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Yao J.A.,Fujian Academy of Agricultural science FAAS | Yu D.Y.,Fujian Academy of Agricultural science FAAS | Lu L.M.,Citrus Research Institute of Zhejiang Province | Huang P.,Fujian Academy of Agricultural science FAAS | Lan C.Z.,Fujian Academy of Agricultural science FAAS
Plant Disease | Year: 2015

Chinese banyan (Ficus microcarpa Linn. f.) is an evergreen plant with high ornamental, ecological, and medicinal values in southern China. During May 2011 and August 2013, surveys were conducted to identify the causal agent of black leaf spot on F. microcarpa in Zhangzhou, Fuzhou, and Quanzhou cities of Fujian Province. Symptoms generally first appeared on the tip and margin of the leaf. As the disease progressed, the lesions became oval or irregular in shape with black center and puce border. Black mold growth was usually observed on the surface of the lesions under suitable temperatures (25°C to 30°C) and high humidity. Multiple lesions often coalesced, causing the leaves to wilt and defoliate. Thirteen diseased leaf samples were collected from Fuzhou and Zhangzhou. Leaf sections were cut from the edge of the lesion with some healthy leaf area, surface sterilized with 0.5% sodium hypochlorite for 5 min, and then rinsed in sterile water before plating onto potato dextrose agar (PDA). Twenty-five monoconidial cultures were obtained from diseased leaves showing typical symptoms of black leaf spot. Colonies of these isolates were dark olivaceous, fluffy, and 8.5 cm in diameter after 7 days of culture at 28°C in the dark. Conidiophores were straight, septate, light to olive golden brown, solitary or clustered, and measured 30.5 to 85.0 µm × 3.0 to 5.0 µm. Conidia were produced in long chains, pale to light brown, obpyriform or nearly oval, with a cylindrical or coniform beak (2.5 to 13.0 µm × 2.5 to 4.0 µm), 1 to 7 transverse and 1 to 3 longitudinal septa, and measured 10.0 to 42.5 µm × 6.5 to 13.5 µm. These morphological characteristics matched the description of Alternaria alternata (Zhang 2003). Furthermore, the 5.8S subunit and its flanking internal transcribed spacers (ITS1 and ITS2) of rDNA of these isolates were amplified with universal primers ITS1 and ITS4. The resultant DNA fragments were sequenced and submitted to GenBank (Accession No. KC010550). The BLAST results showed that the ITS1-5.8S-ITS2 sequences exhibited 100% identity with those of A. alternata isolates (Accession Nos. KC478610, KJ735925, KJ677249, etc.). For pathogenicity tests, 12 potted F. microcarpa plants were wound-inoculated with mycelial discs of 5-mm diameter taken from a 6-day-old culture grown on PDA at 28°C in the dark. Inoculated plants were individually covered with a plastic bag and maintained in a greenhouse for 1 week at 25 ± 2°C. Three control plants were wound-inoculated with only agar plugs. Assays were performed twice. After 7 days of inoculation, black leaf spots identical to those in the field were observed on all the inoculated plants, and A. alternata was reisolated from these spots. No disease symptoms were observed on control plants. In this way, A. alternata was determined to be the causal agent of black leaf spot of F. microcarpa in China. Previous reports showed that A. alternata causes leaf spot of Juglans regia (Belisario et al. 1999), Panicum virgatum (Vu et al. 2012), and Aloe vera (da Silva and Singh 2012). To the best of our knowledge, this is the first report of A. alternata causing black leaf spot on F. microcarpa in China. This disease may cause considerable economic losses, so proper control strategies should be implemented promptly. © The American Phytopathological Society.

Fang X.,Citrus Research Institute of Zhejiang Province | Ye X.,Zhejiang University | Zhao K.,Citrus Research Institute of Zhejiang Province | Cao X.,Citrus Research Institute of Zhejiang Province | Lin M.,Citrus Research Institute of Zhejiang Province
Journal of Chinese Institute of Food Science and Technology | Year: 2013

The joint production technique of citrus peel oils and pectin were studied in this paper. The best peel hardening process through test screening results show that the use of calcium chloride solution, calcium chloride mass fraction of 0.5%, the 5 h conditions of immersion time, through this processing the squeezing fluid viscosity is low, you can have to get a better essential oil yield; peel residue after oil extraction is directly used for pectin extraction, the optimum extraction conditions: extraction temperature 90°C, the processing time is 30 min, the pH value of 2.0, add water to 450%, acidifier for sulfuric acid. Contrast joint production and traditional laws and extraction yield and quality of essential oils and pectin, the results show that the essential oil yield is similar to two processes, but the oil quality of the joint production method is better than the traditional method; pectin extraction rate of the joint production than the traditional method to improve 15.9%, the ash and acid insoluble substance of pectin from the joint production method is higher than the traditional method, but conformed the line marked and national standard requirements. The joint production technique of citrus reticulata peel essential oils and pectin can be used for industrial production.

Chen F.,Citrus Research Institute of Zhejiang Province | Lu L.,Citrus Research Institute of Zhejiang Province | Wang D.,Forestry and Science Institute of Taizhou | Wang Y.,Citrus Research Institute of Zhejiang Province | And 2 more authors.
European Journal of Plant Pathology | Year: 2013

Chinese bayberry (Myrica rubra Siebold & Zucc) is an evergreen fruit tree with high ecological and economic values in China. In recent years, a new twig dieback disease caused by Pestalotiopsis mangiferae and P. vismiae was observed in major M. rubra-producing areas of Zhejiang and Fujian Provinces, causing serious economic losses. In this study, 16 isolates of P. mangiferae and 27 isolates of P. vismiae were obtained from diseased leaves, roots and branches of M. rubra from different regions. The optimum growth temperature of the two species of Pestalotiopsis was determined to be 20-25 °C, while the optimum temperature for the germination of conidia was 25-35 °C. The two species of Pestalotiopsis showed rich genetic diversity. Inoculating the conidial suspension of one or both of the two species of the Pestalotiopsis on detached leaves or branches of M. rubra could cause lesions surrounding the inoculation sites with the frequency of 100 %. Moreover, necrotic lesions could be observed on inoculated potted plants with the frequencies of 33.3 % for P. mangiferae, 25 % for P. vismiae and 50 % for a mixed inoculum. © 2013 KNPV.

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