CORN, WHEAT, OATS, BARLEY, RYE 



81 



all seed kept separate, etc. For these reasons they are not dis- 

 cussed in detail here. 



Pests of small grains. — The common pests of small grains may 

 be divided into three classes: (1) Weeds; (2) insects; (3) para- 

 sitic fungi. The methods most generally employed to combat 

 these pests are: (1) Crop rotation; (2) cultivation; (3) quick 

 growing crops; (4) seed treatment; (5) pure seed. 



Weeds as a pest are always present and without exception 

 cause considerable loss by using up the available plant food and 

 water as well as by shading and preventing proper root develop- 

 ment of the plants. This loss in the grain fields of Minnesota 

 alone is estimated at $2,000,000 annually. 



Weeds are of three classes: (1) Annuals, plants maturing in 

 one year; (2) Biennials, plants maturing in two years; (3) Per- 

 ennials, plants that grow many years, but seed every year. 

 Examples of these weeds that are bad in grain fields together 

 with control method follow : 



Insect pests are of two classes: (1) Those that attack the 

 growing plant; (2) those tliat attack the threshed grain. The 

 most destructive members of each class are given below with a 

 brief description of method of control : 



