PREVENTION AND ERADICATION OF WEEDS 45 



must be applied early enough in the life of the weeds to pre- 

 vent any danger of seed formation even in the most forward 

 specimens. So much seed is produced by individual plants 

 of docks, thistles, poppies, and others that if even half a dozen 

 plants are allowed to ripen they can supply sufficient seed -to 

 restock a large area the following year. 



(3) Large numbers of weed seeds are carried about the 

 country by agricultural implements, and now that machinery 

 of larger type, that passes from farm to farm, is coming into 

 common use the danger of contamination from this source is 

 increasing. Steam ploughs and cultivators, motor ploughs, 

 and other types of machinery tend to carry about clods of 

 soil in which numerous weed seeds are buried. Threshing 

 machines, binders, wagons, and other appliances for dealing 

 with the harvested crops become thoroughly infested with 

 large numbers of weed seeds and these are carried from 

 place to place unless the utmost care is taken to keep the 

 machines scrupulously cleaned out after use 



(4) Large collections of weed seeds occur at the bottom 

 of corn and hay ricks, in barns and similar places. All such 

 rubbish should be burned if possible, or, if suitable for feeding 

 animals, may be steamed or thoroughly ground up in a mill 

 in order to crush the weed seeds beyond possibility of germina- 

 tion. This, however, is hardly feasible, as it is not worth the 

 cost. Too often this source of infection is overlooked, even 

 on farms that are otherwise well protected against the ingress 

 of weed seeds, and much damage is thereby caused. 



Eradication. 



The most effective measures of weed prevention are 

 bound to fail unless a constant system of eradication is in 

 force. From one year's end to another it is possible and 

 necessary for the farmer to be combating the weeds, so 

 that he always remains master and never lets them get the 

 upper hand. The methods of eradication are many, but most 

 of them can be summed up under the heads of eradication 

 by} mechanical and by chemical means. A few special 

 methods are occasionally used which cannot quite be classified 

 in this way, but these are the exception rather than the rule. 



From the very early days of agriculture cultivation has 

 been regarded as the principal means of getting rid of weeds. 

 The old husbandman knew nothing of our modern agricultural 

 machinery and carried on his work with the old-fashioned 



