502 
Journal of Agricultural Research 
Vcl. XXX, No. 6 
modification of symptoms. These ob¬ 
servations confirm similar phenomena 
recorded previously. 8 It appears that 
distinct ruffling of the foliage in the 
Rurals, even in the absence of mot¬ 
tling, denotes mosaic infection mainly 
of the leaf-rolling type (pi. 4, B and 
C). Curly dwarf in Rurals often indi¬ 
cates the presence of rugose mosaic. 
Curly dwarf in series 111 appeared on 
Green Mountains as a combination of 
rugose mosaic and unmottled curly 
dwarf. (Pis. 4, D, and 5, D.) 
Streaking and slight rugosity in the 
seedling lot in series 130 and 133 
apparently are symptoms of rugose 
mosaic; current-season symptoms in 
1922® also corroborate these second 
generation reactions. Series 139, 141, 
and 142 disclose double and triple 
combinations of leaf-rolling and rugose 
mosaic and spindle tuber, with mottling 
often less conspicuous in Irish Cobblers 
than in Green Mountains (pis. 4, E and 
5, E). Such combinations may be¬ 
come common in originally healthy 
Cobbler stock grown for several 
seasons where these various diseases 
are present, without mosaic being 
disclosed by mottling. 
INTERVARIETAL LEAP MUTILATION IN¬ 
OCULATIONS IN INSECT CAGES 
Leaf mutilation inoculations with 
degeneration disease combinations, be¬ 
tween the Green Mountain and other 
varieties, were performed in insect 
cages at the same time and in the 
same plot as those described in Tables 
I and II. A major series of inoculated 
plants consisted of 12 plants grown 
from 3 tubers, each tuber having been 
quartered. The 4 plants from each 
tuber were grown respectively in 4 
cages and each cage contained 3 
plants, or a minor series. Thus the 
plants in each cage, or minor series, 
represented all 3 tubers of the major 
series, and one uninoculated minor 
series served as a control to the others. 
At the time of the first inoculation the 
average height of the plants was about 
7 cm. One application was given to 
each series with the exception of series 
A-III and B-I1I which received three 
inoculations at weekly intervals. The 
results of these inoculations for 1922 
and 1923 are recorded in Table III. 
Here each major series is denoted by a 
letter and each minor series or cage by 
the letter with a Roman numeral. 
Repeated inoculations with mild 
mosaic in series A-III produced a 
higher percentage of diseased plants 
than the single inoculation in series 
E-III between the same varieties, 
while the same is true of spindle 
tuber but with a smaller difference. 
The symptoms in those two series 
appeared the same regardless of the 
difference in the number of inocula¬ 
tions. In 1923, spindle tuber appeared 
in every variety including the seedling. 
The percentage of infection with this 
malady was higher than with any 
other disease represented in these 
inoculations, even in the series origin¬ 
ally healthy as indicated by the con¬ 
trols. No mottling resulted from in¬ 
oculations with mild mosaic on Irish 
Cobblers in series B-III, which is in 
marked contrast to the high percent¬ 
age of infection obtained with three 
applications of the same inoculum on 
Green Mountains in series A-III. 
Also, with a single inoculation, the 
slight amount of infection in Green 
Mountains, Bliss Triumphs, and seed¬ 
ling 39374 was absent in Irish Cobblers. 
“Mosaic dwarf” inoculations pro¬ 
duced rugose mosaic and spindle tuber 
in Green Mountains and in Bliss 
Triumphs but not in Irish Cobblers 
(considering the controls). In the 
seedling, one hill showed streak in 1922, 
followed in 1923 by either no growth or 
extreme dwarfing. These facts indicate 
that “mosaic dwarf” may sometimes 
consist of a combination of rugose 
mosaic, spindle tuber, and .streak. 
The inoculum from the seedling plants 
produced spindle tuber in Green Moun- 
8 Schultz, E. S., and Folsom, D. Op. cit. p. 65. 76, 79. 
9 Schultz, E. S., and Folsom, D. Op. cit. See Table XVII. 
EXPLANATORY LEGEND FOR PLATE 5 
A.—Spindling-sprout tuber Photographed on May 2, 1923. See Plate 5, B, for other tubers fiom the 
same lot, and Plate 5, C, for the plants grown from this tuber 
B —Tubers from the same lot as that shown in Plate 5, A, but without spindling sprouts. Photographed 
on May 2,1923. See Plate 7, B and C for the plants grown from these tubers 
C—Plants grown from the tuber shown in Plate 5, A. Photographed on Aug. 11, 1923. Leaf-roll and 
mild mosaic are present 
D —Green Mountains of series 111 of Table II. The small hill represents the progeny of the inoculated 
hills and is infected with rugose mosaic and unmottled curly dwarf. The large hill represents the progeny 
,of the sister hills of the inoculated hills, and is healthy. Photographed on Aug. 27, 1923. See Plate 4, D, 
1 or the source of inoculum 
E.—Green Mountains of series 139 of Table II. The small hill represents the progeny of the inoculated 
hills and is infected with a leaf-rolling-mosaic spindle-tuber combination commonly known as curly dwarf 
(distinct from unmottled curly dwarf). The large hill represent the progeny of the sister hills of the in¬ 
oculated hills, and is healthy. Photographed on Aug. 11, 1923. See Plate 4, E, for the source of inoculum. 
Compare with Plate 1, B, and Plate 4, B and C 
