88 ELEMENTARY AGRICULTURE 



root and branch not an easy thing to do. Perennials 

 give most trouble to the farmer. To this class belong 

 the large number of "noxious" weeds, Canada thistle, 

 ox-eye daisy, couch grass, sorrel and common dock. 

 As soon as any of the above make their appearance 

 on the farm the farmer should dig them up and burn 

 them. If they are allowed to spread they will soon 

 have possession of the farm. The writer has seen 

 whole plantations, thousands of acres, in the South 

 surrendered to the ox-eye daisy. When weeds have 

 driven the farmer off the land is rendered valueless, 

 as it is next to impossible to subdue them if they once 

 have gained control. 



Free Bulletins, U. S. Dept. of Agriculture. 



Farmers' 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 2oacre field at the 

 same rate? 



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

 amount of money equal to this loss pay? 



4. Suppose it required only four days' work to 



