4 o COMMON WEEDS 



It will be observed from these figures that a number 

 of the better grasses were much increased, several being 

 three or four times as plentiful as before irrigation. 

 Dutch clover disappeared, but after two years broad 

 clover was doubled. As regards weeds (marked with 

 an asterisk), several of the worst had disappeared after 

 four years, while others were much reduced. In short, 

 Buckman remarked that the field on which the experi- 

 ment was made was " trebled in value in four years." 



Feeding-off with sheep may occasionally be employed 

 to suppress weeds, such as Ragwort and Spurrey, but 

 the operation should always take place before the time 

 the seeds ripen. It is known that sheep eat certain 

 plants which cattle reject, such as Ragwort (Senecio 

 Jacobcea), Knapweed (Centaurea m'gra), and Ox-eye Daisy 

 (Chrysanthemum Leucanthemum). It may therefore be 

 useful to run a few sheep with the larger stock on 

 pastures where these weeds abound. 



Spraying with plant poisons is a valuable method of 

 suppressing weeds ; for example, Charlock in young 

 corn crops can be destroyed by means of sulphate of 

 copper, Wild Onion has been largely reduced by the 

 use of carbolic acid, and Dodder by the use of several 

 chemical preparations. 



The sulphates of copper and iron, salt, carbolic acid, 

 arsenite of soda, and other materials have all been used 

 for the destruction of weeds. In an experiment on a 

 very weedy plot of wheat at the North Dakota Experi- 

 ment Station 1 a 10 per cent solution of copper sulphate 

 was used on June ist when the wheat was 3 to 5 

 inches high, " the principal weeds being Charlock, Wild 

 Barley, Wild Rose, Penny Cress, Shepherd's Purse, Wild 

 Buckwheat, Lamb's Quarter, and Great Ragweed." On 

 August 8th " all the weeds except the Wild Rose and the 



1 U.S. Dept. Agric., Farmers' Bull. 124. 



