scholarly journals First Report of Botryosphaeria iberica and B. viticola Associated with Grapevine Decline in California

Plant Disease ◽  
2007 ◽  
Vol 91 (6) ◽  
pp. 772-772 ◽  
Author(s):  
J. R. Úrbez-Torres ◽  
W. D. Gubler ◽  
J. Luque
Keyword(s):  
Dna Sequences ◽  
Aerial Mycelium ◽  
Width Ratio ◽  
Optimum Growth ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Grapevine Decline ◽  
San Luis ◽  
Length Width ◽  
Dark Green

Grapevine decline symptoms in California include dead spurs and cordon and trunk dieback due to canker formation in the vascular tissue. Seven Botryosphaeria spp. are known to be associated with grapevine cankers in California, viz. Botryosphaeria australis, B. dothidea, B. lutea, B. obtusa, B. parva, B. rhodina, and B. stevensii (3). Recently, B. iberica and B. viticola also were isolated from grapevine cankers in a field survey that was conducted throughout California. Identification was based on morphological comparisons along with DNA analyses with previously identified isolates from Spain (1,2): B. iberica (CBS115035, ex-type) and B. viticola (CBS117006 and CBS117009, ex-type). DNA sequences of the rDNA internal transcribed spacer region (ITSI-5.8S-ITS2), part of the β-tubulin gene (BT2), and part of the translation elongation factor 1-α gene (EF1-α) from B. iberica and B. viticola isolates from California were amplified using primers ITS4/ITS5, Bt2a/Bt2b, and EF-728F/EF-986R, respectively. All DNA sequences of B. iberica and B. viticola from California showed 99 to 100% homology with those previously identified and deposited in GenBank. B. iberica, isolated from grapevine cankers from San Luis Obispo County (central coast), formed colonies on potato dextrose agar (PDA) that were dark green with aerial mycelium, optimum growth at 20 to 25°C, and formed pycnidia after 15 days of incubation at 25°C. Conidia were brown, one-septate, oblong to ovoid with a rounded apex, and measured (20.1-) 22.5 to 23.5 (-27.1) × (8.1) 9.3 to 9.8 (-11.2) μm, length/width ratio = 2.4 (n = 60). B. viticola, isolated from grapevine cankers in Sonoma (north coast), San Luis Obispo, Santa Barbara (south coast), Riverside (southern California), and Yolo (Sacramento Valley) counties, formed colonies on PDA that were dark green to grayish with aerial mycelium, optimum growth at 25°C, and formed pycnidia after 2 weeks. Conidia were brown, one-septate, oval to oblong, and measured (16.6-) 19.3 to 20.3 (-23.5) × (8.1) 9.3 to 9.6 (-11.1) μm, length/width ratio = 2.1 (n = 60). Two isolates of each species were used to complete pathogenicity tests (B. iberica: ATCC MYA-4110, ATCC MYA-4111; B. viticola: ATCC MYA-4115, ATCC MYA-4116). Ten fresh pruning wounds on 15-year-old cv. Zinfandel vines were inoculated per isolate using 50 μl of a 5 × 106 conidia per ml suspension. Twenty control pruning wounds were inoculated with the same amount of sterile water. Twelve months after inoculation, all wood inoculated with B. iberica and B. viticola showed internal necrosis extending 35 to 50 and 30 to 35 mm from the point of inoculation, respectively. Necrosis and extent of vascular discoloration in infected wounds was significantly greater (P < 0.05) than in control inoculations (6.5 mm). B. iberica and B. viticola were reisolated from the necrotic region surrounding all inoculation sites. Representative isolates of B. iberica and B. viticola from California were deposited at the American Type Culture Collection (B. iberica: MYA-4110, MYA-4111; B. viticola: MYA-4112 to MYA-4116). Sequences from the studied DNA regions of all isolates were deposited at GenBank. To our knowledge, this is the first report implicating either species as a cause of grapevine decline in California and B. iberica as a pathogen of Vitis vinifera anywhere in the world. References: (1) J. Luque et al. Mycologia 97:1111, 2005. (2) A. J. L. Phillips et al. Mycologia 97:513, 2005. (3) J. R. Úrbez-Torres et al. Plant Dis. 90:1490, 2006.

scholarly journals First Report of Neofusicoccum parvum Associated with Grapevine Trunk Diseases in Croatia

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1656-1656 ◽  
Author(s):  
J. Kaliternam ◽  
T. Milicevic ◽  
D. Bencic ◽  
B. Duralija
Keyword(s):  
Aerial Mycelium ◽  
Morphological Data ◽  
Width Ratio ◽  
Vitis Vinifera L ◽  
Internal Transcribed Spacer Region ◽  
Foeniculum Vulgare ◽  
Neofusicoccum Parvum ◽  
First Report ◽  
Grapevine Trunk Diseases ◽  
Trunk Diseases

In September 2010, during survey of diseased grapevines (Vitis vinifera L.) in vineyards at localities Zmajevac (BZ), Orahovica (SO), Cilipi (KC), and Novalja (PN), symptoms characteristic of grapevine trunk diseases (GTD) (3) were observed, showing on cross-sectioned cordons and trunks as brown, wedge-shaped perennial cankers and/or dark streaking of the wood. In Croatia, these symptoms were traditionally associated with Eutypa Tul. & C.Tul. and with fungi from Diaporthaceae (2). From affected grapevines (cvs. Grasevina, Pinot bijeli, Malvazija dubrovacka, and Gegic), samples of symptomatic cordons and trunks were collected (n ≥ 35). To isolate the causal agents from the samples, woodchips of symptomatic tissue, surface-sterilized in 2% sodium hypochlorite for 2 min, were placed on potato dextrose agar amended with streptomycin sulphate (50 μg/ml) and incubated for 7 days at 25°C in darkness. A percentage of samples (72, 15, 27, and 54% from BZ, SO, KC, and PN, respectively) yielded fungal colonies with abundant aerial mycelium, initially white, but turning olivaceous grey after 5 days. From these colonies, monohyphal isolates were obtained and pycnidial formation stimulated by cultivation on 2% water agar with stems of plant species Foeniculum vulgare Mill. at 25°C under diffuse light for 3 weeks. Pycnidia contained conidia that were hyaline, unicellular, ellipsoid with round apices and truncated bases, and thin walled with smooth surface. Dimensions of conidia (n ≥ 50) were (12.8) 15.3 ± 1.4 (17.6) × (5.4) 6.3 ± 0.8 (7.6) μm, with length/width ratio (2.0) 2.5 ± 0.5 (3.2). Based on morphological data, species Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips was suspected (1). For molecular identification, isolates BZ330, SO334, KC342, and PN121 were used for PCR to amplify internal transcribed spacer region and partial translation elongation factor 1-alpha gene, using primers ITS5/ITS4 and EF1-728F/EF1-986R, respectively. Obtained sequences were shown to be identical between the four isolates (GenBank: KF296318, KF296319) and when compared with sequences for reference N. parvum isolate CMW9080 (AY236942, AY236887) they showed >99% homology, confirming the isolates as species N. parvum. Pathogenicity tests were done by inoculation of detached green shoots (GS) and lignified canes (LC) (n = 5) of grapevine cv. Skrlet by either mycelial plugs of the same four isolates, or sterile agar plugs for the controls. Inoculated GS were kept in flasks with sterile water in a glasshouse for 10 days, and LC in humid dark chambers for 30 days, at 25°C. Resulting vascular necrosis measured 62 to 81 mm (GS) and 215 to 246 mm (LC), but was absent on controls. Koch's postulates were satisfied by successful reisolation of N. parvum only from plants inoculated with mycelial plugs. N. parvum has been recognized as a serious grapevine pathogen, causing similar symptoms worldwide (3). To our knowledge, this is the first report of N. parvum associated with GTD in Croatia, and due to its relatively high incidence at surveyed localities, it could present considerable threat, particularly for neighboring vine growing regions. Diplodia seriata De Not., a weak pathogen (3), was also identified from a percentage of samples in this survey. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) J. Kaliterna et al. Arh. Hig. Rada Toksikol. 63:471, 2012. (3) J. R. Urbez-Torres. Phytopathol. Mediterr. 50(Suppl.):S5, 2011.

scholarly journals First Report of Cylindrocarpon pauciseptatum Associated with Grapevine Decline from Castilla y León, Spain

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 361-361 ◽  
Author(s):  
M. T. Martin ◽  
L. Martin ◽  
M. J. Cuesta ◽  
P. García-Benavides
Keyword(s):  
Morphological Characteristics ◽  
Vascular Lesions ◽  
Width Ratio ◽  
Morphological Identification ◽  
Malt Extract ◽  
Internal Transcribed Spacer Region ◽  
Current Season ◽  
First Report ◽  
Grapevine Decline ◽  
Agar Plug

During a survey for grapevine decline, 10 young grapevines (cvs. Tempranillo and Verdejo) with low vigor and little foliage were collected between June 2008 and August 2009. Small pieces of vascular and brown wood were placed onto malt extract agar supplemented with 0.25 g/liter of chloramphenicol and incubated at 25°C. Fifteen resulting colonies were transferred to potato dextrose agar in petri dishes (90 mm). Colonies with white mycelium covered the dishes after 10 days of incubation at 25°C in darkness; mycelium gradually became yellowish with some brownish aspect. Macroconida were predominantly three septate (40 to 45 to 50 × 8.6 to 9 to 9.5 μm with a length and width ratio of 4.7 to 5 to 5.4), straight, and cylindrical with both ends broadly rounded. Chlamydospora and ovoidal microconidia were observed on synthetic nutrient-poor agar (1). Cylindrocarpon pauciseptatum was not easy to distinguish from other Cylindrocarpon species based on morphological characteristics. Ribosomal internal transcribed spacer region sequences of single-spore cultures confirmed the morphological identification and revealed 100% genetic identity with other isolates of C. pauciceptatum present in GenBank (EF607090), a sequence of the fragment was deposited with Accession No. EU983277. Pathogenicity tests were conducted with two isolates. The inoculations were done on 110R rootstock wood of four different young plants and 15 detached canes of current-season growth (cv. Tempranillo). Plants were inoculated with an agar plug containing C. pauciceptatum; controls were treated with agar only. Grapevines were maintained in a greenhouse at 20 to 25°C. After 3 to 4 months, C. pauciceptatum was reisolated from brown tissues and internal vascular lesions in 45% of inoculated samples, fulfilling Koch's postulates. Control plants were asymptomatic and C. pauciceptatum was not recovered. To our knowledge, this is the first report implicating C. pauciceptatum as a cause of grapevine black foot disease in Spain with potentially significant impact on grapevine nurseries. Reference: (1) H. J. Schroers et al. Mycol. Res. 112:82, 2008.

scholarly journals First Report of Phytophthora nicotianae on German Statice in Bulgaria

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 842-842
Author(s):  
S. G. Bobev ◽  
K. Van Poucke ◽  
M. Maes
Keyword(s):  
Average Length ◽  
Aerial Mycelium ◽  
Its Region ◽  
Soil Extract ◽  
Phytophthora Nicotianae ◽  
Maximum Temperature ◽  
Width Ratio ◽  
First Report ◽  
Initial Symptoms ◽  
Length Width

In June of 2008, rapidly developing necrotic symptoms were observed on 2-month-old seedlings of German statice (Goniolimon tataricum, synonym Limonium tataricum) that were started from field-collected seeds and grown in plastic pots under greenhouse conditions in the region of Plovdiv, Bulgaria. Initial symptoms were slight yellowing and wilting of single, lower leaves. Subsequently, necrosis affected several petioles and stem bases, which led to complete plant collapse. Isolations from symptomatic petioles, stem bases, and main roots were performed on potato dextrose agar (PDA) and corn meal agar (CMA). When incubated at 24 to 25°C, white, round, arachnoid colonies with fluffy aerial mycelium developed on the PDA isolation plates, whereas the mycelium was less dense on CMA. Sporangia were formed sporadically when cultures were maintained on V8 medium and formed abundantly in nonsterile soil extract after 1 to 2 days of incubation at 20°C. Sporangia were noncaducous, ovoid to spherical, semipapillate (sometimes with two papilla), measured 47.5 to 65 μm (average 53.6 μm) × 35 to 53.5 μm (average 42.9 μm) with an average length/width ratio of 1.25:1. Terminal and intercalary chlamydospores (25 to 48 μm in diameter; average 37 μm) and hyphal swellings were also present. Maximum temperature for growth was 36°C. Pathogenicity of the presumable Phytophthora nicotianae (1) isolate was proved by placing 5-mm-diameter mycelial plugs of 7-day-old cultures grown on V8 medium onto the petiole bases of three 3-month-old G. tataricum plantlets. Each inoculation site was first wiped with 70% ethanol and then scalpel wounded. Sterile V8 plugs were used as controls and all inoculated sites were wrapped with Parafilm. The plantlets were incubated at room temperature (22 to 26°C) and the first necrotic lesions around the mycelial plugs appeared 5 to 7 days after inoculation. Plantlets collapsed approximately 2 weeks later. Additionally, three plantlets were inoculated under the same conditions by watering their stem bases with a 15-ml suspension of mycelium and spores obtained by washing 2-week-old V8 cultures with sterile distilled water. Within a 4-week period, the plantlets died due to a stem base and petiole necrosis. Simultaneously, the pathogen was reisolated from all inoculated samples but not from any control plants that were symptomless. The internal transcribed spacer (ITS) region of mycelial DNA was amplified (ITS6 and ITS4 primers) and the PCR product was sequenced (GenBank Accession No. FJ410333). BLAST analysis showed 100% homology with P. nicotianae. To our knowledge, this is the first report of P. nicotianae on G. tataricum in Bulgaria and one of the few reports from Europe of Phytophthora invasion of related Limonium species (2,3). References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) E. Ilieva et al. Plant Dis. 85:445, 2001. (3) A. Pane et al. J. Plant Pathol. 87:301, 2005.

scholarly journals The First Report of Downy Mildew Caused by Peronospora belbahrii on Sweet Basil in Greenhouses in the Czech Republic

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1579-1579 ◽  
Author(s):  
I. Šafránková ◽  
L. Holková
Keyword(s):  
Czech Republic ◽  
Downy Mildew ◽  
Width Ratio ◽  
Specific Sequence ◽  
The Czech Republic ◽  
First Report ◽  
Sweet Basil ◽  
Potted Plants ◽  
Length Width ◽  
Necrotic Spots

Sweet basil (Ocimum basilicum L.) is an aromatic plant that is cultivated as a pot plant in greenhouses or in fields in the Czech Republic. The plants are intended for direct consumption or for drying. In April of 2012, the first large chlorotic from the middle necrotic spots occurred gradually on leaves of pot plants O. basilicum cv. Genovese in greenhouses in Central Bohemia. The characteristic gray to brown furry growth of downy mildew appeared on abaxial surfaces of leaves in the place of chlorotic spots within 3 to 4 days. The infested leaves fell off in the late stages of pathogenesis. The infestation gradually manifested itself in ever-younger plants and in July, cotyledons and possibly the first true leaves were already heavily infected and damaged and these plants rapidly died. The plant damage reached 80 to 100%, so it was necessary to stop growing the plants in the greenhouse at the end of July. The causal agent was isolated and identified as Peronospora belbahrii Thines by means of morphological and molecular characters (2,3). Conidiophores were hyaline, straight, monopodial, 280 to 460 μm, branched three to five times, ended with two slightly curved branchlets with a single conidia on each branchled tip. The longer branchlets measured 13 to 24 μm (average 18.2 μm), the shorter one 4 to 15 μm (average 9.7 μm). Conidia were rounded or slightly ovoid, from brownish to dark brownish, measured 22 to 31 × 20 to 28 μm (length/width ratio 1.2). A pathogen-specific sequence was detected with the help of the pathogen ITS rDNA specific primers in symptomatic leaves (1). DNA from plant tissues was isolated using the DNeasy plant Mini Kit (Qiagen, Germany) following the standard protocol. PCR was performed using KAPA2G Robust HotStar kit (Kapa Biosystems, United States) according to the conditions recommended in Belbahri et al. (1). The specific products were visualized by electrophoresis through 1.5% agarose gels. Leaves of 20-day-old potted plants O. basilicum ‘Genovese’ were inoculated by spraying with 5 × 105 conidia/ml of the pathogen. Each pot contained 10 plants. Sterilized distilled water was applied to control plants. Plants were covered with polyethylene bags during the entire incubation period to maintain high humidity, and kept at a temperature of 22 to 24°C. Typical disease symptoms appeared on leaves 5 to 9 days after inoculation. Control plants were symptomless. P. belbahrii was re-isolated from the lesions of inoculated plants, thus fulfilling Koch's postulates. Downy mildew on sweet basil was reported in countries in Africa, Europe, and South and North America (4). To our knowledge, this is the first report of downy mildew on sweet basil in the Czech Republic. References: (1) L. Belbahri et al. Mycol. Res. 109:1276, 2005. (2) Y.-J. Choi et al. Mycol. Res. 113:1340, 2009. (3) M. Thines et al. Mycol. Res. 113:532, 2009. (4) C. A. Wyenandt et al. HortScience 45:1416, 2010.

scholarly journals First report of Diaporthe ueckerae causing stem canker on soybean (Glycine max L.) in Colombia

Plant Disease ◽  
2021 ◽  
Author(s):  
Nathali López-Cardona ◽  
YUDY ALEJANDRA GUEVARA ◽  
Lederson Gañán-Betancur ◽  
Carol Viviana Amaya Gomez
Keyword(s):  
Management Strategies ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Stem Canker ◽  
Growth Stages ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Glycine Max L ◽  
Soybean Plants

In October 2018, soybean plants displaying elongated black to reddish-brown lesions on stems were observed in a field planted to the cv. BRS Serena in the locality of Puerto López (Meta, Colombia), with 20% incidence of diseased plants. Symptomatic stems were collected from five plants, and small pieces (∼5 mm2) were surface sterilized, plated on potato dextrose agar (PDA) and incubated for 2 weeks at 25°C in darkness. Three fungal isolates with similar morphology were obtained, i.e., by subculturing single hyphal tips, and their colonies on PDA were grayish-white, fluffy, with aerial mycelium, dark colored substrate mycelium, and produced circular black stroma. Pycnidia were globose, black, occurred as clusters, embedded in tissue, erumpent at maturity, with an elongated neck, and often had yellowish conidial cirrus extruding from the ostiole. Alpha conidia were observed for all isolates after 30 days growth on sterile soybean stem pieces (5 cm) on water agar, under 25ºC and 12 h light/12h darkness photoperiod. Alpha conidia (n = 50) measured 6.0 – 7.0 µm (6.4 ± 0.4 µm) × 2.0 – 3.0 µm (2.5± 0.4 µm), were aseptate, hyaline, smooth, ellipsoidal, often biguttulate, with subtruncate base. Beta conidia were not observed. Observed morphological characteristics of these isolates were similar to those reported in Diaporthe spp. by Udayanga et al. (2015). DNA from each fungal isolate was used to sequence the internal transcribed spacer region (ITS), and the translation elongation factor 1-α (TEF1) gene, using the primer pairs ITS5/ITS4 (White et al. 1990) and EF1-728F/EF1- 986R (Carbone & Kohn, 1999), respectively. Results from an NCBI-BLASTn, revealed that the ITS sequences of the three isolates (GenBank accessions MW566593 to MW566595) had 98% (581/584 bp) identity with D. miriciae strain BRIP 54736j (NR_147535.1), whereas the TEF1 sequences (GenBank accessions MW597410 to MW597412) had 97 to 100% (330-339/339 bp) identity with D. ueckerae strain FAU656 (KJ590747). The species Diaporthe miriciae R.G. Shivas, S.M. Thomps. & Y.P. Tan, and Diaporthe ueckerae Udayanga & Castl. are synonymous, with the latter taking the nomenclature priority (Gao et al. 2016). According to a multilocus phylogenetic analysis, by maximum likelihood, the three isolates clustered together in a clade with reference type strains of D. ueckerae (Udayanga et al. 2015). Soybean plants cv. BRS Serena (growth stages V3 to V4) were used to verify the pathogenicity of each isolate using a toothpick inoculation method (Mena et al. 2020). A single toothpick colonized by D. ueckerae was inserted directly into the stem of each plant (10 plants per isolate) approximately 1 cm below the first trifoliate node. Noncolonized sterile toothpicks, inserted in 10 soybean plants served as the non-inoculated control. Plants were arbitrarily distributed inside a glasshouse, and incubated at high relative humidity (>90% HR). After 15 days, inoculated plants showed elongated reddish-brown necrosis at the inoculated sites, that were similar to symptoms observed in the field. Non-inoculated control plants were asymptomatic. Fungal cultures recovered from symptomatic stems were morphologically identical to the original isolates. This is the first report of soybean stem canker caused by D. ueckerae in Colombia. Due to the economic importance of this disease elsewhere (Backman et al. 1985; Mena et al. 2020), further research on disease management strategies to mitigate potential crop losses is warranted.

scholarly journals First Report of Lasiodiplodia theobromae Causing Dieback of Aquilaria sinensis in Taiwan

Plant Disease ◽  
2013 ◽  
Vol 97 (5) ◽  
pp. 690-690 ◽  
Author(s):  
M.-C. Fan ◽  
H.-C. Yeh ◽  
C.-F. Hong
Keyword(s):  
Uv Light ◽  
Aerial Mycelium ◽  
Molecular Characteristics ◽  
Width Ratio ◽  
Sodium Hypochlorite Solution ◽  
Aquilaria Sinensis ◽  
Lasiodiplodia Theobromae ◽  
First Report ◽  
Tree Survival ◽  
Pathogenicity Tests

Incense trees (Aquilaria sinensis (Lour.) Gilg) belong to a plant family used for alternative medicine in China and the production of wood. In the summer of 2012, at a nursery in Niaosong district, Kaohsiung City, Taiwan, more than 30% of a total of 400 incense trees had dieback symptoms on twigs with leaves attached, leading to eventual death of the entire plant. Symptomatic twigs and trunk pieces from six trees were collected and discolored tissues were excised, surface sterilized in 0.5% sodium hypochlorite solution, rinsed in sterilized distilled water, dried on sterilized filter paper, and then placed in petri dishes containing 2% water agar (WA). The dishes were incubated at room temperature for 1 to 2 days to obtain fungal strains from diseased tissues. The hyphal tips from developing fungal colonies were transferred to potato dextrose agar (PDA, Difco) dishes and placed under UV light (12 h/day) at 30°C. The purified colonies were used as inoculum in the pathogenicity tests. Pathogenicity tests were performed on 2-month-old A. sinensis seedlings, each treatment had three plants. Each plant was wounded by removing bark of the twigs with a disinfected scalpel enough to place a mycelium plug (about 5 × 10 mm2) of 7-day-old fungal isolate on the wound. The inoculated area was wrapped with a wet paper towel and Parafilm. Control plants were treated with PDA plugs. The symptoms described above were observed on inoculated plants 4 to 8 days after inoculation whereas control plants did not show symptoms. Diseased twigs were cut and placed in a moist chamber 21 days after inoculation and conidia oozing from pycnidia were observed. The same fungal pathogen was reisolated from inoculated plants, but not from the control. To identify the pathogen, the fungus was cultured as described above. The colonies were initially white with green to gray aerial mycelium after 5 to 6 days and eventually turned darker. Immature conidia were hyaline and one-celled, but mature conidia were dark brown, two-celled, thin-walled, and oval-shaped with longitudinal striations. The average size of 100 conidia was 25.23 ± 1.97 × 13.09 ± 0.99 μm with a length/width ratio of 1.92. For the molecular identification, the internal transcribed spacer (ITS) region of ribosomal DNA was PCR amplified with primers ITS1 and ITS4 (2) and sequenced. The sequences were deposited in GenBank (Accession No. JX945583) and showed 99% identity to Lasiodiplodia theobromae (HM346871, GQ469929, and HQ315840). Hence, both morphological and molecular characteristics confirmed the pathogen as L. theobromae (Pat.) Griffon & Maubl (1). To the best of our knowledge, this is the first report of L. theobromae causing dieback on Incense tree. This disease threatens tree survival and may decrease the income of growers. References: (1) W. H. Ko et al. Plant Dis. 88:1383, 2004. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

scholarly journals First Report of Persian Buttercup Downy Mildew Caused by Peronospora sp. in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 422-422
Author(s):  
Y. J. Choi ◽  
K. S. Han ◽  
J. H. Park ◽  
H. D. Shin
Keyword(s):  
Downy Mildew ◽  
The United States ◽  
Commercial Production ◽  
Ornamental Plant ◽  
Width Ratio ◽  
Sterile Water ◽  
First Report ◽  
Ranunculus Asiaticus ◽  
Length Width ◽  
Ficaria Verna

Persian buttercup (Ranunculus asiaticus L.) is an ornamental plant cultivated mainly in the countries surrounding the Mediterranean Sea, and has recently become popular in Korea. During March and April 2012, Persian buttercups ‘Elegance’ showing symptoms of downy mildew were found in plastic greenhouses in Hwaseong City of Korea. Infection resulted in chlorotic leaves with a dark greyish and dense fungal-like growth on the lower surfaces, and finally led to necrosis of the lesions. A sample was deposited in the Korea University herbarium (KUS-F26431). Conidiophores emerging from stomata were hyaline, 250 to 550 × 7 to 15 μm, straight, and dichotomously branched in 6 to 8 orders. Ultimate branchlets were mostly in pairs, slightly curved, 5 to 15 μm long, and had obtuse tips. Conidia were brown, broadly ellipsoidal to subglobose or ellipsoidal, often pedicellated, and measured 24 to 33 × 20 to 27 μm with a length/width ratio of 1.15 to 1.30. Fourteen species of Peronospora have previously been described on the genus Ranunculus (2), of which P. ficariae was mostly considered the causal agent of downy mildew on Persian buttercup (1,3). The present Korean accession is morphologically distinct from P. ficariae on R. ficaria (a synonym of Ficaria verna) by somewhat larger conidia with often pedicel-like ends. The nuclear ribosomal LSU and ITS regions were PCR-amplified and sequenced as described in Göker et al. (4), and the resulting sequences deposited in GenBank (Accession Nos. KC111207 and JX465737, respectively). A comparison with the GenBank sequences revealed that the present Korean pathogen differed from P. ficariae on R. ficaria at 10 of 688 characters (about 1.5%) in LSU (AF119600) and 11 of 802 characters (about 1.4%) in ITS sequences (unpublished sequence). In addition, the ITS sequence exhibits a dissimilarity of 1.5 to 2.0% from three species of Peronospora parasitic on Ranunculus; P. alpicola on R. aconitifolius (AY198271), P. illyrica on R. illyricus (AY198268), and P. ranunculi on R. acris (AY198267) and R. recurvatus (AY198269). Based on morphological and molecular distinction between P. ficariae and the Korean pathogen, we provisionally indicate this pathogen as an undetermined species of Peronospora. Pathogenicity was demonstrated by shaking diseased leaves onto the leaves of healthy Persian buttercup ‘Elegance’, incubating the plants in a dew chamber at 20°C for 24 h, and then maintaining them in a greenhouse (20 to 24°C and relative humidity 60 to 80%). After 3 to 4 days, inoculated plants developed downy mildew symptoms, from which an identical fungus was observed, thus fulfilling Koch's postulates. Control plants treated with sterile water did not develop any symptoms of downy mildew. To our knowledge, this is the first report of a downy mildew on Persian buttercup in Asia, although this disease has been found in other continental countries, such as Italy (1), New Zealand, South Africa, and the United States (3). The presence of a downy mildew on Persian buttercup in Asia can be considered as a potentially new and serious threat to commercial production of this ornamental plant. References: (1) E. Buonocore and R. Areddia. Informatore Fitopatologico 49:25, 1999. (2) O. Constantinescu. Thunbergia 15:1, 1991. (3) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved August 4, 2012. (4) M. Göker et al. Mycol. Res. 113:308, 2009.

scholarly journals Occurrence of Botryosphaeria obtusa, B. dothidea, and B. parva Associated with Grapevine Trunk Diseases in Castilla y León Region, Spain

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 835-835 ◽  
Author(s):  
J. R. Úrbez-Torres ◽  
W. D. Gubler ◽  
H. Peláez ◽  
Y. Santiago ◽  
C. Martín ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Common Disease ◽  
Internal Transcribed Spacer Region ◽  
Grapevine Trunk Diseases ◽  
Eutypa Dieback ◽  
Castilla Y Leon ◽  
Pure Cultures ◽  
Dark Green ◽  
Production Areas

Between 2000 and 2004, 176 vineyards were surveyed for disease symptoms throughout the main grapevine-production areas of Bierzo, Cigales, Ribera del Duero, Rueda, and Toro in the Castilla y León region of Spain. Symptoms resembling Eutypa dieback, such as stunted chlorotic shoots, deformed leaves with necrotic areas, and typical wedge-shaped cankers in the wood, were observed in 80% of surveyed vineyards. The second most common disease observed was esca. The mild form of esca, interveinal chlorosis or reddened patterns on the leaves, was observed in 35% of surveyed vineyards. Severe esca symptoms that include sudden defoliation of some or all parts of the vine followed by shriveling of fruit clusters were observed in vineyards during very hot and dry summer periods. Wood from vines with esca was yellowish, soft, and often partially or completely surrounded by necrotic wood. Black vascular streaking in the wood was also observed in some vines with esca. Samples of wood from vines with symptoms of Eutypa dieback or esca were collected from different cultivars (Tempranillo, Cabernet Sauvignon, Mencía, Garnacha, Viura, and Verdejo). Small pieces of symptomatic wood were placed on 4% potato dextrose agar amended with tetracycline hydrochloride (0.01%) (PDA-tet) and incubated at room temperature. Pure cultures were obtained by excising hyphal tips and transferring to PDA-tet. Species of Botryosphaeria were most frequently isolated from wedge-shaped cankers as well as from wood with necrosis or black vascular streaking. Botryosphaeria spp. also were isolated from the soft yellowish wood, however, Fomitiporia punctata, Stereum hirsutum, and Phaeoacremonium spp. were the most common fungi associated with this symptom. On the basis of morphological characteristics in culture (1), three species were isolated (B. obtusa, B. dothidea, and B. parva). Colonies of B. obtusa were green to dark green with moderate aerial mycelium. Pycnidia developed after 6 days and conidia (n = 50) measured 19 to 27 × 9 to 17 μm and were hyaline and light brown, becoming dark brown when mature, mostly aseptate, and rounded in shape. Colonies of B. dothidea were white, becoming dark green with age and with copious aerial mycelium. Pycnidia started to develop after 10 days, and conidia measured 17 to 31 × 4 to 8 μm, were hyaline, aseptate, and fusiform in shape. Colonies of B. parva were similar in appearance to those of B. dothidea but pycnidia developed after 5 weeks. Conidia measured 11 to 21 × 4 to 9 μm, were hyaline when immature, becoming light brown with two septa with age, and ellipsoidal in shape. Identity of the three Botryosphaeria species was confirmed by comparing morphology with growth of the following identified California isolates: B. obtusa (UCD352Mo and UCD666Na), B. dothidea (UCD1066So), and B. parva (UCD642So) and by comparing sequences of the internal transcribed spacer region (ITSI-5.8S-ITS2) rDNA, and a partial sequence of the β-tubulin gene (BT2) of our isolates with those of previously identified and sequenced isolates deposited in GenBank. Sequences of B. obtusa (UCD343Spa, UCD461Spa, UCD468Spa, and UCD621Spa), B. dothidea (UCD303Spa), and B. parva (UCD577Spa and UCD578Spa) were deposited in GenBank. To our knowledge, this is the first report of B. obtusa, B. dothidea, and B. parva on grapevines in the Castilla y León region in Spain. Reference: (1) A. J. L. Phillips. Phytopathol. Mediterr. 41:3, 2002.

scholarly journals First Report of Stem Dieback Caused by Lasiodiplodia parva on Styphnolobium japonicum in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Ziwei Zhou ◽  
Cuiping Wu ◽  
Jing Yang ◽  
Jieying Xu ◽  
Zhenpeng Chen ◽  
...  
Keyword(s):  
Robinia Pseudoacacia ◽  
Elongation Factor ◽  
Aerial Mycelium ◽  
Random Trees ◽  
Molecular Evidence ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
Accurate Identification ◽  
Individual Tree ◽  
First Report

Styphnolobium japonicum (L.) Schott is a variant of Robinia pseudoacacia and is a popular Asian tree widely used in traditional medicine. From March 2019 to 2021, a disease was found on the campus of Nanjing Forestry University and several landscape sites of Xuanwuhu Park, causing dieback. Most of the trees (approximately 40%) have rotted branches. On average, 60% of the branches per individual tree were affected by this disease. The initial round lesions were grayish brown. In the later stage, the whole branch becomes black and produces spherical fruiting bodies . Twenty diseased branches were picked from three random trees. Small tissues (3-4mm²) were surface-sterilized in 75% ethanol for 30 s followed by 1% NaClO for 90 s and placed on potato dextrose agar (PDA), and incubated in the dark at 25°C for three days. Hyphae were visibly emerged from 70% of the samples. Three representative isolates (Lth-soj1, Lth-soj2, and Lth-soj3) were obtained and deposited in China’s Forestry Culture Collection Center (Lth-soj1: cfcc55896, Lth-soj2: cfcc55897, Lth-soj3: cfcc55898). The colonies of three isolates on PDA were fast growing and white, which turned grey to dark grey after 3 days of incubation in the dark at 28°C . Two-weeks old colonies were black and fluffy on PDA, with abundant aerial mycelium, and the reverse side too was black in color. The fungus usually grew well on PDA and produced pycnidia and conidia within 3–4 weeks. Conidia were initially hyaline and aseptate, ellipsoid to ovoid, with granular content, apex broadly rounded, remaining hyaline and later becoming dark brown, one septate, thick walled, base truncate or round and longitudinally striate. The conidia (n=30) of a representative isolate（Lth-soj1）, measured 24.3 ± 0.3 μm in length and 13.3 ± 0.5 μm in width . The morphological characters of the three isolates matched those of Lasiodiplodia parva(Alves et al. 2008). For accurate identification, the DNA of the three isolates was extracted. The internal transcribed spacer region (ITS), translation elongation factor (EF1-α), and β-tubulin 2 (TUB2) genes were amplified using the primer pairs ITS1/ITS4 , EF1-728F/EF1-986R, and Bt2a/Bt2b , respectively. The sequences were deposited in GenBank under accession numbers MZ613154, MZ643245 and MZ643242 for Lth-soj1, MZ613155, MZ643246 and MZ643244 for Lth-soj2, and MZ613157, MZ643247 and MZ643243 for Lth-soj3. The ITS, EF1-α, and TUB2 sequences of isolate Lth-soj1 (GenBank Acc. No. MZ613154, MZ643245, MZ643242) were 100% (519/519 nt), 99.34% (299/301 nt), and 99.77% (436/437 nt) identical to those of MZ182360, EF622063, and MK294119, respectively. Interspecific differences were observed in a maximum-likelihood tree of Lasiodiplodia species using the concatenated dataset. Based on the morphological and molecular evidence, the isolates were identified as L. parva. The pathogenicity of three isolates were tested on potted three-year-old seedlings (100-cm tall) of S. japonicum maintained in a greenhouse. Healthy stems were wounded with a sterile needle then inoculated with 10 µL of conidial suspension. Control plants were treated with ddH2O. In total, 12 seedlings were inoculated including three controls. Three seedlings per isolate and 10 stems per seedling were used for each treatment. The plants were kept inside sealed polythene bags for the first 24 h and sterilized H2O was sprayed into the bags twice a day to maintain humidity and kept in a greenhouse at the day/night temperatures at 25/16°C. Within seven days, all the inoculated points showed lesions similar to those observed in field and the conidiomatas growing on the surface of the branches, whereas controls were asymptomatic . The infection rate of each of the three isolates was 100%. The strain was re-isolated from the lesions and sequenced as L.parva, whereas not from control stems. This is the first report of L. parva causing rotten branches of S. japonicum in China and the worldwide. These data will help to develop effective strategies for managing this newly emerging disease.

scholarly journals First Report of Powdery Mildew Caused by Podosphaera spiraeae on Japanese Spiraea in China

Plant Disease ◽  
2014 ◽  
Vol 98 (4) ◽  
pp. 571-571 ◽  
Author(s):  
H. H. Xing ◽  
C. Liang ◽  
S. E. Cho ◽  
H. D. Shin
Keyword(s):  
Powdery Mildew ◽  
Width Ratio ◽  
Pathogenicity Test ◽  
Voucher Specimen ◽  
First Report ◽  
Powdery Mildews ◽  
White Spots ◽  
Length Width ◽  
Qingdao City ◽  
Leaf Distortion

Japanese spiraea (Spiraea japonica L.f.), belonging to Rosaceae, is widely planted for its ornamental value in China. Since July 2011, powdery mildew infections on leaves and stems of Japanese spiraea have been noticed in some parks and gardens of Chengyang District in Qingdao City, China (GPS coordinates 36°31′04.22″ N, 120°39′41.92″ E). Symptoms first appeared as white spots covered with mycelium on both side of the leaves and young stems. As the disease progressed, abundant mycelial growth covered the whole shoots and caused growth reduction and leaf distortion with or without reddening. A voucher specimen was deposited in the herbarium of Qingdao Agricultural University (Accession No. HMQAU13013). Hyphae were flexuous to straight, branched, septate, 5 to 7 μm wide, and had nipple-shaped appressoria. Conidiophores arising from the upper surface of hyphal cells produced 2 to 5 immature conidia in chains with a crenate outline. Foot-cells of conidiophores were straight, 60 to 125 × 7 to 9 μm, and followed by 1 to 2 shorter cells. Conidia were ellipsoid-ovoid to doliiform, measured 25 to 32 × 12 to 15 μm with a length/width ratio of 1.8 to 2.6, and had distinct fibrosin bodies. Chasmothecia were not found. The structures and measurements were compatible with the anamorphic state of Podosphaera spiraeae (Sawada) U. Braun & S. Takam. as described before (1). The identity of HMQAU13013 was further confirmed by analysis of nucleotide sequences of the internal transcribed spacer (ITS) regions amplified using the primers ITS1/ITS4 (4). The resulting 564-bp sequence was deposited in GenBank (Accession No. KF500426). A GenBank BLAST search of complete ITS sequence showed 100% identity with that of P. spiraeae on S. cantoniensis (AB525940). A pathogenicity test was conducted through inoculation by gently pressing a diseased leaf onto five healthy leaves of a potted Japanese spiraea. Five non-inoculated leaves served as controls. The plants were maintained in a greenhouse at 22°C. Inoculated leaves developed typical symptoms of powdery mildew after 5 days, but the non-inoculated leaves remained symptomless. The fungus presented on the inoculated plant was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. Powdery mildew of S. japonica caused by P. spiraeae has been recorded in Japan, Poland, and Switzerland (2,3). To our knowledge, this is the first report of powdery mildew caused by P. spiraeae on Japanese spiraea in China. 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, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ September 10, 2013. (3) T. Kobayashi. Index of Fungi Inhabiting Woody Plants in Japan. Host, Distribution and Literature. Zenkoku-Noson-Kyoiku Kyokai Publishing Co. Ltd., Tokyo, 2007. (4) S. Matsuda and S. Takamatsu. Mol. Phylogenet. Evol. 27:314, 2003.

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