By the middle of the nineteenth century, deterioration of cultural property due to environmental agents was recognized and efforts at control initiated. Lichen-induced biodeterioration of exterior stone, such as architectural facades, sculpture, tombstones, and even stained-glass windows, had been been identified as one such agent. Conservation's uneasy relationship with lichen has continued; indeed, it has become increasingly more complex. For example, lichen's possible role in dating and as an indicator of environmental conditions militates for its preservation, while its deleterious effect on cultural materials prompts its eradication. Broader environmental concerns increasingly move conservators away from biocides, the standard method of lichen control. This paper will present an overview of control of lichen on cultural property through a summary review of historic and current literature. It will also explain data bases that address this issue. Lastly, a promising new avenue for control of lichen on cultural property will be described.

Key words: biodeterioration of cultural property, conservation of stone, lichen control, lichen-induced deterioration