CUCUMBER 341 
should be waged on these pests, not only for the damage 
which they may inflict by feeding, but also as transmitters 
of these two diseases. Spraying is of no value for either 
of the wilts. Infected plants should be pulled up and 
burned. 
Greenhouse Mosaic Disease has been studied by Selby 
in Ohio. Concerning it he writes: “This disease is 
analagous in character to the mosaic disease of tobacco 
and tomatoes and to the yellows of the peach. It is due 
to an oxidizing ferment in the leaves and is transmitted 
like the tobacco mosaic disease, by touching first diseased 
and then healthy plants. The fruitfulness of these varie- 
gated yellow plants is very low, and it is best at all times, 
upon the appearance of the disease, to remove the dis- 
eased plants and destroy them.” 
Other diseases such as Leaf Spot, Pickle Spot, White 
Pickle or Mosaic may appear on plants growing under 
greenhouse conditions, but none of them should prove 
Fig. 120.—Three grades of cucumbers. 
