Summary:
Key diagnostic features are the brownish to amber colored, cushion-shaped fruitbodies, erumpent whitish conidial stage, large granular conidia, and growth on Populus. It may cause serious canker formation in native and exotic poplars, especially hybrids and young nursery stock. Cankered areas "first appear slightly more sunken than surrounding tissue, and bark may be discolored orange", acervuli then develop "in concentric waves around the points of inoculation, usually around a lenticel", (Callan). Some authorities regard this as a Pezicula species: Seaver transferred it to Pezicula, and according to Dictionary of the Fungi 10th Edition, molecular data do not support separation of Neofabraea from Pezicula.

Microscopic:
spores 16-22 x 5-6 microns, oblong-elliptic, straight or slightly curved, or unilaterally flattened, up to 3-septate, colorless; asci 8-spored, 80-112 x 9-12 microns, cylindric to clavate, short-stemmed; conidia 25-45 x 4-5 microns, cylindric to spindle-shaped, nonseptate, colorless, often with granular cytoplasm; acervuli are covered by colorless, septate, simple or branched conidiophores measuring 25-35 x 4 microns, (Callan), spores 18-20 x 5-6 microns, elliptic, becoming indistinctly 3-septate, usually with 2 oil droplets, 2-seriate in upper part; asci apparently normally 8-spored but with only 5 or 6 of the 8 developed, reaching a length of 80 microns and a width of 12 microns, clavate; paraphyses enlarged in upper part, colorless, (Seaver)

Notes:
At the time of Seaver''s description, it was known only from the type locality in ON (Seaver), but it is now known more widely, including BC, Europe, and Japan (Callan).

Synonyms and Alternate Names:
Pezicula populi (Thompson) Seaver
Trichophaea hybrida (Sowerby) T. Schumach.