S82 WEEDS : GENERAL 



numbers of their offspring are ultimately carried back to the 

 land. 



The litter used in the yards and stables often contain weeds 

 and their seeds, which become mixed with dung. Moreover 

 many seeds and fruits possess hard protective testas and peri- 

 carps which enable them to pass through the digestive tract of 

 animals without injury. Dung often contains seeds of this 

 character derived from the impure oats, hay, and other materials 

 fed to the stock producing it. 



6. Extermination of Weeds. — To combat weeds successfully, it 

 is necessary to study their life-history and habit of growth ; their 

 power of reproduction, whether by seeds or by bulbs, stolons, 

 rhizomes, roots, and other vegetative parts ; their means of dis- 

 persal over the land; the structure and growth of their roots and 

 stems, and the soil most suited to their development. The more 

 the farmer studies them, the better able is he to find out 

 their weaknesses, and to arrange his plans for their destruction 

 accordingly. 



Weeds differ from each other considerably, and to some 

 extent require special individual treatment : no single method 

 of attacking them can be devised which is applicable to all 

 cases, and the particular system of farming adopted has to be 

 considered in carrying out any scheme for their extermination. 

 There are, however, certain principles which are capable of 

 being almost universally applied. 



{a) Weeds should be prevented from producing seeds, and this 

 can only be accomplished by completely destroying the plants 

 before flowering takes place. The younger the weeds, the more 

 easily are they subdued, and the sooner work is begun the better 

 is the result. It is not infrequent to see ground weeded too late, 

 and the operation having to be repeated all over again, because 

 of seeds having been allowed to fall to the ground before the first 

 weeding was done. Many annuals bear seeds after a few weeks' 

 growth, and some plants, such as coltsfoot, produce flowers and 



