OVERWINTERING OF TOMATO MOSAIC: 
Max W. GARDNER AND JAMES B. KENDRICK 
(WITH PLATE XVII) 
The annual recurrence of the mosaic disease in epiphytotic form 
in the canning tomato crop of Indiana has made it highly important 
to ascertain the mode of overwintering of the causal virus. It 
seemed within the realm of possibility that the virus might be per- 
petuated over winter in hothouse tomato crops, in tomato seed, in 
related perennial weed hosts, and by insects. The agency of insects 
in this connection has not been studied. The’work of McCuintock 
and SMITH (9) on aphids as carriers of spinach blight would indicate 
that such insects might perpetuate other mosaic viruses, but 
McC iintock (10) has been unable to find this true for tomato 
mosaic. Doo.ittrte’s (7) work on cucumber mosaic has failed to 
incriminate any of the insects studied in connection with that disease. 
The present work has to do mainly with the second and third 
possibilities just mentioned. 
Hothouse tomatoes as carriers 
The mosaic disease has been found very commonly in hothouse 
tomato crops, and in the immediate neighborhood of hothouses it 
is possible that the disease may be carried from the late hothouse 
crop to the field crop plant-beds. This danger is very great in 
cases in which the plants for the field crop are started in hothouses 
or coldframes adjacent thereto. In one case noted in June 1920 at 
okomo, a severe early infestation of mosaic was present in a 
field, the plants for which had been grown in part of a hothouse 
occupied by a tomato crop. In fact, mosaic was found on many of 
the tomato plants left in the plant-bed. Hothouse tomatoes, how- 
€ver, are grown only in a relatively few localities in the state, and 
are usually near the towns and cities. The canning tomato crop, 
on the other hand, is contracted primarily among general farmers 
*Contribution from the Botanical Department of Purdue University Agri- 
cultural Experiment Station, Lafayette, Indiana. 
469] {Botanical Gazette, vol. 73 
