56 INTENSIVE FARMING 



appears as velvety brown spots on the under 

 surface of the leaves and if not immediately 

 checked it will spread through the house and 

 destroy the crop. It causes the leaves affected 

 to turn yellow, then brown, and finally to dry 

 up. It can be controlled by spraying the plants 

 with ammoniacal carbonate of copper or by 

 Bordeaux mixture. Vigilance and quick action 

 are the price of control of this disease. The 

 difficulties are not insurmountable and the suc- 

 cessful crop is a profitable one. 



In growing vegetables under glass agricul- 

 ture reaches its highest perfection. In the forc- 

 ing house the grower has complete control of 

 more factors of crop production than under any 

 other conditions. In fact, the only factor not 

 under his control is sunlight. The grower regu- 

 lates more completely than in any other type of 

 agriculture the mechanical character of the soil, 

 its fertility, its water content, its heat, and the 

 temperature and humidity of the atmosphere. 

 The sunlight is beyond his control save in so 

 far as he is able to take advantage of those 

 localities having the greatest amount of sun- 

 shine during the forcing season. 



Cucumbers. The cucumber is one of the 

 more important members of the forcing colony. 

 As a rule, they occupy the houses a.t the close 



