer, the macroconidia act as a secondary inoculum.

[1] They act as spermatia in the sexual stage of the S. ulmea’s life cycle.

[1] During late summer and fall perithecia, the sexual structure, begins to develop.

[1] In commercial growing arenas, it is suggested that overhead watering should not be used, because it helps spread the pathogen.