田七炭疽病的病原及其生物学特性的研究

STUDIES ON THE IDENTIFICATION OF PATHOGENS OF TIANQI (PANAX NOTOGINSRNG) ANTHRACNOSE AND ITS BIOLOGICAL CHARACTERISTICS

炭疽病是靖西县田七〔Panax notoginseng(Burk.)F.H.Chen〕的主要病害,其病原有以C_1、C_2、C_3和C_4菌株为代表的四种形态型。经鉴定,C_1和C_2菌株为Colletotrichum gloeosporioides Penz.,C_3和C_4为C.dematium(Pers.ex Fr.)Grove。过去认为靖西田七幼苗猝倒病是由丝核菌Rhizoctonia sp.引起的,经研究证实,其病原是C.gloeosporioides引起的一种幼苗炭疽病。 C_1菌株是田七炭疽病的优势菌株,其生长温度范围4～32℃,最适温度为15～28℃;水滴或水膜是分生孢子形成和萌发的主要条件。C_1菌株在PDA培养基上有产孢型与不产孢型之分,但用“植物组织+PDA”培养不产孢型,可在植物组织上诱发产孢成功,其中以茄科和豆科的一些植物组织上产孢量较大。

Tianqi [Panax notoginseng (Burk.) F. H..Chen] anthracnose is a major disease on Tianqi Production in Jingxi County, Guangxi. The causa- tive pathogens were found to have four morphological forms labeled by C_1, C_2, C_3 and C_4. According to the morphological characters, cultural properties and the host range, C_1 and C_2 were identified as Colletotrichum gloeosporioides Penz.; C_3 and C_4 as C. dematium (Pers. ex Fr.) Grove. The causative pathogen of seedling damping-off which had been regarded as Rhizoctonia sp. was proved to be in fact the Colletotrichum gloeosporioides Penz. under the current study. C_1 was most frequently found among the isolates. It could grow between 4℃ and 32℃ but its optimum temperature for growth was 15～28℃. Its conidia normally germinated under the condition of the presence of water drop or water film. When cultured on PDA, It showed two types-producing and unproducing of conidia. The latter could normally produce conidia in different kinds of plant tissues. The plant tissues from some species of Solanaceae and Leguminosae were better substrates for producing conidia.