First Report of Daylily Leaf Streak Caused by Kabatiella microsticta in China

Daylily (Hemerocallis spp.) is an herbaceous, perennial plant, cultivated for its flowers. Daylily is sold in Asian markets as fresh or dried flowers (the flowers of some species, e.g., Hemerocallis citrina, are edible) or as the corm, which is used for medicinal purposes. In June 2011, daylily leaf streak was found in a nursery of Jilin Agricultural University, Jilin Province, China. Symptoms included water-soaked, irregular spots along the leaf midvein that turned orange to reddish brown and eventually enlarged to coalesce into extensive, necrotic streaks along the length of the leaf, as previously reported (2). Heavily infected leaves often withered and died. Four isolates were recovered from necrotic tissue of leaf spots and cultured on potato dextrose agar (PDA) at 25°C. All colonies were initially cream to peach colored and appeared slimy. With the maturation of the culture, the colonies became dark brown to black with sparse aerial hyphae. Blastic conidia formed simultaneously on intercalary or terminal, undifferentiated conidiogenous cells, and were scattered in dense sections on culture surface. When the conidia dropped from conidiogenous cell, an indistinct scar or a denticle remained. Conidia were hyaline, one-celled, smooth, ellipsoidal, and variable in size (2.73 to 6.01 × 8.45 to 19.36 μm), and all morphological characteristics were consistent with Kabatiella microsticta Bubak (syn. Aureobasidium microstictum; 2,4). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (1). ITS (534 bp) was identical among all four isolates (GenBank Accession No. HE798117) and 100% identical to that of K. microsticta CBS 114.64 (FJ150873). Pathogenicity was confirmed by spraying 20 seedlings of daylily, propagated in tissue-culture medium, with a conidial suspension (106 conidia/ml) of each isolate. A second set of 20 seedlings was sprayed with the same volume of sterile water as the noninoculated 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 5 days, the foliar symptoms described earlier for the field plants appeared on the leaves, whereas the control plants remained healthy. K. microsticta was reisolated from the leaf spots of all 20 inoculated plants. Leaf streak is the most destructive disease of daylily, and was previously reported in Japan and the United States (Illinois, Kentucky, Mississippi, Louisiana, Pennsylvania, Maryland, Virginia, Florida, North Carolina, and Georgia) (3). To our knowledge, this is the first report of the disease caused by K. microsticta in China. References: (1) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (2) E. J. Hermanides-Nijhof. Stud. Mycol. 15:153, 1977. (3) R. M. Leahy et al. Plant Pathology Circular No. 376, 1996. (4) P. Zalar et al. Stud. Mycol. 61:21, 2008.

Download Full-text

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.

Download Full-text

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.

Download Full-text

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.

Download Full-text

First Report of Pestalotiopsis microspora Causing Leaf Spot of Hidcote (Hypericum patulum) in Japan

Plant Disease ◽

10.1094/pdis-94-8-1064b ◽

2010 ◽

Vol 94 (8) ◽

pp. 1064-1064 ◽

Cited By ~ 3

Author(s):

M. Zhang ◽

H. Y. Wu ◽

T. Tsukiboshi ◽

I. Okabe

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

Basal Cells ◽

Single Spore ◽

Management Options ◽

First Report ◽

Leaf Spots ◽

Plastic Bags ◽

Pestalotiopsis Microspora

Hidcote, Hypericum patulum Thunb. ex Murray, is a deciduous shrub that is cultivated as an ornamental in landscape gardens and courtyards in Japan. In early August 2008, severe leaf spotting was observed on plants growing in a courtyard in Nasushiobara, Tochigi, Japan. More than 30% of the leaves on five shrubs exhibited leaf spot symptoms. Small, round, pale brown lesions were initially observed. Later, they expanded to 5 to 12 mm in diameter, round to irregular-shaped with pale brown centers and dark brown margins. Under continuously wet or humid conditions, black acervuli developed on the leaf lesions. Conidia were straight or slightly curved, fusiform to clavate, and five-celled with constrictions at the septa. Conidia ranged from 17 to 21 × 5 to 8 μm with hyaline apical and basal cells. Fifteen percent of apical cells had two and the rest had three appendages (setulae) ranging from 10 to 21 μm long. The basal hyaline cell tapered into a 2 to 4 μm pedicel. The three median cells ranged from light or dark brown to olive green. These morphological characteristics matched those of Pestalotiopsis microspora (Speg.) G.C. Zhao & N. Li (1,2). The identity of the fungus was confirmed by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. GU908473) from single-spore isolates, which revealed 100% homology with those of other P. microspora isolates (e.g., GenBank Accession Nos. FJ459950 and DQ456865). Koch's postulates were confirmed using leaves of three detached branches of a field-grown asymptomatic plant of H. patulum. Thirty leaves of each branch were inoculated by placing mycelial plugs obtained from the periphery of 7-day-old single-spore cultures on the leaf surface. Potato dextrose agar plugs without mycelium served as controls. Leaves on branches were covered with plastic bags for 24 h to maintain high relative humidity in a greenhouse (approximately 24 to 28°C). After 5 days, all inoculated leaves showed symptoms identical to those described above, whereas control leaves remained symptom free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was P. microspora. To our knowledge, this is the first report of leaf spots on H. patulum caused by P. microspora in Japan. Management options may have to be developed and implemented to protect Hidcote plants in areas where leaf spot cannot be tolerated. References: (1) P. A. Saccardo. Sylloge Fungorum III:789, 1884. (2) G. C. Zhao and N. Li. J. Northeast For. Univ. 23(4):21, 1995.

Download Full-text

First Report of Bipolaris peregianensis Causing Leaf Spot of Cynodon dactylon in China

Plant Disease ◽

10.1094/pdis-12-11-1066-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 917-917 ◽

Cited By ~ 2

Author(s):

Z. Y. Wang ◽

S. N. Xie ◽

Y. Wang ◽

H. Y. Wu ◽

M. Zhang

Keyword(s):

Leaf Spot ◽

Cynodon Dactylon ◽

Control Strategies ◽

Tap Water ◽

Morphological Characteristics ◽

Its Region ◽

Basal Cells ◽

First Report ◽

Leaf Spots ◽

Plastic Bags

Cynodon dactylon is widely cultivated as a sod crop in warm climates worldwide. In early September 2009, heavy leaf spot infection was observed on C. dactylon from Zhengzhou, Henan, China. Early symptoms appeared as small, elliptical, pale brown lesions on the leaves. Lesions later expanded to 5 to 10 mm long and 1 to 2 mm wide, becoming brown to dark brown. A fungus was consistently isolated from leaf spots on potato dextrose agar (PDA), but with poor sporulation. Morphological characteristics were observed from single-conidium cultures on tap water agar + wheat straw (TWA+W) after 5 to 7 days. Conidiophores were light to medium brown, cylindrical, solitary or clustered, unbranched, usually with basal cells enlarged, and 94.5 to 147.0 × 4.0 to 9.0 μm. Conidia were fusoid, strongly curved, end cells broadly hemiellipsoidal, brown, 58.5 to 84.5 × 13.5 to 18.5 μm, with 6 to 10 septa. These morphological characteristics are similar to those of Bipolaris peregianensis (2). The identity of our fungus was confirmed to be B. peregianensis by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. JQ316121), which was 99% homologous to those of other B. peregianensis isolates (= Cochliobolus peregianensis; Accession Nos AF071328 and AF158111) (1). Koch's postulates were performed with the leaves of three pots of C. dactylon. Leaves were sprayed with 1 × 105 conidia/ml of B. peregianensis; an equal number of leaves in the pots of the same plant sprayed with sterile distilled water served as the control. All test plants were covered with plastic bags for 24 h to maintain high relative humidity at 23 to 25°C. After 7 days, more than 50% of inoculated leaves showed symptoms identical to those observed in natural condition, whereas controls remained symptom free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was B. peregianensis. To our knowledge, this is the first report of leaf spots caused by B. peregianensis on C. dactylon in China. The disease cycle and the control strategies in the regions are being further studied. References: (1) M. L. Berbee et al. Mycologia 91:964, 1999. (2) A. Sivanesan. Mycol. Pap. 158:1, 1987.

Download Full-text

First Report of Phoma rhei as a Pathogen of Rheum rhabarbarum in China

Plant Disease ◽

10.1094/pdis-01-14-0019-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1154-1154 ◽

Cited By ~ 1

Author(s):

Y. N. Liu ◽

N. Nan ◽

B. H. Lu ◽

W. Y. Xia ◽

X. Y. Wu ◽

...

Keyword(s):

Early Stage ◽

Morphological Characteristics ◽

Its Region ◽

Control Treatment ◽

Perennial Herb ◽

Morphological Identification ◽

First Report ◽

Plastic Bags ◽

Initial Symptoms ◽

Necrotic Spots

Rheum rhabarbarum L., rhubarb, is a perennial herb planted mainly in Hebei, Hubei, Shanxi, Heilongjiang, and Jilin provinces as well as Inner Mongolia, China. The plant grows about 1,000 meters above sea level (4), and is used widely in China to treat constipation and gout. From June to September 2012, a leaf spot was observed on R. rhabarbarum in the medicinal garden of Jilin Agricultural University, Changchun, Jilin Province, causing significant effects on the leaves of all infected plants. In the early stage of disease development, small red lesions were visible on infected leaves, which subsequently developed into irregularly shaped or circular necrotic spots, each with a light colored center, pink-red alternating concentric rings, and surrounded by a chlorotic halo. Some lesions became perforated in the center. Lesions ranged from 1 to 15 mm in diameter. Extensive spotting resulted in general browning and yellowing of entire leaves. As lesions enlarged and coalesced, some leaves died from the margin inwards. Lesions on the stem were fusiform and sunken. Small pieces of diseased leaves and stems were surface-disinfested in 75% ethanol for 60 s, rinsed twice in distilled water, dried, and plated on potato dextrose agar (PDA). A Phoma species was isolated that produced a gray or dark gray colony after 5 to 7 days. The isolate was transferred to oatmeal agar (OA) (3). Pycnidia were dark brown to black, globose to subglobose, and 121 to 354 × 100 to 262 μm. Conidia were ellipsoidal or reniform, colorless, unicellular, and 3.8 to 6.5 × 1.7 to 4.1 μm. On the basis of these characteristics, the fungus was identified as Phoma rhei (1). A PCR assay with the ITS4 and ITS5 primers was used to amplify the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) (2). The amplified product (567 bp) was sequenced and the sequence submitted to GenBank (Accession No. KF531831). The ITS sequence exhibited 99% identity to that of a P. rhei isolate in GenBank (GU237743.1), confirming the morphological identification. Pathogenicity of eight isolates on rhubarb was confirmed by spraying a spore suspension (1 × 106 spores/ml) produced on PDA on the leaves of each 6-year-old R. rhabarbarum (cv. Boyedahuang) plant. Each isolate was inoculated onto five plants, and five plants were sprayed similarly with sterilized water as a control treatment. The plants were then covered with plastic bags for 48 h, and kept in a greenhouse (20 to 30°C with a 12-h photoperiod/day). Initial symptoms on inoculated leaves were observed 3 to 4 days after inoculation, while the control plants remained healthy. Re-isolations from lesions on the inoculated leaves, using the same protocol as the original isolations, produced fungal colonies with the same morphological characteristics as the original isolates of P. rhei, but no fungi were re-isolated from the control plants. This fungus has been found on R. rhaponticum in New Zealand (1), but to our knowledge this is the first report of P. rhei on R. rhabarbarum in China. References: (1) G. H. Boerema et al. Phoma Identification Manual. Diffferentiation of Specific and Infra-Specific Taxa in Culture. CABI Publishing. Wallingford, UK, 2004. (2) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (3) Z. D. Fang. Research Method of Phytopathology. China Agricultural Press (In Chinese), 1998. (4) A. J. Li et al. Flora Reipublicae Popularis Sinicae. Tomus 25:171, 1998.

Download Full-text

First Report of Leaf Spot Disease on Dictamnus dasycarpus Caused by Phoma dictamnicola in China

Plant Disease ◽

10.1094/pdis-01-11-0039 ◽

2011 ◽

Vol 95 (6) ◽

pp. 771-771 ◽

Cited By ~ 1

Author(s):

Q. Bai ◽

Y. Xie ◽

J. Gao ◽

B. Lu ◽

W. Wang ◽

...

Keyword(s):

Its Region ◽

Leaf Spot Disease ◽

Conidial Suspension ◽

Sterile Water ◽

Nuclear Rdna ◽

First Report ◽

Leaf Spots ◽

Plastic Bags ◽

Pathogenicity Tests ◽

Herbal Plant

Fraxinella, Dictamnus dasycarpus Turcz (Rutaceae), is a perennial herbal plant and mainly distributed in Eurasia and North America. It is often used to treat jaundice, cough, rheumatism, and other diseases and is extensively cultivated in the northeast and northwest of China (3). In June 2009, a severe foliar disease was observed on D. dasycarpus in medicinal plantations in Antu, China. The disease occurred on 100% of the plants and at least 25% of the surface was affected. In the early stages of disease development, symptoms were visible on the top and bottom of infected leaves as small brown spots. Subsequently, these spots became elliptical to irregularly shaped, with beige or grayish white centers and dark brown margins. Within the spots, numerous, dark brown or black, subglobose or ostiolate pycnidia measuring 152 to 367 μm in diameter were observed. Fungal isolates were obtained from the infected leaves on potato dextrose agar (PDA) medium, with conidia that were aseptate or one-septate and ellipsoidal or reniform, measuring approximately 4.7 to 12.6 × 2.1 to 4.5 μm. On the basis of these characteristics, the fungus was identified as a Phoma sp. Four well-sporulating isolates, designated as DdPh-1, DdPh-2, DdPh-3, and DdPh-4, were selected for further studies. The morphological and cultural characteristics of these four isolates were studied as described by Boerema et al. and the fungus was identified as Phoma dictamnicola Boerema et al. (1). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified and sequenced using primers ITS4/ITS5 (2). All four of the ITS sequences were identical (GenBank Accession No. FR681861) and were 99% identical to P. dictamnicola strains CBS507.91 (Accession No. GU237877) and KACC42445 (Accession No. EF600960). Pathogenicity tests were performed by spraying the leaves of healthy D. dasycarpus plants with a conidial suspension (1 × 106 conidia/ml). Five plants were inoculated with each isolate (DdPh-1, DdPh-2, DdPh-3, and DdPh-4) and five plants were mock inoculated with sterile water. The plants were covered with plastic bags and kept in a greenhouse at 20 to 25° for 72 h. After 9 to 13 days, all inoculated plants showed characteristic symptoms as previously described, while the control plants remained healthy. The 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 in production of D. dasycarpus with the cultivation area increasing. The fungus was found in the Netherlands and Korea, but to our knowledge, this is the first report of P. dictamnicola on D. dasycarpus in China. References: (1) G. H. Boerema et al. Phoma Identificatión Manual: Differentiation of Specific and Infra-Specific Taxa in Culture. CABI Publishing. Wallingford, U.K., 2004. (2) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (3) S. S. Jiang et al. Biosci. Biotechnol. Biochem. 72:660, 2008.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe heraclei on Chervil in Korea

Plant Disease ◽

10.1094/pdis-07-13-0797-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 426-426

Author(s):

K. S. Han ◽

S. E. Cho ◽

J. H. Park ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

The United States ◽

Control Treatment ◽

Width Ratio ◽

Anethum Graveolens ◽

First Report ◽

Powdery Mildews

Chervil (Anthriscus cerefolium (L.) Hoffm.), belonging to the family Apiaceae, is an aromatic annual herb that is native to the Caucasus. It is widely used as a flavoring agent for culinary purposes. This herb was recently introduced in Korea. In April 2013, plants showing typical symptoms of powdery mildew disease were observed in a polyethylene film-covered greenhouse in Seoul, Korea. White mycelium bearing conidia formed irregular patches on leaves and stems. Mycelial growth was amphigenous. Severe infections caused leaf withering and premature senescence. Voucher specimens were deposited in the Korea University Herbarium (KUS). Hyphae were septate, branched, with moderately lobed appressoria. Conidiophores presented 3 to 4 cells and measured 85 to 148 × 7 to 9 μm. Foot-cells of conidiophores were 37 to 50 μm long. Conidia were produced singly, oblong-elliptical to oblong, measured 30 to 50 × 13 to 18 μm with a length/width ratio of 2.0 to 3.3, lacked conspicuous fibrosin bodies, and with angular/rectangular wrinkling of the outer walls. Germ tubes were produced in the subterminal position of conidia. Chasmothecia were not found. These structures are typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The specific measurements and morphological characteristics were consistent with those of E. heraclei DC. (1). To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) region of rDNA of KUS-F27279 was amplified with primers ITS5 and P3 (4) and sequenced directly. The resulting 561-bp sequence was deposited in GenBank (Accession No. KF111807). A GenBank BLAST search of this sequence showed >99% similarity with those of many E. heraclei isolates, e.g., Pimpinella affinis (AB104513), Anethum graveolens (JN603995), and Daucus carota (EU371725). Pathogenicity was confirmed through inoculation by gently pressing a diseased leaf onto leaves of five healthy potted chervil plants. Five non-inoculated plants served as a control treatment. Plants were maintained in a greenhouse at 22 ± 2°C. Inoculated plants developed signs and symptoms after 6 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was identical morphologically to that originally observed on diseased plants. Chervil powdery mildews caused by E. heraclei have been reported in Europe (Bulgaria, France, Germany, Hungary, Italy, Romania, Switzerland, and the former Soviet Union) and the United States (2,3). To our knowledge, this is the first report of powdery mildew caused by E. heraclei on chervil in Asia as well as in Korea. The plant is cultivated in commercial farms for its edible leaves in Korea. Occurrence of powdery mildew is a threat to quality and marketability of this herb, especially those grown in organic farming where chemical control options are limited. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11, CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., Online publication. ARS, USDA. Retrieved July 29, 2013. (3) S. T. Koike and G. S. Saenz. Plant Dis. 88:1163, 2004. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

Download Full-text

First Report of Leaf Spot on Japanese Plum Caused by an Alternaria sp. in Korea

Plant Disease ◽

10.1094/pd-89-0343a ◽

2005 ◽

Vol 89 (3) ◽

pp. 343-343 ◽

Cited By ~ 3

Author(s):

Youngjun Kim ◽

Hyang Burm Lee ◽

Seung Hun Yu

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Conidial Suspension ◽

First Report ◽

Japanese Plum ◽

Leaf Spots ◽

Causal Fungus ◽

Pathogenicity Tests ◽

Alternaria Sp

Japanese plum (Prunus salicina Lindley) is a deciduous tree in the family Rosaceae. In Korea, this plant is widely distributed in orchards as an important stone fruit as well as in gardens as an ornamental tree because of their abundant white blossoms. Every September to November since 2001, leaf spots were observed on Japanese plum in a garden in Cheongyang, Chungnam District, Korea. Early symptoms consisted of small, brown spots that were 2 to 5 mm in diameter. Later, the leaf lesions became circular or irregular, dark brown, expanded to 15 mm in diameter, and resulted in discoloration with necrosis on twisted leaves that was followed by defoliation. In November, older lesions sometimes appeared blackish brown as sporulation occurred on the lesions. The causal fungus was isolated from diseased leaves and cultured on potato dextrose agar. A culture has been placed in the CABI Herbarium (IMI Accession No. 387139). Conidial dimension averaged 34 × 12 μm. On the basis of morphological characteristics of conidia and conidiophores, the causal fungus was identified as a small-spored species of Alternaria as described by E. G. Simmons (1). Pathogenicity tests were conducted by inoculating slightly wounded and nonwounded leaves with a conidial suspension adjusted to 1 × 106 conidia/ml. Four leaves per each experiment were either wounded or not and inoculated with a spore suspension. The eight leaves were placed in a moist chamber at 25°C. After 6 to 10 days, small brown spots appeared on 87% of the wounded and nonwounded leaves. Control leaves sprayed with distilled water did not develop any symptoms. The causal fungus was consistently reisolated from the leaf spots. Results from pathogenicity tests were similar in a repeated test. It is possible that small-spored Alternaria spp. isolates are host specific (2). Eight Alternaria spp., including A. alternata, A. tenuis, A. tenuissima, and A. citri, have been found to cause black spot on fifteen Prunus spp. in China, Japan, Hong Kong, Libya, Mexico, Australia, and the United States (2). Further studies on the host-specific toxin production, geographical distribution, and host ranges for the species of Alternaria isolated from Japanese plum are in progress. To our knowledge, this is the first report of leaf spot on Japanese plum (P. salicina) caused by a small-spored Alternaria sp. in Korea. References: (1) E. G. Simmons. Mycotaxon 55:79, 1995. (2) K. Inoue and H. Nasu. J. Gen. Plant Pathol. 66:18, 2002.

Download Full-text

First Report of Leaf Blight of Basella alba Caused by Alternaria alternata in India

Plant Disease ◽

10.1094/pdis-06-11-0513 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1476-1476 ◽

Cited By ~ 6

Author(s):

N. Ravi Sankar ◽

A. Sreeramulu ◽

D. Sai Gopal ◽

G. Bagyanarayana

Keyword(s):

Alternaria Alternata ◽

Disease Incidence ◽

Morphological Characteristics ◽

Infected Leaf ◽

Conidial Suspension ◽

First Report ◽

Perennial Plant ◽

Basella Alba ◽

Leaf Spots ◽

Severe Infections

Basella alba is a perennial plant of the Basellaceae, native to India, and is distributed widely in the tropics as an ornamental. It is also known as Indian spinach, Ceylon spinach, vine spinach, Malabar spinach or Malabar nightshade and is mostly cultivated as a leafy vegetable or spinach substitute, being rich in vitamin A and C. From 2008 to 2010, severe foliar disease was observed on B. alba in the region of Southern Andhra Pradesh, India. Approximately 75 to 85% of the fields were affected with disease incidence ranging from 70 to 90%. Leaf lesions were elliptical to irregular oval, yellow brown to dark brown, and sometimes concentrically zonate with diffuse margins frequently surrounded by light-colored haloes. Infection often started at the leaf tips and progressed to the base of leaves as symptoms developed. In severe infections, lesions enlarged and coalesced, causing necrosis, wilting, and ultimately death of leaves. Tissues from the margin of infected leaf parts were surface sterilized in 1% sodium hypochlorite for 1 min, plated on potato dextrose agar (PDA), and then incubated at 27°C in the dark for 7 days. Hyphal tips from the margin of each developing colony were subcultured on PDA. Fungal colonies were initially white, becoming olivaceous, and turning brown with age. Conidiophores were brown, short, simple, or sometimes branched. Conidia were obclavate, obpyriform or ellipsoidal with a short conical beak, borne in long chains, branched or unbranched, pale brown to brown, and 18 to 32 μm long and 5 to 14 μm wide at the broadest point. Conidia had three to eight transverse septa and one to two longitudinal septa. On the basis of conidial morphological characteristics, the pathogen was identified as Alternaria alternata (Fr.) Keissler (2). For pathogenicity tests, inoculations were performed on detached, surface sterilized, healthy leaves following the method of Belisario (1). A 5-μl drop of conidial suspension containing 1 × 105 CFU/ml was placed on each leaf and 12 leaves per isolate were used. Leaves were incubated in a growth chamber (90% relative humidity with a 12-h photoperiod). After 7 days, leaf spots that were similar to the original symptoms developed on all inoculated leaves and A. alternata was consistently reisolated from symptomatic leaf tissues on PDA. Control leaves inoculated with sterile distilled water remained asymptomatic. The experiment was performed three times. To our knowledge, this is the first report of A. alternata on B. alba in India. References: (1) A. Belisario et al. Plant Dis. 83:696, 1999. (2) E. G. Simmons. Alternaria: An Identification Manual. The American Phytopathological Society, St. Paul, MN, 2007.

Download Full-text