Journal of Agricultural Research 
Vol. XXV, No, a 
114 
(16) Leaf-mutilation inoculation of Green Mountains in 1921 effected 
intervarietal transmission of streak, rugose mosaic and streak together, 
rugose mosaic, leaf-rolling mosaic, and mild mosaic in insect cages 
(uncontrolled in the open field), but not leaf roll. With spindling tuber 
(uncontrolled in the open field) present in the progeny, leaf-rolling 
mosaic having been transmitted formed a curly-dwarf combination. 
Rugose mosaic was thus transmitted from Carman No. 3 (Rural group) 
to Rural New Yorker, and from this and two seedling varieties to both 
Green Mountains and Irish Cobblers, but the symptom complexes were 
not identical in any two varieties. 
(17) Streak did not appear the same before and after tuber perpetuation. 
(18) Comparison inoculations with juice in capillary glass tubes were 
much less effective than leaf mutilation, with rugose mosaic and streak. 
(19) Aphid inoculations of Green Mountains in 1921 effected inter¬ 
varietal transmission of leaf-rolling mosaic from curly-dwarf plants in 
three varieties of the Rural group, of unmottled curly dwarf and spin¬ 
dling tuber (separately) from Irish Cobblers, of rugose mosaic from one 
seedling variety, and of leaf-rolling mosaic and rugose mosaic together 
from two seedling varieties. Aphids also transmitted rugose mosaic to 
Irish Cobblers from two seedling varieties. 
(20) Leaf-mutilation inoculations of Green Mountains in 1922 resulted 
in current-season symptoms of streak, rugose mosaic and streak com¬ 
bined, and rugose mosaic with and without streaking. Comparison 
inoculations with mild mosaic, leaf roll, and spindling tuber gave no 
current-season symptoms in the open field. Comparison inoculations 
under insect cages gave current-season symptoms with mild mosaic and 
spindling tuber. Several different symptom complexes yielded only 
rugose mosaic as the current-season effect of inoculation, sometimes 
with rugose mosaic somewhat masked in the original complex. Results 
with Green Mountains were somewhat duplicated in Irish Cobblers and 
Bliss Triumphs, but some varietal modification of symptoms apparently 
occurred in these and seedling varieties. 
(21) In greenhouse inoculations, transmission of mild mosaic from 
Bliss Triumphs to Green Mountains was effected to some extent with 
juice in capillary glass tubes, but not with immersion of a split stem in 
diseased juice. It was effected more readily with leaf mutilation as the 
number of inoculated leaves was increased, and more readily with aphids 
as the number of individual insects was increased, being possible with 
one individual aphid. 
(22) In greenhouse leaf-mutilation inoculations, rugose mosaic was 
transmitted from a seedling variety to Green Mountains and from Green 
Mountains to Irish Cobblers, but leaf roll was not transmitted from Irish 
Cobblers to Green Mountains. 
(23) Interspecific inoculations with leaf mutilation and aphids indicate 
that tobacco mosaic is not identical with potato mild mosaic, that tomato 
is susceptible to both of these mosaics and also to potato rugose mosaic, 
and that nightshade (Solatium nigrum L.) is susceptible to potato mild 
mosaic. Raspberry mosaic seems harmless to potatoes. 
(24) The various degeneration diseases of potatoes are different as to 
their economic importance resulting from their distribution and effect 
upon yield rate and quality. 
(25) Natural transmission by insects contributes to the difficulty of 
the control problem. 
(26) Perpetuation occurs in tubers and not in soil alone. 
