First Report of Stem Canker Caused by Neofusicoccum parvum and Pseudofusicoccum kimberleyense on Carya illinoinensis in Brazil

A field survey conducted in September 2009 at five plantations of six different cultivars of southern highbush blueberries (Vaccinium spp.) in Huelva, Spain, yielded 35 diseased plants. Diseased plants exhibited red-brown cankers and stem dieback. Blueberry cultivation in Huelva rose from 290 ha in 2007 to 777 ha in 2012, and the increase of these symptoms is of concern to producers. Stem pieces cut from the edge of lesions on infected plants were surface-disinfected with 5% sodium hypochlorite and cultured on potato dextrose agar (PDA). Based on colony characteristics on PDA, 18 colonies (one each from 18 different plants) were identified as Botryosphaeria spp. Species identities were confirmed by analysis of nucleotide sequences of the internal transcribed spacer (ITS), rDNA, and elongation factor 1-alpha (EF1-α) sequences, using ITS1-ITS4 (3) and EF728f-EF986r (2) as primer pairs, respectively. BLAST searches of GenBank showed a high similarity of the isolate sequences to the reference sequences. Molecular results confirmed these species as Neofusicoccum parvum, N. australe, and B. dothidea. N. parvum was the most prevalent (on 34% of the plants analyzed), followed by N. australe and B. dothidea (9% each). In phylogenetic analyses, isolates that clustered in the same group belonged to the same species with a high homogeneity index (>99%). One representative isolate of each species was selected for a pathogenicity assay. Amplified sequences from each selected isolate were deposited in GenBank with the following accession numbers: N. parvum, KC556958 (ITS) and KC556961 (EF); N. australe, KC556959 (ITS) and KC556962 (EF); and B. dothidea, KC556960 (ITS) and KC556963 (EF). The pathogenicity assay of these three isolates was conducted using two cultivars of southern highbush blueberry, ‘Misty’ and ‘Star.’ The isolates were cultured on acidified PDA at 25°C for 5 days. Stems of the plants were wounded at a height of 10 cm with a drill (5 mm diameter and ~4 mm deep). Six replicates per cultivar were inoculated per isolate by placing a colonized agar plug (4 to 5 mm diameter) in the hole and wrapping the stem with Parafilm. Plants treated identically with sterile agar plugs were used as controls. The plants were then maintained at 100% relative humidity for 2 h. This trial was conducted in a growth chamber at 28°C (night) and 30°C (day) with a 14-h photoperiod for 3 months. Disease was measured on a six-point scale: 0 = healthy plant; 1 = plant with a canker smaller than 3.5 cm; 2 = plant with a canker bigger than 3.5 cm; 3 = plant with one dry shoot; 4 = plant with some dry shoots; 5 = dead plant. At the end of the trial, disease was expressed as area under the disease progress curve. The results showed the N. parvum isolate to be the most aggressive, followed by the N. australe isolate. Espinoza et al. (1) also found that N. parvum showed more aggressiveness than N. australe on blueberries in Chile. B. dothidea was not pathogenic and behaved similarly to the controls (P < 0.05). Each pathogen was reisolated from all the inoculated plants, fulfilling Koch's postulates. To our knowledge, this is the first report of isolates of these pathogens, N. parvum and N. australe, causing stem canker and dieback on blueberry bushes in Spain. References: (1) J. G. Espinoza et al. Plant Dis. 93:1187, 2009. (2) A. J. L. Phillips et al. Mycol. 97:513, 2005. (3) T. J. White et al. Pages 315-322 in: PCR Protocols: a Guide to Methods and Amplifications. M. A. Innis et al., eds. Academic Press, San Diego, CA. 1990.

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First Report of Stem Canker and Dieback Caused by Neofusicoccum parvum on Plum in Guangxi, Southern China

Plant Disease ◽

10.1094/pdis-03-19-0434-pdn ◽

2019 ◽

Vol 103 (11) ◽

pp. 2952-2952

Author(s):

Qili Li ◽

Lihua Tang ◽

Wenxiu Sun ◽

Suiping Huang ◽

Tangxun Guo ◽

...

Keyword(s):

Southern China ◽

Stem Canker ◽

Neofusicoccum Parvum ◽

First Report

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First Report of Neofusicoccum parvum Associated with Stem Canker and Dieback of Asian Pear Trees in Taiwan

Plant Disease ◽

10.1094/pdis-94-8-1062b ◽

2010 ◽

Vol 94 (8) ◽

pp. 1062-1062 ◽

Cited By ~ 5

Author(s):

Y. M. Shen ◽

C. H. Chao ◽

H. L. Liu

Keyword(s):

Disease Incidence ◽

Stem Canker ◽

Storm Event ◽

Pyrus Pyrifolia ◽

Neofusicoccum Parvum ◽

First Report ◽

Asian Pear ◽

Wide Range ◽

Pathogenicity Tests ◽

Pear Trees

Asian pear tree (Pyrus pyrifolia) is an important fruit crop in Asian countries. Between the autumn of 2008 and the summer of 2009, stem cankers and twig diebacks of Asian pear trees were observed in middle Taiwan. Necrotic lesions extending from branch scars progressed with age, resulting in darkened vascular discoloration. Two cultivars of Asian pear, Taichung No. 2 grown in Changhwa County and Heng-shan grown in Taichung County, showed the same symptoms. Disease incidence increased rapidly after a rain or storm event, eventually exceeding 50%. Pycnidia on severely infected branches contained one-celled, fusiform to ellipsoidal, smooth- and thin-walled hyaline conidia, with an average length (L) and width (W) of 19.1 (11.3 to 24.8) × 5.9 (4.5 to 8.0) μm and a L/W ratio of 3.2 (n = 44). Diseased branch tissues collected from the two locations were surface sterilized in 0.6% NaOCl, rinsed with water, and plated on potato dextrose agar (PDA). Fungal isolates, recovered from both locations, produced white, aerial mycelium and became dull gray within a week after incubating plates at 25°C. To confirm the identities of the isolates, the internal transcribed spacer (ITS) regions amplified with primers ITS1/ITS4 were deposited in GenBank (Accession Nos. GU395186 and GU395187). Both of the sequences were 99% identical to that of Neofusicoccum parvum (Accession No. EU882162) over a 534-bp alignment. Thus, both morphological and molecular characters confirmed this species as N. parvum (3), reported as the anamorph of Botryosphaeria parva (1). The two voucher isolates (BCRC34605 and BCRC34609) were deposited in Bioresource Collection and Research Center, Hsinchu, Taiwan. Pathogenicity tests were first conducted on 2-year-old greenhouse-potted Asian pear trees utilizing N. parvum isolate BCRC34605. Ten plants of the cv. Mi-li were stem wounded with a 5-mm cork borer at a depth of 2 mm. Inoculation consisted of inserting 5-mm mycelium plugs of the pathogen into the wounds and wrapping with Parafilm. Sterile PDA plugs applied to an equal number of plants with the same methods served as the controls. After 2 months incubation at an average temperature of 21°C, all inoculated plants exhibited necrotic lesions with a mean length of 23.5 mm and the control plants remained symptomless. The pathogen was reisolated from lesions of inoculated stems, thus fulfilling Koch's postulates. Pathogenicity tests were repeated by inoculating the other N. parvum isolate (BCRC34609) on pear cv. Taichung No. 2, resulting in similar results. N. parvum has been reported causing dieback and canker in a wide range of fruit trees, including grapevine (4) and mango trees (2). To our knowledge, this is the first report of N. parvum associated with stem canker and dieback on Asian pear trees. In addition, this is a newly recorded species for the mycobiota of Taiwan. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) J. Javier-Alva et al. Plant Dis. 93:426, 2009. (3) S. R. Mohali et al. Fungal Divers. 25:103, 2007. (4) J. R. Urbez-Torres and W. D. Gubler. Plant Dis. 93:584, 2009.

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First Report of Stem Canker of Salsola tragus Caused by Diaporthe eres in Russia

Plant Disease ◽

10.1094/pdis-93-1-0110b ◽

2009 ◽

Vol 93 (1) ◽

pp. 110-110 ◽

Cited By ~ 1

Author(s):

T. Kolomiets ◽

Z. Mukhina ◽

T. Matveeva ◽

D. Bogomaz ◽

D. K. Berner ◽

...

Keyword(s):

United States ◽

Biological Control ◽

Biological Control Agent ◽

Aqueous Suspension ◽

Stem Canker ◽

The United States ◽

Invasive Weed ◽

Voucher Specimen ◽

First Report ◽

Stem Lesions

Salsola tragus L. (Russian thistle) is a problematic invasive weed in the western United States and a target of biological control efforts. In September of 2007, dying S. tragus plants were found along the Azov Sea at Chushka, Russia. Dying plants had irregular, necrotic, canker-like lesions near the base of the stems and most stems showed girdling and cracking. Stem lesions were dark brown and contained brown pycnidia within and extending along lesion-free sections of the stems and basal portions of leaves. Diseased stems were cut into 3- to 5-mm pieces and disinfested in 70% ethyl alcohol. After drying, stem pieces were placed into petri dishes on the surface of potato glucose agar. Numerous, dark, immersed erumpent pycnidia with a single ostiole were observed in all lesions after 2 to 3 days. Axenic cultures were sent to the Foreign Disease-Weed Science Research Unit, USDA, ARS, Ft. Detrick, MD for testing in quarantine. Conidiophores were simple, cylindrical, and 5 to 25 × 2 μm (mean 12 × 2 μm). Alpha conidia were biguttulate, one-celled, hyaline, nonseptate, ovoid, and 6.3 to 11.5 × 1.3 to 2.9 μm (mean 8.8 × 2.0 μm). Beta conidia were one-celled, filiform, hamate, hyaline, and 11.1 to 24.9 × 0.3 to 2.5 μm (mean 17.7 × 1.2 μm). The isolate was morphologically identified as a species of Phomopsis, the conidial state of Diaporthe (1). The teleomorph was not observed. A comparison with available sequences in GenBank using BLAST found 528 of 529 identities with the internal transcribed spacer (ITS) sequence of an authentic and vouchered Diaporthe eres Nitschke (GenBank DQ491514; BPI 748435; CBS 109767). Morphology is consistent with that of Phomopsis oblonga (Desm.) Traverso, the anamorph of D. eres (2). Healthy stems and leaves of 10 30-day-old plants of S. tragus were spray inoculated with an aqueous suspension of conidia (1.0 × 106 alpha conidia/ml plus 0.1% v/v polysorbate 20) harvested from 14-day-old cultures grown on 20% V8 juice agar. Another 10 control plants were sprayed with water and surfactant without conidia. Plants were placed in an environmental chamber at 100% humidity (rh) for 16 h with no lighting at 25°C. After approximately 24 h, plants were transferred to a greenhouse at 20 to 25°C, 30 to 50% rh, and natural light. Stem lesions developed on three inoculated plants after 14 days and another three plants after 21 days. After 70 days, all inoculated plants were diseased, four were dead, and three had more than 75% diseased tissue. No symptoms occurred on control plants. The Phomopsis state was recovered from all diseased plants. This isolate of D. eres is a potential biological control agent of S. tragus in the United States. A voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 878717). Nucleotide sequences for the ribosomal ITS regions (ITS 1 and 2) were deposited in GenBank (Accession No. EU805539). To our knowledge, this is the first report of stem canker on S. tragus caused by D. eres. References: (1) B. C. Sutton. Page 569 in: The Coelomycetes. CMI, Kew, Surrey, UK, 1980. (2) L. E. Wehmeyer. The Genus Diaporthe Nitschke and its Segregates. University of Michigan Press, Ann Arbor, 1933.

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First Report of Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽

10.1094/pdis-09-11-0813 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287

Author(s):

K. S. Han ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

United States ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

First Report ◽

Cornell University ◽

Plastic Bags ◽

Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (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 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

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First Report of Black Spots on Avocado Fruit Caused by Neofusicoccum parvum in Mexico

Plant Disease ◽

10.1094/pdis-08-11-0699 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287 ◽

Cited By ~ 8

Author(s):

E. Molina-Gayosso ◽

H. V. Silva-Rojas ◽

S. García-Morales ◽

G. Avila-Quezada

Keyword(s):

Average Length ◽

Black Spot ◽

Persea Americana ◽

Universal Primers ◽

Internal Transcribed Spacer Region ◽

Pathogenic Potential ◽

Neofusicoccum Parvum ◽

First Report ◽

Black Spots ◽

Avocado Fruit

Avocado (Persea americana L.) production for export markets has increased in Mexico during the past 10 years. The production system, however, is affected by several sanitation factors, including diseases. During the spring of 2009, smooth, black, circular spots were noted on the surface of avocado fruit. A study was conducted during the winter of 2010 to ascertain the etiology and identify the fungus associated with black spot symptoms on avocado fruit in orchards of Nuevo Parangaricutiro County (19°25′00″ and 102°07′43″) in Michoacan, Mexico. Several fungal isolates were obtained on potato dextrose agar (PDA) from the margin of lesions on immature fruit. The internal transcribed spacer region (ITS) of the rDNA from representative isolates was sequenced with universal primers ITS5 and ITS4 (2). BLAST searches in GenBank showed 100% similarity of the nucleotide sequences with Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, GenBank Accession Nos. GU188001 to GU188007 and GU187985 to GU187987. A representative nucleotide sequence of this region was deposited in GenBank under the Accession No. JN203129. Strains of N. parvum produced aerial and compact mycelium on acidified PDA, the anamorph state of Botryosphaeria parva. Mycelium was initially white, turning gradually gray to black. Conidia were one celled, hyaline, ellipsoidal to fusiform, externally smooth, thin walled, nonseptate, with one or two septa with age, and an average length and width of 14.5 (9.5 to 19) × 5.8 (4.0 to 7.2) μm (n = 100). Pathogenicity tests were conducted with six avocado fruit cv. Hass. Fruit were inoculated at three evenly spaced locations on the fruit surface, either by wounding the tissue with a needle that had been dipped in a conidial mass from an 8-day-old monoconidial culture of N. parvum strain CIAD-021-11 or by placing 5 μl of 1 × 106 conidia ml–1 suspension on each inoculation site. Inoculated fruit were maintained in a moist chamber at 25°C for 2 weeks. Black lesions appeared on all wounded sites 2 days postinoculation (dpi) and on unwounded sites 4 dpi. The delay of symptom development was likely due to penetration through the lenticels, which took longer to initiate infection. No symptoms were observed in the control fruit. The pathogen was reisolated from the lesions of all inoculated fruit, thus fulfilling Koch's postulates. The results confirmed the pathogenic potential of this fungus and indicated its possible involvement in the etiology of black spot on avocado fruit. N. parvum is a cosmopolitan, plurivorous pathogen causing disease in several hosts of economic importance, such as grapes and kiwi, as well as causing stem-end rot of avocado fruit in New Zealand (1) and avocado twigs in Spain (3). To our knowledge, this is the first report of N. parvum causing black spots on avocado fruit in Mexico. References: (1) W. F. T. Hartill et al. N.Z.J. Crop Hortic. Sci. 30:249. 2002. (2) T. J. White et al. Page: 315 in: PCR Protocols: A Guide to Methods and Application. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990. (3) T. Zea-Bonilla et al. Plant Dis. 91:1052, 2007.

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