16 FARM WEEDS OF CANADA 



lands foul with persistent growing perennials, a thorough sum- 

 mer-fallow will usually be the most effective and, in the end, 

 the least expensive method of bringing the weeds under control. 



The amount and nature of the cultivation of a summer- 

 fallow will depend on the habits of the weeds, the kind of soil, 

 and the climatic conditions. In some extreme cases of peren- 

 nial weeds, it may be advisable to allow the plants to exhaust 

 their reserve vigor by growth until the flowers are formed, then 

 cut and remove the surface growth, plow to a depth of four 

 or five inches, and bring the rootstocks to the surface before 

 they have had time to renew growth. After cutting and removing 

 the surface growth cultivators may, after several applications, 

 be forced to the bottom of the furrow, thus unearthing the net- 

 work of rootstocks. Much machine labour in working out and 

 destroying the rootstocks before they have had time to renew 

 growth after the first plowing will be most economical in the end. 

 Perennial weeds having deep rootstocks may require a second 

 and deep plowing before all the underground vegetation can be 

 unearthed. If perennials alone are to be dealt with, they may 

 be treated as above directly after an early hay crop. 



Periodical cultivation of the summer-fallow throughout the 

 growing season is effective in bringing weed seeds to the surface, 

 stimulating their germination and destroying the seedling 

 plants. When the destruction of annual weeds is the chief 

 purpose of cultivation, deep plowing two or three times during 

 the summer, with surface cultivation each week during June 

 and July and less frequently later in the season, should secure 

 the germination and destruction of the maximum number of 

 seeds. On account of the soil and climate, one plowing of 

 summer-fallow is favoured in the Prairie Provinces. In moist 

 seasons a second deep plowing is apt to stimulate too rank a 

 growth of straw and delay the ripening of the grain. The ger- 

 mination of weed seeds is stimulated most by cultivation during 

 the early growing season, and summer-fallows intended primarily 



