Eradication of Mustard. 153 



which come np in the fall along with the 

 grain are too securely rooted in the spring 

 to be removed by the harrow. 



J. A regular rotation of crops which 

 includes the introduction at frequent and 

 regular intervals of cultivated crops and 

 meadow, with the recurrence of small grain 

 not oftener than once in three years, is an 

 excellent means of preventing the growth 

 of mustard and similar weeds, but one 

 which in many sections can hardly yet be 

 deemed practicable. Where such a rota- 

 tion is practiced and proper attention given 

 the cultivated crop and the sowing of clean 

 seed, these and similar weeds are not likely 

 to give trouble. If they are introduced in 

 some way, a modification of the rotation 

 may be necessary in any particular field 

 where they become common, by dropping 

 small grains out of it till these weeds are 

 subdued. 



4. Fall cultivation of stubble -fields is 

 effective, but of course can only be prac- 

 ticed where clover or grass seed has not 

 been sown with the grain. A shallow plow- 

 ing or thorough disking immediately after 

 harvest will cause the seeds of mustard 

 and many other weeds to sprout if moist- 



