306 Diseases of Truck Crops 



Control. It may be controlled in a way similar to 

 that recommended for lettuce drop, see p. 143. 



DISEASES OF THE POTATO (Solanum 

 tuberosum) 



General Consideration. Potato diseases are caused 

 for the most part by definite parasitic organisms. 

 However, there are many indirect causes which may 

 predispose the plant to various diseases. 



Color. The shade of red or pink in the tuber is 

 usually affected by the health of the plant and by its 

 nutrition. Color is usually intensified in run out 

 stock. The White Ohios, for instance, may show 

 much red at the eyes and at the eye end under poor 

 conditions, but are white under proper culture and 

 climate. Deep eyed and poor shaped tubers are 

 likely to be densely colored. The flesh of the Early 

 Rose variety may become red under unfavorable 

 conditions. Whiteness of flesh is also influenced by 

 the degree of ripeness. The color therefore may 

 often serve as a general indicator of the health of the 

 tuber. Sharp and long eyed ends with numerous 

 eyes usually indicate a weak and run out strain. 



Position of the Eyes. On examining a tuber, we 

 find a cluster of well developed eyes at the blossom 

 end, generally termed the "seed end. " The other is 

 generally known as the "stem end" of the tuber and 

 it contains but few if any of the eyes. Careful 

 growers are in the habit of discarding the "stem 

 ends. " Plants resulting from the stem ends develop 



