TWO NEW HOSTS FOR PERIDERMIUM PYRIFORME 
By George Grant Hedgcock, Pathologist , and William H. Long, Forest Pathologist , 
Investigations in Forest Pathology , Bureau of Plant Industry 
Peridermium pyriforme Peck, which is the aecial form of Cronartium 
pyriforme (Peck) Hedge, and Long, was collected for the first time on 
Pinus rigida Mill, by the senior writer on June 16, 1915, near Essex 
Junction, Vt. (F. P. 17708). 1 This is the first collection which has been 
reported on this host. The senior writer had previously found the 
uredinial and telial forms in abundance in the same locality on Comandra 
umbellata (L.) Nutt. (F. P. 8655) on July 31, 1913. This find is impor¬ 
tant, since it may serve to clear up the mystery associated with the 
identity of the host in the case of the type specimen on Pinus spp., 2 col¬ 
lected by Prof. J. B. Ellis (2040) in 1880, possibly near Newfield, N. J., 
Ellis not being certain as to the locality. Since the telial form was col¬ 
lected by Ellis (Ellis and Everhart, N. A. Fungi, No. 1082) near New¬ 
field in 1879 and as Pinus rigida is the only native species of pine in this 
locality known to be attacked by the fungus, it is very probable that 
this species is the host of the type. In measurements and shape the 
spores of the writers' specimen agree with those of the type which the 
writers have examined at the herbarium of the State Museum at Albany, 
N. Y. The type specimen consists of a young pine twig whose bark 
closely resembles in color and markings that of Pinus rigida . 
Mr. Roy G. Pierce, of this office, collected a number of specimens of 
Peridermium pyriforme on Pinus divaricata (Ait.) Du Mont de Cours 
(PL XXVII, fig. 1) in several localities near Cass Lake, Minn., during the 
month of June, 1915 (F. P. 18044, 18046, 18047, 18058, 18060, 18072, and 
18076). So far as the writers know, only one specimen of the fungus has 
hitherto been reported on Pinus divaricata , and that was found by 
Mr. J. J. Davis in Douglas County, Wis. Mr. Pierce reported that the 
fungus was common where he collected it, and it is probably common also 
in other localities. He also found the uredinial form, Cronartium pyri¬ 
forme , on July 11, 1915, on Comandra umbellata in the same locality as 
one of his previous collections of the aecial form. 
The junior writer also has a specimen of this rust (F. P. 19440) on 
Pinus divaricata collected at Roscommon, Mich., by State Forester Mar¬ 
cus Schaaf. This specimen was sent in with Peridermium cerebrum , 
which on this host produces typical globular swellings, while Peridermium 
pyriforme causes the typical fusiform swellings. Peridermium pyriforme , 
however, does not always produce fusiform swellings, since the junior 
writer has recently received a specimen (F. P. 19437) on a 4-year-old 
1 “P. P.”= Forest-Pathology Investigations number. 
2 Hedgcock, G. G., and Long, W. H, A disease of pines caused by Cronartium pyriforme. U. S. Dept. 
Agr. Bui. 247, p. 7- 1915 - 
Journal of Agricultural Research, Vol. V, No. 7 
Dept, of Agriculture, Washington, D. C. Nov. 15, 1915 
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