WEEDS— PECULIARITIES AND DISTRIBUTION 437 



depends upon methods of application and upon the weather 

 prevailing at the time of spraying. A heavy thunderstorm soon 

 after the process may render all the labour ineffectual. In some 

 countries spraying is carried on with solutions of iron sulphate. 

 During the last four or five years, this method of destroying 

 Charlock in cereal crops has been largely practised in Denmark 

 with most excellent results. At the present time, nearly all 

 Danish agriculturists are adopting the plan. In some parts 

 of England the best results have been obtained by continuous 

 hand-pulling during many years but this method is now far 

 too expensive to carry out efficiently, owing to the increased 

 cost of labour and to the difficulty on account of legislative 

 changes in getting boy labour for the purpose. 



The foregoing sketch touches but lightly upon a few of the 

 varied aspects of the Weed problem. The subject is many- 

 sided and the time will come when it will be possible and 

 necessary to attempt to co-ordinate the heterogeneous mass of 

 information into a homogeneous whole. Meanwhile the import- 

 ance of increasing our knowledge of every branch of the subject 

 can hardly be over-estimated, since the question of food supply 

 is so intimately bound up with it. The system of intensive 

 culture by which the utmost output is exacted from each acre 

 of ground is spreading rapidly and farmers are no longer 

 content to leave their land to produce more or less what it will. 

 But while the conditions are being so much improved and the 

 growth of crops facilitated by efficient systems of cultivation 

 and manuring, pari passu the weeds are gaining, as they are 

 prepared to benefit quite as much as any crop from improvements 

 in the soil and so the more intense the system of cultivation 

 the more essential is it to fight down weeds in an efficient and 

 scientific manner, as weed and crop cannot exist side by side 

 without detriment to the latter more often than not in quality 

 as well as quantity. Consequently the need is obvious of 

 obtaining as much precise information as possible with regard 

 to the habits, life-histories and associations of weeds, so that 

 we may learn to attack them either at the weakest point in their 

 structure or at the most vulnerable periods of their existence, 

 thus rendering the task of suppression or eradication far easier 

 and more effectual. 



