Cucumber Diseases 



135 



Symptoms. At first, the plants have a vigorous 

 appearance, but soon turn yellow and fail to form 

 fruit. The leaves of affected plants become spotted^ 

 resembling somewhat mosaic. 



Cucumbers are often grown in the same beds for 

 a number of years. Each year as new manure and 

 fertilizers are added, the salt content of the soil 

 becomes higher and more concentrated. Although 

 there is an abundance of available food in the soil, 

 the cucumber suffers because it is unable to stand a 

 concentrated form of food. Chemical analysis of 

 a normal and an overfed soil throws much light on 

 this important subject. These analyses are given 

 in the accompanying Table 17. 



Table 17 



Average Composition of an Overfed Soil Com- 

 pared with Normal Soil 



Total water soluble salts. 



Soluble nitrogen 



Soluble pota^ 



Soluble phosphoric add. . 

 Soluble calduin oxide. . . . 



Soluble sodium oxide . 



Soluble magnesiuin oxide 

 S(duble sulphates 



From Table 17 it is seen that an overfed soil has a 

 marked increase of soluble plant food. If we should 

 express this in terms of fertilizers it would make 3^ 



