412 
Journal of Agricultural Research 
Vol. XIV, No. IO 
treated this species under C. ribicola, but stated that its occurrence on 
Ribes (longiflorum) aureum in the parks of Denver and Boulder was unex¬ 
plainable. That this rust is not C. ribicola was predicted by Hedgcock 
and Long (4) in 1915 and by Bethel in 1917 in North American Uredi- 
nales No. 1609. 
In connection with the white-pine blister-rust investigations 1 during 
the summer of 1917, a thorough investigation of the rust was begun. 
The species of caulicolous Peridermiums previously known in Colorado 
and Arizona are Peridermium pyriforme Peck, P. filamentosum Peck, 
and P. harknessii Moore, all of which attack Pinus ponderosa and P. 
contoria , and whose telial stages are well known. The first problem, 
therefore, was to find a species of Peridermium which could be shown 
to be the aecial stage of this species of Cronartium. Since the northern 
and central parts of the State had long been a favorite collecting ground 
of mycologists and no such species of Peridermium had been dis¬ 
covered, it seemed probable that it would be found in the southern part 
of the State, where less collecting had been done. The first collection 
of this species of Cronartium had been made in the Ute Indian Reser¬ 
vation along Los Pinos River near Bayfield, about 20 miles north of the 
Colorado-New Mexico boundary; so this region was surveyed first. 
On May 25, 1917, the senior writer found a Peridermium, apparently 
a new species, on Pinus edulis south of Bayfield. The following day 
two of the writers (Hedgcock and Bethel) found the telia of the Cro¬ 
nartium on fallen leaves of Ribes aureum north of Bayfield, near the 
spot where Mr. Bethel had collected the fungus in 1897. Culture mate¬ 
rial of the species of Peridermium was sent to Washington, D. C., where 
another of the writers (Hunt) made inoculations with seciospores on 
species of Castilleja, Comandra, and Ribes, with the result that R. odora- 
tum became infected with the species of Cronartium, establishing the 
new species of Peridermium as the aecial stage of the western species of 
Cronartium. Repeated inoculations given elsewhere in this paper have 
fully corroborated this result. 
This species of Cronartium was first found in Arizona by Mr. Good- 
ding on October 2 at Prescott, Ariz., and was at first supposed to 
be C. ribicola . Dr. Long, assisted by Messrs. Goodding and Llew¬ 
ellyn, made a thorough survey of the region around Prescott in October 
and found this species of Cronartium abundant on both cultivated and 
wild plants of Ribes spp. in several localities, some widely separated, but 
did not find the secial form on pines. On October 28 one of the writers 
(Bethel) found one tree of pinon (Pinus monophylla) near Prescott dis- 
1 The work in Colorado was in charge of Dr. G. G. Hedgcock, assisted by Messrs. E. Bethel, N. R. Hunt, 
E. B. Payson, E. E. Johnson, R. Thompson, and H. L. Gaymon. Dr. W. H. Long was in charge in New 
Mexico and Arizona, assisted by Messrs. C. S. Eewellyn and L. N. Goodding. Mr. A. S. Rhoads assisted 
in the work of inoculation at Washington, D. C. The work in Colorado was in cooperation with the Colo* 
rado Agricultural Experiment Station, which was in charge of the inspection of nursery stock and nur¬ 
series for the white-pine blister-rust. 
