Pathogen identification and occurrence regularity of a novel disease——Angelica anthracnose

A suspected anthracnose disease on Angelicastems was found in the main producing areas in Gansu province in 2012 and 2013.The major damage of this disease is to the plant stem.In the initial stages of the disease,many light brown spots appear on stems,and then expand to dark brown rectangular lesions,leaf chlorosis and wilting.Stems gradually dry up from outside to inside,abundant black acervuli appear on the spots,and then the plant dies.Through pathogenicity testing,morphology and ITS sequence analysis we determined that the pathogen of Angelicaanthrax is Colletotrichum dematium.As far as we know,this study is the first report for this disease.An inoculation test using potted plants indoors shows that puncturing,root-irrigation and spraying with conidial suspension all can cause disease.Puncturing caused the most severe symptoms.Spraying with suspension induced the lightest symptoms.C.dematium can infect Angelica through wounds,roots and aerial parts.This disease first appears in mid or late June,and incidence peaks in late August or early September.Field temperature and relative humidity are significantly positively correlated with disease incidence and severity,suggesting that high temperature and high humidity promote progress of the infection.The impact of humidity on disease development is greater than temperature.This study provides a basis for developing prevention and control methods for Angelicaanthrax.