16 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 
the center of infection or, vice versa, may spread from the point of 
infection on a limb to that part of the trunk adjacent to the diseased 
area on the limb. In this it resembles P '. jilamentosum (5) and the 
fusiform type of P. cerebrum (P. fusiforme) (7, p. 248). Such in- 
stances in the case of both P. pyriforme and P . filamehtosum on Pinus 
ponder osa have been observed by the senior writer in Colorado and 
Wyoming and noted by Spaulding (11, p. 28, 34) in the case of Peri- 
dermium strobi on white pines in the northeastern United States. 
EFFECT OF THE UREDINIAL AND TELIAL FORMS ON COMANDRA PLANTS. 
The effect of the uredinial and telial forms of the fungus, Cronartium 
pyriforme, on Comandra plants can not be separated into two distinct 
sets of symptoms, since the two forms are produced on the same 
area of tissue, the one following the other in a few days. Both the 
uredinia or the telia may occur on either surface of the leaves, as 
well as on the younger portions of the stems, and occasionally on the 
floral parts. 1 In badly infected plants there is a decided shortening 
of both the stems and the leaves in their growth, so much so as to 
change the entire aspect of the plants. This is usually accompanied 
by a slight chlorosis of the leaves. Where the infection is slight, the 
diseased spots on the leaves are usually a lighter green color than the 
uninfected portions. Late in the growing season the reverse colora- 
tion sometimes takes place, and the chlorophyll is retained longest 
in light-green areas in the leaves where the mycelium of the fungus 
is found, even after the remainder of the leaf has become yellow from 
fall coloration. 
In badly infected Comandra plants defoliation takes place prema- 
turely; that is, before drought, frost, or cold weather bring it about. 
No data have been obtained as to the final effect of the rust on 
Comandra plants. The effect, however, is decidedly stunting, and 
plants infected badly for several seasons would undoubtedly be killed. 
ERADICATION AND CONTROL OF THE FUNGUS. 
One of the most serious facts in connection with the prevalence of 
Peridermium pyriforme in some portions of the western United States 
is the danger of introducing it into localities now free from it through 
the shipment of trees in the work of artificial reforestation. For this 
purpose nursery stock is often shipped long distances. The forest 
nursery if situated in mountain regions is apt to be in a locality where 
Comandra plants are common. Since these serve as host plants for 
both the uredinial and telial forms of the fungus, their presence may 
lead directly to the infection of the young pines in the nursery and 
indirectly to the infection of localities hitherto free from the disease. 
i In Comandra pallida this is the case. In Comandra umbellata the uredinia and telia are found uniformly 
on the under surface of the leaves. 
