202 The Potato ■ 



moisture favored a rapid growth of the vines. Cultural 

 practices that aid in the conservation of moisture com- 

 bined with frequent appHcations of bordeaux mixture 

 will reduce the amount of leaf-area injured. 



Arsenical injury 



This is a burning caused by a heavy application of 

 paris green or other insecticides containing free arsenious 

 acid. The injury often resembles early blight, but is 

 lighter colored and usually occurs about flea-beetle punc- 

 tures or other injuries to the leaf, while early blight spots 

 may occur on the otherwise uninjured leaf. The neces- 

 sary amount of the more caustic poisons used with bor- 

 deaux mixture or with equal parts of lime should cause no 

 biu-ning. 



Spindling sprout (Plate XII) 



Spindling sprout is a disease characterized by very 

 small, weak, needle-like sprouts coming from the eyes 

 instead of large vigorous ones. Vines from such sprouts 

 remain small and weak and only small unmarketable 

 tubers are produced from such hills. It is believed that 

 tubers becoming unduly heated by the hot soil during 

 their growth produce sprouts of this character. If this 

 is true, northern-grown seed is less likely to be affected. 



Net necrosis 



This name is applied to a diseased condition of tubers in 

 which brown streaks occur within the tuber.- These 

 streaks are confined largely to the vascular system, though 

 they do not appear as a dark ring on the surface of a cut 

 across the tuber as is usually the case with other vascular 



