THE MOSAIC DISEASE OF CUCURBITS. 67 
(4) the caging. of plants to Jseep insects away. None of these methods 
has proved entirely effective and practicable under field conditions. 
In the field, removal of diseased plants has proved of little value 
except for the first cases early in the season, because they may be 
sources of infection for one to three days before they are found. 
Even with the best insect-control methods available, enough beetles 
are left to cause a wide dissemination of mosaic. All efforts at find- 
ing strains of cucumbers resistant to the disease have given negative 
results. The use of cages is practicable for a few plants in the 
home garden, but not feasible on larger areas. 
Under greenhouse conditions the elimination of insects and the 
removal of mosaic plants are possible, and these control measures 
have proved of great value. 
Satisfactory control measures for field conditions will necessarily 
have to await the discovery of more definite data regarding the 
sources of primary infection. 
The importance of wild host plants as a means of overwintering 
the mosaic disease, the possibilities of infection through seeds from 
diseased plants, and the relation of insects to overwintering must be 
studied further before effective control recommendations can be made. 
