4«4 
Journal of Agricultural Research 
Vol. VII, No. ii 
ing 9 plants were inoculated in the same manner with the virus of the 
mosaic disease of N. tabacum . For a period of several weeks numerous 
inoculations were made from time to time in each lot of plants. The 
plants of each lot were also cut back severely several times and the virus 
inoculated into all cut surfaces. The plants were kept under observa¬ 
tion for several months. Every plant in the series inoculated with the 
virus of the mosaic disease of N. viscosum developed the disease, the 
first observable symptoms appearing 21 days after the first inoculation. 
In this experiment the datura plants proved to be highly resistant to the 
virus of the mosaic disease of N. tabacum , as none became diseased. In 
those plants affected with the mosaic disease of N. viscosum the symptoms 
were particularly malignant. The leaves became greatly curled, wrinkled, 
and depauperate. Mottling of the leaves, however, was less marked 
than in those instances where Datura stramonium has been affected with 
the mosaic disease of N> tabacum . 
The virus of the mosaic disease affecting N. viscosum differs from the 
virus of the mosaic disease of tobacco as follows: 
CHARACTERISTICS OR THE VIRUS OP THE 
MOSAIC DISEASE OP TOBACCO (n. 
tabacum) 
(1) Transmission through the seed has 
never occurred. 
(2) Incubation period short (minimum 
6 days). 
(3) Needle inoculations readily pro¬ 
duce the disease. 
(4) All attempts to infect belladonna 
(Atropa belladonna) and Solanum tubero¬ 
sum have been unsuccessful. 
, (5) All attempts to infect poke weed 
(.Phytolacca decandra) have been unsuc¬ 
cessful. 
(6) All attempts to infect the hybrid 
N. tabacum 9 X N. viscosum <£ have been 
unsuccessful. 
(7) Highly infectious to tomatoes. 
(8) Infectious to the pepper ( Capsicum 
cerasiforme). 
(9) All attempts to infect sweet peas 
have been unsuccessful. 
(10) All attempts to infect Datura fas- 
tuosa (Golden Queen variety) have been 
unsuccessful. 
(11) Affects Jimson weed ( Datura stra¬ 
monium) producing typical symptoms. 
characteristics of the virus op the 
MOSAIC DISEASE AFFECTING N. VIS¬ 
COSUM 
(1) Transmission through the seed has 
never occurred. 
(2) Incubation period in N. viscosum 
rather long (minimum may be several 
weeks). 
(3) Needle inoculation rather uncer¬ 
tain. Grafts of mosaic-diseased shoots of 
N. viscosum upon susceptible plants 
readily produce infection. 
(4) All attempts to infect belladonna 
and Solanum tuberosum have been un¬ 
successful. 
(5) All attempts to infect poke weed 
have been unsuccessful. 
( 6 ) The hybrid N. tabacum 9 X N. 
viscosum $ is susceptible, manifesting 
typical symptoms of the disease. 
(7) All attempts to infect tomatoes have 
been unsuccessful. 
(8) All attempts to inoculate the pepper 
have been unsuccessful. 
(9) All attempts to infect sweet peas 
have been unsuccessful. 
(10) Datura fastuosa (Golden Queen 
variety) is susceptible, manifesting symp¬ 
toms more or less typical of the disease. 
(11) Affects Jimson weed, producing 
symptoms very similar to those produced 
