1922] GARDNER & KENDRICK—TOMATO MOSAIC 481 
MOsAIC TRANSMISSION 
The means by which the mosaic disease may be transmitted 
from Physalis to tomato have not been thoroughly studied, although 
from analogy with other mosaic diseases it has seemed safe to 
assume that insects are the responsible agents. Certain it is that 
insects are responsible for much of the spread of mosaic among 
tomatoes, because, by the use of cages to exclude insects, the 
occurrence of mosaic has been uniformly prevented. Plants thus 
caged remain free from mosaic in badly diseased fields. 
The occurrence of aphids on mosaic Physalis plants early in the 
season, and the successful transmission of the disease to a tomato 
plant by these insects has been mentioned. Flea-beetles (Epitrix 
cucumeris) are abundant on Physalis plants throughout the season, 
and these insects also attack young tomato plants. A preliminary 
test indicates that they may carry the disease. On July 16, 1921, 
a number of flea-beetles collected on mosaic Physalis plants were 
placed in a large cloth cage containing young tomato plants. On 
August 17 six of the 338 plants in this cage showed mosaic, while 
no mosaic was found in the 218 control plants in a similar cage in 
which no flea-beetles had been placed. 
Mosaic ON PHYSALIS HETEROPHYLLA AND SOLANUM CAROLINENSE 
Although not as abundant as the two Physalis species previ- 
ously discussed, Physalis heterophylla and Solanum carolinense 
are of common occurrence in cultivated fields in Indiana, the former 
usually in sandy soils. Mosaic in a conspicuous form was found in 
abundance on both of these species in a peach orchard near Vin- 
cennes, June 28,1921. Aclump of five mosaic P. heterophylla plants 
was found on July 27 along the edge of a field near Lafayette in 
which tomato mosaic occurred the previous year. Mosaic was 
noted on S. carolinense near a canning factory at Indianapolis, 
September 7. Successful cross inoculations of mosaic from both 
of these species to tomatoes have previously been described. Both 
species are commonly attacked by flea-beetles. 
Among the eighty-one tomato fields visited in the survey, 
P. heterophylia was noted in seven fields and S. li: in thirteen 
