464 Identification and Eradication of Weeds, [sept., 



(2) the prevention of seeding and the concurrent destruction 

 of both seedlings and old plants by mechanical means ; and 



(3) the destruction of the weed by spraying. 



(1) The first suggestion is obvious, and need not be enlarged 

 on here. 



(2) The second plan may often prove very successful, and 

 in root and pulse crops the weed may generally be kept in 

 check by regular hand and horse hoeing, while a crop of early 

 potatoes, with the constant tillage it receives, is particularly 

 useful in reducing charlock. Corn crops may also be hand 

 hoed, and if the weed is allowed to grow tall, hand pulling will 

 be necessary. When the plants are in flower, seeding may to 

 some extent be prevented by chopping off the flowering heads 

 by means of specially constructed machines, by scythes, reap- 

 ing hooks, or hooks with jagged teeth ; by this time, however, 

 the damage for the current year will have been accomplished* 



An excellent plan is to resort to surface cultivation in spring, 

 by harrowing the soil to a fine tilth in order to encourage the 

 seeds to germinate, then destroying the seedlings by harrow- 

 ing or the use of the American weeder. In bad cases the 

 process may be repeated, while the practice is often useful in 

 a mild autumn, the young plants being killed by the first frost. 



Finally, where the reaper is used, a good practice is to 

 employ a trough attachment to the pan of the reaper, in which 

 seeds shaken or beaten out may be caught, and subsequently 

 destroyed. The trough should be covered with a perforated 

 lid, through which the seeds may fall. According to Maier- 

 Bode,* in a trial conducted at' Leipzig in connection with 

 wheat and oats, no less than 30*4 lb. of pure weed seeds were 

 collected per acre in the case of wheat, and 35*6 lb. per acre 

 in the case of oats, while many seeds in seed vessels were 

 trapped in addition. Of the seeds caught in harvesting the 

 wheat and oats, 22*15 per cent, and 21*12 per cent, respectively 

 were charlock. 



(3) As regards spraying, the principle is based upon the 

 fact that a weak solution of copper sulphate or iron sulphate 

 sprayed on a cereal crop has little effect on the cereal, while 

 it quickly destroys the seedlings of charlock. This is doubtless 

 because the leaves of cereals are narrow, smooth, and more or 

 less erect, hence not retaining much of the solution used, and 



* Fr. Maier-Bode, Die Bekcimpfting der Acker-Unkrcinler, 1908, p. 123. 



