CHARACTERISTICS OF SOME FORAGE-GRASS DISEASES 



Ergot 



Ergot, a fungus disease 

 caused by Claviceps pur- 

 purea (Ft.) Tul., attacks 

 many grasses and is com- 

 mon on smooth bromegrass. 

 It attacks only the flower 

 and seed parts of its host 

 and is of economic impor- 

 tance only when grasses are 

 grown for a seed crop or are 

 allowed to flower and set 

 seed prior to grazing or cut- 

 ting for hay. The initial 

 symptoms appear at flower- 

 ing time, when a sticky 

 exudate, called the honey- 

 dew stage, is noticeable. 

 This exudate, containing 

 the conidial stage of the 

 fungus, attracts flies and 

 other insects, and much 

 secondary infection results 

 from insect transmission. 

 As the disease progresses, 

 black horny bodies called 

 sclerotia develop in place of 

 seeds (fig. 9). TV hen ma- 

 ture, the sclerotia fall to the 

 ground or are harvested 

 with the seed crop. In 

 either case, they carry the 

 fungus over winter. AT hen 

 planted with the seed or 

 carried over on the ground 

 by natural means, they 

 develop the perfect spore 

 stage of the fungus the fol- 

 lowing summer, and the 

 spores released cause the 

 initial infection each year. 

 Ergot development is fa- 

 vored by periods of warm, 



1 P 



Figure 9. — Ergot on smooth bromegrass, 

 showing typical sclerotia. 



