First Report of Zonate Leaf Spot of Cinnamomum kanehirae Caused by Hinomyces moricola in Taiwan

Cinnamomum kanehirae, a native tree of Taiwan, is an important tree that hosts popular medicinal fungi. In the winter of 2011, zonate leaf spots were observed at a nursery garden in Wu-Lai, Taiwan. Initial symptoms included small brown lesions on leaves that became larger leaf spots after expanding or fusing together, causing a leaf blight and eventually defoliation. Sporophores on the host were generally hypophyllous but sometimes amphigenous, solitary, erect, easily detachable. The upper portion of the sporophore was considered an individual conidium and consisted of a pyramidal head that was fusiform to ventricose, 320 to 580 μm long and 100 to 130 μm wide at the broadest point. Branches within the pyramidal head were short and compact, and dichotomously or trichotomously branched. The sporophore initials were hyaline, broad, septate, tapering toward an acute apex, and sometimes constricted at the basal septum. Sclerotia were observed in older lesions, grey or black, spherical, and 1 to 2.5 mm in diameter. The fungus was isolated from infected tissue and sporophores, maintained on potato dextrose agar (PDA) at 20°C in darkness. Sclerotia were produced on PDA after 4 to 5 weeks and were irregular or spherical, but sporophores didn't develop on agar medium. The fungus was identified as Hinomyces moricola on the basis of morphological characteristics (1). Koch's postulates were performed by inoculating four 1-year-old, asymptomatic, potted C. kanehirae plants; every plant was inoculated with sporophores from infected leaves on each of five leaves. Four noninoculated plants were kept in separate pots and served as controls. All plants were covered with transparent plastic bags individually and incubated in a growth chamber at 18 to 20°C. Symptoms were observed after 2 to 4 days on every inoculated plant but not on uninoculated plants. The leaf spots were similar to those originally observed. The pathogen was reisolated from spots of inoculated plants. The pathogenicity test was repeated once. H. moricola is known to cause severe defoliation on woody and annual plants, including at least 73 host species and 36 families distributed in the eastern United States and Japan (2). References: (1) N.-S. Tomoko et al. Mycoscience. 47:351, 2006. (2) J. C. Trolinger et al. Plant Dis. Reptr. 62:710, 1978.

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First Report of Zonate Leaf Spot of Vigna vexillata var. tsusimensis Caused by Cristulariella moricola

Plant Disease ◽

10.1094/pdis.2002.86.4.440c ◽

2002 ◽

Vol 86 (4) ◽

pp. 440-440 ◽

Cited By ~ 3

Author(s):

H. B. Lee ◽

C.-J. Kim

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Leaf Spot Disease ◽

Eastern United States ◽

Leaf Spots ◽

Vigna Vexillata ◽

Initial Symptoms ◽

Pathogenicity Tests ◽

Basal Septum ◽

Bull's Eye

A zonate leaf spot disease on a wild bean variety, Vigna vexillata L. var. tsusimensis Mat., occurred in the patch fields and foothills of Chungnam and Kyonggi districts in Korea during late September, October, and early November of 1999 to 2001. The zonate lesions were particularly prevalent in October following periods of heavy dew accumulation. Initial symptoms were small, circular lesions with darkbrown marginal rings that later developed into large spots with characteristic target-shaped rings. The spots were gray to bright or blackish brown, progressed rapidly, and sometimes fused together to form lesions of up to 20 mm in diameter. Sporophores on the natural host were generally hypophyllous but sometimes amphigenous, abundant on large spots, fewer on small spots, solitary, erect, easily detachable, and up to 864 μm long. The upper portion of the sporophore is considered an individual conidium and consisted of a pyramidal head that was fusiform to ventricose and cristulate, 495 to 534 μm long, and 210 to 290 μm wide at the broadest point. Branches within the pyramidal head were short and compact, and dichotomously or trichotomously branched. The central axis within the conidium was hyaline, broad, septate, tapering toward an acute apex, and sometimes constricted at the basal septum. Conidiophores were 272 to 330 μm long and up to 24 μm wide. The fungus was identified as Cristulariella moricola (Hino) Redhead based on morphological characteristics (1,2). The fungus was isolated from Vigna leaf spots, placed on 2% water agar or potato dextrose agar (PDA), and maintained on PDA amended with 2% Vigna leaf extract. For pathogenicity tests, 4- to 5-week-old leaves of V. vexillata var. tsusimensis were surface-sterilized in 1% NaOCl. Agar disks (approximately 10 mm diameter) containing mycelia of the fungus were placed on the upper leaf surface. The inoculated plants (two leaflets per plant × 2) were then sprayed with distilled water, covered with premoistened polyethylene bags, and incubated at 15 to 25°C. Within 5 days, small leaf spots appeared that were similar to those originally observed on all inoculated leaflets. Uninoculated control leaves exposed to the same environmental conditions remained healthy. C. moricola was consistently reisolated from the infected leaves. The hyphomycete fungus C. moricola has been known to cause a bull's eye or zonate leaf spot and defoliation on woody and annual plants, including at least 73 host species and 36 families distributed in the central and eastern United States and Japan (1). In Asia, the occurrence of Cristulariella spp. on several hosts has been reported only in Taiwan and Japan (3,4). No species in the genus has ever been reported from Korea. To our knowledge, V. vexillata var. tsusimensis represents a previously unreported host for C. moricola. References: (1) M. C. Niedbalski et al. Mycologia 75:988, 1983. (2) S. A. Redhead. Mycologia 71:1248, 1979. (3). H. J. Su and S. C. Leu. Plant Dis. 67:915, 1983. (4) T. Yokoyama and K. Tubaki. Trans. Mycol. Soc. Jpn. 15:189, 1974.

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First Report of Zonate Leaf Spot of Artocarpus altilis Caused by Cristulariella moricola in Taiwan

Plant Disease ◽

10.1094/pdis.2002.86.10.1179a ◽

2002 ◽

Vol 86 (10) ◽

pp. 1179-1179 ◽

Cited By ~ 1

Author(s):

B. Y. Hu ◽

W. W. Hsiao ◽

C. H. Fu

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Eastern United States ◽

First Report ◽

Artocarpus Altilis ◽

Leaf Spots ◽

Plastic Bags ◽

Basal Septum ◽

Bull's Eye ◽

Northern Taiwan

Breadfruit (Artocarpus altilis (Parkinson) Fosberg) is an important landscape and garden tree in Taiwan. During the spring of 2002, zonate leaf spots of breadfruit were observed at a Taipei nursery in northern Taiwan. Initially, several small, brown, zonate lesions developed on leaves. As lesions enlarged, they coalesced, leading to blighting of leaves and premature defoliation. Sporophores on the host were generally hypophyllous but sometimes amphigenous, solitary, erect, easily detachable, and as much as 850 μm long. The upper portion of the sporophore is considered an individual conidium and consisted of a pyramidal head that was fusiform to ventricose and cristulate, 495 to 534 μm long and 210 to 290 μm wide at the broadest point. Branches within the pyramidal head were short and compact, and dichotomously or trichotomously branched. The conidia were hyaline, broad, septate, tapering toward an acute apex, and sometimes constricted at the basal septum. Conidiophores were 400 to 680 × 20 to 100 μm. The fungus was isolated from infected tissue and maintained on potato dextrose agar (PDA). Sclerotia were produced on PDA after 4 to 5 weeks at 20°C without light, but conidia were not observed in culture. The fungus was identified as Cristulariella moricola (Hino) Redhead based on morphological characteristics (1,2). To complete Koch's postulates, three sporophores from infected leaves or three sclerotia from cultures were placed individually on each of 10 breadfruit leaves. The plants were placed in plastic bags and incubated at 16 to 20°C. Symptoms were observed after 2 to 3 days on 100% of plants inoculated with sporophores and after 6 days on 50% of plants inoculated with sclerotia. The pathogen was reisolated from lesions on plants inoculated with sporophores and sclerotia. No symptoms were observed on the control plants. C. moricola has been known to cause a bull's eye or zonate leaf spot and defoliation on woody and annual plants, including at least 51 host species and 36 families distributed in the central and eastern United States (1). To our knowledge, this is the first report of zonate leaf spot and defoliation of breadfruit caused by C. moricola. References: (1) T. T. Chang. Bull. Taiwan For. Res. Inst. New Ser. 10 (2):235, 1995. (2) S. A. Redhead. Can. J. Bot. 53:700, 1975.

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Veronica sibirica Leaf Spots Caused by Phacellium veronicae, a New Disease in China

Plant Disease ◽

10.1094/pdis-11-12-1052-pdn ◽

2013 ◽

Vol 97 (12) ◽

pp. 1662-1662 ◽

Cited By ~ 1

Author(s):

Q. R. Bai ◽

S. Han ◽

Y. Y. Xie ◽

J. Gao ◽

Y. Li

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Control Treatment ◽

Perennial Herb ◽

Conidial Suspension ◽

New Disease ◽

Medical College ◽

Leaf Spots ◽

Plastic Bags ◽

Insect Bites

Veronica sibirica (Veronicastrum sibiricum) is an erect perennial herb, an ornamental, and a traditional Chinese medicine plant distributed mostly in northeastern, northern, and northwestern China. It has dehumidifying and detoxifying properties, and is mainly used for the treatment of cold, sore throat, mumps, rheumatism, and insect bites (4). In June 2008 through 2012, leaf spots of V. sibirica were observed in the Medicinal Herb Garden of Jilin Agricultural University (43°48′N, 125°23′E) and the medicinal plantations of Antu County (43°6′N, 128°53′E), Jilin Province. Leaf spots were amphigenous, subcircular, angular-irregular, brown, and 1 to 10 mm in diameter; they occasionally merged into a larger spot with an indefinite margin or with a pale center and dark border. Pale conidiomata were hypophyllous and scattered on the spots. The conidiophores were 100 to 400 μm high and clustered together to form synnemata 20 to 50 μm in diameter, which splayed out apically and formed loose to dense capitula. Conidiophores occasionally emerged through the stomata individually and produced conidia on the surface of the infected leaves. The conidiogenous cell terminal was geniculate-sinuous with somewhat thickened and darkened conidial scars. Conidia were solitary or catenulate, ellipsoid-ovoid or subcylindric-fusiform, hyaline and spinulose, 4.01 to 7.18 × 11.16 to 20.62 μm with obtuse to somewhat attenuated ends, and slightly thickened, darkened hila. Six isolates were obtained from necrotic tissue of leaf spots and cultured on potato dextrose agar at 25°C. After incubation for 14 days, colony surfaces were white to pinkish. The colony diameter increased by 12 mm after 21 days' incubation. Hyphae were hyaline, septate, and branched. Conidiophores grew individually or fascicularly. The symptoms and morphological characteristics were consistent with previous descriptions (1,2), and the fungus was identified as Phacellium veronicae (Pass.) (U. Braun 1990). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (3). The ITS was identical among all six isolates (HE995799) and 98% identical to that of P. veronicae (JQ920427, HQ690097). Pathogenicity was confirmed by spraying five 1-year-old V. sibirica seedlings with a conidial suspension (106 conidia/ml) of each isolate and five seedlings with sterile water as a control treatment. Plants were grown in the greenhouse at 20 to 25°C and were covered with plastic bags to maintain humidity on the foliage for 72 h. After 15 days, the same symptoms appeared on the leaves as described earlier for the field-grown plants; the control plants remained healthy. The same fungus was reisolated from the leaf spots of inoculated plants. Currently, the economic importance of this disease is limited, but it may become a more significant problem, as the cultivated area of V. sibirica is increasing. To our knowledge, although P. veronicae was recorded on the other species of Veronica (V. austriaca, V. chamaedrys, V. grandis, V. longifolia, V. paniculata, and V. spicata ssp. incana) in Europe (Germany, Denmark, Ireland, Romania) and V. wormskjoldii in North America (Canada) (1), this is the first report of V. sibirica leaf spots caused by P. veronicae in the world, and it is a new disease in China. References: (1) U. Braun. A monograph of Cercosporella, Ramularia and allied genera (phytopathogenic Hyphomycetes) 2, IHW-Verlag, Germany, 1998. (2) U. Braun. Nova Hedwigia 50:499, 1990. (3) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (4) Jiangsu New Medical College. Dictionary of Chinese Materia Medica. Shanghai: Shanghai Scientific and Technical Publishers, China, 1977.

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First Report of Leaf Spot and Root Rot Caused by Phoma betae on Beta vulgaris subsp. vulgaris (Garden Beet Group) in Italy

Plant Disease ◽

10.1094/pdis-91-11-1515c ◽

2007 ◽

Vol 91 (11) ◽

pp. 1515-1515 ◽

Cited By ~ 7

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Beta Vulgaris ◽

Morphological Characteristics ◽

Its Region ◽

Pathogenicity Test ◽

Vegetable Crops ◽

Plastic Bags ◽

Blastn Analysis ◽

Commercial Farms ◽

Pathogenicity Tests ◽

Phoma Betae

In the winter of 2007 in Piedmont (northern Italy), symptoms of a previously unknown disease were observed on beet (Beta vulgaris L. subsp. vulgaris) (garden beet group) grown under a tunnel on several commercial farms near Cuneo. First symptoms appeared on 1-month-old plants, occurring as brown, round-to-oval spots as much as 2 cm in diameter with dark concentric rings near the perimeter. Small, dark pycnidia were present throughout the spots in concentric rings. Generally, older, lower leaves were affected more than the younger ones. Ten to fifteen percent of the plants were affected. Symptoms on the roots began near the crown as small, dark, sunken spots that became soft and water soaked. Eventually, spots on the roots turned dark brown to black and black lines separated diseased and healthy tissues. Older infected tissues were black, dry, shrunken, and spongy. Pycnidia were not observed on affected roots. From infected leaves and roots, a fungus was consistently isolated on potato dextrose agar (PDA) amended with 25 mg/l of streptomycin. The fungus was grown on PDA and maintained at 22°C (12 h of light, 12 h of dark). After 10 days, black pycnidia (130 to 328 [204] μm in diameter) developed, releasing abundant hyaline, elliptical, nonseptate conidia measuring 3.9 to 6.7 (5.1) × 2.4 to 5.9 (3.6) μm. On the basis of its morphological characteristics, the fungus was identified as a Phoma sp. (1). The internal transcribed spacer (ITS) region was amplified using primers ITS4/ITS6 (2) and sequenced. BLASTn analysis of the 557 bp obtained showed an E-value of 0.0 with Phoma betae. The nucleotide sequence has been assigned GenBank Accession No. EU003450. Pathogenicity tests were performed by spraying leaves of healthy 20-day-old potted B. vulgaris plants with a spore and mycelial suspension (1 × 106 spores or mycelial fragments per ml). Noninoculated plants sprayed only with water served as controls. Fifteen plants (three per pot) were used for each treatment. Plants were covered with plastic bags for 5 days after inoculation and kept in a growth chamber at 20°C. Symptoms previously described developed on leaves of all inoculated plants 5 days after inoculation, while control plants remained healthy. Later, pycnidia and conidia, with the same dimensions and characteristics previously described, were observed on the infected leaves. The fungus was consistently reisolated from the lesions of the inoculated plants. The pathogenicity test was carried out twice. P. betae on B. vulgaris var. cycla has been reported in Canada (3) as well as in other countries. The same pathogen was reported in Italy on sugar beet (2). References: (1) G. H. Boerema and G. J. Bollen. Persoonia 8:111, 1975. (2) A. Canova. Inf. Fitopatol. 16:207, 1966. (3) D. E L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) J. R. Howard et al. Diseases of Vegetable Crops in Canada. Canadian Phytopathological Society, 1994.

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First Report of Alternaria heveae Causing Black Leaf Spot of Rubber Tree in China

Plant Disease ◽

10.1094/pdis-01-14-0065-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1011-1011 ◽

Cited By ~ 1

Author(s):

Z. Y. Cai ◽

Y. X. Liu ◽

G. X. Huang ◽

M. Zhou ◽

G. Z. Jiang ◽

...

Keyword(s):

Rubber Tree ◽

Morphological Characteristics ◽

Black Spot ◽

Its Region ◽

Post Inoculation ◽

First Report ◽

Leaf Spots ◽

Plastic Bags ◽

Manual Pressure ◽

Tree Leaf

Rubber tree (Hevea brasiliensis Muell. Arg.) is an important industrial crop of tropical areas for natural rubber production. In October 2013, foliar spots (0.1 to 0.4 mm in diameter), black surrounded by a yellow halo, and with lesions slightly sunken were observed on the rubber tree leaf in a growing area in Heikou County of Yunnan Province. Lesion tissues removed from the border between symptomatic and healthy tissue were surface sterilized in 75% ethanol and air-dried, plated on PDA plates, and incubated at 28°C with alternating day/night cycles of light. The pathogen was observed growing out of many of the leaf pieces, and produced abundant conidia. Colonies 6.1 cm in diameter developed on potato carrot agar (PCA) after 7 days, with well-defined concentric rings of growth. Colonies on PCA were composed of fine, dark, radiating, surface and subsurface hyphae. Conidia produced in PCA culture were mostly solitary or in short chains of 2 to 5 spores, long ovoid to clavate, and light brown, 40 to 81.25 × 8 to 20 μm (200 colonies were measured), with 3 to 6 transverse septa and 0 to 2 longitudinal or oblique septa. Morphological characteristics were similar to those described for Alternaria heveae (3,4). A disease of rubber tree caused by Alternaria sp. had been reported in Mexico in 1947 (2). DNA of Ah01HK13 isolate was extracted for PCR and sequencing of the ITS region with ITS1 and ITS4 primers was completed. From the BLAST analysis, the sequence of Ah01HK13 (GenBank Accession No. KF953884), had 97% similarity to A. dauci, 96% identical to A. macrospora (AY154701.1 and DQ156342.1, respectively), indicating the pathogen belonged to Alternaria genus. According to morphological characteristics, this pathogen was identified as A. heveae. Pathogenicity of representative isolate, Ah01HK13 was confirmed using a field rubber tree inoculation method. Three rubber plants (the clone of rubber tree Yunyan77-4) were grown to the copper-colored leaf stage and inoculated by spraying spore suspension (concentration = 104 conidia/ml) to the copper-colored leaves until drops were equally distributed on it using manual pressure sprayer. Three rubber plants sprayed with sterile distilled water were used as controls. After inoculation, the plants were covered with plastic bags. The plastic bags were removed after 2 days post-inoculation (dpi) and monitored daily for symptom development (1). The experiment was repeated three times. The typical 0.1 to 0.4 mm black leaf spots were observed 7 dpi. No symptoms were observed on control plants. A fungus with the same colony and conidial morphology as A. heveae were re-isolated from leaf lesions on inoculated rubber plants, but not from asymptomatic leaves of control plants, fulfilling Koch's postulates. Based on these results, the disease was identified as black spot of rubber tree caused by A. heveae. To our knowledge, this is the first report of A. heveae on rubber tree in China. References: (1) Z. Y. Cai et al. Microbiol Res. 168:340, 2013. (2) W. J. Martin. Plant Dis. Rep. 31:155, 1947. (3) E. G. Simmons. Mycotaxon 50:262, 1994. (4) T. Y. Zhang. Page 111 in: Flora Fungorum Sinicorum: Alternaria, Science Press, Beijing, 2003.

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Leaf Spot Caused by Alternaria sp. on Iberis sempervirens in Italy

Plant Disease ◽

10.1094/pd-89-1243b ◽

2005 ◽

Vol 89 (11) ◽

pp. 1243-1243 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Leaf Spot ◽

Single Cells ◽

Morphological Characteristics ◽

Weather Conditions ◽

The United States ◽

Plant Diseases ◽

Pathogenicity Test ◽

Aesthetic Quality ◽

Leaf Spots ◽

Alternaria Sp

Iberis sempervirens (candytuft) is increasingly grown in Liguria (northern Italy) as a potted plant for ornamental purposes, particularly under cool-weather conditions. At the end of the summer of 2003, extensive necrosis was observed on leaves and young stems of 4-month-old plants grown in 14-cm diameter pots outdoors at a commercial farm. In many cases, on the upper side of the leaves, necrotic spots were surrounded by a chlorotic halo that turned progressively black. The necrotic areas often coalesced, generating larger and irregularly shaped spots. On the lower side of the leaves, no chlorotic areas were observed. Severely affected plants were defoliated. Infected plants rarely died, but the presence of lesions on mature plants decreased aesthetic quality and subsequently market value. The disease occurred on 40% of plants at each of the two farms. Leaf spots contained dark brown, multicellular pear-shaped conidia. Conidia were 22.5 to 50.0 μm (average 32.8 μm) long and 7.5 to 15.0 μm (average 12.3 μm) wide, with 5 to 7 longitudinal cross walls and an average of 6 to 7 single cells. From infected leaves, a fungus identified on the basis of its morphological characteristics as Alternaria sp. was consistently isolated on potato dextrose agar. Pathogenicity tests were performed by spraying leaves of healthy 12-month-old potted I. sempervirens plants with a spore and mycelial suspension (105 CFU/ml). Plants without inoculation served as control. Ten plants were used for each treatment. Plants were covered with plastic bags for 10 days after inoculation and kept outdoors for 60 days at temperatures ranging from 0 to 32°C (average 12°C). The first lesions developed on leaves 45 days after inoculation, while control plants remained healthy. From such lesions, Alternaria sp. was consistently reisolated. The pathogenicity test was carried out twice. The presence of A. brassicae was reported in Tanganica on Iberis sp., I. umbellata in Denmark (2), and I. amara in the United States (4); A. matthiolae was observed on seeds of I. amara and I. umbellata (3). A leaf spot incited by Alternaria sp. on I. amara was observed in Florida (1). This is, to our knowledge, the first report of Alternaria sp. on I. sempervirens in Italy as well as worldwide. References: (1) S. A. Alfieri et al. Index of Plant Diseases in Florida. Bull. 11, 1984. (2) P. Neergaard. Rev. Appl. Micol. 18:572, 1939. (3) P. Neergaard. Rev. Appl. Micol. 25:382, 1946). (4) R. D. Raabe. Comb. Proc. Int. Plant Propagators Soc. 40:160, 1991.

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First Report of Leaf Blight in Chinese Hickory (Carya cathayensis) Caused by Alternaria petroselini in China

Plant Disease ◽

10.1094/pdis-02-13-0176-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1253-1253 ◽

Cited By ~ 1

Author(s):

Y. H. Liu ◽

C. Q. Zhang ◽

B. C. Xu

Keyword(s):

Management Practices ◽

Morphological Characteristics ◽

Morphological Characterization ◽

Leaf Blight ◽

Internal Transcribed Spacers ◽

Infected Leaf ◽

First Report ◽

Plastic Bags ◽

Initial Symptoms ◽

Carya Cathayensis

Chinese hickory (Carya cathayensis) is one of the important economic forest crops in Zhejiang and Anhui Provinces, China. In 2012, nearly 40% of hickory orchards and 6.8% of hickory trees were affected by leaf blight in Zhejiang. Initial symptoms consisted of small, brown, water-soaked lesions, which subsequently enlarged and developed a black sporulating necrotic center surrounded by a chlorotic halo. Infected leaf samples collected from 25 different orchards in Lin'an and 13 different orchards in Chun'an were surface sterilized with 1.5% sodium hypochlorite for 1.5 min, rinsed in water, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Single conidium cultures were consistently isolated and cultured on PDA and V8 agar for morphological characterization (1,3). On both agar media, colonies were dark olive brown with smooth margins and concentric rings of sporulation. Conidia were solitary, darkly pigmented, predominantly ovoid-subsphaeroid, and 23 to 52 × 13 to 23 μm with up to six or seven transepta and one to three longisepta. The ribosomal internal transcribed spacers ITS1 and ITS2 of 10 isolates were amplified using primers ITS1/ITS4 on DNA extracted from mycelium and nucleotide sequences showed 100% similarity to that of A. petroselini (GenBank Accession Nos. AY154685.1 and EU807868.1). To confirm pathogenicity, 10 uninfected leaves from each of 10 C. cathayensis trees were sprayed either with a conidia suspension (105 conidia per ml) or with distilled water only to serve as an un-inoculated control. Leaves were subsequently wrapped in plastic bags to retain moisture, and incubated for 48 h. After 1 week, 8 of 10 isolates caused lesions identical to those initially described whereas no symptoms developed on water inoculated leaves. Cultures reisolated from lesions and cultured on PDA exhibited morphological characteristics identical to A. petroselini (1,2,3), confirming Koch's postulates. To our knowledge, this is the first report of leaf blight in C. cathayensis, and this identification would allow producers to identify for appropriate management practices. References: (1) P. M. Kirk et al. The Dictionary of the Fungi, 10th edition, page 159. CABI Bioscience, UK, 2008. (2) B. M. Pryor et al. Mycologia 94:49, 2002. (3) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007.

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First report of Cercospora cf. citrulina causing leaf spot of Ipomoea pes-caprae in China

Plant Disease ◽

10.1094/pdis-05-20-1081-pdn ◽

2020 ◽

Author(s):

Min Li ◽

Meijiao Hu ◽

Zhaoyin Gao ◽

Xiaoyu Hong ◽

Chao Zhao ◽

...

Keyword(s):

Molecular Identification ◽

Leaf Spot ◽

Plant Protection ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Xisha Islands ◽

First Report ◽

Initial Symptoms ◽

Leaf Surfaces

Ipomoea pes-caprae plays an important role in protecting the tropical and subtropical coastal beach of the world. In 2018, a leaf spot was observed on I. pes-caprae in Xisha islands of China, 13.2–25.8% of leaves were infected. The initial symptoms were small (1–3 mm diameter), single, circular, dark gray spots with a light-yellow center on the leaves. The lesions enlarged and were scattered or confluent, distinct and circular, subcircular or irregular, occasionally vein-limited, pale to dark gray-brown, with a narrow dark brown border surrounded by a diffuse yellow margin. Microscopic observations of the spots revealed that caespituli were dark brown and amphigenous, but abundant on the underside of the leaves. Mycelia were internal. Conidiophores were fasciculate, occasionally solitary, pale olivaceous-brown throughout, 0- to 3-septate, 27.9–115.8 (63.4±22.5) µm × 3.2–5.3 (4.3±0.87) µm (n=100). Conidial scars were conspicuously thickened. Conidia were solitary, hyaline, filiform, acicular to obclavate, straight to slightly curved, subacute to obtuse at the apex, truncate at the base, multi-septate, 21.0–125.5 (60.2±20.1) µm × 2.0–5.0 (3.8±0.83) µm (n=100). Single-conidium isolates were obtained from representative colonies grown on potato dextrose agar (PDA) incubated at 25℃ in the dark. The colonies grew slowly and were dense, white to gray and flat with aerial mycelium. Mycelia were initially white, and then became gray. Conidia were borne on the conidiophores directly. The pure isolate HTW-1 was selected for molecular identification and pathogenicity test, which were deposited in Microbiological Culture Collection Center of Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences. The internal transcribed spacer (ITS) region of rDNA, translation elongation factor 1-alpha (tef1) and histone H3 (his3) genes were amplified with ITS1/ITS4, EF-1 / EF-2, and CYLH3F / CYLH3R primers, respectively (Groenewald et al. 2013). The obtained sequences of HTW-1 were all deposited in GenBank with accession numbers MT410467 for ITS, MT418903 for tef1 and MT418904 for his3. The ITS, tef1 and his3 genes all showed 100% similarity for ITS (JX143582), tef1 (JX143340) and his3 (JX142602) with C. cf. citrulina (MUCC 588; MAFF 239409) from I. pes-caprae in Japan. Based on the morphological characteristics and molecular identification, the pathogen was identified as Cercospora cf. citrulina (Groenewald et al. 2013). The pathogenicity test was conducted by spraying conidial suspension (1×104 conidia/mL) on wounded and unwounded leaves for seedling of I. pes-caprae in greenhouse and in sterile vitro condition. The conidial suspension was prepared using conidia from 30-day-old culture grown on PDA at 25℃ in the dark. Leaf surfaces of seedling in greenhouse were wounded by lightly rubbing with a steel sponge and detached leaf surfaces were wounded by sterile needles. the treatments were sprayed with conidial suspensions on wounded and unwounded leaf surfaces. The control was sprayed with sterile water. After eight days, the typical symptoms of spots which were small, single, circular and dark gray appeared on the inoculated wounded leaves, while the inoculated unwounded leaves and the control leaves were symptomless. The pathogen was only re-isolated from the inoculated wounded leaves. The pathogen may be infected by wound. A total of 20 Cercospora and related species was found on Ipomoea spp. (García et al. 1996). Cercospora cf. citrulina has been reported on I. pes-caprae in Japan, although it was unclear if it was a pathogen or saprophyte (Groenewald et al. 2013). To our knowledge, this is the first report of C. cf. citrulina causing leaf spot of I. pes-caprae in China. This disease could threat the cultivation of I. pes-caprae in China.

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First Report of Volutella Blight on Pachysandra Caused by Volutella pachysandricola in China

Plant Disease ◽

10.1094/pdis-11-11-0997 ◽

2012 ◽

Vol 96 (4) ◽

pp. 584-584

Author(s):

Q. Bai ◽

Y. Xie ◽

R. Dong ◽

J. Gao ◽

Y. Li

Keyword(s):

Morphological Characteristics ◽

Stem Canker ◽

Botanical Garden ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

Conidial Suspension ◽

First Report ◽

Leaf Spots ◽

Plastic Bags

Pachysandra (Pachysandra terminalis, Buxaceae) and Japanese Pachysandra, also called Japanese Spurge, is a woody ornamental groundcover plant distributed mostly in Zhejiang, Guizhou, Henan, Hubei, Sichuan, Shanxi, and Gansu provinces in China. In April 2010, P. terminalis asymptomatic plants were shipped from Beijing Botanical Garden Institute of Botany Chinese Academy of Science to the garden nursery of Jilin Agricultural University (43°48′N, 125°23′E), Jilin Province. In June 2011, Volutella blight (sometimes called leaf blight and stem canker) of P. terminalis was observed on these plants. Infected leaves showed circular or irregular, tan-to-brown spots often with concentric rings and dark margins. The spots eventually grew and coalesced until the entire leaf died. Cankers appeared as greenish brown and water-soaked diseased areas, subsequently turning brown or black, and shriveled and often girdled the stems and stolons. During wet, humid weather in autumn, reddish orange, cushion-like fruiting structures of the fungus appeared on the stem cankers and undersides of leaf spots. Symptoms of the disease were consistent with previous descriptions (2–4). Five isolates were obtained from necrotic tissue of leaf spots and cankers of stems and stolons and cultured on potato dextrose agar. The colony surface was salmon colored and slimy. Conidia were hyaline, one celled, spindle shaped, and 12.57 to 22.23 × 3.33 to 4.15 μm with rounded ends. Morphological characteristics of the fungus were consistent with the description by Dodge (2), and the fungus was identified as Volutella pachysandricola (telemorph Pseudonectria pachysandricola). The internal transcribed spacer (ITS) regions of the nuclear rDNA were amplified using primers ITS4/ITS5 (1). The ITS sequences were 553 bp long and identical among these five isolates (GenBank Accession No. HE612114). They were 100% identical to Pseudonectria pachysandricola voucher KUS-F25663 (Accession No. JN797821) and 99% identical to P. pachysandricola culture-collection DAOM (Accession No. HQ897807). Pathogenicity was confirmed by spraying leaves of clonally propagated cuttings of P. terminalis with a conidial suspension (1 × 106 conidia/ml) of the isolated V. pachysandricola. Control leaves were sprayed with sterile water. Plants were covered with plastic bags and kept in a greenhouse at 20 to 25°C for 72 h. After 5 to 8 days, typical disease symptoms appeared on leaves, while the control plants remained healthy. V. pachysandricola was reisolated from the leaf spots of inoculated plants. Pachysandra leaf blight and stem canker also called Volutella blight, is the most destructive disease of P. terminalis and previously reported in the northern humid areas of the United States (Illinois, Connecticut, Ohio, Indiana, Iowa, Massachusetts, Missouri, Kentucky, and Wisconsin), northern Europe (Britain, Germany, and Poland), and the Czech Republic. To our knowledge, this is the first report of the disease caused by V. pachysandricola in China. The disease may become a more significant problem in P. terminalis cultivation areas if the disease spreads on P. terminalis in nursery beds. References: (1) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (2) B. O. Dodge. Mycologia 36:532, 1944. (3) S. M. Douglas. Online publication. Volutella Blight of Pachysandra. The Connecticut Agricultural Experiment Station, 2008. (4) I. Safrankova. Plant Protect. Sci.43:10, 2007.

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Curvularia Blight on Lolium perenne on Turfgrasses in Argentina

Plant Disease ◽

10.1094/pdis-91-3-0323b ◽

2007 ◽

Vol 91 (3) ◽

pp. 323-323

Author(s):

L. Goldring ◽

M. Lacasa ◽

E. R. Wright

Keyword(s):

Lolium Perenne ◽

Pathogenic Fungi ◽

Natural Soil ◽

Curvularia Lunata ◽

Distilled Water ◽

Transparent Plastic ◽

Conidial State ◽

Plastic Bags ◽

Initial Symptoms ◽

Intermediate Cells

Lolium perenne L. is commonly used alone or in association with blue-grass and fescues in sport fields, parks, and gardens. During 2003, symptoms of an unknown disease were observed on L. perenne turfgrass in western Buenos Aires. Initial symptoms were indefinite yellow and green dappled spots that extended downward from the leaf tip, turned brown and finally gray, causing leaf death. Segments of symptomatic leaf tissues were surface sterilized and placed on 2% potato dextrose agar in petri dishes. After 4 days at room temperature, blackish brown colonies developed with dark brown septate conidiophores. Conidia were 21 to 29 × 9 to 13 μm, 3-septa, curved at the third cell from the base that is longer and darker than the others. Cells at each end are subhyaline and intermediate cells are medium brown. These characteristics are consistent with Curvularia lunata (Wakker) Boedijng (1). Pathogenicity tests were performed in five plastic trays with substrate of natural soil and sand (1:1 [v/v]) where the turfgrass (L. perenne cv. El Cencerro) was seeded. Plants were inoculated by spraying a suspension of 2 × 106 conidia per ml of sterile distilled water. Controls were sprayed with sterile distilled water. The trays were covered with transparent plastic bags, sprayed periodically with water, and incubated at 25°C in a greenhouse for 20 days. The first symptoms were observed 3 days later. After 9 days, 24% of the grass surface area showed blight lesions. C. lunata was consistently reisolated from affected tissues. Control plants remained symptomless. To our knowledge, this is the first report of C. lunata affecting L. perenne in Argentina. Reference: (1) M. B. Ellis and I. A. S. Gibson Cochliobolus lunatus (conidial state: Curvularia lunata). Page 474 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1975.

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