Tomato Diseases i8i 



the phosphoric acid. Tomato plants require a lib- 

 eral supply of water. However, overwatering will 

 encourage numerous diseases. On bright, sunny 

 days there is little danger of overwatering, but great 

 care is required not to overwater during cloudy 

 weather. 



The temperature for greenhouse tomatoes is very 

 important. At night and on cloudy days it should 

 be maintained at about 60 degrees F. During 

 bright, suimy days higher temperatures will not be 

 harmful. The house should be given all the ven- 

 tilation possible. Even during cold days, the ven- 

 tilators should be opened slightly at frequent in- 

 tervals while a close watch should be kept on the 

 indoor thermometer. 



Diseases of Tomatoes 



Greenhouse tomatoes are subject to a large num- 

 ber of diseases. Many of these are of economic 

 importance. 



Hollow Stem 



Cause, physiological. 



Symptoms. Hollow stem is a trouble manifested 

 by seedlings in the bed, or after transplanting. The 

 central portion of the head of the plant remains 

 green while the lower leaves turn yellow. In se- 

 vere cases, affected plants fall over as in damping 

 off, with the absence, however, of signs of rotting. 



