Zhang C Q, Xu B C
Department of Crop Protection, Zhejiang Agriculture and Forest University, Lin'an 311300, China.
The Forest Pest Control Station of Hangzhou Municipal, Hangzhou 310009, China.
Plant Dis. 2011 Oct;95(10):1319. doi: 10.1094/PDIS-05-11-0457.
In the late 1990s, sporadic occurrence of Botryosphaeria canker on Carya cathayensis was recorded in Zhejiang Province, China. From 2005 to 2009, nearly 90% of orchards in Zhejiang and Anhui provinces were seriously affected by this disease. Symptoms were similar to those of canker of C. illinoinensis (2); small, elliptical lesions that developed on the bark at points of infection and then enlarged to form large, sunken, elongated cankers. The cankers coalesced, forming large diffuse areas of blighted tissue, which turned black. Tissue samples from the margin of trunk lesions from 35 different diseased trees from five counties were surface sterilized with 1.5% sodium hypochlorite for 3 min, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Gray-black mycelia and colorless, aseptate, thin-walled conidia, 17.3 ± 0.8 long and 4.5 ± 0.5 μm wide, were produced. On the basis of these morphological characteristics, the fungus was identified as Botryosphaeria dothidea (Moug. ex Fr.) Ces. & De Not (1). The internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 from DNA extracted from mycelium produced on PDA and was recorded as GenBank Accession Nos. HQ731442 and HQ731443. The results of BLAST showed that it had more than 98% similarity to records for B. dothidea. Uninfected twigs and stems of C. cathayensis were wounded with a scalpel and then sprayed with a conidia suspension of 10 conidia per ml in distilled water as inoculum or distilled water only to provide an noninoculated control, wrapped in plastic bags to retain moisture, and incubated for 48 h. For each isolate, five twigs and stems per tree and a total of 10 trees were inoculated. After 2 weeks, 14 of 15 isolates caused lesions on inoculated stems and twigs, whereas no symptoms developed on the noninoculated controls. Cultures isolated from lesions and cultured on PDA exhibited morphological characteristics identical to those of B. dothidea, confirming completion of Koch's postulates. Currently, the distribution of Botryosphaeria canker of C. cathayensis is confined to Zhejiang and Anhui provinces. The identification of the pathogen now allows for appropriate forest management measures. To our knowledge, this is the first report of Botryosphaeria canker of pecan (C. cathayensis) in China. References: (1) S. Denman et al. Stud. Mycol. 45:129, 2000. (2) W. A. Sinclair and H. H. Lyon. Diseases of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.
20世纪90年代末，中国浙江省记录到山核桃上偶发葡萄座腔菌溃疡病。2005年至2009年，浙江和安徽省近90%的果园受到这种病害的严重影响。症状与伊利诺伊胡桃溃疡病相似（2）；在感染部位的树皮上形成小的椭圆形病斑，然后扩大形成大的、凹陷的、细长的溃疡斑。溃疡斑融合，形成大片枯萎组织，变为黑色。从五个县的35棵不同病树上采集树干病斑边缘的组织样本，用1.5%次氯酸钠进行表面消毒3分钟，接种到2%马铃薯葡萄糖琼脂（PDA）平板上，于25℃黑暗中培养1周。产生了灰黑色菌丝体和无色、无隔、薄壁的分生孢子，分生孢子长17.3±0.8μm，宽4.5±0.5μm。根据这些形态特征，该真菌被鉴定为葡萄座腔菌（Botryosphaeria dothidea (Moug. ex Fr.) Ces. & De Not）（1）。从PDA上产生的菌丝体提取的DNA，用引物ITS1/ITS4扩增内部转录间隔区（ITS），记录为GenBank登录号HQ731442和HQ731443。BLAST结果表明，它与葡萄座腔菌的记录相似度超过98%。用手术刀对未感染的山核桃嫩枝和茎进行创伤处理，然后分别喷洒每毫升含10个分生孢子的分生孢子悬浮液作为接种物或仅喷洒蒸馏水作为未接种对照，用塑料袋包裹以保持湿度，培养48小时。对于每个分离株，每棵树接种5个嫩枝和茎，共接种10棵树。2周后，15个分离株中有14个在接种的茎和嫩枝上引起病斑，而未接种对照未出现症状。从病斑分离并在PDA上培养的菌株表现出与葡萄座腔菌相同的形态特征，证实了柯赫氏法则。目前，山核桃葡萄座腔菌溃疡病的分布仅限于浙江和安徽省。病原菌的鉴定使得能够采取适当的森林管理措施。据我们所知，这是中国山核桃葡萄座腔菌溃疡病的首次报道。参考文献：（1）S. Denman等人，《真菌学研究》45:129，2000年。（2）W. A. Sinclair和H. H. Lyon，《树木和灌木病害》第2版，康奈尔大学出版社，纽约州伊萨卡，2005年。
