248 
Journal of Agricultural Research 
Vol. II, No. 3 
* 
and P. virginiana , and that fusiform swellings occur on Pinus serotina 
and P. taeda. The former are commonly produced by Peridermium cere¬ 
brum and the latter by Peridermium fusiforme. In the same locality on 
pines of the 2-needle group the swellings are spheroid and typical of 
Peridermium cerebrum , and on adjacent pines of the 3-needle group they 
are usually fusiform and typical of Peridermium fusiforme. 
The junior writer has observed that the fusiform type of swelling 
{Peridermium fusiforme) on Pinus taeda is often accompanied by a 
marked development of hexenbesen (witches'-brooms) at the distal end 
of the swelling. At Brooksville, Fla., many trees of P. taeda are badly 
infected with this Peridermium, and in almost every instance the dis¬ 
eased branches terminate in hexenbesen. Occasionally the fusiform 
swellings are very long, ranging from several inches to over 4 feet in 
length. The largest swellings are found on the trunks of trees 3 to 6 
inches in diameter. Those on the 3-needle pines often originate near 
the extremity of a branch, and, as the side branches develop, the fungus 
invades them, producing an enlargement of the base of each branch. In 
such cases a continuous swelling is formed, extending in both directions 
on the main branch and to the adjacent side branches. 
The junior writer collected on March 6, 1914, sporulating specimens of 
Peridermium fusiforme on Pinus taeda (F. P. 15138) 1 near Gainesville, 
Fla., associated directly with the young leaves of Quercus nigra . On 
March 23 he found Cronartium cerebrum on Q. nigra (F. P. 15170) and 
on Q. phellos in direct contiguity with Peridermium fusiforme on P. taeda 
(F. P. 15177) near Brooksville, Fla. Inoculations were made by the 
senior writer with the aeciospores of the first collection (F. P. 15138) on 
oaks {Quercus spp.) on March 10, 1914, in the pathological greenhouses 
at Washington, D. C. On April 3 the telia of C. cerebrum were present 
sparsely on the leaves of Q. rubra (F. P, 15217) and of Q. velutina (F, P. 
I 5 218 )* 
Later and more abundant collections of Peridermium fusiforme were 
made by the junior author in Florida, South Carolina, and North Carolina 
on Pinus serotina and P. taeda . Inoculations made with aeciospores 
from these on several species of oaks resulted in nearly every instance 
in the appearance of abundant uredinia of Cronartium cerebrum in 7 to 
10 days (PL XI, fig. 4) and of numerous telia in 15 to 21 days from the 
time of inoculation. All control plants in every set remained free from 
infection. The following species of oaks were most abundantly in¬ 
fected with the Cronartium from inoculations made with Peridermium 
fusiforme: Quercus californica (F. P. 15316), Q. digitata (F. P. 15300), 
Q . gambelii (F. P. 15287), Q. imbricaria (F, P. 15286), Q. lobata (F. P. 
I 5 2 99)> Q* michauxii (F. P. 15294), Q. phellos (F. P. 15278), and Q . rubra 
(F. P. 15297). The following species of trees were infected less abun¬ 
dantly: Castanopsis chrysophylla (F. P. 15334), Quercus alba (F. P. 
Q. bicolor (F. P. 15331), Q. emoryii (F. P. 15318), Q. velutina 
(F. P. 15330), and Q. virginiana (F. P. 15317). 
The uredinia, telia, and sporidia of the Cronartium resulting from 
inoculations with the aeciospores of Peridermium fusiforme differ in no 
essential feature from those obtained by inoculating the same species of 
oaks with the aeciospores of P . cerebrum; in fact they can not be dis¬ 
tinguished morphologically from the latter (PL XI, fig. 3). 
1 The numbers in parentheses refer to specimens in the collections for study in the Office of Investiga¬ 
tions in Forest Pathology. 
