5 ° 
Journal of Agricultural Research 
Vol.XXV, No. a 
INSECT INOCULATIONS 
It is thought that mild mosaic alone was involved with several experi¬ 
ments previously reported (45, p. 261—66; 40 , p. 326-28; 41 , p. 54 ~ 55 ) 
as giving transmission with aphids within Green Mountains, but further 
experiments were made. 
In 1921, six healthy hills of as many tuber units were caged, each 
cage containing two of these hills separated by a hill having both mild 
mosaic and the spindling-tuber disease. Potato aphids, Macrosiphum 
solanifolii Ashmead, 3 were introduced upon the diseased plants and from 
each of these either dispersed or were transferred to the healthy hill 
or hills in the same cage. Later they were sprayed with nicotine solu¬ 
tion. Data are presented in Table II. 
Two of the five inoculated hills became mosaic, with symptoms only 
in the progeny. The five control hills in the same tuber units but in 
different cages were healthy and their progeny, 15 tuber units, were 
healthy. It is to be noted that complete mosaic infection occurred only 
in the hill (No. 1 of cage B-3) where there was the earliest dispersal of 
aphids, where the aphids were not all killed by the first spray application, 
and where there was only one healthy hill to which to disperse. 
In 1921, in another cage, aphids transmitted both mild mosaic and 
spindling tuber (Table XVI, inoculation No. 14). 
Table II .—Mild mosaic and spindling-tuber inoculations of caged Green Mountains 
with aphids, in 1921 
Cage. 
Diseased hill. 
Healthy hills. 
Num¬ 
ber. 
Aphids intro¬ 
duced. 
Num¬ 
ber. 
Aphids transferred. 
Date of 
spraying 
for 
aphids. 
Progeny. 
Spind¬ 
ling- 
tuber. 
Total 
tuber- 
units. 
Mosaic. 
Per cent • 
Per cervU 
fjune 28. 
I 
July 9 and 13.. 
July 18. . 
4 
0 
O 
B-i 
2 
1 Tiilv n 
•7 
.do. 
4 
25 
O 
u ua j y . 
[June 28. 
0 
I 
July 9 and 18.. 
July 23.. 
2 
O 
IOO 
B-2 
2 
I July 9 and 
3 
4 
0 
75 
l July 13- 
X 
July 13 (dis¬ 
July 18 
5 
IOO 
O 
persal by 
and Aug. 
B-3 
2 
June 24. 
July 9)- 
22. 
1 3 
Further data on aphids will be given in connection with interspecific 
transmission. ■ . 
Negative current-season results have been reported from transferring 
flea beetles, Epitrix cucumeris Harris, in abnormally large numbers from 
mosaic to healthy plants (40, p. 329) . The progeny of the healthy plants 
were all healthy, whereas 65 per. cent of corresponding ones treated with 
aphids were mosaic. ... 
In 1920, flea beetles again were introduced from mosaic plants into 
field insect cages in large numbers and allowed to feed upon healthy 
» The authors wish to thank Dr. Edith M. Patch of the Maine Agricultural 
A. C. Baker of the Bureau of Entomology, U. S. Dept, of Agriculture, for frequent identifications of aphids 
