42 



A Clover Fungus. 



liable to be infected. Prillieux says that this fungus also 

 injures lucerne and fenugreek.* 



The first indications of the attack are brown spots upon 

 the leaves, and sometimes on the leaf stems of the clover 

 plants, towards the autumn of the year in which the clover 

 seed was sown (Fig. i, i). In the case of Tri folium incarnatum 

 these spots appear directly the plants have become estab- 

 lished. The infected leaves and stems soon wither and die, 

 and the root itself gradually decays in most cases. Some- 

 times only part of it dies and the remaining part throws out 

 fresh shoots in the spring, but this growth is late and 

 generally weak. 



The examination of plants infected by Sclerotinia trifoliorum 

 shows that they are infected by the branching mycelia of the 

 fungus, which breaks down the parenchyma, or tissues, 

 speedily causing the leaves and stems to wither and die. 

 Tubeuf holds that as in the case of the allied species Sclei'o- 

 tinia sclerotiorum, instanced by De Bary, the mycelial threads 

 of Sclerotinia trifolioriwi give off a fluid which enters into 

 and kills living plants. " This deadly fluid separated by the 

 fungus contains as an essential constituent an enzyme 

 soluble in acid solutions and capable of dissolving the cell 

 walls ; also a number of imperfectly known organic and 

 inorganic salts, amongst which oxalates can certainly be 

 proved. "t If there is suitable moisture the mycelia are able 

 to penetrate the exterior of their host plants and to attack 

 other plants near them ; as clover plants grow very closely 

 together, the danger of infection being rapidly and extensively 

 propagated is naturally very great. From these external 

 mycelia sclerotia (Fig. i, 3) are finally formed, either upon the 

 leaves, or stems, or at the base of the stems (Fig. i, 2), or 

 below the crown of the roots ; and according to Eriksson^ 

 and Rostrup§, the sclerotia often fall to the ground from the 

 decayed stems. In infected fields of red clover investigated 



^''Maladies des Plantes Agricoles, by E. Prillieux. 



t Pflanzenkraitkheiteii durch kryptoganie Parasiten vernrsacht. Dr. Karl Freiherr 

 von Tubeuf, 1895. 



X Om Kl'ojverrdtan. Jakob Eriksson, 1880. 



§ Kloverens Bcegersvamp. Sclerotinia trifoliorunt. Docenl E. Rostrup, 1890. 



