38 



pollen grain. At this stage the spore or conidtun can germinate in the 



' the 



nectar of the flower and then extend into^'cavity of the ovary and aroimd 



the houle. 



Stager (248) on the other hand, ohtained infection by 

 artificial inoculation v^ith honey dew from Anthoxanthum odor a turn even 

 when tlie plants were in "Verbliien". This tends to show that infection 

 icay tsJsB place even after fertilization. TschermarK (274) observed that, 

 in rye, infection takes place in pollenated as well as in unpollenated 

 flov/ers. The failure of florets to become pollenated offers a greater 

 . chance for ergot infection both in rye and in barley as the gl-«mes then 

 remain open for a longer time. No sclerotia are formed on plants infected 

 after the period of blossoming has yassed Stager (248) showed also that 

 plants inoculated with ergot three to four days before flov/ering become 

 infected very refdily. He thinks, however, that infection does not take 

 place inBTiediately but that the conidia preserve their germinating power 

 until the flowers open and then germinate and cause infection in the usual 

 way. It may be true also that the spores germinate imnediately and then 

 continue to grow if there is sufficient moisture, produce new conidia, 

 and then infect the plant when in full blossom. 



Source of inoculiSft. . 

 From the previous discussion it is apparent that the 

 original source of infection is the germinating sclerotium. On plants 

 infected with ascospores, masses of conidia are soon produced. These 

 are also able to cause infection and again produce new conidia. This 

 process is continued as long as there are susceptible plants in blossom. 

 Only a few infections v/ith ascospores are sufficient, therefore, to cause 

 an enidemic. if other conditions are favorable. 



