THE MOSAIC DISEASE OF CUCURBITS. 6 
ported to have caused serious losses in Illinois as early as 1908 and 
was present about as early in Michigan and Wisconsin. The center 
of the pickle-growing industry is located in these States, which 
devote a large acreage to the crop. Here the disease is present to 
some extent in almost all localities, and in most cases there is infec- 
tion every year. 
The disease occurs commonly in New York and is becoming serious 
in the seed-growing districts of Ohio and Iowa. It has been found 
quite prevalent in the fields around Rocky Ford and Greeley, Colo., 
causes severe losses in the trucking region about Norfolk, Va., and 
does much injury in many sections of Florida and Louisiana. Recent 
inspections of the principal city markets of the Western and Pacific 
Coast States have shown the mosaic disease to be present in practi- 
cally all of them, and in many cases it was very prevalent. It is 
also reported in the field from Maine, Massachusetts, Minnesota, Ver- 
mont, Connecticut, West Virginia, New Jersey, Pennsylvania, 
Georgia, Texas, California, Nebraska, and Ontario, Canada. 
In the greenhouse it has caused serious injury for several 
years in Michigan, Wisconsin, Illinois, and New York and has also 
been reported from Mississippi, Ohio, Indiana, Minnesota, Pennsyl- 
vania, Louisiana, and Kansas. Up to the present the disease has 
been found only in the United States and Canada, but the fact that 
it has not been reported from other parts of the world may be due 
to its not having been extensively studied elsewhere. 
ECONOMIC IMPORTANCE. 
Cucurbit mosaic is the most serious disease of cucumbers in the 
Middle West, and yearly it increases in severity in districts where 
this crop is grown on a large scale. The disease is not confined to 
the cucumber, but causes considerable loss on the muskmelon and 
to a less extent on squash and pumpkin. 
The greater losses on the cucumber are due partly to the special 
severity of the disease on the fruits of this host, but more especially 
to the fact that the acreage of cucumbers far exceeds that of any 
other cucurbit. The increase in the pickling and trucking industries 
in certain sections has localized much of this crop in restricted areas, 
and thus furnished conditions very favorable to the spread of such 
a highly infectious disease. The other cultivated cucurbits ordi- 
narily are grown on a smaller scale, and thus the loss is distributed 
among many small growers, so that it is less noticeable. Cucumber 
plants infected with mosaic are practically worthless, owing to the 
great reduction in yield and to the fact that the fruits produced 
are so mottled and deformed that they are usually refused by pick- 
ling companies and are of little value for market purposes. The 
disease spreads very rapidly, and many fields may become 50 to 75 
per cent diseased almost before picking has begun. As a result of 
