IDEAL FERTILIZERS 77 



Chapter XIII 



Diseases in General 



One cannot fail to be impressed with the number of in- 

 sects and disease troubles that may occur. He is almost 

 inclined to feel despair in ever producing the crops when 

 there is such an array of enemies awaiting him. But he 

 should consider the matter in two ways: First, it is as 

 impossible for all or eyen a small percentage of these 

 troubles to attack a single crop as for one person to suffer 

 from all the diseases common to the human family; sec- 

 ond, that there is a preventive or remedy for nearly every 

 trouble mentioned. Shutting one's eyes to evil does not 

 overcome it. The best policy is to recognize all draw- 

 backs and either avoid them or stamp them out. 



Most plant diseases are caused by parasitic fungous 

 or bacterial growth. We can imagine a fungus as a tiny 

 plant, the spore or seed of which lodges upon a leaf, 

 fruit or twig and sends out "roots" which enter the pores 

 and make their way through the cells of the inner tissue, 

 feeding upon the elaborated sap, taking 5 the nourishment 

 prepared for the plant's own use and clogging and dis- 

 arranging the cells, causing disease and death to the 

 attacked area. On the surface the fungus develops and 

 produces quantities of other spores which are carried 

 by dew, rains, winds, insects, etc., to other points where 

 further infection can take place. Potato blight is a good 

 example of this. The control of such diseases is based 



