CHAPTER XII 

 CORN INSECTS AND DISEASES 



CORN is practically free from the attacks of insects and diseases. 

 There is no disease that does great damage, though occasionally corn 

 smut may do considerable damage. Insects are also easily con- 

 trolled with the exception of the corn weevils in southern States. 



Corn Insects Below Ground. Insects attacking corn may be 

 grouped in two classes, as (1) those working below ground and (2) 

 those above ground. The corn rootworm and root-louse are most 

 important of those below ground. Both of these can be easily con- 

 trolled by rotation. Both live over in the soil, and usually do not 

 become very destructive until the land has been in corn three years 

 in succession. A change to any other kind of crop for one to two 

 years is effective in destroying them. 



Two other insects, the wireworm and the grub worm, are not 

 peculiar to corn, and therefore are not controlled so easily by rota- 

 tion. In fact, both are apt to be more destructive after sod than at 

 any other time. The wireworm does most damage by boring into 

 young plants, soon after they come up. The grubworm lives under 

 the corn plant most of the summer, eating off the roots. The only 

 remedy suggested is to fall plow the land, late in the season, to 

 expose the larvae and worms to winter killing. 



Cutworms do some damage to young corn, and occasionally may 

 completely destroy a stand. Usually the cutworms pupate in 

 June, so a second planting made, running the rows half way be- 

 tween the first rows, will usually escape with little damage. 



Insects Above Ground. Earworms and Mil bugs ordinarily 

 do only slight damage. Occasionally the earworm may damage to 

 considerable degree the market value of sweet corn to be sold green 

 on the ear. , 



Migratory insects that occasionally damage corn are chinch 

 bugs, army worms, and grasshoppers. Chinch bugs and army 

 worms, moving on the ground, can be prevented from entering a 

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