茎枯菌(Corynespora cassiicola)侵染红麻的发病因素

Pathogenic factors of kenaf infected by Corynespora cassiicola

从红麻茎枯病标本中分离出茎枯菌(Corynespora cassiicola),镜检其形态特征,红麻接种茎枯菌后对发病因子进行试验研究.结果表明:发病适温28℃,饱和湿度有利于发病;孢子悬液最适含量为5.5×103个.mL-1以上,其含量愈高发病情况愈严重;病菌主要侵染麻秆,其次叶片,典型病斑梭形,表生黑色绒毛状霉层,分生孢子多为单生,倒棍棒状,3-26个假隔膜;菌丝和孢子皆能直接或从伤口侵入麻秆发病;幼苗10 d内为感病期;嫩叶易感病;不同品种接种后在麻秆上产生的病斑长度和病情指数有显著差异.

Corynespora cassiicola was isolated from symptomatic kenaf plants,the pathogenic factors of kenaf inoculated with C.cassiicola were investigated under different temperatures and humidities.The results were as follows： the optimum temperature for infection was 28 ℃ and saturation humidity was beneficial to infection;the optimum suspension content was above 5.5×103 conidia·mL-1,the kenaf stems could be infected under this concentration,and the disease was more severe by increasing the concentrations;typical stem spot was spindle and suspended with sooty mold;conidia were solitary,obclavate,with 3-26 pseudosepta.The results also indicated that both hyphae and conidia could penetrate kenaf stems via stomata or wound.The young leaves were susceptible with the seedling age less than 10 days.The result of inoculation test showed that there was significant difference（P0.05） among the length of spot and disease index in 7 kenaf accessions.