Plant Pathology: Extension: Plant Disease Library

Entomosporium

Important diseases:   Leaf spots of numerous woody ornamentals and fruit trees.

Entomosporium is the conidial stage of the Ascomycete fungus Fabraea (or Diplocarpon). Sometimes Entomosporium leaf spot diseases are referred to as Fabraea leaf spots in some references.

Leaf spot symptoms may vary with host. Initially leaf spots are small purplish, circular spots. The spots are sunken and have a white to grayish center and a raised dark purple to black border as the spot ages. Within the center of each spot the fungus produces a raised black fruiting body (acervulus). Extensive defoliation will occur if the leaf spots are numerous. Some leaf spots, such as on Bradford pear, may be small, circular and have a black, oily appearance.

A darkly pigmented to black, disk-shaped acervulus is produced within the center of each spot. The acervulus opens through the leaf cuticle cells revealing spores (conidia) on short conidiophores.

Conidia are clear, 4-celled, with the lateral cells smaller than the two central cells. All cells, except the basal cell, have a slender bristle-like appendage. Conidia have the appearance of insects, hence the name Entomosporium.