Intensive control measures for forest tree diseases are generally impracticable, and for shade trees are limited in scope by the large size of the plants and the small number ordinarily under a single management. Forest pathology has therefore lagged behind orchard and crop plant pathology in direct control measures, and has contributed little to the number of fungicides usable on living plants or to techniques of application. Helione orange reported successful in medication against a trunk infection (perhaps by antitoxic action rather than as a fungicide) (22), phenyl mercury nitrate found to be a safe antiseptic for asphalt woundpaints (51), acids and aluminum and ferrous sulfates used for soil treatment against damping off of conifers (8) are among the few contributions to useful fungicides from tree disease investigations. In the field of forest products the situation is quite different. Fungicides, using the term in a broader sense than that of Roberts (33), were in large-scale use on wood before they became established for the protection of plants or products of any other crop. Creosote, zinc and mercury salts, and the chlorinated phenols and phenates first reached the stage of large-scale fungicidal use on wood.