Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests

Nanning, China

Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests

Nanning, China
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Li Q.,Guangxi Academy of Agricultural science | Li Q.,Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests | Mo J.,Guangxi Academy of Agricultural science | Mo J.,Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests | And 9 more authors.
Plant Disease | Year: 2016

Curcuma wenyujin Y. H. Chen & C. Ling (family Zingiberaceae) is a traditional medicinal herb in China, used for alleviating pain and protecting the liver. In November 2012, a severe leaf spot disease was observed on leaves of C. wenyujin in Long’an County, Guangxi, south China. The disease was found on over 90% of the plants in this field of 0.5 ha and was also observed on some other fields in Guangxi Province. The symptoms began as water-soaked, yellow-green spots that became brown, round, diamond-shaped or elliptical lesions, with clear yellow halos, 1 to 3 cm wide and 2 to 6 cm long. These spots enlarged and overlapped, extending until the leaves withered entirely. At later stages, numerous acervuli appeared on the lesions. Acervuli were mostly epiphyllous, and setae were two to three-septate, dark brown, acicular, and up to 155 μm long. On potato dextrose agar (PDA), a fungus was consistently recovered from symptomatic leaf samples, with a 92.5% isolation rate from 40 leaf pieces that were surface sterilized in 75% ethanol for 30 s and then in 0.1% mercuric chloride for 45 s. The colonies on PDA were iron-gray to black with few aerial hyphae. Pionnotes were produced after 10 days at 25°C on PDA plates. Conidia were hyaline, falcate, and aseptate, 16 to 22 × 4 to 5.5 μm (mean = 19.7 × 4.7 μm). A single-spore isolate, Zhong11-1, was selected as representative for molecular identification. The rDNA internal transcribed spacer region (ITS), a partial sequence of the actin gene (ACT), chitin synthase 1 gene (CHSI), and glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH) of isolate Zhong11-1 were sequenced and deposited in GenBank as Accession Nos. KT004507, KT004508, KT004509, and KT004510. These were compared with the GenBank nucleotide sequence database and they showed between 99 and 100% identity to ITS (NR_111459), ACT (GU227991), CHSI (GU228383), and GAPDH (GU228285) of C. curcumae isolate IMI 288937 (Damm et al. 2009). The fungus was identified as Colletotrichum curcumae (Syd. & P. Syd.) E. J. Butler & Bisby, based on the morphological and molecular phylogenetic analysis (Damm et al. 2009). Pathogenicity tests were performed with this isolate by spraying a conidial suspension (1 × 106 conidia/ml) containing 0.1% Tween 20 onto the surfaces of leaves of 3-month-old and 0.8 to 1 m high plants in the field. Young leaves (between 5 to 7 days old) from five replicate plants were treated because younger leaves were found to be more susceptible. Control plants were treated with water containing 0.1% Tween 20. All plants were covered with plastic bags for two days to maintain high humidity. Typical yellow to brown symptoms were observed on all inoculated leaves after 14 days, but no symptoms were seen on water-treated control plants. Koch’s postulates were fulfilled by reisolation of C. curcumae from the diseased leaves. The fungus has been reported on Curcuma longa Linn, Solanum xanthocarpum Schrad. & H. Wendl, and Colocasia esculenta (L.) Schott in India (Palarpawar and Ghurde 1988); however, to our knowledge, this is the first report of C. curcumae infecting C. wenyujin in China. © 2016 The American Phytopathological Society.


Li Q.L.,Guangxi Academy of Agricultural science | Li Q.L.,Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests | Deng T.J.,Plant Protection Station of Guangxi Province | Huang S.P.,Guangxi Academy of Agricultural science | And 6 more authors.
Journal of Plant Pathology | Year: 2014

Mango (Mangifera indica) is an important fruit crop in southern China, and gummosis is one of the most important diseases. In September 2012, symptomatic branches were collected in Panzhihua, Sichuan province. On potato dextrose agar, isolates of similar morphological characteristics were consistently recovered from surface-sterilized branch pieces. The fungus was identified as Neofusicoccum parvum based on morphology and DNA sequence comparisons (Costa et al., 2010). Conidia were hyaline, thin walled, spindle-shaped to ellipsoid, nonseptate, and ranged from 15 to 23.5 × 4 to 7 μm (average 19.5 × 5.6 μm). The rDNA internal transcribed spacer region, a partial sequence of the β-tubulin gene, and the translation elongation factor 1-α gene of one isolate (L13), showed 100% identity to N. parvum (GenBank accession Nos GU997685, HM480386 and HQ859955). Pathogenicity of three isolates was tested in three green twigs and three 3-year-old branches in mango orchards of Guangxi Academy of Agricultural Sciences, Guangxi, China.Five wounds were made for each location with a sterilized needle. Mycelial plugs were placed at wounds and then covered with parafilm. Control twigs were inoculated with uncolonized PDA plugs. Two weeks later, typical brown lesions were observed on inoculated branches, and gum exuded from infected tissues wound. No symptoms were seen on the controls. Koch’s postulates were fulfilled by reisolation of N. parvum from diseased branches. In China, the disease was mainly associated with Lasiodiplodia theobromae (Li et al., 2013) and Botryosphaeria dothidea (Mo et al., 2013). To our knowledge, this is the first report of N. parvum causing mango gummosis in China. © 2014, Edizioni ETS. All rights reserved.


Wang Y.,Guangxi Academy of Agricultural science | Wang Y.,Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests | Yang Y.,Guangxi Academy of Agricultural science | Zhou Q.,Guangxi Academy of Agricultural science | And 2 more authors.
Polish Journal of Environmental Studies | Year: 2014

The dissipation and final residues of picoxystrobin in banana and soil were determined by gas chromatography equipped with an electron capture detector (GC-ECD). The dissipation half-lives of picoxystrobin were 10.7-12.1 days in banana, and 12.5-13.4 days in soil at Nanning (Guangxi) and Zhanjiang (Guangdong). The final residues of picoxystrobin in banana and soil were determined after the third and fourth applications at recommended dose and 1.5 times recommended dose, respectively. Picoxystrobin residues in banana 28 days after the last treatment were below 0.686 mg/kg, in banana sarcocarp below 0.159 mg/kg, and in soil below 0.227 mg/kg. © 2014, Polish Journal of Environmental Studies. All Rights Reserved.

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