Reprinted from PHYTOPATHOLOGY, Vol. VI, No. 3, June, 1916 



PERIDERMIUM HARKNESSII AND CRONARTIUM 

 QUERCUUM 1 



E. P. MEINECKE 

 WITH Two FIGURES IN THE TEXT 



INTRODUCTION 



Peridermium harknessii was first reported on the Pacific Coast on 

 Pinus radiata by Moore; Farlow and Seymour's 2 Host Index adds P. 

 contorta, P. ponderosa and P. sabiniana to the list. Hedgcock 3 further 

 reports it on P. jeffreyi. The writer has found it very common on Pinus 

 attenuata, and occasionally also on P. coulteri. Of all these hosts P. 

 radiata, sabiniana, attenuata and contorta are undoubtedly most subject 

 to attacks from the fungus. Numerous galls appear on the same tree. 

 The writer has counted thirty-seven galls on a sapling of Pinus radiata, 

 three feet high, selected at random from a group of similarly affected 

 trees. Another specimen contained thirty-four galls on a witches'- 

 broom fourteen inches high which had developed from a large old gall on 

 the main stem. Another tree (diameter at base three inches, height 

 eight feet) had 173 galls. A fourth tree (diameter at base six inches, 

 height twelve feet) carried not less than 529 galls. 



There can be little doubt but that each gall is the result of an individual 

 infection. The tissues, even between neighboring galls, are perfectly nor- 

 mal, and rather commonly a tree develops only one gall, which may grow 

 to large size. Unless the mycelium kills its substratum, as is often the 

 case, it may grow and cause the gall to enlarge for many years, but it is 

 always strictly confined to the gall itself and its immediate surroundings. 



1 A preliminary note appeared in Science, n.s. 43: 73. 1916. 



2 Farlow, W. G. and Seymour, A. B. A provisional host index of the fungi of 

 the United States, Part III, pp. 160-162. 



3 Hedgcock, G. G. Notes on some western Uredinae which attack forest trees. 

 Mycologia 4: 143. 1912. 



