First Report of Neocosmospora striata Causing Peanut Pod Rot in China

In 2008, an outbreak of pod rot of peanut (Arachis hypogaea L.) occurred on most of the peanut cultivars in the Old Yellow River drainage area, the largest peanut-growing region in China. Disease incidence reached as high as 90% in some fields, causing severe yield losses. The black rot of pods and blackened, nonrotting taproots is similar to symptoms of peanut black rot caused by Cylindrocladium parasiticum, but the reddish orange perithecia of C. parasiticum were not found on the taproots close to the surface of the soil. The foliage of affected plants was generally asymptomatic, but some plants turned greener. This pod rot disease was further investigated in 2008 and 2010. Twenty-three Fusarium-like isolates were obtained from symptomatic, surface-disinfested pods with a frequency of 82%. These isolates were fast growing, with flat, thin, and grayish white colonies when cultured on potato dextrose agar (PDA) at 28°C for 3 to 4 days. The hyaline, elongated to cylindrical conidia, aggregated in slimy heads on conidiogenous cells developed from undifferentiated hyphae when observed with the light microscope. The size of conidia (single celled or one septum) varied from 3 to 9 μm long and 1.5 to 3.5 μm wide on the basis of the measurement of 50 spores. Some conidia appeared slightly curved. Ascomata formed within 10 to 14 days, with a punctate appearance on the colony. The cerebriform ascomata were dark brown, pyriform, ostiolate, glabrous, 120 to 170 × 90 to 130 μm, and with necks 30 to 50 μm long. Asci measured 60 to 90 × 6 to 10 μm, were cylindrical to cylindric-clavate, thin walled, and had an apical ring. Ascospore arrangement was obliquely uniseriate or partially biseriate, very pale yellow to hyaline, ellipsoidal, and measured 8 to 12 × 4.5 to 6 μm. Some spores had a median transverse straight or curved septum and were slightly constricted at the septum, with 6 to 10 thin, transverse, hyaline flanges. Morphological characteristics of the isolates with ascomata dark brown and ascospores with 6 to 10 transverse hyaline flanges matched the description for Neocosmospora striata (1). The internal transcribed spacer (ITS) region of rDNA was amplified from extracted template DNA with primer pairs ITS4/ITS5 and sequenced. A 591-bp amplicon (GenBank Accession No. HM461900) had 99% sequence identity with Fusarium solani (HQ607968 and HQ608009) and N. vasinfecta (GU213063), which indicated that these fungi belong to the genus Neocosmospora or Fusarium, although there is no direct sequence evidence that they are N. striata. N. striata has only been previously reported in Japan (2). This species is unique because of the dark brown ascomata and there is no comparable species (1). Koch's postulates were completed by surface-disinfesting 80 peanut pods of cv. Jihua 9813 and soaking them in conidial suspensions (105 conidia/ml) for 2 min. Another 80 other pods soaked in sterile water served as controls. All peanuts were incubated in moist petri dishes under darkness at 28°C. Symptoms similar to those originally observed in the field formed within 10 days on all inoculated peanut pods and not the controls. N. striata was reisolated from all affected peanut pods. To our knowledge, this is first report of N. striata causing peanut pod rot in China and the first description of the anamorph of the fungus. References: (1) P. F. Cannon et al. Trans. Br. Mycol. Soc. 82:673, 1984. (2) S. Udagawa et al. Trans. Mycol. Soc. Jpn. 16:340, 1975.

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First Report of Fruit Rot of Melon Caused by Fusarium asiaticum in China

Plant Disease ◽

10.1094/pdis-08-20-1857-pdn ◽

2020 ◽

Author(s):

Fangmin Hao ◽

Quanyu Zang ◽

Weihong Ding ◽

Erlei Ma ◽

Yunping Huang ◽

...

Keyword(s):

Disease Incidence ◽

Elongation Factor ◽

Morphological Characteristics ◽

Its Region ◽

Fruit Rot ◽

Post Inoculation ◽

Basal Cells ◽

First Report ◽

Fusarium Asiaticum ◽

Sterile Needle

Melon (Cucumis melo L.) is a member of the Cucurbitaceae family, an important economical and horticultural crop, which is widely grown in China. In May 2020, fruit rot disease with water-soaked lesions and pink molds on cantaloupe melons was observed in several greenhouses with 50% disease incidence in Ningbo, Zhejiang Province in China. In order to know the causal agent, diseased fruits were cut into pieces, surface sterilized for 1 min with 1% sodium hypochlorite (NaClO), 2 min with 75% ethyl alcohol, rinsed in sterile distilled water three times (Zhou et al. 2018), and then placed on potato dextrose agar (PDA) medium amended with streptomycin sulfate (100 μg/ml) plates at 25°C for 4 days. The growing hyphae were transferred to new PDA plates using the hyphal tip method, putative Fusarium colonies were purified by single-sporing. Twenty-five fungal isolates were obtained and formed red colonies with white aerial mycelia at 25°C for 7 days, which were identified as Fusarium isolates based on the morphological characteristics and microscopic examination. The average radial mycelial growth rate of Fusarium isolate Fa-25 was 11.44 mm/day at 25°C in the dark on PDA. Macroconidia were stout with curved apical and basal cells, usually with 4 to 6 septa, and 29.5 to 44.2 × 3.7 to 5.2 μm on Spezieller Nährstoffarmer agar (SNA) medium at 25°C for 10 days (Leslie and Summerell 2006). To identify the species, the internal transcribed spacer (ITS) region and translational elongation factor 1-alpha (TEF1-α) gene of the isolates were amplified and cloned. ITS and TEF1-α was amplified using primers ITS1/ITS4 and EF1/EF2 (O’Donnell et al. 1998), respectively. Sequences of ITS (545 bp, GenBank Accession No. MT811812) and TEF1-α (707 bp, GenBank Acc. No. MT856659) for isolate Fa-25 were 100% and 99.72% identical to those of F. asiaticum strains MSBL-4 (ITS, GenBank Acc. MT322117.1) and Daya350-3 (TEF1-α, GenBank Acc. KT380124.1) in GenBank, respectively. A phylogenetic tree was established based on the TEF1-α sequences of Fa-25 and other Fusarium spp., and Fa-25 was clustered with F. asiaticum. Thus, both morphological and molecular characterizations supported the isolate as F. asiaticum. To confirm the pathogenicity, mycelium agar plugs (6 mm in diameter) removed from the colony margin of a 2-day-old culture of strain Fa-25 were used to inoculate melon fruits. Before inoculation, healthy melon fruits were selected, soaked in 2% NaClO solution for 2 min, and washed in sterile water. After wounding the melon fruits with a sterile needle, the fruits were inoculated by placing mycelium agar plugs on the wounds, and mock inoculation with mycelium-free PDA plugs was used as control. Five fruits were used in each treatment. The inoculated and mock-inoculated fruits were incubated at 25°C with high relative humidity. Symptoms were observed on all inoculated melon fruits 10 days post inoculation, which were similar to those naturally infected fruits, whereas the mock-inoculated fruits remained symptomless. The fungus re-isolated from the diseased fruits resembled colony morphology of the original isolate. The experiment was conducted three times and produced the same results. To our knowledge, this is the first report of fruit rot of melon caused by F. asiaticum in China.

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First Report of Leaf Blight Caused by Septoria allii on Garlic Chives in Korea

Plant Disease ◽

10.1094/pdis-08-12-0809-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 147-147

Author(s):

J. H. Park ◽

S. E. Cho ◽

K. S. Han ◽

H. D. Shin

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Leaf Blight ◽

Plant Diseases ◽

Cultivated Plants ◽

Sequence Information ◽

Conidial Suspension ◽

Korean Society ◽

First Report

Garlic chives, Allium tuberosum Roth., are widely cultivated in Asia and are the fourth most important Allium crop in Korea. In June 2011, a leaf blight of garlic chives associated with a Septoria spp. was observed on an organic farm in Hongcheon County, Korea. Similar symptoms were also found in fields within Samcheok City and Yangku County of Korea during the 2011 and 2012 seasons. Disease incidence (percentage of plants affected) was 5 to 10% in organic farms surveyed. Diseased voucher specimens (n = 5) were deposited at the Korea University Herbarium (KUS). The disease first appeared as yellowish specks on leaves, expanding to cause a leaf tip dieback. Half of the leaves may be diseased within a week, especially during wet weather. Pycnidia were directly observed in leaf lesions. Pycnidia were amphigenous, but mostly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, separate, unilocular, 50 to 150 μm in diameter, with ostioles of 20 to 40 μm in diameter. Conidia were acicular, straight to sub-straight, truncate at the base, obtuse at the apex, hyaline, aguttulate, 22 to 44 × 1.8 to 3 μm, mostly 3-septate, occasionally 1- or 2-septate. These morphological characteristics matched those of Septoria allii Moesz, which is differentiated from S. alliacea on conidial dimensions (50 to 60 μm long) (1,2). A monoconidial isolate was cultured on potato dextrose agar (PDA). Two isolates have been deposited in the Korean Agricultural Culture Collection (Accession Nos. KACC46119 and 46688). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequence of 482-bp was deposited in GenBank (JX531648 and JX531649). ITS sequence information was at least 99% similar to those of many Septoria species, however no information was available for S. allii. Pathogenicity was tested by spraying leaves of three potted young plants with a conidial suspension (2 × 105 conidia/ml), which was harvested from a 4-week-old culture on PDA. Control leaves were sprayed with sterile water. The plants were placed in humid chambers (relative humidity 100%) for the first 48 h. After 7 days, typical leaf blight symptoms started to develop on the leaves of inoculated plants. S. allii was reisolated from the lesions of inoculated plants, confirming Koch's postulates. No symptoms were observed on control plants. The host-parasite association of A. tuberosum and S. allii has been known only from China (1). S. alliacea has been recorded on several species of Allium, e.g. A. cepa, A. chinense, A. fistulosum, and A. tuberosum from Japan (4) and A. cepa from Korea (3). To the best of our knowledge, this is the first report of S. allii on garlic chives. No diseased plants were observed in commercial fields of garlic chives which involved regular application of fungicides. The disease therefore seems to be limited to organic garlic chive production. References: (1) P. K. Chi et al. Fungous Diseases on Cultivated Plants of Jilin Province, Science Press, Beijing, China, 1966. (2) P. A. Saccardo. Sylloge Fungorum Omnium Hucusque Congnitorum. XXV. Berlin, 1931. (3) The Korean Society of Plant Pathology. List of Plant Diseases in Korea, Suwon, Korea, 2009. (4) The Phytopathological Society of Japan. Common Names of Plant Diseases in Japan, Tokyo, Japan, 2000.

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First Report of Lasiodiplodia pseudotheobromae Causing Stem End Rot of Mango Fruit in Pakistan

Plant Disease ◽

10.1094/pdis-01-21-0099-pdn ◽

2021 ◽

Author(s):

Muhammad Waqar Alam ◽

Arif Malik ◽

Abdul Rehman ◽

Mubeen Sarwar ◽

Tahir Shafeeq ◽

...

Keyword(s):

Disease Incidence ◽

Mangifera Indica ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Postharvest Disease ◽

Single Spore ◽

Mango Fruit ◽

First Report ◽

Field Samples ◽

Rot Disease

Mango (Mangifera indica L.) is considered a desirable fruit in international markets and is grown throughout tropical and sub-tropical countries around the world (Alemu, 2014). Stem end rot is the most damaging and complex postharvest disease of mango, resulting in losses of up to 40% in Pakistan, which is the leading producer and exporter (Alam et al. 2017). A field survey was conducted in June of 2017 and 2018 in the Rahim Yar Khan and Multan- major mango producing regions of Punjab Province. After mature but unripe mango fruit (cv. Samar Bahisht Chaunsa) were stored at 12°C for 2 weeks to permit ripening, water-soaked, dark brown to purplish black decay began to appear around the stem end portion. The decay gradually enlarged and covered the whole fruit after 7 days. Disease incidence was estimated at 30%. Small pieces (3 to 4 mm2) from the periphery of 15 diseased fruit were surface disinfected with 1% sodium hypochlorite for 2 min, rinsed three times in sterilized distilled water, air dried, and then placed aseptically onto potato dextrose agar (PDA) medium and incubated at 25°C under a 12-h light/dark photoperiod for 7 days. Twelve single-spore isolates with similar morphology were isolated from the infected tissues. Initially the fungus produced thick, fluffy and greyish-white aerial mycelium, that later turned into dark gray colonies. Conidia were unicellular, ellipsoidal, and initially hyaline, but with age became dark brown and developed a central septum. Conidia measured 24.5 to 31.5 × 11.4 to 15.7 µm (n = 60). Conidiophores were inflated at their base with one diaphragm which reduced to conidiogenous cells. Conidiogenous cells were hyaline and cylindrical. On the basis of morphological characteristics, the fungus was tentatively identified as Lasiodiplodia sp., a member of the family Botryosphaeriaceae (Alves et al. 2008). For molecular identification, genomic DNA was extracted from mycelium following the CTAB method. The internal transcribed spacer (ITS) region of rDNA and translation elongation factor 1-alpha (TEF1-α) gene were amplified using ITS1/ITS4 (White et al. 1990) and EF1-728F/EF1-986R primer sets (Carbone and Kohn 1999), respectively. BLASTn searches of sequences revealed 99% to 100% identity with the reference sequences of various Lasiodiplodia pseudotheobromae isolates (GenBank accession nos. MH057189 for ITS; MN638768 for TEF-1a). The sequences were deposited in GenBank (accession nos. MW439318, MW433883 for ITS; and MW463346, MW463347 for TEF-1a). To fulfill Koch’s postulates, a suspension of 105 conidia/ml from a 7-day-old culture of L. pseudotheobromae was used to inoculate fully mature but unripe mango fruit (cv. Samar Bahisht Chaunsa). Fruit were pricked with a sterilized needle to a depth of 4 mm at the stem end portion, injected with 50 μl of the prepared spore suspension (Awa et al. 2012), and stored at 12°C for 3 weeks under 70 to 80% RH. Twenty mango fruit were inoculated, and 10 were inoculated with sterile water only. After 15 days, most fruit showed typical symptoms at the stem end. Reisolations from symptomatic fruit following the procedures described above for isolating and identifying the fungal cultures from infected field samples, consistently yielded a fungus identical to L. pseudotheobromae. Control fruit remained disease-free. Although L. pseudotheobromae was previously reported on several forest and fruit trees (Alves et al. 2008; Awan et al. 2016), this is the first report of the pathogen causing stem end rot disease of mango in Pakistan. This report is important for the new studies aiming at management of stem end rot disease of mango caused by L. pseudotheobromae in Pakistan.

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First report of internal black rot on Carica papaya fruit caused by Fusarium sulawesiense in China

Plant Disease ◽

10.1094/pdis-04-21-0721-pdn ◽

2021 ◽

Author(s):

Run Hua Yi ◽

Ting Lian ◽

Jun Jie Su ◽

Jing Chen

Keyword(s):

Carica Papaya ◽

Elongation Factor ◽

Morphological Characteristics ◽

Black Rot ◽

Internal Transcribed Spacer Region ◽

Tropical Fruit ◽

First Report ◽

Plastic Bag ◽

Rot Disease ◽

Dilution Plate Method

Papaya (Carica papaya L.) is a tropical fruit consumed worldwide due to its nutritional, medicinal and pharmacological properties. In China, papaya was widely planted in Guangdong, Guangxi, Hainan, Yunnan, Fujian and Taiwan provinces. From September to December in 2015-2020, fruit with internal black rot disease was observed in papaya plantation in Xuwen, Guangdong province (N20°20’9”; E110°14’45”), approximately 5% fruits on about 85% trees were infected every year. The infected fruits showed the symptom of ‘false-ripening’ and the pericarp color changed from green to yellow earlier than that of normal fruits. In the cavity of diseased fruits, the sarcocarp black rotted and conspicuous mycelia were observed. Mycelia and infected tissues from symptomatic fruits were picked up, placed on potato dextrose agar (PDA) with 50mg/L ampicillin and incubated at 25± 2 ℃ in the dark. The fungus was purified by spore dilution plate method. Fast-growing colonies with dense, floccose, cottony mycelium were initially white gradually becoming buff brown. Macroconidia were falcate, 3-5 septa with foot-shaped cell and 10.35-41.50 (av. 25.41±6.82) ×1.90-5.95 (av. 3.67±0.85) µm (n>140) in size after 7 days of incubation on carnation leaf agar (CLA). There were scarce microconidia. Chlamydospores were intercalary, solitary or in chains, globose or irregular, hyaline to light brown. The morphological characteristics of the fungus were similar to that of Fusarium sulawesiense (Maryani et al. 2019). The internal transcribed spacer region (ITS) (KU881904 and KY436233), translation elongation factor 1-alpha (tef1) (KU894408 and KY436232), and RNA polymerase second largest subunit (rpb2) (KU894409 and KY436231) were sequenced from two isolates to cofirm species identification. Blast analysis in the FUSARIUM-ID and the NCBI databases revealed above 99 to 100% identity match with the F. sulawesiense strains NRRL34056, NRRL34059, NRRL34004 and NRRL43730 (Xia et al 2019). Maximum likelihood (ML) analysis and Bayesian inference (BI) based on the concatenated sequences using RAxML v.1.0.0 and MrBayes v. 3.2.1 software revealed that the isolates were resolved in the same clade with the F. sulawesiense strains. Thus, the fungus was identified as F. sulawesiense based on morphological characteristics and molecular criteria. To confirm pathogenicity, five healthy fruits were injected with 200 μl of spore suspension (approximately 104 spores/ml) in the field and laboratory, and isovolumetric sterile water served as control. Each fruit was sealed with a plastic bag and kept at natural temperature (about 25-30 ℃). All the inoculated fruits developed typical symptoms after 30 days in the field and 15 days in the laboratory, whereas no symptoms were observed on the control fruits. F. sulawesiense was reisolated from inoculated fruits, but not from non-inoculated fruits. F. sulawesiense displayed a broad host which included Oryza sativa, Musa nana, Citrus reticulata, and Colocasia esculenta etc. in China (Wang et al. 2019). To our knowledge, this is the first report of F. sulawesiense causing internal black rot on papaya fruit. This work is important for papaya growers to prevent this disease in time.

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First Report of Colletotrichum godetiae Causing Anthracnose and Twig Blight on Persian Walnut in Hungary

Plant Disease ◽

10.1094/pdis-03-20-0607-pdn ◽

2020 ◽

Author(s):

Virág Varjas ◽

Tamás Lakatos ◽

Tímea Tóth ◽

Csilla Kovács

Keyword(s):

Disease Incidence ◽

Juglans Regia ◽

Morphological Characteristics ◽

Unknown Origin ◽

Its Region ◽

Colletotrichum Acutatum ◽

Width Ratio ◽

Single Spore ◽

First Report ◽

Persian Walnut

Persian walnut (Juglans regia L.) fruit with preharvest anthracnose symptoms, necrotic fruit stalks, and twigs with necrotic buds, and peaks were collected in a Hungarian orchard next to Nágocs, in September 2018. Disease incidence was approximately 15% on a Hungarian bred walnut cultivar ‘Milotai 10’. Similar symptoms were found on Persian walnut in other locations (eg. Milota, Érd, Sarród, and Kocs). Acervuli were observed on necrotic lesions on fruit, and twigs with pale orange conidial masses. Conidia were hyaline, unicellular, and fusiform. Morphometric measurements of conidia showed mean length ± SD × width ± SD = 15.9 ± 1.7 × 4.5 ± 0.4 μm, length/width ratio 1:0.3 (n=100). The fungus was isolated from conidial masses on potato dextrose agar (PDA) medium amended with Chlorampenicol (25 mg/L). A total of 12 isolates were obtained as pure cultures by single-spore isolations and incubated at 23°C in dark for 10 days. The colonies were white to gray or grayish-orange on the upper side and with black spots on the reverse side. The isolates showed morphological characteristics of Colletotrichum acutatum in sensu lato (Jayawardena et al. 2016). Molecular analyses were conducted to identify the exact species. Internal transcribed spacer (ITS) region, actin (ACT), and calmodulin (CAL) partial genes were amplified by ITS1F/ITS4R, ACT512F/ACT783R and CAL1/CAL2 primers (White at al. 1990, Carbone and Kohn 1999, O’Donnell et al. 2000). The sequences of ITS region (GenBank Accession Nos: MK367398-99, MK367401-02) showed 100% identity with C. godetiae sequence. Based on ACT gene (GenBank Accession Nos: MK415991-92, MK415994-95) were 100% identity with the deposited C. godetiae type strains from walnut. The obtained sequences of CAL gene (GenBank Accession Nos: MK415998-99, MK416001-02) were same and showed 100% with other C. godetiae sequences from other host plants. The fungus was identified as Colletotrichum godetiae Neerg. Pathogenicity tests were accomplished in the field and under laboratory conditions (25°C on thermostat) on 10 green ‘Milotai 10’ walnut fruit, and 10 walnut twigs each. Tests were conducted on living trees, collected fruit, and two-year-old twigs by inserting mycelial agar plugs (5 mm in diameter) onto wounded pericarp tissues, which were then wrapped with wet cotton and parafilm. Wounded tissues on 5 fruit and 5 two-year-old twigs were treated with non-colonized PDA plugs as noninoculated controls. After 14 d necrotic lesions 9 to 17 mm in diameter developed on fruit on living trees. Lengths of 12 to 17 mm and width of 7 to 12 mm necrosis was measured on phloem of walnut twigs, and almost two times larger in cambium. No necrosis developed around control wounds. Koch's postulates were fulfilled with the reisolation of the pathogen from symptomatic tissues, isolates were identical morphologically and by sequence analysis of ITS region, ACT, and CAL partial genes to the original isolates. Damm et al. (2012) described two C. godetiae strains associated with walnut, one isolated in Austria and another one of unknown origin. An epidemic event of walnut anthracnose caused by Colletotrichum species mainly C. godetiae was reported in France (Da Lio et al. 2018). The pathogen was isolated from nuts, buds, insects, and stems. To our knowledge, this is the first report of anthracnose of walnut fruit caused by C. godetiae in Hungary. Anthracnose caused by C. godetiae, and previously reported C. fioriniae (Varjas et al. 2019) is becoming an increasing preharvest problem on Persian walnut in Hungary.

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First Report of Peanut Cylindrocladium Black Rot Caused by Cylindrocladium parasiticum in Fujian Province, Eastern China

Plant Disease ◽

10.1094/pdis-11-11-0982 ◽

2012 ◽

Vol 96 (4) ◽

pp. 583-583 ◽

Cited By ~ 4

Author(s):

R. Pan ◽

Q. Deng ◽

D. Xu ◽

C. Ji ◽

M. Deng ◽

...

Keyword(s):

Southern China ◽

Disease Incidence ◽

Eastern China ◽

Black Rot ◽

Brown Pigment ◽

Fujian Province ◽

First Report ◽

Calonectria Ilicicola ◽

Cylindrocladium Parasiticum ◽

Wheat Kernels

During late July and early August of 2010, a serious disease of peanut (Arachis hypogaea L.) resembling Cylindrocladium black rot (CBR) was found in Longyan City, Fujian Province of Eastern China. Aboveground symptoms were chlorosis and yellowing of leaves, a black rot of the basal stem and pegs, and wilting of the vines. Underground plant parts (including pods, pegs, taproots, and hypocotyls) were blackened and rotted. Orange-to-reddish spherical fruiting bodies appeared on the lesions of the basal stems and pegs of peanut. Disease incidence was approximately 20%. A fungus was consistently isolated from the edge of lesions on potato dextrose agar (PDA) amended with streptomycin and incubated at 25°C. The fungus produced white-to-pale buff mycelia with a yellowish brown pigment. Optimum growth of the fungus on PDA was at 25 to 30°C. Conidiophores were borne laterally on a stipe that terminated in a hyaline, globose vesicle measuring 5.5 × 10.9 μm in diameter. Conidia were hyaline, cylindrical, rounded at both ends, slightly wider at the base than at the apex, with one to three septa (mostly one septa), and measured 27.3 to 70.9 × 4.1 to 8.2 μm. Orange-to-reddish perithecia were readily formed in old cultures. The perithecia were subglobose to oval or obovate and measured 215.6 to 609.4 × 309.4 to 496.9 μm. The asci were hyaline, clavate, thin walled, long stalked, with each containing eight ascospores. Ascospores were hyaline, falcate, had one septum, and measured 27.3 to 54.5 × 4.1 to 6.8 μm. The fungus was identified as Cylindrocladium parasiticum Crous, M.J. Wingfield, & Alfenas (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment was amplified using the T1/Bt2b primers (3) and sequenced. The sequences of three isolates (GenBank Accession Nos. JF343965, JF429656, and JF429657), when compared with existing sequences in GenBank, had 95 to 99% sequence identity with Calonectria ilicicola (GenBank Accession Nos. AY725643 and AY725639). Pathogenicity tests were conducted by first culturing the fungus on wheat kernels for 2 weeks. Inoculated kernels were then used as inoculum and mixed with sterilized soil in a proportion of 1:20 by weight in plastic pots (10 × 9 cm). Noninoculated wheat kernels were mixed with sterilized soil in the same proportion and served as the control. Two-week-old peanut seedlings (cv. Yueyou No. 7) were transplanted into inoculated or noninoculated pots. There were five plants per pot and each treatment was replicated four times. The plants were incubated in a greenhouse at 25 ± 2°C. All of the treated plants exhibited typical basal stem and root rot symptoms of CBR 2 weeks after inoculation, while all of the control plants remained healthy. C. parasiticum was reisolated from the diseased plants. To our knowledge, this is the first report of CBR on peanut in Fujian Province in Eastern China. The disease has been previously reported in Guangdong Province in Southern China but is not known elsewhere (4). This pathogen may pose a serious threat to peanut production in China, where peanut is an important crop. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Can. J. Bot. 77:1813, 1999. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.

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First Report of Corynespora Leaf Spot Caused by Corynespora cassiicola on Gynura in China

Plant Disease ◽

10.1094/pdis-12-13-1284-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1007-1007 ◽

Cited By ~ 1

Author(s):

B. J. Li ◽

J. X. Chuan ◽

M. Yang ◽

G. F. Du

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Leaf Spot Disease ◽

Herbaceous Plant ◽

Distilled Water ◽

Corynespora Cassiicola ◽

Single Spore ◽

First Report

Gynura (Gynura bicolor DC.) is a perennial herbaceous plant in the family Compositae. It is an important Chinese vegetable, and is commonly used as a Chinese herbal medicine. In 2010, a severe leaf spot disease was observed on gynura grown in the main production areas in Tong Nan County, Chongqing City, China. Some farms experienced 60% disease incidence. Symptoms usually began on the lower leaves, as circular to elliptical or irregular spots with concentric rings. Individual spots were dark brown with grayish centers, sometimes coalescing and leading to extensive necrosis. The fungus associated with lesions was characterized as follows: Conidiophores were single or in clusters, straight or flexuous, unbranched, percurrent, cylindrical, pale to dark brown, 87.5 to 375.0 μm long and 5.0 to 10.5 μm wide. Conidia were solitary or catenate, straight to slightly curved, obclavate to cylindrical, 3 to 14 pseudoseptate, 82.8 to 237.5 μm long and 7.0 to 7.8 μm wide, and pale brown. The morphological characteristics of the conidia and conidiophores agreed with the descriptions for Corynespora cassiicola (1). To isolate the causal pathogen, surface-sterilized tissue at the margin of lesions was immersed in 75% ethanol for 30 s, rinsed in sterile water, dried in a laminar flow bench, transferred to PDA, and incubated at 28°C. Four single-spore cultures of the isolates were obtained and named from ZBTK10110637 to ZBTK10110640. All strains were identified as C. cassiicola. The isolate ZBTK10110637 was selected as representative for molecular identification. Genomic DNA was extracted by CTAB (2). The internal transcribed spacer (ITS) region of the rDNA was amplified using primers with ITS1 (5′-TCCGATGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′). Amplicons were 433 bp (GenBank Accession No. JX867272) and shared 100% similarity with that of C. cassiicola (NRC2-1 No. AB539285.1). To confirm pathogenicity, four isolates were used to inoculate 12 gynura plants (6 weeks old) by mist spray-inoculation with 108 spores/ml suspension in sterile distilled water on the leaves. Control plants were misted with sterile distilled water. After inoculation, all plants were incubated in a greenhouse maintained at 20 to 28°C with relative humidity of 80 to 85%. Five days after inoculation, dark brown spots with a grayish center typical of field symptoms were observed on all inoculated plants. No symptoms were seen on water-treated control plants. The fungus was re-isolated from inoculated plants. The morphological characteristics of isolates were identical with the pathogen recovered originally. This is the first report of C. cassiicola on gynura. References: (1) M. B. Ellis. CMI Mycological Papers 65(9):1-15, 1957. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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

Plant Disease ◽

10.1094/pdis-09-14-0895-pdn ◽

2015 ◽

Vol 99 (1) ◽

pp. 161-161 ◽

Cited By ~ 1

Author(s):

I. Y. Choi ◽

S. H. Hong ◽

S. E. Cho ◽

J. H. Park ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Organic Farming ◽

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Petroselinum Crispum ◽

Width Ratio ◽

First Report ◽

Potted Plants ◽

Powdery Mildews

Peucedanum japonicum Thunb., belonging to the family Apiaceae, is distributed in many Asian countries, including Korea. This plant was recently developed as an edible green and is cultivated under organic farming in Korea. In June 2013, plants showing typical symptoms of powdery mildew were found with approximately 50% disease incidence in polyethylene-film-covered greenhouses in Iksan City, Korea. Symptoms first appeared as circular white colonies, which subsequently showed abundant mycelial growth on the leaves, often covering the whole surface. Infected plants were unmarketable mainly due to signs of white fungal growths and reddish discoloration on the leaves. The same symptoms were found on P. japonicum in poly-tunnels in Iksan City and Jinan County of Korea in 2014. Voucher specimens (n = 3) were deposited in the Korea University Herbarium (KUS). Appressoria were lobed, and solitary or in opposite pairs. Conidiophores were cylindrical, 80 to 145 × 8 to 10 μm, and composed of three to four cells. Foot-cells of conidiophores were straight to substraight, cylindrical, and 25 to 63 μm long. Singly produced conidia were oblong-elliptical to oblong, occasionally ovate, 35 to 50 × 13 to 16 μm with a length/width ratio of 2.3:3.1, with angular/rectangular wrinkling of outer walls, and lacked distinct fibrosin bodies. Germ tubes were produced on the perihilar position of conidia. Primary conidia were apically conical, basally truncate, and generally smaller than the secondary conidia. No chasmothecia were 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. (2). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F27872 was amplified with primers ITS1/ITS4 and sequenced. The resulting 560-bp sequence was deposited in GenBank (Accession No. KM491178). The obtained ITS sequence shared >99% similarity with those of E. heraclei from apiaceous hosts, e.g., Daucus carota (KC480605), Pimpinella affinis (AB104513), and Petroselinum crispum (KF931139). Pathogenicity was confirmed through inoculation by gently dusting conidia onto leaves of five healthy potted plants. Five non-inoculated plants served as controls. Inoculated plants developed symptoms after 6 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was identical in morphology to those observed in the field. Powdery mildew of P. japonicum caused by E. heraclei has been reported in Japan (4), and numerous reports of E. heraclei on various species of Peucedanum plants have been made in most part of Europe and East Asia (Japan and far eastern Russia) (1,3). However, this is the first report of powdery mildew caused by E. heraclei on P. japonicum in Korea. Occurrence of powdery mildews is a threat to the quality and marketability of this plant, especially in organic farming. References: (1) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Scientific Societies Press, Tokyo, 1986. (2) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No.11. CBS, Utrecht, 2012. (3) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., online publication. ARS, USDA. Retrieved August 18, 2014. (4) S. Tanda and C. Nakashima. J. Agric. Sci., Tokyo Univ. Agric. 47:54, 2002.

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First Report of Downy Mildew Caused by Peronospora belbahrii on Basil (Ocimum spp.) in Ontario

Plant Disease ◽

10.1094/pdis-01-13-0026-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1248-1248 ◽

Cited By ~ 6

Author(s):

C. Saude ◽

S. Westerveld ◽

M. Filotas ◽

M. R. McDonald

Keyword(s):

Downy Mildew ◽

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Research Field ◽

Research Station ◽

Marketable Yield ◽

First Report ◽

Sweet Basil ◽

High Disease Severity

Basil (Ocimum spp.) is one of the most commercially significant fresh culinary herb crops worldwide. In Ontario, basil is grown both in the field and in the greenhouse. In the summer of 2011, basil plants grown in a research field at the Simcoe Research Station in Norfolk County, Ontario, Canada (44°15′N, 77°35′W), were infected with downy mildew. Infected leaves exhibited interveinal chlorotic lesions on the upper surface and clear to black sporulation on the abaxial leaf surfaces. Leaf senescence and defoliation occurred at high disease severity, which reduced marketable yield. Basil downy mildew symptoms were severe on leaves of cultivars Genovese and Sweet Basil, with 40 to 100% disease incidence. Based on morphological characteristics, the basil downy mildew causal agent was identified as Peronospora belbahrii Thines (4). Infected leaves were collected and microscopic observations of the sporulating lesions were carried out and the structures measured. Sporangiophores (n = 20) were hyaline with relatively long, straight trunks and were monopodially branched, with a length of 150 to 360 μm (average 285 μm). Sporangiophores ended with two slightly curved branchlets, the longer one measuring 15 to 27 μm (average 19 μm) and the shorter one 5 to 15 μm (average 9 μm). Sporangia (n = 50) were round, or slightly ovoid, olive to brown in color, and measured 29 × 25 μm (25 to 35 × 20 to 30 μm). Genomic DNA was extracted from 10 isolates and the nuclear ribosomal internal transcribed spacer (ITS) region was amplified with ITS4 and ITS5 primers and sequenced. The sequences of the 10 isolates were nearly identical. A BLAST search of the NCBI database with the ITS sequences (GenBank Accession No. KC756923) revealed a 98 to 100% similarity to the sequences of P. belbahrii (HQ730979, FJ436024, and HQ702191) isolated from sweet basil in Florida (3), California (1), and Hungary (2), respectively. To confirm pathogenicity, 5-week-old ‘Genovese’ seedlings were sprayed with a suspension of 1 × 105 sporangia/ml. Plants were kept in a growth chamber maintained at 23/18°C, 60 to 85% relative humidity, and 12/12 h light/dark. Non-inoculated plants served as controls. Basil downy mildew symptoms developed after 8 days on the inoculated plants and the pathogen was identified in association with symptoms consistent with downy mildew. The non-inoculated controls remained healthy. In North America, the occurrence of basil downy mildew has been reported since 2007 (3) and the disease has spread into several U.S. states. To our knowledge, this is the first report of downy mildew on sweet basil in Canada. References: (1) C. L. Blomquist et al. Plant Dis. 93:968, 2009. (2) G. Nagy and A. Horvath. Plant Dis. 95:1034, 2011. (3) P. D. Roberts et al. Plant Dis. 98:199, 2009. (4) M. Thines et al. Mycol. Res. 113:532, 2009.

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First Report of Alternaria alternata Causing Fruit Rot on Fig (Ficus carica) in Montenegro

Plant Disease ◽

10.1094/pdis-07-13-0770-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 424-424 ◽

Cited By ~ 2

Author(s):

N. Latinović ◽

S. Radišek ◽

J. Latinović

Keyword(s):

Alternaria Alternata ◽

Direct Sequencing ◽

Disease Incidence ◽

Morphological Characteristics ◽

Fruit Rot ◽

Conidial Suspension ◽

Culture Collections ◽

First Report ◽

Control Fruit ◽

Rot Disease

In July 2012, a fruit rot disease was observed in several commercial fig tree orchards located in the Podgorica region in Montenegro. Symptoms on fruits initially appeared as small circular to oval, light brown, necrotic, sunken spots located mostly on the areas surrounding the ostiolar canal with an average diameter of 5 to 10 mm, which gradually enlarged in size leading to total fruit rot. Disease incidence on fruit across the fields ranged from 15 to 20% but the disease did not increase further due to hot and dry conditions thereafter. No foliar symptoms were observed. Small pieces (5 mm2) of symptomatic fruits were excised from the junction of diseased and healthy tissue, surface sterilized in 70% ethanol solution for 1 min, washed in three changes of sterile distilled water, air dried, and transferred to potato dextrose agar (PDA). After 2 to 3 days of incubation at 25°C, a fungus was consistently isolated. The isolates had radial growth and produced sooty black colonies. Microscopic observations of the colonies revealed brown septate hyphae and simple or branched conidiophores 30 to 65 μm long and 3 to 4.5 μm wide. Dark brown conidia were in chains (3 to 7), sized 10 to 35 × 5 to 9 μm, ellipsoid to ovoid, with 2 to 5 transverse and a few (1 to 3) to no longitudinal septa. Based on morphological characteristics, the fungus was identified as Alternaria alternata (3). For molecular identification, DNA was extracted from mycelia and conidia of two representative single spore isolates designated as ALT1-fCG and ALT2-fCG. PCR was carried out using internal transcribed spacer (ITS) region primers ITS4/ITS5 and A. alternata species-specific primers AAF2/AAR3 (1). Both primer pairs gave PCR products that were subjected to direct sequencing. BLAST analysis of the 546-bp ITS4/ITS5 (KF438091) and 294-bp AAF2/AAR3 (KF438092) sequences revealed 100% identity with several A. alternata isolates. Pathogenicity tests were conducted on 30 detached almost ripe and healthy fig fruit (cv. Primorka) by spraying them with a conidial suspension of the isolated fungus (106 conidia/ml) with a handheld sprayer. Thirty fruit inoculated with sterile water served as the non-inoculated control. Inoculated and control fruit were kept in a moist chamber at 25°C. Symptoms appeared on inoculated fruit 2 to 3 days after inoculation and all fruit were completely rotted 5 to 6 days after inoculation. Control fruit did not display any symptoms. A. alternata was consistently re-isolated from inoculated fruit, fulfilling Koch's postulates. The fig fruit rot caused by A. alternata has been reported before in California (2) and elsewhere mainly as postharvest pathogen. To our knowledge, this is the first report of fruit rot caused by A. alternata on fig in Montenegro. Considering Podgorica as the largest fig-producing area and the importance of fig as a traditionally grown crop, it could pose a threat to fig production in Montenegro. Voucher specimens are available at the culture collections of the University of Montenegro, Biotechnical Faculty. References: (1) P. Konstantinova et al. Mycol. Res. 106:23, 2002. (2) T. J. Michailides et al. Plant Dis. 78:44-50, 1994. (3) E. G. Simmons. Page 775 in: Alternaria and Identification Manual. CBS Fungal Biodiversity Centre, 2007.

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