July i, 1925 Overwintering and Dissemination of Cucurbit Mosaic 
47 
the remainder of the plant shows no evidence of the disease. Inocu¬ 
lations from various parts of such plants to healthy martynias have 
indicated that the infective principle is localized in the branches, 
which show visible symptoms of the disease. Eventually, however, 
the entire plant develops definite symptoms of mosaic. While these 
cases are somewhat abnormal in martynia, they are of great interest, 
since in all other plants which have been infected with cucurbit 
mosaic, the symptoms of the disease manifest themselves at all 
growing points at approximately the same time. Mosaic martynia 
plants are much dwarfed when infected with mosaic and the older 
leaves wilt and die in a manner very similar to those of the cucumber 
(pi. 5, A, B). In most cases the fruits are much dwarfed but show 
no mottling, but in one instance plants were found whose fruits were 
slightly mottled with yellow and showed wartlike protuberances 
very similar to those found on mosaic cucumber fruits. 
Experiments with Pepper Plants 
CROSS INOCULATIONS FROM MOSAIC CUCUMBERS TO THE PEPPER 
The appearance of a mosaic disease on pepper plants {Capsi¬ 
cum annuum L .) which were growing in the vicinity of mosaic 
cucurbits led to the first cross inoculations with this host. The 
cucumber aphis will occasionally feed on the pepper, and it was 
found that cucurbit mosaic could be transmitted to the pepper by 
means of these insects. As in the case of martynia, the disease was 
later successfully transmitted to the pepper by artificial methods of 
inoculation, but the percentage of infection has always been consid¬ 
erably lower by this method than when aphids were used. The 
results of the inoculations from the cucumber to the pepper are given 
in Table XIX. As in the case of martynia, there is considerable 
field evidence of the transmission of mosaic from the cucumber to the 
pepper. Where pepper plants are grown next to mosaic cucumber 
plants in the field, a large percentage of the plants have always shown 
symptoms of mosaic before the end of the season. The experimental 
E lat in which these experiments were conducted was at a considera¬ 
te distance from any fields of tobacco or tomatoes and there was no 
reason to believe that the infection on the pepper had come from any 
source other than the cucumber. 
CROSS INOCULATIONS FROM MOSAIC PEPPERS TO THE CUCUMBER 
Cross inoculations from mosaic peppers to healthy cucumber 
plants have been successful, as shown by the data in Table XX. 
These inoculations were made from peppers inoculated from mosaic 
cucumber plants and also from those found naturally infected with 
mosaic in the field. The inoculations from naturally infected pepper 
plants included those grown near mosaic cucurbits and presumably 
infected from that source and also mosaic plants found at other points 
where there were no mosaic cucurbits in the neighborhood. Infection 
was brought about both by artificial methods of inoculation and by 
,the use of aphids, but the latter method was considerably more 
successful although artificial inoculations have given a considerably 
higher percentage of infection than in the case of the inoculations 
from cucumber to pepper. 
