22 



CROP PRODUCTION 



Insect and Fungous Enemies 



Potato leaves are almost universally attacked by the 

 Ten-lined Potato Bug, the most destructive enemy of 

 the crop. The adult beetle appears as soon as the 

 plants come up, feeding upon the young leaves and 

 depositing clusters of yellow eggs. These eggs soon 

 hatch into dark brown larvae that also eat the leaves 

 and if undisturbed soon 

 defoliate the plants. The 

 larvae become full-grown in 

 about a month. Then they 

 enter the soil and change to 

 pupae, to change again a 

 little later to the second 

 brood of adult beetles. 

 These lay eggs for the 

 second brood of larvae, 

 which is likely to be much 

 more numerous and destruc- 

 tive than the first. Spray- 

 ing or dusting the leaves 

 with arsenate of lead or other arsenical is the general 

 remedy for this pest. 



The Leaf Blight or Early Blight of Potatoes is one of 

 the most widespread of diseases. It is due to the attack 

 of a parasitic fungus that develops only in the leaves and 

 stems. About the time the plants blossom the disease 

 begins to show as small grayish or brownish spots scat- 

 tered over the leaflets. These spots are dry and brittle. 

 They enlarge from day to day as the threads of the fungus 

 invade new cells in the green tissues. Finally many of 



Potato Leaf affected with 

 Late Blight 



