784 
Journal of Agricultural Research 
Vol. V, No. 17 
developed the bright orange eruptions of the rust later. It is safe to 
draw the conclusion that the spore tubes which produce the infections 
in the seedlings penetrate the host in the absence of all surface openings 
due to the mechanical injuries. The period of development between the 
time of penetration of the host and the appearance of the aecial eruptions 
on the stems is about 10 to 11 months. The seedlings in question were 
produced from seed sown in the spring of 1913, and the spring of 1914 
some of the seedlings produced the aecial eruptions. The seedlings must 
have been infected in the period following germination and have developed 
the fruiting stage in the spring of the following year. The infecting 
spores could have been either sporidia from the species of Cronartium on 
Castilleja miniata or possibly aedospores from the surrounding lodgepole 
pines infected with Peridermium filamentosum. Facultative autoecism in 
Peridermium ftlamentosum is as yet not proved, but it is suspected of 
being a “ repeater." 
During the period froiri May 29 to June 2, 1915, Mr. E. C. Rogers, of 
the Forest Service nursery at Haugan, Mont., assisted in the work of 
visiting and inspecting the various plantation areas near Wallace, Idaho, 
on the Coeur d'Alene National Forest, and those in the vicinity of Savenac 
nursery and Deborgia, Mont., on the Tolo National Forest. In all an 
area of approximately 500 acres was covered. The inspection was con¬ 
fined principally to the yellow-pine plots, with particular attention to 
the plants taken from the infected 2-year-old yellow-pine beds at Savenac 
nursery. Very few infections caused by species of Peridermium were 
recorded, some of the areas bdng entirely free from visible signs of the 
rust, although it may be present and not appear until the following year 
or later. In the case of the “2-year-old yellow pine, unfertilized" plot, 
which was planted in the spring of 1915, the few infections observed 
were found to be covered by the moist earth because of deep planting 
and thus were rendered practically incapable of spreading. Two of these 
infections were molded and the spores were no longer viable. The 
Placer Creek area near Wallace, Idaho, is a clean-bum site, the fires of 
1910 having destroyed all living timber. No living pines or castilleja 
plants are to be found growing within a considerable distance of this 
area. Castilleja miniata and Pinus contorta are plentiful in the area 
containing 4-year-old yellow-pine seedlings located on the ridge west of 
the Savenac nursery. Very little visible infection was found on this 
plot. These facts prove the effectiveness of the inspection work in 
checking the spread of the disease and the necessity for culling out and 
burning the infected seedlings as soon as the eruptions make their 
appearance. 
On June 1, 1915, a survey was made of the area surrounding the nur¬ 
sery beds for a distance of half a mile. Fifty per cent of the lodgepole- 
pine stand in close proximity to the beds was badly infected with Peri¬ 
dermium ftlamentosum. A group of 61 trees, having diameters (breast 
