A DISEASE OF PINES CAUSED BY CEONARTIUM PYEIFOEME. 17 
If it were possible to distinguish all of the diseased trees at the time 
of planting, it would be an easy matter to discard them and thus 
prevent the further spread of the disease. Such, however, is not the 
case, since the disease may not become evident until three or four 
years after the young trees are infected and until after they are planted 
in the forest. This being the case, other means for the control of the 
disease must be adopted. The most feasible plan to prevent further 
infection in the nursery and the subsequent dissemination of the 
disease through infected nursery stock appears to be the elimination 
of all Comandra plants in the vicinity of the nursery. 
In order to protect the nursery from infection whenever the dis- 
ease is present in adjacent forests, all diseased pines that can be 
found within a radius of at least half a mile from the nursery should 
be cut down. These can be selected most easily by a person familiar 
with the fungus, at the time the secia mature in the pines. As pre- 
viously stated, this period varies from the middle of May till in 
August, depending upon both the latitude and the altitude of the 
locality. This cutting-out process should be repeated each year until 
no more diseased trees can be found in the proposed neutral zone. 
The elimination of all diseased pines will not suffice, however, 
absolutely to control the disease hi the nursery when Comandra plants 
are in the vicinity, since it is quite certain that the fungus can spread 
by the urediniospores from one Comandra plant to another for long 
distances in one season. By this means the disease could be carried 
from diseased pines outside of the neutral zone or belt of removal to 
the young pines in the nursery. To protect the nursery against infec- 
tion from this fungus all Comandra plants within 1,000 feet of the 
outer boundaries of the nursery should be removed by digging them 
out. 
Comandra plants are herbaceous perennials and spread primarily 
by means of seeds and secondarily by means of underground runners. 
The secondary method is the more common. The seeds, being 
edible, are much liked by birds and rodents, and it is possible that 
they may be carried by these animals to a considerable distance from 
the original place of growth, thus starting new plant colonies. The 
eradication of Comandra plant colonies will be difficult, owing to the 
numerous underground runners, any of which are liable to be broken 
off and left in the ground to start new plants. It will no doubt be 
necessary to dig up the plants repeatedly before they can be com- 
pletely eradicated. All species of Comandra are parasitic and derive 
part of their food supply from other plants by a direct attachment 
of the smaller side roots of Comandra to the roots of the host plants. 
It is not yet known how many species of plants are thus parasitized, 
but several widely different species are attacked. Species of Vac- 
