WEEDS OF ARABLE LAND 55 



Channel Islands, but, according to Hooker, is rare 

 north of the Tay. P. dubium, however, is, according 

 to the same authority, found in Britain north to the 

 Shetland Islands. Both species are most commonly 

 found on light, dry, sandy, and gravelly soils, but 

 flourish even on heavy wheat land, though not to the 

 same extent as on the lighter soils, such as barley 

 land. It is during damp, warm weather in spring, 

 on a soil in good tilth, that the Poppy seed germi- 

 nates most freely, the established plants growing most 

 strongly and rapidly in hot summer weather, when 

 they may quickly mature and scatter their seed broad- 

 cast. 



Poppies maybe combated in several ways: (i) By 

 employing pure seeds for sowing. (2) When the seeds 

 are present in the soil deep ploughing should not be 

 practised, as the seeds will only be brought to the sur- 

 face later. Surface cultivation should be the rule, and 

 after producing a fine tilth in the spring, and en- 

 couraging the seeds to germinate, thousands of the 

 young plants may be destroyed later by the use of the 

 hoe, light harrows, the Poppy Killer (Fig. 3), and 

 various types of American Weeder. Such a method 

 should be repeated until the corn crop is too high to 

 permit of it, when hand weeding may be necessary. 

 (3) Where Poppies are very plentiful it is useful to take 

 an extra root crop in the rotation. (4) Spraying with 

 the sulphates of copper and iron has been found to 

 injure the Poppy. At the Woburn Experimental Farm 

 in 1900 and 1901, P. Rhaas was sprayed with a 2 per 

 cent solution of copper sulphate, and when the solu- 

 tion was applied to the underside of the leaves as well 

 as to the upper surface, " the leaves turned brown, 

 became shrivelled, and to a great extent the plant was 

 killed, for the seeding was almost entirely prevented, 



