480 BOTANICAL GAZETTE [UNE 
wilt in these imported transplants necessitated the use of large 
numbers of locally grown replants to fill the blank spaces. Mosaic 
was distinctly more prevalent on these locally grown re- 
plants. 
An examination was made of the plant-beds in three localities 
which served as sources of these replants, and Physalis plants were 
found in or near these beds in all cases. No mosaic, however, was 
noted on these Physalis plants. The replants from one of these 
localities had been very generally diseased in every field in which 
they were used, and on July 20 mosaic was found very general on 
the tomato plants remaining in the outdoor plant-beds from which 
these replants had been taken. These plant-beds were grown up 
to weeds at this time, and thirty Physalis plants were found, but 
none showed mosaic. In fact, Physalis was a particularly abundant 
weed in this neighborhood, and was also noted in the coldframes of 
another grower. 
The occurrence of Physalis plants in and about coldframes and 
plant-beds is considered of especial significance, because here 
tomato plants are grown year after year, and once mosaic gains a 
foothold in these weeds, all succeeding crops of tomato plants will 
be exposed to infection before they are transplanted to the fields. 
This source of infection is considered especially dangerous, because 
from the plant-beds the disease may be introduced into numerous 
fields, and because mosaic reduces the yield much more severely 
on plants infected when very young. It has been shown that the 
mosaic disease, once introduced into a locality, may persist year 
after year in the perennial weed relatives of the tomato. Since, 
under Indiana conditions, canning tomatoes are grown in rotation 
with other crops, and many new fields are being used each year 
for tomato production, the mosaic disease will undoubtedly be 
thus introduced into the perennial weed flora of new fields and 
localities each season. This will inevitably result, it would seem, 
in the disease becoming more and more widespread in the weed 
flora each year, and consequently in an alarming annual increase 
in the reservoir of mosaic infection for future tomato crops unless 
the vicious cycle is broken. 
