Cryptic killer or indulgent insect? Matsucoccus macrocicatrices and its relationship with pinus strobus in the southern Appalachian mountains

Eastern white pine (Pinus strobus) is an ecologically and economically important conifer species in North America. It has been grown for everything from wildlife habitat to old coal mine soil reclamation, Christmas tree, ship mast, and match production. Recently, white pines in the southeastern United States started showing signs of dieback including branch flagging, crown thinning and canker development. Upon closer examination, a scale insect was found and identified as Matsucoccus macrocicatrices. The scale insect is typically found under lichen, epiphytic mats or branch crotches and is often associated with cankers. Since eastern white pine dieback has become more prevalent, it has become critical to understand the white pine, associated fungal pathogen and scale insect complex.

To understand the correlations between the insect, fungus and tree, we collected six white pine saplings from 40 sites across six states (GA, NC, SC, TN, VA and WV). The saplings received an overall health rating ranging from one to five, where one is a healthy tree and five is a dead tree.  Starting from the top first node, we cut the saplings up to 1m down to the base. From each tree we determined the number of each life stage of scale insect (shell and nymph stages), size and location of cankers, presence/absence of Caliciopsis pinea and Septobasidium pinicola, and small and large end diameters of the sapling. A linear regression analysis will be used to determine correlations that may occur between the scale, white pine saplings and cankers.