Abstract: An ecological survey of ergot production on various hosts in Changpei and Kuyan districts was made in 1957.Alkaloid contents of ergot collections from the above mentioned districts as well as from Northeastern China were analysed. The average percentages of ergot infection of Aneurolepidium chinese,A.dasystachys,Hordeum brevisubulatum,H.violaceum,Secale cereale,Agropyron cristatum and Clinelymus dahuricus were 68.48,60.97,60.00,50.00,42.00,14.00 and 6.59 respectively.Calamagrostis epigeios was very lightly infected,while there was no infection at all on wheat,barley and Bromus inermis.A.dasystachys,A.chinense,and Clinelymus dahuricus were most widely distributed among wild hosts,and their average numbers of culms per square meter were 61,79,and 38 respectively.According to preliminary estimation,the annual production of ergot in Changpei and Kuyan exceeded 60 tons.The ecological factors that favored the ergot epidemic were:(1)The presence of widely distributed susceptible host plants,(2)The presence of large amount of inoculum,(3)Severe winter that favors the venalization of ergot and wet summer that favors infection.Ergots were mostly formed from July 20 to August 10,with the middle part of August being the most suitable time for harvest. The total alkaloid contents of ergot varied with different hosts and decreased by the following order:Calamagrostis epigeios(0.577% estimated as ergotoxine),Clinelymus sibiricus(0.44%),Clinelymus dahurious(0.30—0.34%),Aneurolepidium dasystachys(0.13—0.15%),Aneurolepidium chinense(0.115%),rye(0.061—0.065%).The amount of total alkaloid of the ergots from same host species was rather stable and there seemed no significant differences among different localities.It appeared that there was no relationship between the size or color of ergot and the amount of alkaloid contents.Ergots of Aneurolepidium dasytachys,A.chinense,Clinelymus dahuricus,C.sibiricus and of rye were identified as Claviceps purpurea(Fr.)Tnl.and ergot of Calamagrostis epigeios was identified as C.microcephala(Wallr.)Tul.