香樟叶斑病病原菌的鉴定、菌丝生长速率及防治药剂筛选研究

Identification of the Pathogen Causing Leaf Spot of Cinnamomum camphora,Mycelial Growth Rate,and Its Fungicide Selection

[目的]鉴定引起万州区香樟叶斑病的病原菌,明确病原菌菌丝生长特性,筛选出有效抑制叶斑病病原菌的杀菌剂,为该病的防治提供理论基础。[方法]采用组织分离法分离和纯化病原菌,用柯赫氏法则进行致病性测定,通过形态特征及ITS、tub2、GAPDH、ApMat多基因联合分析鉴定其病原菌种类;用菌丝生长速率法研究其菌丝生长特性,并进行杀菌剂的筛选。[结果]分离菌株在PDA培养基上培养3 d呈现灰褐色,边缘灰白色,后期有橘红色孢子堆出现,分生孢子呈长椭圆形、两端钝圆、透明无色、为独立的单胞,测量其孢子大小为(9.8~18.6)μm×(4.2~6.0)μm;用两种方法对优势菌株ZT-1进行致病性检验,均能引起香樟叶片发病;代表菌株ZT-1和ZT-5与胶孢炭疽菌(Colletotrichum gloeosporioides)聚在一支,支持率达100%;菌落的最适生长温度为28℃,最适pH值为6.0,马铃薯葡萄糖琼脂培养基利于菌丝生长,最适碳源和氮源分别为葡萄糖、甘氨酸,最适的光照条件是全黑暗;在化学和生物杀菌剂中,15%三唑酮可湿性粉剂、1%蛇床子素水乳剂的室内毒力较强,对C.gloeosporioides的抑制效果明显,其EC50值均小于10μg·mL^(−1)。[结论]C.gloeosporioides是万州区香樟炭疽病的病原菌,15%三唑酮可湿性粉剂可作为防治的杀菌剂。

[Objective]To Identify the pathogen causing leaf spot of Cinnamomum camphora in Wanzhou District,clarify the characteristics of mycelium growth,and select fungicides that effectively inhibit the pathogen for providing a theoretical basis for prevention and control of leaf spot disease.[Method]The pathogen was isolated and purified by the tissue separation method,and the pathogenicity was tested by Koch's method.Pathogens were identified based on morphological characteristics and multilogues phylogenetic analysis combined with ITS,tub2,GAPDH,and ApMat genes;The hyphae growth rate method was used to study the characteristics of mycelium growth,and the fungicides were selected.[Result]The isolated strains were grayish and the edge was white when the mycelium was cultured on PDA medium for 3 days.The orange conidiomata appeared in the late.The conidia were long oval,blunt round at both ends,transparent and colorless were independent cells.The measured spore size was(9.8~18.6)μm×(4.2~6.0)μm;Pathogenicity of strain ZT-1 was tested by two methods,both of which could cause the leaf spot disease of C.camphora leaves;The representative strains ZT-1 and ZT-5 clustered with Colletotrichum gloeosporioides,and the reliability was 100%;The optimum growth temperature of the pathogen was 28℃;The optimum pH value was 6.0;Potato Dextrose Agar medium was beneficial to mycelial growth;The optimum carbon and nitrogen sources were glucose and glycine;The optimum lighting condition was total darkness.Among the chemical and biological fungicides,15%triadimefon WP and 1%osthol EW were highly toxic and the inhibition effect of C.gloeosporioides was obvious.Their EC50 values were less than 10μg·mL^(−1).[Conclusion]C.gloeosporioides is the pathogen causing anthracnose on C.camphora in Wanzhou District and 15%triadimefon WP can be used as a fungicide for control.