64 BULLETIN 879, U. S. DEPARTMENT OF AGRICULTURE. 
INSECT CONTROL. 
The attempts at insect control have been under the direction of 
Mr. Neale F. Howard, of the Bureau of Entomology. This work 
was conducted at Madison, Wis., and Plymouth, Ind., and is still 
in progress. It is possible to control insects to such a degree as will 
prevent severe injury to the plants, but complete insect elimination 
is necessary to prevent disease transmission by them, and methods 
for accomplishing this have not yet been worked out. In the green- 
house, insect elimination is more easily possible, and if the grower 
is well acquainted with mosaic he might succeed in eradicating or 
at least so checking the disease that little loss would occur. In 
the field, however, some further knowledge of the method of over- 
wintering of the disease and the cause of its sudden appearance in 
the spring is necessary before adequate methods of control can be 
devised. 
RESISTANT VARIETIES. 
Attempts have been made to obtain a variety of cucumber re- 
sistant to the mosaic disease, but so far this work has been unsuc- 
cessful. Selections made in a mosaic field at Muscatine, Iowa, in 
1915 by Mr. W. W. Gilbert were tested at Holland, Mich., in 1916, 
but the amount of infection present in the field was not sufficient 
for a fair trial. Selections from this strain which gave some promise 
of resistance were again planted at Madison, Wis., in 1917, but all the 
plants developed mosaic symptoms early in the season. During the 
past four seasons the writer has never observed any indication of 
resistance in any variety of cucumbers, and the fact that little 
evidence of resistance has appeared in the case of other mosaic 
diseases indicates that the development of a resistant variety is 
likely to be difficult, if at all possible. 
SUMMARY. 
The mosaic disease of cucurbits has apparently been present in 
the United States for nearly 20 }^ears, but prior to 1914 its im- 
portance was practically unrecognized. 
The disease appears both in the field and in the greenhouse in 
nearly all sections where cucurbits are of commercial importance. 
Nearly all cultivated cucurbits are susceptible to the disease, but 
the cucumber crop seems to be most seriously affected, particularly 
in the Central States and the trucking regions of the South. 
The diseased plants develop a yellow mottling of the younger 
leaves, accompanied by a wrinkled or savoyed appearance. The 
older leaves gradually turn yellow and die, leaving the basal por- 
tion of the stem bare. These bare stems terminate in a rosettelike 
cluster of dwarfed leaves, which lie close to the ground, owing to the 
