First Report of a Canker Disease of Walnut Caused by Botryodiplodia theobromae in Egypt

Botryodiplodia spp. are known to produce cankers and dieback of several woody hosts. Botryodiplodia diseases were observed in 7-year-old orchards in Rhafah, north of Sinai, Egypt, in July 2005 and 2006. Symptoms appeared as dieback and cankers with dead leaves that were covered mostly with grayish white fungal growth; black pycnidia appeared on the surface of the infected branches. Plant foliage was discolored and partially or completely dry. When the outer bark was removed, the affected tissue appeared dark brown, in contrast to the yellowish green of healthy inner bark. On the basis of morphological characteristics (3), these fungi were identified as Botryodiplodia theobromae Pat. by the Plant Pathology Department, National Research Centre. Sporulating lesions were black and had a rough surface caused by the erumpent, confluent arrangement of pycnidia formed in infected tissue. The pycnidia were smallest in naturally infected twigs in nutritionally rich medium such as oatmeal agar (190 to 887 × 155 to 705 μm). Conidia were initially hyaline and unicellular, subovoid to ellipsoidal with a granular content. Mature conidia were two-celled, cinnamon to light brown, and often with longitudinal striations. Conidia measured 20 to 30 × 12 to 15 μm. Pathogenicity of isolates from symptomatic branches was determined by branch inoculations on rooted cuttings made from 7-year-old walnut trees growing in plastic pots. One isolate was inoculated on wounded and unwounded twigs using 100 μl of a suspension of 5 × 105 conidia per ml. Control branches were sprayed with water. All inoculated and control plants were kept in a greenhouse and watered as needed. There were three replicate plants for each isolate and inoculation technique that was used. After 3 weeks, cankers and grayish necrotic lesions developed on all inoculated plants. Samples of tissue from 10 infected walnut branches were plated on water agar. B. theobromae was recovered from all sampled plants. Control plants did not display any symptoms. B. theobromae has been reported on species of walnut from the Hermosillo Coast of Mexico (1) and India (2). To our knowledge, this is the first report of walnut dieback and canker caused by this pathogen in Egypt. References: (1) J. A. Arredondo. Rev. Mex. Fitopatol. 12:138, 1994. (2) B. Kusum. Indian J. Mycol. Plant Pathol. 21:295, 1991. (3). S. Masilamani and J. Muthumary. Mycol. Res. 100:1383, 1996.

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First Report of Wood Canker Caused by Botryosphaeria dothidea, Diplodia seriata, Neofusicoccum parvum, and Lasiodiplodia theobromae on Grapevine in Turkey

Plant Disease ◽

10.1094/pdis-07-13-0726-pdn ◽

2014 ◽

Vol 98 (4) ◽

pp. 568-568 ◽

Cited By ~ 8

Author(s):

D. S. Akgul ◽

N. G. Savas ◽

A. Eskalen

Keyword(s):

Morphological Characteristics ◽

Botryosphaeria Dothidea ◽

Outer Bark ◽

Western Turkey ◽

Diplodia Seriata ◽

Neofusicoccum Parvum ◽

Lasiodiplodia Theobromae ◽

First Report ◽

Multiple Species ◽

Botryosphaeriaceae Species

The Aegean region (western Turkey) is the center of table, raisin, and wine grape cultivation. During the 2012 growing season, wood canker symptoms were observed in vineyards in Manisa city. Symptoms adjacent to pruning wounds, including shoot dieback and wedge-shaped wood discolorations observed in cross section, were among the most prevalent symptoms of the vines. To identify the causal agents, symptomatic woody tissues were surface disinfested with 95% ethanol and flame-sterilized and the discolored outer bark was cut away. The internal tissues (0.5 cm2) were excised from cankers of vines and plated onto potato dextrose agar amended with tetracycline (0.01%) (PDA-tet). The most frequently isolated fungi, based on general growth pattern, speed of growth, and colony color, resembled species in the Botryosphaeriaceae family. According to morphological characteristics, four different groups have been identified based on visual discrimination. After DNA extraction, ribosomal DNA fragments (ITS1-5.8S-ITS2) (2) amplified with ITS4 and ITS5 primers were sequenced and sequences were compared with those deposited in NCBI GenBank database. Four different Botryosphaeriaceae isolates were identified, including Botryosphaeria dothidea (MBAi25AG), Diplodia seriata (MBAi23AG), Lasiodiplodia theobromae (MBAi28AG), and Neofusicoccum parvum (MBAi27AG) (Accession Nos. KF182329, KF182328, KF182331, and KF182330, respectively) with species nomenclature based on Crous et al. (1). Pathogenicity tests were conducted under greenhouse conditions (24°C, 16/8-h day/night, 70% RH) on 1-year-old own rooted grapevine (Vitis vinifera) cv. Sultana Seedless seedlings using one isolate from each of the Botryosphaeriaceae species specified above. Stems of grapevine seedlings were wounded by removing bark with 4-mm cork borer and fresh mycelial plugs were inoculated into the holes and covered with Parafilm. Sterile PDA plugs were placed into the wounds of control seedlings. Five vines were inoculated per isolate. The experiment was repeated twice. After 4 months of incubation, grapevine seedlings were examined for the extent of vascular discoloration and recovery of fungal isolates. Mean lesion lengths on wood tissues were 85.3, 17.2, 13.9, and 13.1 mm for N. parvum, B. dothidea, L. theobromae, and D. seriata, and 6.3 mm for control. Each fungal isolate was successfully re-isolated from inoculated seedlings to fulfill Koch's postulates. To our knowledge, this is the first report of multiple species in the Botryosphaeriaceae causing wood canker and dieback on grapevine in Turkey. These results are significant because Botryosphaeriaceae species are known causal agents of grapevine trunk disease worldwide (3). References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) B. Slippers et al. Mycologia 96:83, 2004. (3) J. R. Urbez-Torres. Phytopathol. Mediterr. 50:S5, 2011.

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First Report of Colletotrichum truncatum on Alfalfa in Turkey

Plant Disease ◽

10.1094/pdis.2000.84.1.100a ◽

2000 ◽

Vol 84 (1) ◽

pp. 100-100 ◽

Cited By ~ 2

Author(s):

C. Eken ◽

E. Demirci

Keyword(s):

Morphological Characteristics ◽

Conidial Suspension ◽

Colletotrichum Truncatum ◽

First Report ◽

Clear Area ◽

Granular Cytoplasm ◽

Symptomatic Tissue ◽

Medicago Sativa L ◽

Stem Lesions ◽

And Control

During the summer of 1997 and 1998, a pathogen identified as Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore was isolated from lesions on stems of alfalfa (Medicago sativa L.) plants in Erzurum, Turkey. Typical symptoms on stems of mature plants were large, sunken, irregularly shaped black lesions. Twenty-eight cultures of C. truncatum were isolated from stem lesions. Acervuli containing spores and dark setae were observed within lesions. Conidia were hyaline, one-celled, falcate to nearly straight with a prominent clear area in the center of highly granular cytoplasm, and measured 16.3 to 20.6 × 3.1 to 4.5 μm. These morphological characteristics were consistent with the description of C. truncatum (1). The pathogenicity of two isolates was determined on alfalfa cv. Bilensoy. Alfalfa seedlings (6-week-old) were inoculated with a conidial suspension of the fungus (1.4 × 107 conidia per ml), incubated in a moist chamber for 3 days, and subsequently transferred to growth chambers maintained at 25°C with a 12-h photoperiod. Ten plants were inoculated with each isolate. Symptoms first appeared on stems 12 days after inoculation. Sunken, irregularly shaped black lesions occasionally girdled stems of plants inoculated with C. truncatum. Symptoms did not appear on stems of control plants inoculated with sterile distilled water. C. truncatum was reisolated from symptomatic tissue. This is the first report of C. truncatum on alfalfa from Turkey. Reference: (1) B. C. Sutton. 1992. Pages 1–27 in: Colletotrichum Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, U.K.

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First Report of Colletotrichum siamense Causing Anthracnose of Chili Pepper Fruit in Korea

Plant Disease ◽

10.1094/pdis-10-20-2297-pdn ◽

2020 ◽

Author(s):

Moe Oo May ◽

Mi-Reu Kim ◽

Dae-Gyu Kim ◽

Tae-Seok Kwak ◽

Sang-Keun Oh

Keyword(s):

Morphological Characteristics ◽

Chili Pepper ◽

Pathogenicity Test ◽

Disease Symptoms ◽

First Report ◽

Pepper Fruit ◽

Genes Encoding ◽

Reference Sequences ◽

And Control ◽

Morphology Characteristics

In October 2015, typical anthracnose symptoms were observed on approximately 15 to 20% of the chili fruits (cv. Manita) growing in Goesan County, Chungcheong Province, South Korea. Infection of fruits were characterized by the presence of circular, sunken lesions with concentric rings of orange conidial acervuli. Fresh samples were collected from the infected fruits and lesions from seven symptomatic fruits were cut into small pieces (5 mm2) and surface sterilized by soaking them in 1% sodium hypochlorite for 3 min, followed by rinsing thrice using sterilized water, and drying on sterilized filter paper. The tissue pieces were then placed on potato dextrose agar (PDA) and incubated at 25 ± 2°C with 12hrs photoperiod. After 2 to 3 days, single hyphal tips were transferred to fresh PDA and a total of seven isolates were selected from typical single hyphae. The upper surfaces of the colonies formed on PDA were white to gray in color with cottony mycelia, in which salmon-colored acervuli were clearly visible (Supplementary 1). Thirty conidia were examined; all were hyaline, smooth-walled, aseptate, straight, mainly cylindrical with round ends, 12 to 17 µm long, and 3 to 4.5 µm wide. Appressoria were oval to irregular inshape, dark brown in color, and range from 9.5 to 11.5 µm × 6.5 to 7.5 µm in sizes. Morphological characteristics of the seven isolates were identical and resembled those of C. siamense (Weir et al. 2012). To confirm the identification of the fungal isolates, DNA from seven isolates were extracted (Cenis et al. 1992) and the genes encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH), internal transcribed spacer (ITS) rDNA regions, and β-Tublin-2 (TUB2) were partially amplified and sequenced. Sequences from all seven isolates were identical each other. Nucleotide sequences of ITS, GAPDH, and TUB2 from representative isolates CNU180002 and CNU180012 were deposited in GenBank under accession numbers MH085103, MH085105, and MH085107 for CNU180002 and MK033503, MK033504, and MK033505 for CNU180012, respectively. The sequences for all three genes exhibited 99 to 100% identity with C. siamense, GenBank accession nos. FJ972613 (ITS), FJ972575 (GAPDH), and FJ907438 (TUB2) for both isolates. A multi-locus phylogenetic tree with closely related reference sequences downloaded from the GenBank database demonstrated that these two isolates were aligned with C. siamense. Pathogenicity of isolates CNU180002 and CNU180012 was confirmed on healthy fruits (Manita) by using a pin-pricked wound/drop (1 mm depth) and non-wound/drop inoculation method (Oo et al. 2017) and control fruits were mock-inoculated with sterilized distilled water. Three fruits were inoculated for each isolate and pathogenicity test were repeated thrice. After inoculation, the fruits were placed on a sterilized paper tissue in moistened clean boxes with a relative humidity of approximately 90% and incubated for 7 days at 25°C in the dark. Disease symptoms were appeared 5 to 7 days after inoculation on wounded fruits whereas non-wounded fruits were observed after 10 days. The two isolates showed identical symptoms and control fruits remained symptomless. Both isolates were re-isolated from infected fruits and were identical to the original isolates in morphology characteristics as well as on molecular sequences of ITS, GAPDH and TUB2 genes. To our knowledge, this is the first report of anthracnose caused by C. siamense on chili pepper fruit in Korea.

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First Report of the Prevalence of Benzimidazole-Resistant Isolates in a Population of Cylindrocladium pauciramosum in Italy

Plant Disease ◽

10.1094/pdis.2001.85.11.1210b ◽

2001 ◽

Vol 85 (11) ◽

pp. 1210-1210 ◽

Cited By ~ 5

Author(s):

G. Polizzi ◽

A. Vitale

Keyword(s):

Inhibitory Concentration ◽

Morphological Characteristics ◽

Fungal Growth ◽

Control Measures ◽

Agar Culture ◽

Benzimidazole Fungicides ◽

First Report ◽

Benzimidazole Resistance ◽

Type Studies ◽

Slow Growing

Cylindrocladium pauciramosum C.L. Schoch & Crous (teleomorph Calonectria pauciramosa C.L. Schoch & Crous), described as a member of the Cylindrocladium candelabrum Viégas complex (4), was recently reported from Europe (3). In southern Italy, the fungus has caused extensive losses, and chemical control measures are necessary, especially in ornamental nurseries. Several researchers have found benzimidazole fungicides to be effective for control of different species of Cylindrocladium, however, in fungicide trials conducted on myrtle plants infected by C. pauciramosum, benomyl was ineffective (2). Another study showed that mycelial growth of six isolates was completely inhibited by carbendazim at a concentration of 1 μg a.i./ml whereas, concentrations of 10, 100, and 500 μg a.i./ml did not completely inhibit growth of four isolates (1). To examine benzimidazole resistance in C. pauciramosum, 200 single-conidia isolates were tested. These were collected during 1996 and 1997 from several symptomatic hosts in different nurseries located in Sicily and Calabria and identified through morphological characteristics as well as mating-type studies with tester strains. Sensitivity to benomyl was determined by plating mycelial plugs on potato dextrose agar (PDA) amended with benomyl at 1, 10, 100, and 500 μg a.i./ml. For 20 benomyl-resistant isolates, fungal growth was also determined at the same concentrations on carbendazim-amended PDA. Sensitivity was expressed as the minimum inhibitory concentration (MIC) (the lowest fungicide concentration that completely prevented fungal growth). Isolates that did not grow on benzimidazole-amended PDA were classed as sensitive. Isolates were considered resistant to benzimidazole if MIC values were greater than 1 μg a.i./ml. Of the 200 isolates tested, 58% were resistant to benomyl. The benomyl-resistant isolates tested for carbendazim sensitivity were cross-resistant to carbendazim. Most resistant isolates grew in the presence of benomyl at 500 μg a.i./ml. On agar culture, the isolates were either the fast-growing or slow-growing type. The slow-growing phenotype appears to be related to the higher level of resistance (500 μg a.i./ml). On the basis of these data, the use of benzimidazole for the control of this pathogen should be seriously questioned. To our knowledge, this is the first report of the prevalence of benzimidazole resistance in a population of C. pauciramosum. References: (1) G. Polizzi. Inf. Fitopatol. 11:39, 2000. (2) G. Polizzi and A. Azzaro. Petria 6:117, 1996. (3) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (4) C. L. Schoch et al. Mycologia 91:286, 1999.

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First Report of Soft Rot on Dendrobium officinale caused by Epicoccum sorghinum in China

Plant Disease ◽

10.1094/pdis-04-21-0866-pdn ◽

2021 ◽

Author(s):

Caiyun Xiao ◽

Rongyu Li ◽

Xingchen Song ◽

Xujun Tian ◽

Qijun Zhao

Keyword(s):

Internal Transcribed Spacer ◽

Elongation Factor ◽

Morphological Characteristics ◽

Reference Value ◽

Soft Rot ◽

Dendrobium Officinale ◽

First Report ◽

Rdna Its ◽

And Control ◽

Internal Transcribed Spacer Rdna

In recent years, soft rot is one of the most serious diseases in the production of Dendrobium officinale. In this study, we took the diseased plants of Dendrobium officinale in Guizhou as samples, through Koch's rule and sequence analysis of rDNA internal transcribed spacer (rDNA-ITS), calmodulin (cmdA), the second largest subunit of RNA polymerase Ⅱ (RPB2), elongation factor EF-1 α and β-tubulin (β-Tub), it was determined that the pathogen of Dendrobium officinale soft rot was sorghum accessory cocci. This is our first report on the soft rot of Dendrobium officinale caused by Epicoccum sorghinum in China. The morphological characteristics of the pathogen shown in the study will have a certain reference value for the prevention and control of the soft rot of Dendrobium officinale in the future.

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First Report of Ascochyta Leaf Spot Caused by Phoma exigua var. exigua on Common Bean in Greece

Plant Disease ◽

10.1094/pdis-92-4-0653c ◽

2008 ◽

Vol 92 (4) ◽

pp. 653-653 ◽

Cited By ~ 3

Author(s):

G. A. Bardas ◽

G. T. Tziros ◽

K. Tzavella-Klonari

Keyword(s):

Common Bean ◽

Leaf Spot ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Weather Conditions ◽

Conidial Suspension ◽

Phoma Exigua ◽

First Report ◽

Plastic Bags ◽

And Control

Common bean (Phaseolus vulgaris L.) is cultivated extensively in Greece for dry and fresh bean production. During 2005 and 2006, a disease with typical blight symptoms was observed occasionally on dark red kidney, brown kidney, and black bean plants in most bean-producing areas of Greece. It rarely was destructive unless the crop had been weakened by some unfavorable environmental conditions. Infected leaves had brown-to-black lesions that developed concentric zones 10 to 30 mm in diameter and also contained small, black pycnidia. Concentric dark gray-to-black lesions also appeared on branches, stems, nodes, and pods. Infected seeds turned brown to black. Plants sometimes showed defoliation and pod drop. The fungus was consistently isolated on potato dextrose agar from diseased leaves and pods and identified as Phoma exigua var. exigua Sutton and Waterstone on the basis of morphological characteristics of conidia and pycnidia (1,2). Spores were massed in pycnidia from which they were forced in long, pink tendrils under moist weather conditions. Conidia were cylindrical to oval, allantoid, hyaline, pale yellow to brown, usually one-celled, and 2 to 3 × 5 to 10 μm. To satisfy Koch's postulates, a conidial suspension (1 × 106 conidia per ml) of the fungus was sprayed onto leaves and stems of bean seedlings (first-leaf stage) (cv. Zargana Hrisoupolis). Both inoculated and control seedlings (inoculated with sterile water) were covered with plastic bags for 72 h in a greenhouse at 23°C. Inoculated plants showed characteristic symptoms of Ascochyta leaf spot 12 to 15 days after inoculation. The fungus was reisolated from lesions that developed on the leaves and stems of all inoculated plants. The pathogen is present worldwide on bean. To our knowledge, this is the first report of P. exigua var. exigua on common bean in Greece. References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2007. (2) B. C. Sutton and J. M. Waterstone. Ascochyta phaseolorum. No. 81 in: Descriptions of Pathogenic Fungi and Bacteria. CMI/AAB, Kew, Surrey, England, 1966.

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First Report of Botryosphaeria ribis as a Branch Dieback Pathogen of Olive Trees in Spain

Plant Disease ◽

10.1094/pd-89-0208a ◽

2005 ◽

Vol 89 (2) ◽

pp. 208-208 ◽

Cited By ~ 12

Author(s):

M. A. Romero ◽

M. E. Sánchez ◽

A. Trapero

Keyword(s):

Peat Soil ◽

Severe Disease ◽

Conidial Suspension ◽

Outer Bark ◽

Middle Point ◽

Affected Tissue ◽

Wild Olive ◽

Olive Trees ◽

Branch Dieback ◽

And Control

Botryosphaeria spp. are known to produce cankers and dieback in several woody hosts. Since 2001, a severe disease resulting in the dieback of branches was observed in olive (Olea europaea) orchards in Andalucía, southern Spain, where the only cultivar affected was Gordal de Sevilla. The affected trees showed abundant dead twigs, and wilted leaves remained attached. These symptoms were similar to those caused by Resseliella oleisuga, a bark borer insect common in the region. Closer inspection showed no evidence of insects, but revealed reddish brown bark lesions that girdled the affected branches. When the outer bark was removed, the affected tissue appeared dark brown, in contrast to the yellowish green of healthy inner bark. A Fusicoccum sp. was consistently isolated from the necrotic bark. Conidia produced in black pycnidia were hyaline, aseptate, fusoid, with a truncate base averaging 19.9 × 6.7 μm, becoming pale brown with all cells the same color, and developing one or two septa when germinated. These characteristics conform to Fusicoccum ribis (1), the anamorph of B. ribis. Pathogenicity of two isolates from symptomatic branches was determined by stem inoculations of 4-year-old cv. Gordal de Sevilla grafted on wild olive trees growing in plastic pots containing a sand/lime/peat soil mixture. Both isolates were inoculated by three techniques. In the first, 7-mm-diameter agar plugs bearing actively growing mycelium were applied to 7-mm-diameter bark wounds made with a cork borer on the middle point of stems (averaging 10 mm in diameter). In the second technique, the same type of inoculum was applied directly to the bark without any wounding. For the third technique, 100 μl of conidial suspension in water (2 × 105 conidia per ml) was applied to bark wounds. The inoculated stem sections were wrapped in Parafilm to retain moisture. All inoculated and control plants (only sterile agar medium or sterile water added) were kept in a greenhouse and watered as needed. There were three replicate plants per isolate and inoculation technique. After 3 months, all plants inoculated with mycelium applied to wounds showed girdling and apical death with browning and wilting of leaves above the inoculation point. In the treatments where mycelium was applied to unwounded bark or where conidial suspensions were applied to wounds, small bark cankers developed to 56 mm long, but neither girdling nor foliar wilting were observed. No symptoms developed in the control plants. There were no significant differences in pathogenicity between the two F. ribis isolates. F. ribis was recovered from necrotic bark from every inoculated plant. These results demonstrate that B. ribis is pathogenic on cv. Gordal de Sevilla olives, and they indicate that bark wounding favors lesion development but is not needed for infection. Reference: (1) B. Slippers et al. Mycologia 96:83, 2004.

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First Report of Sawadaea polyfida Causing Powdery Mildew of Acer palmatum in China

Plant Disease ◽

10.1094/pdis-07-21-1566-pdn ◽

2021 ◽

Author(s):

Yu Wan ◽

Yuan-Zhi Si ◽

Yang-Chun-Zi Liao ◽

Li-Hua Zhu

Keyword(s):

Powdery Mildew ◽

Phylogenetic Analyses ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Species Identity ◽

Internal Transcribed Spacer Region ◽

Voucher Specimen ◽

First Report ◽

Effective Strategies ◽

And Control

Acer palmatum Thunb. is an important colorful leaf ornamental tree species widely distributed in Japan, Korea and China (Carlos et al. 2016). In October 2019, powdery mildew was observed on leaves of A. palmatum planted at Qixia Mountain Park and the campus of Nanjing Forestry University, Nanjing, Jiangsu, China. The powdery mildew infected and colonized leaves, covering both leaf surfaces with white mycelia, giving affected plants an unsightly appearance. Nearly 17.4% of the plants (87/501) exhibited these signs and symptoms. Fresh specimens were collected and examined for the identification of the pathogen. Photos were taken with a ZEISS Axio Imager A2m microscope and a scanning electronic microscope. Chasmothecia were scattered or aggregated on the upper and lower surfaces of the leaves, blackish brown, oblate, 157.5 to 238.1 × 152.3 to 217.8 μm (n=30), with numerous appendages (100 to 200). Appendages were often (1−) 2 to 3 times branched from the middle of the stalk, uncinate to circinate at the apex, hyaline, aseptate, 30.0 to 70.8 × 4.1 to 8.2 μm (n=30). Asci were 11 to 21 per chasmothecium (n=30), long oval, oval, oblong, with short stalk or sessile, 80.6 ± 8.6 × 40.3 ± 4.0 um (n=30) in length, 6 to 8 spored (n=30). Ascospores were ovoid, 18.2 ± 1.6 × 11.1 ± 1.2 μm (n=30). Microconidiophores were 25 to 50 × 4.0 to 5.5 μm, producing microconidia in chains. Microconidia were ellipsoidal, subglobose, 8.7 ± 0.6 × 7.2 ± 0.6 μm (n=30). Macroconidia were not observed. Based on the morphological characteristics, the fungus was identified as Sawadaea polyfida (C.T. Wei) R.Y. Zheng & G. Q. Chen (Zheng and Yu 1987). To confirm the causative species identity, a representative voucher specimen collected and deposited at Nanjing Forestry University was used for a molecular analysis. Mycelia and conidia were collected from diseased leaves and genomic DNA of the pathogen was extracted and the internal transcribed spacer region (ITS) was amplified with primers ITS1/ITS4 (White et al. 1990). The resulting sequence of 461 bp was deposited in GenBank (accession no. MW255383). BLAST result showed that this sequence fully agreed with a sequence of S. polyfida [AB193381.1 (ITS), identities = 461/461 (100%)]. A maximum likelihood phylogenetic analyses using IQtree v. 1.6.8 with the ITS sequence placed this fungus in the S. polyfida clade. Based on the morphology and phylogeny, the fungus was identified as S. polyfida (Hirose et al. 2005; Zheng and Yu 1987). Pathogenicity was tested through inoculation by gently pressing the naturally infected leaves onto healthy ones of three potted A. palmatum seedlings wih five leaves. Healthy leaves from three other seedlings served as control. Inoculated and control seedlings were placed in separate growth chambers maintained at 20 ± 2°C, 70% humidity, with a 16 h/8 h light/dark period. Symptoms developed 8 days after inoculation. The powdery mildew developing on the inoculated seedlings was sequenced and confirmed as S. polyfida. The control leaves did not develop powdery mildew. S. polyfida has been reported on Acer catalpifolium in China (Zheng and Chen 1980), A. amoenum, A. australe, A. japonicum, A. palmatum, A. shirasawanum, and A. sieboldianum in Japan (Hirose et al. 2005; Meeboonet al. 2015), as well as A. takesimense in Korea (Lee et al. 2011). To the best of our knowledge, this is the first report of powdery mildew caused by S. polyfida on A. palmatum in China. These results form the basis for developing effective strategies for monitoring and managing this disease.

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First Report of Anthracnose of Gossypium indicum Lam. caused by Colletotrichum theobromicola in Korea

Plant Disease ◽

10.1094/pdis-07-21-1386-pdn ◽

2021 ◽

Author(s):

Donghun Kang ◽

Jungyeon Kim ◽

Youn Mi Lee ◽

Balaraju Kotnala ◽

Yongho Jeon

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Bootstrap Support ◽

Pathogenicity Test ◽

Distilled Water ◽

First Report ◽

Spray Method ◽

Cotton Plants ◽

Leaf Surface Area ◽

And Control

In September 2020, typical anthracnose symptoms were observed on cotton (Gossypium indicum Lam.) leaves growing in Hahoe village, Andong, Gyeongbuk Province, Korea. The leaves of the infected plants initially showed spots with halo-lesions which became enlarged and spread to the entire leaf surface area. The infected leaves later became yellowish and chlorotic (Fig. 1A). The disease incidence was at least 90% in the field. For pathogen isolation, fresh samples collected from symptomatic leaves were cut into small pieces (4 to 5 mm2), surface-sterilized in 1% sodium hypochlorite for 1 min, rinsed three times, and macerated in sterile distilled water (SDW). They were spread onto potato dextrose agar (PDA) plates and incubated at 25 °C for 5 days under a 12-h photoperiod. Five isolates were recovered from the infected leaves. Purified fungal colonies were initially white, later turned yellow on PDA medium. Conidia were yellow-colored, smooth-walled, aseptate, straight or slightly distorted, and cylindrical with one end slightly acute or with broadly rounded ends, and with size ranges from 15.3 to 17.5 µm (length) × 4.5 to 5.2 µm (width) (Fig. 1B). The morphological characteristics of the present isolates were consistent with those of Colletotrichum gloeosporioides (Weir et al. 2012). A single isolate, ANUK97, was selected for identification. The multilocus sequence analysis (MLSA) of the actin (ACT), calmodulin (CAL), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), internal transcribed spacer (ITS) rDNA, and β-tubulin (Tub2) were amplified by PCR with the primer pairs of ACT-521F/ACT-783R, CL1C/CL2C, GDF/GDR, ITS1/ITS4, and T1/T2, respectively (White et al. 1990). The resulting sequences were deposited in GenBank under accession numbers MW580367 (ACT), MW580368 (CAL), MW580369 (GAPDH), MW580370 (ITS), and MW580371 (TUB2). A nucleotide BLAST search revealed that ACT, CAL, GAPDH, ITS, and TUB2 sequences be 99% similar to accession numbers MN307380.1, MH155176.1, MK796226.1, MW580370.1, and JX010377.1, respectively of C. theobromicola. Maximum likelihood (ML) phylogenetic analysis was conducted based on a combined dataset of ACT, CAL, GAPDH, ITS, and TUB2 sequences using MEGA-X 10.1.8. The isolate ANUK97 was clustered with a representative strain C. theobromicola CBS124945 100% bootstrap support (Fig. 2). For the pathogenicity test, two-month-old cotton seedlings (n = 10) were inoculated with conidial suspensions (10⁶ spore/mL) of C. theobromicola obtained from 7-day-old PDA cultures at 25 °C by spray method. Seedlings treated with sterile distilled water served as controls. Inoculated and control cotton plants were incubated in the greenhouse at 25 °C under a 12-h photoperiod. After 7 days, necrotic lesions were observed on the artificially inoculated cotton plants, while control plants did not develop any disease symptoms. The pathogen was re-isolated from infected cotton leaves, but not from control plants to fulfill Koch’s postulates. To our knowledge, this is the first report of anthracnose of cotton caused by Colletotrichum theobromicola in Korea.

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First Report of Fusarium mangiferae Causing Mango Malformation in China

Plant Disease ◽

10.1094/pdis-12-11-1030 ◽

2012 ◽

Vol 96 (5) ◽

pp. 762-762 ◽

Cited By ~ 8

Author(s):

R.-L. Zhan ◽

S.-J. Yang ◽

F. Liu ◽

Y.-L. Zhao ◽

J.-M. Chang ◽

...

Keyword(s):

Mangifera Indica ◽

Elongation Factor ◽

Morphological Characteristics ◽

Fungal Growth ◽

Aerial Mycelium ◽

Laboratory Manual ◽

First Report ◽

Normal Number ◽

Mango Malformation ◽

Fusarium Mangiferae

Mango (Mangifera indica L.) malformation caused by Fusarium mangiferae has been reported in many mango-growing regions of the world (3). The disease was also observed in Yunnan and Sichuan provinces of China (1). Typical symptoms in seedlings included loss of apical dominance, hyperplasia and hypertrophy of vegetative buds, shortened internodes, and leaves that were more brittle than those of healthy plants. Inflorescences were abnormally branched and thickened, with panicles producing as much as two to five times the normal number of flowers. Flowers in the malformed inflorescence were much more enlarged and crowded than the generally hypertrophied axes of the panicle, thus producing no fruit or aborting early. To identify the pathogen, samples of malformed and healthy mango seedlings were collected from the affected plantings. For isolation, portions of stems were cut into 3- to 4-mm segments, surface disinfested, dried, and then plated on potato dextrose agar and incubated at 25°C. Within 5 days, white, fluffy, aerial mycelium developed. With the aid of an inverted microscope, single conidia were transferred to carnation leaf agar (CLA) medium. After 10 days of incubation, morphological characteristics were found to be identical to those of F. mangiferae (4). Aerial mycelium was white with no pigmentation observed on potato sucrose agar. Pigmentation on rice medium was pink. On CLA medium, conidia grew in branched conidiophores with false heads bearing monophialides or polyphialides. No conidiospores in chains were observed. Microconidia were ovate to long and oval, 0 to 1 septate, and 3.1 to 10.2 × 1.5 to 2.2 μm. Macroconidia are falculate, 3 to 5 septate, and 18 to 38 × 1.8 to 2.4 μm. Chlamydospores were not observed. Pathogenicity studies were conducted with 7-month-old asymptomatic mango seedlings. These seedlings, except for the controls, were inoculated by injection of the isolated fungus in the axillary or apical bud position. A 1-ml spore suspension (1 × 106 spores/ml) was injected slowly into the stems using a microsyringe with three buds per seedling, for a total of 10 seedlings. Typical malformation symptoms developed within 3 to 4 months, and none of the plants inoculated with sterile water resulted in malformation symptoms. Reisolations from the induced malformed shoots yielded the same fungus, and no fungal growth was observed to be growing from the control plants. To confirm identity of the causal fungus, the gene encoding translation elongation factor 1 alpha (EF-1α) was amplified and sequenced (2). The EF-1α sequence was 660 bp long. The sequence (GenBank Accession No. HM068871) was 99.68% similar to sequences of FD_01167 in the Fusarium ID database. On the basis of symptoms, fungal morphology, the EF-1α region sequence, and pathogenicity testing, this fungus was identified as F. mangiferae. To our knowledge, this is the first report of F. mangiferae causing mango malformation in China. This report will establish a foundation for further study of F. mangiferae and effectively addressing the disease. References: (1) X. H. Chen. Pract. Technol. (in Chinese) 6:5, 1992. (2) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (3) J. Kumar et al. Annu. Rev. Phytopathol. 31:217, 1993. (4) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

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