6oo 
Journal of Agricultural Research 
Vol. XIV, No. 13 
from the base of the stem was partly or entirely gone. Careful examina¬ 
tion, however, indicated that even these lesions could not be attributed 
to any biting insect. The affected seedlings were distributed rather 
evenly over the beds, but in no case were any diseased plants found 
immediately north of posts, or on the north exposed slopes at the ends 
of beds, where the seedlings were somewhat protected from the sun dur¬ 
ing the hottest part of the day. Spruce, a more shade-loving tree than 
Douglas fir, also suffered more from the disease. The observations made 
indicate that the death of these seedlings was due to whitespot lesions 
occurring during the latter part of the preceding summer. The altitude 
of the nursery at first thought renders it improbable that excessive heat 
should have been concerned in causing the injury. While, of course, 
the temperature of the air at such elevations is never very high, the heat 
of rocks and gravel exposed to the sun at high altitudes is well known. 
Tubeuf (17) reports a surface soil temperature of 6o° C. (140° F.) at an 
elevation of 10,000 feet in Yellowstone Park, 200 miles directly north 
of the Wasatch region. 
BASAL STEM-GIRDLE ON OLDER STOCK 
Miinch and others (5,7, p. 13; 12 ,13, p. 397; 74,15, p . 638) have further 
attributed to excessive surface temperatures of the soil the “ Einschnu- 
rungskrankheit” or stem-girdle, of older nursery stock or young forest 
trees of both conifers and broad-leaved trees. Dr. B. T. Galloway, of 
the Bureau of Plant Industry, told the writer that he had found basal 
lesions on young willows at Chico, Cal., which he attributed to excessive 
heat. In conifers this disease involves death of the base of the stem of 
2-to-4~year-old seedlings and transplants. Lesions are definitely limited, 
and the swollen growth of the stem just above the lesion, which results 
from the girdling and interference with food movement, gives an appear¬ 
ance of constriction at the lesion itself. This disease is figured by Tubeuf 
(id, p . 492) and ascribed to Pestalozzia hartigii. Hartig (3) had originally 
ascribed it to the freezing of thin pools of water standing on the surface 
of the beds. The parasitism of P. hartigii has failed of confirmation ( 1) , 
and Tubeuf (17) now seems to favor the view of Miinch, that heat of 
the soil is responsible. This disease has been found at widely separated 
points in the United States. The writer has seen what appeared to be 
stem-girdle on two species of the white and three of the pitch pines, two 
spruces, Abies concolor (Gord) Parry, Pseudotsuga taxifolia (Poir.) Brit. 
Thuja sp., and Juniperus sp. 1 Its appearance and its ability to attack 
representatives of so many different genera favor a nonparasitic diag¬ 
nosis. The thicker cortical tissues of the woody stems should make the 
cambium slower to reach maximum temperature, and prevent quite as 
high a temperature being reached, as in the case of the younger stems, 
1 Several of these observations as to coniferous species affected were communicated by Dr. J. V. 
Hoffman, of the Forest Service, and confirmed by the writer’s examination of his specimens. 
