268 DISEASES OF CULTIVATED PLANTS 



a few days, just about the time when the flower-buds are well 

 developed. If such a drooping stem is examined, the point 

 where it emerges from the ground will be seen to be covered 

 with a white mould, which extends for some distance up the 

 stem. 



If the stem is allowed to fall and remain on the ground, 

 numerous small black sclerotia are formed in its substance, 

 and the following season these sclerotia produce a crop of the 

 white mould or Bofrytis, the spores of which infect the young 

 paeony stems. The fungus also forms sclerotia on the dead 

 portion of the stem underground, and on fragments of plants 

 or humus in the soil. 



Conidiophores pale brown, erect, numerous, not tufted, 

 but forming a thin continuous mould, branched, tips dilated ; 

 conidia forming white heads, ovate-oblong. 



Ascophores unknown. 



Stems that commence to droop should be removed at 

 once, as they invariably die before the flowers expand; as 

 much of the stem below ground as possible should be cut out. 

 Where the disease has existed, the surface soil should be 

 removed, and replaced by fresh soil, mixed with a sprinkling 

 of rlowers-of-sulphur. Mulching with green stable manure 

 favours the disease. 



Clover sickness. This expression is used in the country 

 when clover fails to produce a satisfactory crop. The phrase 

 'clover sick' is also applied to land in some districts to 

 express the same condition of things. Clover sickness may 

 arise from two distinct causes, that is, the primary cause may 

 be due to ' eelworms,' or it may be a parasitic fungus called 

 Sclerotinia trifoliorum (Eriksson). The latter cause is dealt 

 with here. The first indication of disease is a wilting and 

 yellowing of the leaves, which, if carefully examined, will be 

 found to be more or less covered with very delicate white 

 mycelium, which during damp weather spreads from one 

 plant to another. During the summer numerous small black 

 sclerotia are produced on the dead leaves, Stems, and roots. 

 Ascophores are eventually produced on the sclerotia, and the 

 spores from the ascophores infect the leaves directly. 



The disease usually originates in one or more small patches 

 in a field, which are first indicated by a sickly greenish-yellow 

 colour. If the weather is damp these patches quickly increase 

 in size, and may soon become almost or quite bare owing to 



