The First Report of Beech Bark Disease in Ohio Comes Nineteen Years After the First Report of the Initiating Scale.

Abstract

Beech bark disease (BBD) is a two-part disease complex. It first requires the feeding of an initiating insect scale and is only fully developed when scale-altered bark becomes infected by one of two Neonectria species. In Ohio, there was a 19-year lag between discovery of the initiating scale insect and the development of BBD. In September 1984, the BBD-initiating scale (Cryptococcus fagisuga Lind) was discovered in the Holden Arboretum, Geauga County, OH (2). Nineteen years later (December 2003), A. Iskra discovered the exotic BBD-causing fungus, Neonectria coccinea (Pers.:Fr.) Rossman & Samuels var faginata Lohman, Watson & Ayers, on American beech (Fagus grandifolia Ehrh.) in the Holden Arboretum. In 1934, Erlich (1) reported that there was normally a delay of at least 1 year between the appearance of the scale and the first appearance of the Neonectria spp. fungus. In the years immediately after the first report of the scale in Ohio (2), pathologists and arboretum staff made frequent visits to the site in an attempt to find Neonectria spp. fruiting. After a decade of searching, these visits became more infrequent. However, it was on one of these visits that A. Iskra found the fungus. He found it on only four trees, none of which had the extensive bark cankering common in chronic Neonectria spp. infections. In North America, the two species of Neonectria that have been involved in BBD mortality are the native N. galligena (Bres.) Rossman & Samuels, or the exotic N. coccinea var faginata. In the absence of beech scale infestations, reports of the native N. galligena infecting American beech are few. Yet, in West Virginia, western Pennsylvania, Michigan, and possibly North Carolina, the fungus first associated with the killing front has been the native N. galligena and not the exotic variety, N. coccinea var faginata. To our knowledge, this is the first report of BBD in Ohio and it is unique because the associated fungus is the exotic variety.