496 
Journal of Agricultural Research 
Vol. XXX, No. 6 
treatments. A number of series showed 
current season symptoms in 1922 which 
are noted in a previous paper. 3 Only 
inoculations performed in the Green 
Mountain variety are included in 
Table I. 
The disease recorded in the controls 
was contracted because the plants of 
the first generation grew close to dis¬ 
eased vines with transmitting insects 
of at least one species present. Mild 
mosaic, rugose mosaic, and spindle 
tuber spread more to the controls than 
did the other diseases. Inoculations 
with mild mosaic are not included in 
Table I, since most of the controls in 
these series became infected with the 
same disease. However, the high per¬ 
centage of mild mosaic observed in the 
progeny of the inoculated plants in 
comparison with the percentage in 
other series, indicates that the inocula¬ 
tion was generally effective. It will 
be noted that the 1923 progeny of the 
lots serving as sources of inoculum re¬ 
tained the same symptoms as the 1922 
parents, with the exception of the 
apparent addition of rugose mosaic in 
series 38 from field infection. 
As in the first generation, inocula¬ 
tions with rugose mosaic resulted in a 
high percentage of disease. The char¬ 
acteristic symptoms of this disease 
resembled those in the inoculated plants 
in 1922. Rugose mosaic occurred in 
combination in series 10, 38, 79, 83, 
and 127 apparently as a result of inocu¬ 
lation. Another combination inocula¬ 
tion, with leaf-rolling mosaic and 
spindle tuber, was obtained in series 
136. As indicated in a previous 
paper 3 modifications of symptoms oc¬ 
curred in these combinations. Nega¬ 
tive results were obtained with juice 
from plants having glabrous, more 
or less crisp and fleshy leaves suggest¬ 
ing mutation, 4 except for the spindle 
tuber originally in combination. As 
indicated, in series 95, spindle tuber 
was associated with the mutation, 
becoming obvious when the source of 
inoculum was dug in 1922. In series 
22 the tuber cracking of unmottled 
curly-dwarf appeared as a current-sea¬ 
son symptom without the tuber spin¬ 
dlingness, followed by the usual vine 
and tuber symptoms in the progeny 
(pi. 1, A, B, C, and D). 
As in 1922, streak occurred alone 
and in combination with rugose mosaic. 
Perpetuation of streak through the 
tubers soon ceases because of the lack 
of progeny. However, a strain of 
streak from one source has been per¬ 
petuated without any apparent combi¬ 
nation or change, through four succeed¬ 
ing seasons by means of leaf mutilation 
inoculation of a new lot each season. 
Therefore streak is to be regarded as a 
distinct disease, even though it is 
closely resembled by a streaking which 
may occur as a first-season symptom of 
rugose mosaic, as previously recorded. 5 
It is noteworthy that streak alone causes 
more severe dwarfing in the second 
generation than results from most com¬ 
binations of degeneration diseases (pi. 
2). The writers have not yet been 
able to distinguish more than one kind 
of streak, this one including leaf drop¬ 
ping, spotting of the corollas, and both 
spotting and streaking of the leaves 
(pis. 2, 3, and 4, A). 
INTERVARIETAL LEAF MUTILATION IN¬ 
OCULATIONS IN THE FIELD 
Intervarietal leaf mutilation inocu¬ 
lations were performed in the open 
field in 1922 with the same procedure 
and under the same conditions as are 
described in connection with Table I. 
Plants with different symptom aggre¬ 
gates in Irish Cobblers, Rural New 
Yorkers, Bliss Triumphs, and three 
different seedling lots, served as sources 
of inoculum for the inoculation of 
healthy Green Mountain plants. The 
current-season reactions to these treat¬ 
ments are described in a previous 
paper. 6 The second generation re¬ 
actions are given in Table II of the 
present paper. 
Mild mosaic was produced only in 
series 42, 46, and 54, with Bliss 
Triumph as the source of inoculum. 
In series 54 the Bliss Triumph foliage 
showed marked crinkling in addition 
to the apparent mild mottling. As 
indicated, this symptom complex was 
manifested also in the inoculated Green 
Mountain plants as crinkle mosaic. 
The results with leaf-roll, as in 
former leaf-mutilation inoculations, 
were negative. (Series 71.) 
The reactions in series 111, 113, 117, 
119, and 121 regarding mosaic in the 
inoculated plants varied from those in 
the source of inoculum; although 
mottling could not be detected in the 
Rural New Yorker plants, it appeared 
either as the leaf-rolling or rugose 
mosaic type in the inoculated Green 
Mountain plants, indicating a varietal 
3 Schultz, E. S., and Folsom, D. Op. cit. See Table XVII. 
4 Folsom, D. mutations of the potato, two somewhat unstable leaf-form sports of the 
irtsh potato. Jour. Heredity 14: 45-48, illus., 1923. 
5 Schultz E. S.. and Folsom, D. Op. cit. p. 79. 
6 Schultz, E. S., and Folsom, D. Op. cit. See Table XVII. 
