10 EXPERIMENT STATION WORK, L/I. 



the grain crop or the grass, yet they must be sufficiently destructive 

 of weeds to make their use economically practicable. 



In parts of the grain-producing States of the Northwest, wild 

 mustard, or charlock, and wild radish have become especially trouble- 

 some, the wild mustard particularly so. This weed is very common 

 in wheat, oat, flax, and other grain fields from Wisconsin to the 

 Dakotas and adjoining States, and it not only crowds out more 

 valuable plants, but it may become positively injurious through its 

 abundance. Like many others of our most troublesome species, the 

 wild mustard is of European origin, and for many years spraying 

 with corrosive chemicals has been practiced in the warfare against 

 the pest in Europe. Copper sulphate (blue vitriol) and iron sulphate 

 (green vitriol or copperas) are the substances most used. Both are 

 efficient in destroying the wild mustard, the principal difference 

 being in their relative cost. The blue vitriol costs more per pound, 

 but does not require as strong a solution as is necessary of iron sul- 

 phate or copperas. There is now on the market a granular form of 

 iron sulphate that can be secured for about $10 or $12 per ton, or 

 even less when bought in large quantities. This is applied in the 

 form of a solution, about 100 pounds of copperas being dissolved in 

 50 gallons of water. At this rate it makes about a 20 per cent solu- 

 tion, and 50 gallons is sufficient for spraying 1 acre, if properly 

 applied. For its application a good spraying machine is required, 

 and if a considerable area is to be treated one of the better power 

 sprayers that deliver the solution with considerable force should be 

 used. For small areas, hand or knapsack sprayers may be employed. 



The directions given by the Wisconsin Station for spraying oat 

 fields with a solution of iron sulphate for the eradication of wild 

 mustard will apply to the treatment of almost any grain or grass 

 field. 



The spraying should be done on a calm, bright day, after the dew has dis- 

 appeared, as the work is more effective if the solution is put on in the warm 

 sunlight. When rain follows the spraying within a few hours the extermi- 

 nation of the mustard will not be complete. 



The grain fields should be sprayed when the mustard plants are in the third 

 leaf, or before the plants are in blossom, in order to have the spray do the 

 most effective work. The day following the spraying the tips of the blades 

 of grain may be somewhat blackened, but no detrimental effects can be noticed, 

 either to the crop or grasses seeded with it, two weeks after spraying. 



Daisies, cocklebur, bindweed, ragweed, chicory, sheep sorrel, yellow dock, 

 wild lettuce, and many other weeds were partially or wholly eradicated from 

 the fields where tests were made for the extermination of mustard. 



In addition to the charlock, or wild mustard, and those mentioned 

 above, other weeds are destroyed by the spray without injury to the 



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