PARASITIC WEEDS 99 



common in pasture land and is parasitic on the roots of 

 grasses and possibly on some other species also. 



(2) Rhfnanthus major (Fig. 29). Greater yellow rattle, 

 which occasionally makes its appearance in cornfields, where 

 it attacks the cereal crops and does much mischief. 



The small yellow rattle is not usually taken much notice 

 of by farmers, but it reduces the crop and turns black in dry- 

 ing, rendering hay in which it is abundant distasteful to 

 animals. The greater yellow rattle is local in this country 

 the writer has only seen it in part of Wiltshire, 1 but if it 

 gets a good footing it is capable of depreciating or even 

 ruining the cereal crops. 



Unlike dodder and broomrape the yellow rattle develops 

 like a normal plant with an underground branching root 

 system and an aerial stem bearing leaves and flowers. Its 

 roots range themselves alongside the fibrous roots of the 

 host, and at the point of contact suckers are sent out 

 which penetrate to the conducting strands of the host root 

 and absorb nitrogenous food material therefrom (Fig. 30). 

 The attachment is very intimate, and it is impossible to 

 separate host and parasite without breaking the roots badly. 

 Occasionally the suckers appear to penetrate the base of the 

 stem, and in one instance a row of suckers was seen along the 

 outside of the husk of a barley grain. The plant is able to 

 manufacture its own carbohydrate food (as starch and sugar) 

 with the aid of its green leaves and the carbon-dioxide taken 

 in from the air. Large quantities of winged seeds are produced 

 which can retain their vitality in the soil for some years, thus 

 securing the propagation of the plant 



Eradication. On grass-land yellow rattle is most abundant 

 in fields that are regularly cut for hay, as when once it has 

 gained a footing it has yearly opportunities of ripening quan- 

 tities of seed. It is less often seen on grazing land, and can 

 be eradicated or at least greatly reduced if constantly mown 

 land is grazed for a number of years, especially if sheep are 

 used. If hay must be taken it should be cut early so as to 

 forestall the ripening of the yellow rattle seeds. The grazing 

 is more effective if it is supplemented by a dressing of basic 

 slag, 7 cwts. per acre, applied before the end of November. 

 In some cases it is useful to apply about 5 to 7 cwts. per acre 

 of salt early in the year, as soon as possible after the seedlings 



1 Brenchley, W. E. (1913), "Yellow Rattle as a Weed on Arable Land," 

 Jour. Bd. Agric., XIX, pp. 1005-1009. 



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