EXTERMINATION OF WEEDS 89 



be much easier to take care of than a piece of wheat or 

 oats ground. It will contain a far smaller number of 

 weeds, and consequently fewer weed seeds. Corn in such 

 ground is usually quite clean by the time it is "laid by," 

 and there is less chance for weed seeds to mature than in 

 a "small grain" field. This method of cropping insures a 

 smaller number of weed seeds when this corn field is 

 placed in small grain the following year. After the 

 small grain is removed it is always advisable to plow as 

 soon as possible and then harrow in order to expose the 

 roots of weeds already in the soil. If the small-grain crop 

 is followed by clover a crop fairly free from weeds should 

 be produced. It would be better if the clover meadow 

 could be converted into blue grass pasture. 



When there is a tendency for weeds to appear, the blue 

 grass should be encouraged to occupy the vacant spaces. 

 In the East, where alfalfa is grown it should be treated in 

 the same way as clover, but Mr. J. E. Wing of Ohio 

 keeps all of his land, so far as possible, in alfalfa. In the 

 West, especially in the Rocky Mountain country, it is 

 far better to retain an alfalfa meadow for a long term of 

 years. 



There are some notable illustrations in western Wis- 

 consin, eastern Minnesota and northeastern Iowa, where 

 mustard and wild oats were, at one time, as abundant as 

 in the small grain-growing section of Minnesota and the 

 Dakotas ; but by converting the tillable lands largely into 

 pastures and meadows these weeds have ceased to be 

 so troublesome. Small grain fields where rotation has been 

 practiced are almost entirely free from weed seeds. So 

 far as annual weeds are concerned there is no better way 

 of treating them than by a systematic rotation of crops. 



Treatment of Annual Weeds. The most important 

 point in connection with annual weeds is to prevent the 

 formation of seeds. Cultivation of a field should be thor- 

 ough at all times. The best time to kill these annual 



