418 CONTROLLING INSECTS AND PLANT DISEASES 



agement. Do not wait until the crop is seriously injured before 

 methods are considered for the prevention and control of the 

 pests. Watch the crops while young for any evidence of the 

 enemy. Get them upon their first appearance. 



Planting at the proper time will help control insects. Early 

 planting of a quick-maturing variety of cotton helps to control 

 the boll-weevil and boll -worm. Early potatoes and early cabbage 

 are both less affected by their worst enemies. Fall wheat may be 

 sown late to prevent attacks of the Hessian fly. 



Rotation of crops is usually planned by careful farmers or 

 gardeners. When one crop is badly affected with insects it should 

 not be followed with the same kind of crop next time. Systematic 

 rotation should be followed for a number of other reasons, but the 

 control of insects gives us ample need for forethought in this 

 regard. (See chapter on rotation of crops.) 



Volunteer Plants and Weeds. Although many insects feed on 

 only one crop, they will often feed on a -closely related species of 

 weed or perhaps upon volunteer plants of the same variety growing 

 near by. Potato beetles, for example, will feed upon other plants 

 of the potato family the wild night shade, sand brier and' others. 

 Such weeds may be kept down to help starve out the insects and pre- 

 vent their breeding, or these plants may be sprayed and the insects 

 thus "trapped" may be prevented from attacking the main crop. 



Volunteer grain growing in the fall before the sowing of the 

 main crop may feed the Hessian fly and furnish it a breeding 

 place throughout the early fall. An extra harrowing or disking of 

 the field may prevent this. 



Forcing Rapid Growth. If the crop is stimulated to rapid 

 growth, it may overcome the bad effects of attacks made by insects. 

 The apple worm and the plum curculio are sometimes actually 

 killed by the rapid growth of the fruit after the insects enter. 

 Weakened plants are most likely to suffer from the attacks of 

 insects. It is a well-known fact that many insect enemies are 

 most destructive during seasons when the growth of plants is 

 retarded by drought, or in places where the growth is retarded by 

 an impoverished soil. 



Cleaning up after each crop is a good thing to practice. Clean- 

 ing the fence rows so that the insects will not find good hiding 

 places should be systematically practiced. Plant as close to the 

 fences as possible and then cut the weeds, grass and bushes and 

 rake out the litter at least once a year. When a cabbage crop, 



