124 PLANT DISEASES 



A whitish stroma forms on the surface of the ovary, having 

 its wrinkled surface covered with conidiophores, bearing 

 very minute conidia. When the conidia are mature, the 

 stroma becomes bathed in a sweet syrupy substance or 

 'honey-dew,' which attracts insects, who unconsciously 

 convey the conidia from one flower to another. As the 

 conidia germinate at once, the disease, when once intro- 

 duced, spreads rapidly. After the formation of conidia is 

 completed, the stroma continues to increase in size, and 

 becomes black externally, forming the hard, curved body 

 known as ergot, or properl)', a sclerotium. Many of these 

 sclerotia fall to the ground, where they remain in a passive 

 condition until the following spring, when they give origin 

 to two or three stalked bodies which produce ascospores. 

 Some of these spores, carried by wind, alight on grass 

 flowers, and inoculation follows. 



Apart from the direct loss of crop caused by ergot, its 

 action on animal life is very disastrous. Rye bread, con- 

 taining a considerable amount of ergot, causes a terrible 

 malady, characterised by gangrene of the extremities. 

 Abortion is also caused by partaking of the sclerotia along 

 with food. A wholesale epidemic of cattle in the United 

 States, at first considered to be the much-dreaded ' foot- 

 and-mouth' disease, was proved to be caused by ergotised 

 food. 



Preventive Means. — The most certain method is to 

 collect all the large black sclerotia possible, and, along 

 with those separated from the grain cleansing, either burn, 

 or better, sell them to a chemist for medicinal purposes. 

 By persistent removal of sclerotia, the first or spring inocu- 

 lation of grass flowers by means of ascospores is much 

 reduced. If, in addition to this, wild grasses growing in 



