10 
Journal of Agricultural Research 
Vol. XXXI, No. 1 
this latter fact confirmed the results of the seed trials, a series of 
observations was made each year at points where mosaic Micrampelis 
plants had originally been noted. 
CAGING EXPERIMENTS 
Early in the spring of 1919 large cheesecloth cages were constructed 
over two spots where mosaic wild cucumbers had been found during 
1917 and 1918. The cages covered a space of 4 by 6 feet and were 
3 feet high, with the lower edge sunk 6 inches in the ground. The 
first cage was put down on April 10 before any of the Micrampelis 
seed had germinated, and the second was set out on May 1 over 
seedlings that had just appeared. No striped beetles or other 
cucumber insects had appeared at this time and the seedlings showed 
no evidence of insect injury. The cages were watched carefully in 
order to repair any breaks in the cloth and, as far as could be deter¬ 
mined, no insects gained entrance during the experiment. On May 
28 the plants in the cages were examined, and in the first cage 2 out 
of 11 plants showed definite mosaic symptoms. In the cage put 
down on May 1, 4 out of 26 plants were mosaic diseased. No insects 
were found in the cage and the plants showed no insect injury. It 
having been shown that the soil is not a carrier of the disease, these 
results offered further indication that the seed of Micrampelis acts 
as a carrier of cucurbit mosaic. 
FIELD OBSERVATIONS 
Various centers of mosaic wild cucumber plants found between 
1917 and 1919 have since been kept under observation in |order to 
determine the exact period at which the disease appears in the spring. 
These observations, begun in 1918 ( 8 ), have given abundant evidence 
that the disease develops in the same spot each season and that its 
appearance may be noted on the plants while in the seedling stages. 
The results, as shown in Table II, include observations at 12 of these 
points, in all of which the disease was found during successive seasons. 
Table II .—Record of appearance of mosaic on seedlings of Micrampelis lobata at 
same points during successive seasons 
Period of observations 
Plant 
group 
Locality 
May 1 to June 1, 
1919 
May 1 to June 1, 
1920 
May 1 to June 1, 
1921 
Number 
of 
plants 
Number 
of mosaic 
plants 
Number 
of 
plants 
Number 
of mosaic 
plants 
Number 
of 
plants 
Number 
of mosaic 
plants 
« I 
Madison, Wis__ 
68 
9 
12 
2 
0 
II 
__ __do__ _ 
90 
15 
41 
9 
49 
6 
“III 
.do.. .... 
108 
9 
72 
11 
32 
' 7 
“IV 
_do______ 
40 
i 
30 
4- 
33 
6 
V 
.do.... __ 
15 
3 
15 
2 
34 
5 
VI 
__ _ do ___ 
29 
3 
21 
5 
39 
5 
VII 
_,_do_ ___ 
(*) 
( b ) 
( b ) 
625 
60 
300 
18 
VIII 
_do_ _ 
28 
3 
76 
9 
IX 
Portage, Wis_ 
350 
25 
250 
34 
X 
Marengo, Ill _ __ 
125 
- 8 
89 
11 
XI 
do_ __ _ __ 
35 
7 
19 
4 
XII 
_do_ __ _ 
10 
2 
! . 28 
4 
Ppt cent oi plants mosaic-. 
13 
l 
10 
11 
1 
! 
° Mosaic plants also found during May, 1918. b Mosaic plants found during July and August. 
