桑椹缩小性菌核病病原菌的分类和生物学特性及抑菌药剂筛选

对分离到的桑椹缩小性菌核病病原菌进行分类鉴定和生物学特性研究,并进行病原对抑菌药剂敏感性的室内试验,为有效防控该病的危害提供科学依据。在对病原菌形态特征观察的基础上,通过与已知近缘菌株核糖体大亚基rRNA序列的比对,明确该病原菌在分类上属于核盘菌科(Sclrotiniaceae)核地杖菌属(Scleromitrula S.Imai)核地杖菌(Scleromitrula shirai-ana)。该病原菌的主要形态与生物学特性为:子实体单个子囊内的8个子囊孢子在未成熟期排列为2列,随着子囊孢子的生长发育,排列方式逐渐由2列变为不规则的线性排列;病原菌生长的适宜温度为20～30℃,最适宜生长的温度为25℃,菌丝及菌核的致死温度为50℃;病原菌生长的适宜pH范围为5～8,最适宜生长的pH为7。80%百菌清对该病原菌菌丝生长有较强的抑制作用,其EC50值为0.012 0 mg/mL,可选择百菌清对桑椹缩小性菌核病进行化学防控试验。

Classification and Biological Characteristics of the Pathogen Causing Reduced Sorosis Scleroteniosis on Mulberry Fruit and Screening of Bacteriostatic Agent Against It

In order to provide scientific basis for control of the reduced sorosis scleroteniosis on mulberry fruit,we isolated,classified and identified the pathogen from the infected mulberry fruit,observed biological characteristics,and investigated fungicide sensitivity of the pathogen in laboratory.Based on the observation of morphological characteristics,its taxonomic position was identified to be Scleromitrula shiraiana which belongs to the genus Scleromitrula S.Imai in the family Sclerotiniaceae by comparing the large subunit rRNA sequences with closely related strains.The main morphologic and biological characteristics of this pathogen included that 8 ascospores were arranged in two rows in each immature ascus and were changed into one row gradually as the ascospores grew and developed.The appropriate temperature for mycelial growth of the pathogen was 20～30 ℃ and the optimum temperature for mycelial growth was 25 ℃.The lethal temperature of mycelia and sclerotia was 50 ℃.The appropriate pH value for the pathogen to grow was 5～8 and the optimum pH value was 7.It was found that 80% chlorothalonil had strong inhibitory effect on mycelial growth of this pathogen with EC50 value of 0.012 0 mg/mL,being a promising agent for chemical control of the reduced sorosis scleroteniosis on mulberry fruit.