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 i6, 191 5, near Essex 

 Junction, Vt. (F. P. 17708).^ 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.,- col- 

 lected by Prof. J. B. ElHs (2040) in 1880, possibly near Newfield, N. J., 

 Ellis not being certain as to the locaHty. Since the telial form was col- 

 lected by Ellis (Ellis and Everhart, N. A. Fungi, No. 1082) near New- 

 field in 1879 and as Phius rigida is the only native species of pine in this 

 locahty 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 

 (PI. XXVII, fig. i) 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 II, 1 91 5, 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 "F. P. " = Forest- Pathology Investigations number. 



' 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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