CHAPTER VIII. 



INJURIOUSNESS OF WEEDS. 



Weeds are injurious to man in the following ways : 



1. They crowd out the growing crop. 



2. They consume the moisture necessary for a crop. 



3. They consume the mineral or other food elements essential 

 to a crop. 



4. They pull down the crop. 



5. They are injurious because the seeds are difficult to remove. 



6. They are injurious because they harbor insects. 



7. They are injurious because they harbor parasitic fungi. 



8. They prevent the proper cultivation of the soil. 



9. They may cause conditions which breed disease. 



10. They may poison the soil. 



11. They stop drains. 



12. They poison animals and man. 



1. WEEDS CROWD OUT GROWING CROPS. 



When weeds are abundant they crowd out growing crops. Every 

 plant requires a certain amount of space to bring forth a bountiful 

 crop. Two plants cannot grow together in the same place ; sooner 

 or later, one plant will crowd out the other. If the weed is a more 

 vigorous grower, like the greater ragweed, it will prevent the oat 

 plant from maturing a crop. It prevents the proper amount of 

 light coming to the plant, and so the food neecssary for a crop can- 

 not be made. 



2. WEEDS CONSUME THE MOISTURE. 



To produce a crop all weeds need moisture, which should go to a 

 more desirable crop. They transpire water just as cultivated plants 

 do. Long, in "Common Weeds of the Farm and Garden," says: 



Weeds also absorb from the soil and "transpire," or pass off into 

 the atmosphere, large quantities of moisture which would be of 

 great service to the growing crop. For example, a maize plant has 

 been observed to transpire in the 16 weeks between May 22d and 

 September 4th as much as 36 times its own weight. A large oak 



