WEEDS 297 



10. Does the weed have any natural cheek, such as 

 birds, insects or live stock eating the foliage ? 



11. Weeds can be killed either by preventing the 

 formation of seeds, or by preventing the growth of the 

 foliage. Which of these methods is better suited to the 

 weed in hand? 



12. What garden or field crop does this weed injure ? 

 How does it injure it ? 



Write the names of twelve different kinds of weeds 

 and classify as to whether they are annual, biennial, or 

 perennial. 



2. Spraying to Kill Weeds 



Dissolve two pounds of iron sulphate (copperas) in a 

 gallon of water, and spray over a patch of grass and 

 weeds. Observe results after twenty-four hours and 

 note which weeds are killed. 



Free Bulletins, U. S. Dept. of Agriculture 

 Fanners' Bulletins 



No. 28. Weeds and How to Kill Them. 



No. 188. Weeds Used in Medicine. 

 Extracts 



No. 133. Birds as Weed Destroyers. 



Problems 



1. If a clean field produces 60 bu. of corn per acre 

 and a weedy one only 35 bu. per acre, what is the loss 

 caused by weeds with corn at 35 cents per bushel? 



2. What would be the loss on a 20-acre field at the 

 same rate? 



3. For how many days' labor at $1 per day will an 

 amount of money equal to this loss pay? 



4. Suppose it required only four days' work to keep 



