494 
Journal of Agricultural Research 
Vol. XXX, No. 6 
than with mild mosaic. What seems 
to be a fourth type of mosaic, resembles 
mild mosaic but is characterized by a 
much greater degree of crinkling, that 
is, of wrinkling, waviness of the margin, 
and ruffling. This will be called 
“crinkle mosaic” (PI. 6, B, 3). It is 
not identical or even similar to the 
“crinkle” of other systems of nomen¬ 
clature. The latter (crinkle) seems to 
be nearly identical with rugose mosaic, 
but in descriptions based upon symp¬ 
tom aggregates in plants of the Green 
Mountain variety, “crinkle” can not 
replace the well-known term mosaic, 
and furthermore rugose mosaic is 
characterized by less crinkling than 
some other types of mosaic, at least 
in the variety and environment most 
familiar to the writers. 
The distinguishing characteristics of 
leaf-roll (PI. 10, A) include distinct 
rolling and rigidity, especially of the 
lower leaves, dwarfing, chlorosis, and 
some burning. Tubers, usually quite 
sessile, are reduced in size. They may, 
in certain varieties and conditions, show 
net necrosis resulting in spindlingness 
of the sprouts, especially at the stem 
end. Spindlingness of the sprouts also 
may be a symptom without net 
necrosis (pis. 5 and 7). 
Spindle tuber produces spindling 
stems and upright, somewhat darker 
green and slightly rugose and dwarfed 
foliage. Abnormally spindling, spindle- 
shaped, and usually dwarfed tubers 
with more or less conspicuous and 
apparently numerous eyes, are char¬ 
acteristic of this disease. Infection 
with spindle tuber is obtained with 
about the same difficulty as with mild 
or leaf-rolling mosaic. 
The characteristic current season 
symptoms of streak (pis. 2, 3 and 4, A) 
include streaking, spotting, brittleness, 
leaf dropping, and premature death of 
the foliage. The streaking and spotting 
are more pronounced on the lower leaf 
surface than the upper, if they appear 
on the latter. With the exception of 
faint chlorotic spots marking the 
initial stages of streaking and spotting, 
no mottling develops. Second genera¬ 
tion reactions of streak appear as 
severe dwarfing, curling, wrinkling, 
brittleness, streaking, leaf dropping, 
and premature death, often preventing 
tuber development. Brown discolored 
areas frequently appear near the eyes 
on infected tubers. Streaks and spots 
have been observed on the white corol¬ 
las of inoculated plants of the Green 
Mountain variety (pi. 3). 
Mottled curly dwarf (pis. 4, C, and 
5, E) symptoms include distinct dwarf¬ 
ing, spindlingness, curling, wrinkling, 
slight rolling, brittleness, burning, and 
somewhat premature death. The tu¬ 
bers show the same symptoms as in 
spindle tuber, with more dwarfing. 
This symptom aggregate appears to be 
a combination of leaf-rolling mosaic 
and spindle tuber. Unmottled curly 
dwarf (pi. 1, A, B, and C) is different 
from mottled curly dwarf in the absence 
of mottling and in the tubers being 
more gnarled and cracked. This seems 
to be a single disease. The tuber 
cracking may appear, without the 
spindlingness, as a symptom resulting 
from current-season inoculation (pi. 
1, AtoD). 
SECOND GENERATION REACTIONS 
TO INOCULATIONS MADE IN 1922 
LEAF MUTILATION INOCULATIONS MADE 
WITHIN THE GREEN MOUNTAIN VA¬ 
RIETY IN THE FIELD 
In the open field in 1922, leaf mutila- 
tion inoculations with different types of 
mosaic and with leaf-roll, spindle tuber, 
unmottled curly dwarf, and streak, 
were performed on plants of the Green 
Mountain, Irish Cobbler, Bliss Tri¬ 
umph, and Rural New Yorker varieties. 
Either the second or third hill, or both 
of these hills, in each four-hill tuber 
unit were inoculated, leaving two or 
three uninoculated controls in each 
tuber unit. Single inoculations were 
made in each series, with the exception 
of series 38, 58, and 73, in which the 
second hill in each tuber unit received 
two applications, and with the excep¬ 
tion of series 71, which received three 
EXPLANATORY LEGEND FOR PLATE 1 
A. —Tubers produced by unmottled curly-dwarf Green Mountain plants in a lot serving as the source 
of inoculum for inoculation series 22 of Table I. For the effects of the inoculation see Plate 1, B, C, and D. 
Photographed at planting time in 1923 
B. —Unmottled curly dwarf plant grown from one of the cracked tubers shown in Plate 1, C. Photo¬ 
graphed in August, 1923 
C. —Tubers produced by Green Mountain plants inoculated in series 22 of Table I with unmottled 
curly dwarf, showing cracks as a current-season symptom. Photographed at planting time in 1923. For 
the complete tuber symptoms see Plate 1, A, for the controls see Plate 1, D, and for the vine symptoms 
see Plate 1, B 
D. —Tubers produced by sister hills of the plants inoculated with unmottled curly dwarf in series 22 of 
Table I. Four tubers are split and the entire surface of each tuber is shown. One recently formed trans¬ 
verse bruise crack is evident, but is different from the longitudinal healed growth cracks symptomatic 
of diseased plants (pi. 1, C). Photographed at planting time in 1923 
