Delphinella balsameae Tip Blight of Abies lasiocarpa in Vermont.

Abstract

In 1996, a windbreak planting of Abies concolor (Gordon & Glend.) Lindl. ex Hildebr. and A. lasiocarpa (Hook.) Nutt. on a Christmas tree farm in Lamoille County, VT, incurred tip blight caused by a Delphinella sp. Although only scattered new shoots of the intermixed A. concolor and nearby A. balsamea (L.) Mill. were killed, more than 75% of the new shoots in the lower 1.8 m of the crowns of A. lasiocarpa were killed. This posed the question, whether the pathogen was the native D. balsameae (A. M. Waterman) E. Müller in E. Müller & Arx or whether the western species, D. abietis (Rostr.) E. Müller in E. Müller had been introduced. Dead 1996 shoots were collected from all species on 15 July. Most ascomata were immature. However, occasional ascomata bore well-developed bitunicate asci with hyaline, uniseptate ascospores averaging 40 × 9 μm, confirming the pathogen was D. balsameae (1). Funk reported this pathogen on A. lasiocarpa in British Columbia without documentation; this is the first record of it attacking this species in eastern North Amer-ica. Although the seed source was unknown, the extreme susceptibility of A. lasiocarpa in comparison to other Abies spp. in the area suggests that caution should be used in planting this species in the Northeast. Reference: (1) A. M. Waterman. J. Agric. Res. 70:315, 1943.