BULLETIN 
Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
July 20, 1915. 
(PROFESSIONAL PAPER.) 
A DISEASE OF PINES CAUSED BY CRONAKTIUM 
PYRIFORME. 
By George G. Hedgcock, Pathologist, and William H. Long, Forest Pathologist, 
Investigations in Forest Pathology. 
CONTENTS. 
Page. 
History of the fungus 1 
Morphology of the fungus 2 
Synonymy and description of the fungus 3 
Inoculation experiments with the fungus 5 
Distribution of the fungus 8 
Distribution of the serial form 8 
Distribution of the uredinial and telial 
forms 9 
Dissemination of the fungus 12 
Effect of the fungus on its host plants 13 
Effect of the a;rial form on pines 13 
Effect of the uredinial and telial forms on 
Comanclra plants 16 
Eradication and control of the fungus 16 
Literature cited 20 
HISTORY OF THE FUNGUS. 
In 1875 Peck (10) 1 described as a new species under the name Peri- 
dermium pyriforme a caulicolous or stem-inhabiting Peridermium with 
obovate to pyriform spores from a specimen collected by J. B. Ellis 
(No. 2040). In 1882 Ellis issued in his North American Fungi under 
No. 1021 a caulicolous Peridermium which he called "Peridermium 
pyriforme on small branches of Pinus virginiana" and in the Ellis 
Herbarium, now at the New York Botanical Garden is a specimen 
labeled "Peridermium pyriforme on small branches of Pinus rigida, 
Newfield, New Jersey, May, 1890." Both of these latter specimens 
appear to be Peridermium comptoniae; at any rate, neither of them is 
the true P. pyriforme originally described by Peck. Arthur and Kern 
(1) in 1906 described as P. pyriforme Peck what is now known as P. 
comptoniae. 
In 1913 the writers received from Prof. E. Bethel a caulicolous 
species of Peridermium on Pinus contorta, which they described as a 
1 Reference is made by number to " Literature cited," p. 20. 
Note.— This bulletin discusses an important disease of pines which is now for the first time fully de- 
scribed. It is intended for circulation among botanists, foresters, nurserymen, State inspectors, and horti- 
culturists. 
93041°— Bull. 247- 
