CHAPTER XII 



CONTROLLING INSECTS AND DISEASES THAT ATTACK 

 VEGETABLE CROPS 



There are a number of insects and diseases that attack vege- 

 table crops. Some are very general in their distribution, and are 

 likely to be more or less prevalent over a wide range of territory 

 every year. Others are more restricted in their range, or appear 

 to a serious extent only when conditions for their development 

 are especially favorable. If these enemies are allowed undisputed 

 possession of the garden, they will at times utterly destroy certain 

 crops and reduce the yield or quality of others. On the other 

 hand, if proper precautions are taken to control these enemies, 

 serious loss of crops from this cause can usually be avoided. 



Rotation of crops is a potent factor in the control of certain 

 insects and diseases that pass the winter in the soil or in the refuse 

 of crops in the soil. This applies especially to organisms that 

 normally are not distributed in spring to any great distance from 

 the place where they pass the winter. 



Many insects and disease germs can be destroyed by burning 

 the refuse from an infested or infected crop, instead of allowing 

 it to remain in the field or throwing it upon the compost heap 

 where it will later be returned to the land. Also, in the case of 

 crops infected with certain diseases, it is unwise to feed the crop 

 refuse to farm animals, for the disease germs may remain viable 

 in the manure and serve as a source of re-infection when returned 

 to the land. 



Sometimes serious injury from a given insect may be avoided 

 by varying the time of planting so that the crop will not be at 

 the most easily injured stage when the insects are most abundant. 

 Certain plantings of sweet corn may be seriously damaged by 

 the ear-worm, otherwise known as the cotton boll-worm, while 

 both earlier and later plantings may quite largely escape. Late 

 plantings of cucumbers and squashes are much less likely to be 

 severely attacked by striped beetles than are early plantings. 



Late fall plowing can often be made a means of breaking up 

 the winter quarters of certain insects and thus exposing them to 

 the elements and to their enemies. 



83 



