在河南省嵩县烟田发现了茎黑腐病症状；茎枯病症状发现于洛宁县烟田。为明确两种病害的病原种类，试验采用常规组织分离法获得致病菌株，对所得菌株进行了形态学鉴定、DNA 序列分析和致病性测定。结果表明，菌株Ⅰ号菌落呈放射状型，并逐渐变为花瓣型，雄器钟状或不规则，为钟器腐霉（Pythium vexans），侵染烟草引起茎黑腐病，在河南省为首次报道。菌株Ⅱ号菌落初期白色，菌落中部逐渐变为青黑色，分生孢子双胞或单胞，子囊棍棒状，子囊孢子纺锤形，双胞，隔膜处有缢缩，有性时期为菊花疫病菌（Didymella ligulicola），无性时期为菊花壳二孢（Ascochyta chrysanthemi），侵染烟草为首次报道。%The Black stem rot was found in Song county and stem wilt was found in Luoning county in Henan Province. In order to identify the pathogenic species of the two diseases, two fungal strains were isolated from diseased stems with typical symptom through the methods of tissue separation. The strains were identified by morphological identification method and pathogenicity test according to Koch’s postulation. Its rDNA ITS sequence was analyzed for similarity. The results showed that colony of strain I was radial pattern, and turn to petaloid gradually, antheridium was mitriform or irregular on OA, identified as Pythium vexans, which infected tobacco cased stem black rot was first reported in Henan province. The colony of strain II was initially white, the mid of colony gradually turn lividity, conidium was septate or aseptate, ascus was clavate, ascospore was fusiform, septate, constriction on diaphragm, sexual stage was Didymella ligulicola, Asexual period was Ascochyta chrysanthemi, invasion tobacco was the first report.
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