A bacterial gall disease of douglas fir,Pseudotsuga taxifolia

Abstract

does not appear. First page follows. Bacterial diseases of conifers are exceptionally rare; as far as we know only two have been reported in the literature to occur naturally on twigs, branches, and upper stems of members of the family Pinaceae, and both of these are probably produced by the same organism. In 1888 Vuillemin,(3)4 isolated an organism from galls occurring on twigs of Pinus halepensis Mill. and named it Bacterium pini Vuill. In 1911 Von Tubeuf(2) isolated what he considered to be the same organism from galls on twigs and branches of Pinus cembra L. Several attempts were made by Vuillemin and by later investigators to produce the disease by inoculating with pure cultures of B. pini and by transfer of gall material from diseased to healthy plants, but in no case were positive results obtained. In 1933 Hansen and Smith(1) published a brief note recording the finding of bacterial galls on Douglas fir (Pseudotsuga taxifolia Britt.) in California. The present paper reports additional studies of this disease, its transmission, and the pathogene involved. Economic Importance The disease has been observed commonly in parts of Napa, Lake, Santa Cruz, Amador, and Siskiyou counties in California, in marginal localities for the growth of Douglas fir, which here occurs in mixed stands composed of several species of conifers and three or four species of broadleaved trees. These marginal localities, though practically worthless for timber production, are much used for recreational areas, sanitariums, summer resorts, and private summer homes. As far as the value of such places may be materially lowered by the presence of dead, dying, and deformed trees, the disease can be considered to be of economic importance. In its present known range, the Douglas-fir gall disease is otherwise of no economic importance, and of only potential interest to the lumbering industries.