THE MOSAIC DISEASE OF CUCURBITS. 15 
by the growers in Michigan and Wisconsin for some years. The 
more common green and distorted fruits were classed with the imper- 
fect types which are often produced under unfavorable soil or climatic 
conditions, as the name " nubbin" in use in Minnesota indicates. 
All these names, however, neg]ect the mottled character of both 
leaves and fruits, which is the symptom most typical of the disease. 
Since the term mosaic had already been applied to a disease of 
tobacco and other plants in which the symptoms and general char- 
acter were much like those on the cucumber, it seemed best to adopt 
the same name in this case as being more descriptive of the real 
nature of the disease than those already in use by the growers. 
On vines which are old and stunted another type of fruit often 
occurs which is abnormally dark green, with little or no mottling. 
Such fruits have a smooth surface, but are much distorted and swollen 
in appearance and are found only at the end of the season on 
vines which have nearly ceased to set fruit. Vines occasionally 
appear to recover from the effects of the disease and toward the end 
of the season produce fruits with no visible mosaic symptoms. 
Many mosaic fruits show a tendency to become russeted while 
still green, and in the case of the whitish fruits before described this 
tendency is very marked. As they turn yellow and ripen, the fruits 
which show less marked mosaic characters may be almost indis- 
tinguishable from those of healthy plants, but in general they retain a 
misshapen and dwarfed appearance. Seed is usually produced, but 
in the case of fruits set during the later stages of the disease, the seed 
is slow to mature and often small and shrunken. Mosaic fruits may 
also have a slightly bitter flavor, particularly those from plants 
which have had the disease for some time, but this is not a common 
symptom. 
Fruit symptoms on other cucurbits. — Although the leaves of all the 
cucurbits susceptible to mosaic show symptoms which have the same 
general character, the fruits in some cases show no evidence of the 
disease aside from a reduction in size. In general, however, the 
fruits of other mosaic cucurbits have the same mottled and warty 
appearance that is found on those of the cucumber, although these 
symptoms are often less marked or almost obscured as the fruit 
reaches maturity. 
The young fruits of mosaic muskmelon plants are often mottled, 
and a few dark-green warts may appear, but as the fruits mature the 
symptoms of the disease become less pronounced and the fruits are 
nearly normal in appearance. In the case of the Hubbard squash 
the young fruits of mosaic plants are sometimes mottled and lighter 
in color than those of healthy plants, but these symptoms are 
apparently obscured at maturity by the natural wartiness of the 
fruit. On the Summer Crookneck squash, however, the fruits are 
