E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include longitudinal, slightly depressed cankers on hazelnut (filbert) trees. In the mature state the cankers contain numerous hard, dark brown to black stromata (also known as pustules), each about 0.2-1cm long, and each with numerous ostioles. Ascospores infect young vegetative tissue in spring (during bud break and early shoot extension) and the fungus colonizes cambial tissue. Stromata containing perithecia develop within the cankers 12-16 months after infection. Stromata form at the margins of cankers each year, so that the cankers expand every year. In Corylus avellana, these cankers eventually girdle branches, causing death of mature trees in 5-15 years. This is known as eastern filbert blight, a destructive disease of Corylus avellana (European hazelnut) which is cultivated commercially in the Pacific Northwest and other areas. Corylus americana (American hazelnut) is affected only in minor ways. (EPPO(1)). Celeste Paley (pers. comm.) has reported it on Corylus cornutus var. californica in BC.

Anisogramma anomala is found at least in BC, NS, WA, OR, CT, DE, IL, IA, ME, MD, MA, NJ, NY, NC, WI. It occurs naturally on wild Corylus spp. in the eastern United States - it spread to WA in 1973, OR in 1986, and from these states to BC. (EPPO(1))

Fruiting body:
About 5-100 stromata are formed per canker, with 40-60 perithecia per stroma. At an early stage the only external symptom is a series of small bumps 0.2-0.3cm across and less than 0.05cm in height. Lens-shaped fissures containing white mycelium form in the bark. Later visible cankers form, containing stromata. "The stroma is the most conspicuous and most diagnostic character of the fungus. Stromata usually occur in single or double rows within 1-yr-old cankers. In 2- or 3-yr-old perennial cankers, three to five rows of stromata, also known as pustules, are not uncommon. Mature stromata are aligned with their greatest length parallel to the long axis of the stem" and measure 0.2-1.0cm x 0.15-0.3cm and 0.1-0.2cm in height. "First season cankers usually contain less than 20 stromata while in second or third-season cankers, stromata often number in the hundreds." "Death of the cambium in the area of the canker results in a sunken appearance as the surrounding cambium continues to grow." Gottwald(1). Mature stromata are black and measure 1.5-3cm x 0.2–1.0cm and 0.1-0.2cm in height. (EPPO(2)). Stromata are variable in shape from round in outline to ellipsoid. Sometimes they are raised pustules and at other times they occur in a depression or groove in the twig/branch. (Thom O''Dell, pers. comm.)

Microscopic:
spores unequally two celled, colorless, the smaller cell remaining as a hemispheric cap measuring 1.1-1.4 x 1.1 microns, and the larger enlarging slowly from July to November from 5-6 x 2-2.5 microns to 8-12 x 4-5 microns at maturity; spore release is typically from November to April; asci are 8-spored - mature asci are 45-65 x 10-15 microns with a long thread-like stalk, within the asci, spores are uniseriate to biseriate; paraphyses are not present in some perithecia and occur in low number in others - they are 40-50 microns long and 3.5 microns at greatest width, and they are short-lived and gelatinize before full development of the ascocarp; the mature perithecium is 1040-2160 microns x 250-830 microns, (Gottwald(1) who provide considerable further microscopic detail in their study of infections in C. avellanea)