CHAP. ii. 



RED CLOVER. 



933 



is to establish a sub-rotation, so that Broad Clover comes in the first 



four years, White Clover in the second four, and Alsike in the third 



four. As the two latter are not affected by the sickness, and do not 



tend to make the land sick, the usual quantity of sheep-food may be 



secured without great risk. When sown free from admixture with 



other seeds, from 12 to 16 Ib. of seed may be used per acre, though 



even less can be drilled, as usually a larger percentage of seeds may be 



relied upon to grow. The seed should be of a dark purple colour, 



though it is impossible to find a sample in which all the seeds are of 



one colour, as all the 



flower-heads do not ripen 



at one time. Those not 



so fwell ripened are yel- 



low in colour, and will 



in all probability ger- 



minate, but they are not 



so robust as the purple. 



Brown seeds are dead, 



and therefore useless. 



The most injurious weed- 



seeds commonly found 



in a sample of broad 



clover are those of rib- 



grass or plantain (Plan- 



tago lanceolata) and of 



dock. These sufficiently 



resemble the true seed 



in size and density as to 



4 38.-Stem Eelworms 



vprv difficult to <*pna- (Tylenchus devastatrix). Greatly magnified. Also, Embryo 

 \ery mmcmt to sepa in egg> aml (on the right) auterior end of female 



rate, although they are showing mouth spear. 



quite unlike it in shape. 



The seed of plantain resembles a very small polished date-stone ; that 



of dock is triangular like buckwheat. 



Dodder is a common seed in this kind of clover, but is very small 

 and brownish. It is, perhaps, the worst of all weed-seeds in clover, 

 for after the seed has germinated in the ground the young seedling 

 attaches itself to a clover plant, and thenceforward lives as a parasite, 

 gradually spreading from plant to plant (fig. 439) until a patch some 

 yards in diameter is destroyed by a single dodder plant. Nothing but 

 the most careful sifting on a fine sieve, which allows the dodder to fall 

 through, but retains the clover, will free a sample of clover seed from 

 this pest. 



In selecting seed for sowing, great care should be taken that none 

 of the impurities referred to are present, as they all tend to spoil the 

 hay, and to make the land foul in the future. Red clover seed ma} r be 

 sown at the same season as white clover, and under the same conditions, 

 but as red clover is a big plant it is at times difficult to harvest the crop 

 in which it is sown if the clover is put in early. This is particularly 

 the case when the clover is sown in barley, for in a wet harvest it is 



