478 BOTANICAL GAZETTE [JUNE 
years after tomatoes have been grown. The mosaic in field no. 7 
probably was due to the tomatoes in the field at the time, since 
many of these also showed the disease. The scarcity of the disease 
in field no. 8, which had never been in tomatoes, indicates that the 
high incidence of mosaic in field nos. 1 to 6 was due to the previous 
tomato crops. 
DISTANCE MOSAIC MAY SPREAD 
Field no. 8 had never been in tomatoes before, and the nearest 
tomato crop, that of 1919 in field no. 1, was 400 feet distant. The 
few cases of Physalis mosaic in field no. 8 were found along the edge 
nearest to field no. 1, and are probably attributable to long distance 
transmission of mosaic from that crop. In a wheat stubble field 
which had never been in tomatoes, mosaic was found on Physalis 
along the edge adjacent to one of the 1919 tomato fields (field no. 3) 
in a strip 150-200 feet wide. No mosaic Physalis plants were 
noted at a distance of 250 feet from the edge of the field. The 
occurrence of mosaic Physalis plants along the edges of fields adja- 
cent to the Frankfort experimental field has previously been noted. 
The occurrence of two mosaic Physalis plants 40 rods distant from 
this field, if attributable to spread from the tomatoes, would 
represent an exceptionally long distance of mosaic transport. 
Surveys of numerous wheat stubble and corn fields have revealed 
that mosaic very rarely occurs on Physalis plants except in the 
vicinity of tomato crops, past or present. In only two instances 
have apparently spontaneous cases of mosaic on Physalis been 
found. One mosaic plant was found in a wheat stubble near 
Knightstown, and another in a corn field near Monticello. In the 
light of such observations it is unsafe to assume that mosaic is 
indigenous in these wild hosts. It seems evident, however, that 
once the disease is introduced by means of tomatoes, it may become 
enphytotic in the Physalis flora of the immediate vicinity. 
PREVALENCE AND oo OF PHYSALIS AND MOSAIC 
TOMATO FIELDS 
To ascertain the pie prevalence of Physalis and Physalis 
mosaic in Indiana tomato fields, and the correlation between these 
factors and mosaic in the tomato crop, a number of tomato fields 
