Sporulation of Lirula macrospora and Symptom Development on Sitka Spruce in Southeast Alaska. P. E. Hennon, Pathologist, USDA Forest Service, Forest Pest Management and Pacific Northwest Research Station, P.O. Box 21628, Juneau, AK 99802. . Plant Dis. 74:316-319. Accepted for publication 5 December 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/PD-74-0316.

The timing of ascospore release of Lirula macrospora and development of symptoms in needles of different ages on Sitka spruce (Picea sitchensis) were studied for 2 yr at three sites in southeast Alaska. Ascospore release began with spruce budbreak and diminished when shoots were fully elongated. Sporulation peaked during the same week in 19 of 27 spore traps from 4 to 11 June 1987 and in eight of nine traps from 13 to 20 June 1988. The timing of peak sporulation was independent of site. Total spore deposit between April and August averaged 23.6 and 7.1 spores per square millimeter in 1987 and 1988, respectively. The pattern of symptoms and development of hysterothecia on infected needles of different ages was consistent throughout coastal Alaska. First-year needles presumably became infected during the period of sporulation but remained green through their first growing season. Infected second-year needles became reddish brown and developed immature hysterothecia, third-year needles became tan and harbored mature hysterothecia that sporulated in spring, and fourth-year needles were tan, had empty hysterothecia, and began to cast.