Destruction of Charlock. 



467 



cent, solution of copper sulphate, or with a similar quantity 

 of a 15 per cent, solution of iron sulphate. To make the 

 former, dissolve 16 lbs. of copper sulphate, costing about 

 4s. 6d., in 40 gallons of soft water ; while, in the latter case, 

 60 lbs. of iron sulphate, costing about 2s. 6d., are required 

 in a similar quantity of water. Somewhat better results 

 will be got by dressing an acre with 16 lbs. of copper 

 sulphate dissolved in 60 gallons of water, thus making a 

 2f per cent, solution ; but although this entails no extra 

 outlay for material, it implies an increased expenditure 

 on account of labour. Then, again, in place of applying 

 40 gallons per acre of a 4 per cent, solution at a single 

 operation, superior results may sometimes be got by 

 applying 30 to 40 gallons per acre of a 2 per cent, solution at 

 a somewhat early stage of the growth of the weed, and a 

 similar quantity ten days or a fortnight later. As compared 

 with a single dressing this involves no extra expenditure on 

 material, but it entails the application of about twice as much 

 water, and the crop suffers more from mechanical injury. 

 Good results have occasionally been got with weaker 

 solutions and with smaller quantities than those indicated, 

 but on the whole those recommended above have proved 

 most effective. 



The quantities indicated have been found to do no per- 

 manent harm to cereals, or to clover or grass occupying the 

 ground along with the corn crop, but solutions for application 

 to beans or peas should be considerably weaker than those 

 used for corn crops, or for tares. 



A convenient method of procedure is to have two 40-gallon 

 barrels in use, so that while the contents of one are being 

 distributed, the other may be used for the preparation of 

 a fresh solution. 



It may be noted that certain weeds closely allied to common 

 charlock — especially wild radish, or white charlock, and 

 smooth leaved-charlock — are not infrequently met with, and 

 these do not readily yield to treatment. Other weeds such as 

 docks and thistles are more or less crippled, without being 

 destroyed, by the solutions. 



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