Jan. 34,1916 
Peridermium filamentosum 
785 
high) of 5 inches and over and growing within 100 feet of the nursery 
beds, was found to be very seriously infected. Of the 61 trees, 26 had 
large cankers encircling the trunks varying in length from 2 to 8 feet. 
The branches and twigs were infected. Peridermium montanum was also 
present on the needles. Castilleja miniata was found growing in abun¬ 
dance under the trees. Eodgepole-pine seedlings in and near this area 
were, with rare exceptions, heavily infected with the twig and stem and 
the needle forms of Peridermium. Very little native yellow pine was 
found growing in the vicinity, most of the trees having been killed by 
the fires of 1910. A few veteran trees remain growing upon the ridge 
west of the nursery, but these show no evidence of fresh eruptions of 
Peridermium. These facts point to the lodgepole pine as the original 
distributor of infection to the yellow-pine seedling beds in the nursery. 
Experiments are being conducted in an effort to control the disease. 
The seedlings in the nursery beds are being sprayed during the infec¬ 
tion period. An effort is being made to eradicate the alternate host 
from the vicinity by mechanical or chemical means. The felling and 
burning of trees near by infected with Peridermium will reduce the chances 
of infection. The possibility of the fungus possessing facultative auto- 
ecism, the close proximity and abundance of the alternate host, and the 
prolific development of the same fungus upon lodgepole pine in the 
vicinity of the seedling beds all make Peridermium filamentosum a 
dangerous enemy to deal with in this nursery and one to be reckoned 
with in other forest nurseries where similar conditions exist. 
SUMMARY 
Peridermium filamentosum Peck has been found to cause a serious 
disease of yellow-pine seedlings at the Savenac nursery located at Haugan, 
Mont. 
The various forms of Peridermium occurring on lodgepole pine at 
this nursery, with the exception of the foliicolous species, have been 
demonstrated to be Peridermium filamentosum , having an alternate 
stage on species of Castilleja. 
The fact that the same species of Peridermium attacks both the lodge¬ 
pole pine and. the yellow pine increases the difficulty of control of this 
fungus. 
The proximity and abundance of the alternate host (1 Castilleja miniata) 
of Peridermium filamentosum and its prolific development on lodgepole 
pine in the vicinity of the seedling beds tend to make this disease a 
dangerous one in forest nurseries. 
