CHAPTER II. 



CLOVER SICKNESS CLOVER MILDEW. 



Peronospora trifoliorum, D.By. 



THE well-known weakly growth of clover, termed clover 

 sickness, is said perhaps on insufficient grounds to be 

 due to a deficiency of potash in the soil, especially the 

 soluble salts of potassium in the subsoil. When clover is 

 grown too frequently in the same fields, and without alter- 

 nation of crops, the ground becomes " clover sick." Two 

 nematoid or thread worms (nema, a thread) of minute 

 size, and allied to the so-called " worms " of stale vinegar 

 and paste, and to the Nematode which causes ear-cockle 

 in wheat, oats, and rye, have been described as attacking 

 clover. These thread worms have been described under 

 the names of Tylenclius devastatrix and T. Havensteinii ; 

 but the impoverished condition of clover when due to 

 these parasites is said to be distinguishable from clover- 

 sickness proper. Some observers have said that the ail- 

 ment is due to the presence of a fun- \s known as SpTiceria 

 herbarum, Pers., sometimes des,^^ 1 V s Pleospora, and 

 more frequently as Clado$ f an( j ' . ">; fungus is over- 

 1 'ciyiened with synonyn eous pl aT] f ',1 a ^ames, and is so 

 to be tire* all herbaojf clover sic-r nes < '* ^ hardly likely 

 named Peziza Uoorioides, Fr., it is a^' ^Vond fungus, 

 the cause of this ailment, but proL^ edl V with being 

 evidence, although, from what we havt 01 A ^sufficient 

 of the attacks of the spawn or mycelium al ei % learned 

 living potato plants, the presence of P. cibo^f eKiza u P on 

 clover deserves attention. A third fun cms !f ' - Fr> > on 



Sed Pha- 



