2 BULLETIN 879, U. S. DEPARTMENT OF AGRICULTURE. 
these were true mosaic, as the disease was not proved to be infectious 
in any case and no mention was made of symptoms on the fruit. 
Selby (27) stated in 1910 that cucumber mosaic was transmitted like 
that on tobacco. There is no early record of the disease in the field, 
but it is certain that it had caused serious losses in the Central States 
for some time prior to 1914, and from evidence obtained from pickle 
men in the vicinity of Chicago it is practically certain that the mosaic 
had been a serious disease in that section for 10 to 15 years and was 
responsible for forcing at least one pickle company out of business. 
Kuggles and Stakman (25) in 1911 reported the mosaic as occurring 
in Minnesota and used the name wart disease in describing it. Coons 
(10) in 1915 reported that this disease was then causing serious losses 
in the field in Michigan and had been present in some localities for 
seven years. He described the chief symptoms and stated that the 
progress of the disease indicated that it was infectious. 
The first proof of the infectious nature of the disease and the 
methods by which it is transmitted was presented in the papers of 
Gilbert (14), Jagger (17), and Doolittle (11) in 1916. Jagger (18) 
later reported the appearance of another type of cucumber mosaic, 
affecting only the leaves of the plant, and in a further paper (19) 
mentioned a third type as occurring on Summer Crookneck squash. 
Stakman and Tolaas (28) mentioned nubbin or wart disease of 
cucumber as an infectious disease occurring in both the field and 
the greenhouse in Mimiesota. McClintock (22) in 1916 observed 
possible cases of transmission of the disease through the seed and 
described its occurrence in the district near Norfolk, Va. Clinton (9) 
also gave data as to the severity of the disease in Connecticut. 
Freiberg (13) in 1917 reported the disease on various cucurbits in 
Missouri and described inoculation experiments. Jagger (20) in 
1918 also reported numerous cross-inoculations from cucumber to 
other cucurbits and showed that cucumber mosaic could be trans- 
mitted to plants outside the Cucurbitacese. 
These papers include all the available material on cucumber 
mosaic to the present, with the exception of an abstract by Doolittle 
and Gilbert (12) which dealt with certain phases of the work here 
considered in greater detail. 
GEOGRAPHICAL DISTRIBUTION. 
The general occurrence of cucurbit mosaic in the field was not 
recognized until after these studies were begun, but investigation 
has shown that it is widely distributed on Cucurbitacese throughout 
the United States. Doubtless the extensive cultivation of cucumbers 
makes it seem more common on that crop, but it may occur on prac- 
tically all cucurbits in localities where it is found on cucumbers. 
The disease is probably most widespread and serious in Wisconsin, 
Michigan, Indiana, northern Illinois, and on Long Island. It is re* 
