WEEDS OF ARABLE LAND 57 



the flower heads withering up." l The height of the 

 corn crop, however, would forbid spraying by means 

 of horsed vehicles when the Poppies were nearly at the 

 flowering stage, but a 3 per cent solution of copper 

 sulphate (which in the case of Charlock spraying has 

 been found to do little, if any, injury to the cereal 

 crop) might be tried when the Poppies are no more 

 than half grown. If necessary, two applications with 

 an interval of a few days could be tried. It has been 

 stated 2 that the common Scarlet Poppy is very sensitive 

 to a 13 to 20 per cent solution of sulphate of iron, and 

 since a cereal crop can withstand a 15 per cent solu- 

 tion (vide Charlock spraying), a solution of such a 

 strength should be tried. With a solution of either of 

 the sulphates 40 gallons will suffice for an acre. 



(As to the poisonous properties of Poppies, see p. 

 281.) 



FUMARIACE^: 



Common Fumitory (Fumaria officinalis L.) is a common 

 annual of a rather prostrate habit of growth, often 

 plentiful in cornfields on light, sandy, and loamy soils. 

 This plant (Fig. 10) is i to ij feet high, with much 

 divided leaves, and long racemes of many irregular dark 

 or pale rose-purple flowers, which appear between May 

 and September. It is occasionally very troublesome, 

 but, being an annual, can be got rid of by persistent 

 hoeing and surface cultivation in spring and early 

 summer. 



CRUCIFER^E 



Many plants of this order are troublesome weeds, 

 almost all being pests of arable land ; a number must 



1 Jour. R.A.S.E., 1902, p. 360. 



2 F. Maier-Bode, Die Bekanipfiing der Acker- Unkrauter 1908. 



