First Report of Root Rot Caused by Fusarium proliferatum on Blueberry in Argentina

In 2009, a highbush blueberry (Vaccinium corymbosum L. ‘O'Neal’) field located in Rojas, Buenos Aires Province showed 30% of plants with dry or dead branches. Disinfected root pieces were placed on water agar and incubated at 24°C. A fungal colony was obtained and purified by successive transfers of an individual hyphal tip from a sparsely growing colony. Colony color and growth rate were evaluated in potato dextrose agar where the fungus produced white-to-pale pink colonies and grew 3.5 cm after 5 days. The fungus was studied on Spezieller Nährstoffarmer agar (2), carnation leaf-piece agar, and KCl agar where it produced abundant single-celled hyaline microconidia in moderate-length chains and in false heads originated from monophialides and polyphialides. Microconidia measured 6 to 12 × 2 to 3 μm (average 8 × 2.3 μm). On KCl, chains of microconidia and tan-to-light cream sporodochia with 3- to 5-septate, slender, relatively straight macroconidia were easily observed after 4 and 10 days, respectively. Macroconidia measured 38 to 48 × 3.5 to 4 μm (average 43.9 × 3.9 μm). Chlamydospores and sclerotia were not present. Data coincided with the description for Fusarium proliferatum (Matsush.) Niremberg ex Gerlach & Niremberg. The isolate was deposited in the IMYZA Microbial Collection as INTA-IMC 144. The fungus was cultured in 100 ml of Czapek-Dox supplemented with sucrose, peptone, yeast extract, sodium nitrate, and vitamins for 4 days. Genomic DNA was obtained with a DNA extraction kit, PCR amplified with primers ITS1 and ITS4 for the internal transcribed spacer (ITS) region of ribosomal genes, and sequenced. The nucleotide sequence (Accession No JF913468) was compared with GenBank records. The sequence shared 99% identity with Accession No HQ113948 for F. proliferatum. Pathogenicity was confirmed in 1-year-old ‘O'Neal’ plants. A 10-ml suspension (2.4 × 106 conidia/ml in sterile distilled water) was applied to six potted plants grown in sterilized potting mix. Roots were superficially wounded with a needle. Control plants were treated with sterile distilled water. Plants were incubated at 24°C and a 12-h photoperiod. After 90 days, plants showed root rot, leaf chlorosis, and branch necrosis followed by plant death. Control plants remained healthy. F. proliferatum was reisolated from diseased roots of inoculated plants. This fungus was previously cited in Argentina on asparagus (1), corn (1,3), and oat (4). To our knowledge, this is the first report of F. proliferatum as a root pathogen of highbush blueberry in Argentina. References: (1) G. Lori et al. Plant Dis. 82:1405, 1998. (2) H. I. Nirenberg. Releases Fed. Biol. Res. Ctr. Agric. For. (Berlin-Dahlem) 169:1, 1976. (3) D. A. Sampietro et al. Fung. Biol. 114:74, 2010. (4) S. A. Stenglein et al. Plant Dis. 94:783, 2010.

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First Report of Fruit Rot Disease on Pomelo Caused by Lasiodiplodia theobromae in China

Plant Disease ◽

10.1094/pdis-03-11-0214 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1190-1190 ◽

Cited By ~ 5

Author(s):

M. Luo ◽

Z. Y. Dong ◽

S. Y. Bin ◽

J. T. Lin

Keyword(s):

Its Region ◽

Fruit Rot ◽

Economic Losses ◽

Single Spore ◽

Lasiodiplodia Theobromae ◽

First Report ◽

Potted Plants ◽

Diseased Fruit ◽

Long Time ◽

Water Plants

Pomelo (Citrus grandis) is widely cultivated in MeiZhou Guangdong Province of China. In 2008, a disease on pomelo fruit caused significant economic losses by affecting fruit quality. Diseased fruit was collected in December 2008 from MeiZhou Guangdong, surface sterilized in 75% ethanol for 1 min and internal necrotic tissue was transferred to potato dextrose agar (PDA) and incubated at 28°C for 5 days. Three single-spore isolates were obtained from different fruit and identified as Lasiodiplodia theobromae (Pat.) Griffon & Maubl. (synonyms Diplodia natalensis Pole-Evans and Botryodiplodia theobromae Pat.; teleomorph Botryosphaeria rhodina (Cooke) Arx) on the basis of morphological and physiological features. The fungus produced dark brown colonies (initially grayish) on PDA. Young hyphae were hyaline and aseptate, whereas mature hyphae were septate with irregular branches. Cultures of L. theobromae produced globular or irregular pycnidia abundantly on PDA (pH 3.5) at 28°C after 1 month. Mature conidia of L. theobromae were 20 to 26 × 12 to 15.5 μm, subovoid to ellipsoid-ovoid, initially hyaline and nonseptate, remaining hyaline for a long time, and finally becoming dark brown and one septate with melanin deposits on the inner surface of the wall arranged longitudinally giving a striate appearance to the conidia. The internal transcribed spacer (ITS) region of the rDNA was amplified from gDNA using primers ITS1 (5′-TCCGATGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (1). Amplicons were 542 bp long (GenBank Accession No. JF693024) and had 100% nucleotide identity with the corresponding sequence (GenBank Accession No. EU860391) of L. theobromae isolated from a Pinus sp. (2). To satisfy Koch's postulates, six asymptomatic fruit on potted plants were sprayed until runoff with a spore suspension (1 × 106 spores/ml) prepared from 30-day-old cultures of one isolate. Control fruit received water. Plants were covered with sterile wet gauze to maintain high humidity. Fruit spot symptoms similar to those on diseased field fruit appeared after 15 days on all inoculated fruits. L. theobromae was reisolated from all inoculated test fruit. No symptoms were observed on the fruit of control plants. To our knowledge, this is the first report of L. theobromae causing disease on pomelo fruit in China. This pathogen has also been previously reported to be economically important on a number of other hosts by mostly affecting the leaves. References: (1) J. C. Batzer et al. Mycologia 97:1268, 2005. (2) C. A. Pérez et al. Fungal Divers. 41:53,2010.

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First Report of Diaporthe australafricana Associated with Stem Canker on Blueberry in Chile

Plant Disease ◽

10.1094/pdis-12-11-1025-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 768-768 ◽

Cited By ~ 3

Author(s):

B. A. Latorre ◽

K. Elfar ◽

J. G. Espinoza ◽

R. Torres ◽

G. A. Díaz

Keyword(s):

Vitis Vinifera ◽

Vascular Tissue ◽

Its Region ◽

Pathogenic Fungi ◽

Stem Canker ◽

Vaccinium Corymbosum ◽

Academic Press ◽

First Report ◽

Potted Plants ◽

Blastn Analysis

Stem cankers of blueberry (Vaccinium corymbosum L.) have been observed on as much as 15% of the plants in plantations in central and southern Chile since 2006. Symptoms consisted of apical necrosis of the shoots and brown-to-reddish necrotic lesions on the stems. Internally, a brown-to-reddish discoloration of the vascular tissue can be observed. Twenty, single-plant samples were collected in 12 blueberry plantings (approximately 33°27′ to 40°53′S). Isolations from the margins of the necrotic lesions on the stems were made by plating small pieces (5 mm) on potato dextrose agar acidified with 0.5 μl/ml of 92% lactic acid (APDA). The plates were incubated at 20°C for 5 to 7 days, and hyphal tips of white colonies with septate and hyaline mycelium were transferred to APDA. Colonies were then transferred to autoclaved Pinus radiata needles on 2% water agar and incubated for 20 days at 20°C. Twelve isolates producing black pycnidia and alpha conidia were tentatively identified as a Phomopsis sp. (teleomoph Diaporthe Nitschke). Other fungi, including Botryosphaeriaceae spp. and Pestalotiopsis spp., were also isolated. Alpha conidia were smooth, unicellular, hyaline, fusoid, biguttulate, and 6.4 to 7.9 × 2.3 to 3.3 μm (n = 20). Beta conidia were not observed. The internal transcribed spacer (ITS) region of the rDNA was amplified using primers ITS1 and ITS2 (4) and sequenced. BLASTn analysis of the 473-bp fragment (GenBank Accession No. JQ045712) showed 100% identity to Diaporthe australafricana Crous & J.M. van Niekerk from Vitis vinifera (3). The pathogenicity of D. australafricana was studied on blueberry cv. O'Neal using detached stems (n = 4) in the laboratory, on 2-year-old potted plants (n = 4) in a greenhouse, and on attached stems of mature plants (n = 4) established in the ground. Inoculations were done by placing mycelial plugs taken from 7-day-old APDA cultures in a 7-mm long incision made on the stems. Inoculations with sterile mycelium plugs served as negative controls. Inoculation sites were wrapped with Parafilm to avoid rapid dehydration. Dark brown, necrotic lesions on the internal tissues were obtained on all inoculated stems 15 days after inoculation. Mean lesion lengths were 18.0 ± 7.4 mm on detached stems, 7.8 ± 6.9 mm on stems of 2-year-old plants, and 7.3 ± 2.5 mm on mature plants in the field. No symptoms developed on control stems. Reisolations were successful in 100% of the inoculated stems and D. australafricana was confirmed by the presence of pycnidia and alpha conidia. To our knowledge, this is the first report of D. australafricana causing stem canker in V. corymbosum. Previously, this pathogen has been reported to be affecting Vitis vinifera in Australia and South Africa (3). These results do not exclude that other plant-pathogenic fungi may be involved in this syndrome (1,2). References: (1) J. G. Espinoza et al. Plant Dis 92:1407, 2008. (2) J. G. Espinoza et al. Plant Dis. 93:1187, 2009. (3) J. M. van Niekerk et al. Australas. Plant Pathol. 34:27, 2005. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, NY, 1990.

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First Report of Fusarium proliferatum Causing Rot of Garlic Bulbs (Allium sativum) in India

Plant Disease ◽

10.1094/pdis-08-11-0649 ◽

2012 ◽

Vol 96 (2) ◽

pp. 290-290 ◽

Cited By ~ 9

Author(s):

N. Ravi Sankar ◽

Gundala Prasad Babu

Keyword(s):

Sodium Hypochlorite ◽

Allium Sativum ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Its Region ◽

Fusarium Proliferatum ◽

Distilled Water ◽

Sequence Comparisons ◽

First Report ◽

Plant Pathol

In September 2009, diseased garlic bulbs (Allium sativum L. cv. Yamuna Safed) were received from producers and exporters in Hyderabad, Andra Pradesh, India. From 2009 to 2010, similar symptoms were observed on stored garlic bulbs (cvs. Yamuna Safed and Agrifound White) in Chittoor, Kadapa, and Hyderabad districts. In some locations, approximately 60% of the garlic bulbs were affected. At first, infected bulbs showed water-soaked, brown spots and then the disease progressed as small, slightly depressed, tan lesions. A total of 120 diseased samples were collected from all localities. Infected tissues were surface sterilized in 1% sodium hypochlorite for 2 min, rinsed three times in sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 25°C for 7 days. Resultant fungal colonies were fast growing with white aerial mycelium and violet to dark pigments. Hyphae were septate and hyaline. Conidiophores were short, simple, or branched. Microconidia were abundant, single celled, oval or club shaped, measuring 4.5 to 10.5 × 1.3 to 2.5 μm, and borne in chains from both mono-and polyphialides. Macroconidia were not produced. On the basis of morphological characteristics, the pathogen was identified as Fusarium proliferatum (Matsushima) Nirenberg (2). Identification was confirmed by amplification of the internal transcribed spacer (ITS) region. Genomic DNA was extracted from pure cultures of an isolate, and the ITS region was amplified using the ITS4/5 primer pair. PCR amplicons of approximately 574 bp were obtained from isolates, and sequence comparisons with GenBank showed 99% similarity with F. proliferatum (Accession No. FN868470.1). Sequence from this study was submitted to GenBank nucleotide database (Accession No. AB646795). Pathogenicity tests were conducted with three isolates of the fungus following the method of Dugan et al. (1). Each assay with an isolate consisted of 10 garlic cloves disinfected in 1% sodium hypochlorite for 45 s, rinsed with sterile distilled water, and injured to a depth of 4 mm with a sterile 1-mm-diameter probe. The wounds were filled with PDA colonized by the appropriate isolate from a 5-day-old culture. Ten cloves for each tested isolate received sterile PDA as a control. The cloves were incubated at 25°C for 5 weeks; tests were repeated once. After 17 days, rot symptoms similar to the original symptoms developed on all inoculated cloves and F. proliferatum was consistently reisolated from symptomatic tissue, fulfilling Koch's postulates. No fungi were recovered from control cloves. F. proliferatum has been reported on garlic in the northwestern United States (1), Serbia (4), and Spain (3). To our knowledge, this is the first report of F. proliferatum causing rot disease on garlic bulbs in India. References: (1) F. M. Dugan et al. Plant Pathol. 52:426, 2003. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, UK, 2006. (3) D. Palmero et al. Plant Dis. 94:277, 2010. (4) S. Stankovic et al. Eur. J. Plant Pathol. 48:165, 2007.

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First report of Fusarium proliferatum causing stem and root rot on lucky bamboo (Dracaena braunii) in Iraq

Hellenic Plant Protection Journal ◽

10.2478/hppj-2019-0001 ◽

2019 ◽

Vol 12 (1) ◽

pp. 1-5

Author(s):

A.A. Lahuf

Keyword(s):

Ribosomal Dna ◽

Root Rot ◽

Internal Transcribed Spacer ◽

Morphological Characteristics ◽

Its Region ◽

Fusarium Proliferatum ◽

Ornamental Plant ◽

Sequence Analyses ◽

First Report

Summary Lucky bamboo (Dracaena braunii) is a popular ornamental plant in Iraq. Individuals of this plant showing stem and root rot symptoms were observed during a survey conducted from November 2015 to February 2016 in several nurseries in Kerbala province, Iraq. Based on morphological characteristics and sequence analyses of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA), the pathogen was identified as Fusarium proliferatum. This is the first report of stem and root rot caused by F. proliferatum on lucky bamboo (D. braunii) in Iraq.

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First Report of Pythium sterilum Causing Root Rot of Blueberry in the United States

Plant Disease ◽

10.1094/pdis-08-10-0611 ◽

2011 ◽

Vol 95 (5) ◽

pp. 614-614

Author(s):

T. D. Miles ◽

C. I. Woelk ◽

A. Rojas ◽

A. M. C. Schilder

Keyword(s):

United States ◽

Root Rot ◽

Its Region ◽

The United States ◽

Vaccinium Corymbosum ◽

Elisa Test ◽

Cross Reactivity ◽

Peat Moss ◽

First Report ◽

Elisa Testing

In September 2009, ~40 declining blueberry plants (Vaccinium corymbosum L. ‘Jersey’) were observed in a poorly drained area of a 30-year-old field near Fennville, MI. The stunted bushes had yellow leaves and defoliation; others were completely dead. The grower reported that the bushes had been declining over several years. Root samples tested positive in a Phytophthora ELISA test (Agdia Inc., Elkhart IN). Twenty root pieces (2 cm long and 2 to 3 mm in diameter) were surface disinfested and plated on Rye A agar; five yielded fungal-like colonies that were subcultured on potato dextrose agar (PDA). One isolate was white and grew slowly (3 to 4 mm/day at 22 to 24°C). Three isolates were white and grew faster (10 to 12 mm/day at 22 to 24°C) in a chrysanthemal pattern. The fifth was a Fusarium sp. DNA of the white colonies was extracted and the internal transcribed spacer (ITS) region was sequenced using ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) primers. The slow-growing morphotype had 99% identity to Phytophthora sp. isolate 92-209C (Accession No. EU106591) in GenBank but failed to induce symptoms in multiple inoculation tests. The fast-growing morphotype (Accession No. HQ398249) had 98% identity to Pythium sterilum UASWS0265 from declining alder stands in Poland (Accession No. DQ525089). Sequencing of the COXII gene using the FM66/FM58 primer set (3) yielded a product (Accession No. HQ721468) with 100% identity to P. sterilum GD32a from forest soil in Poland (Accession No. EF421185). Hyphae were hyaline, coenocytic, and 4 to 7 μm wide with some swellings at the tips (7 to 9 μm wide). No sporangia, oogonia, or antheridia were observed. Mycelium tested positive in the ELISA test described above. According to Agdia Inc., 10 of 19 tested Pythium spp. have shown similar cross reactivity. Pythium spp. are known to cause root rot of blueberries in Oregon (2). In British Columbia, P. sterilum was commonly isolated from roots of declining blueberry bushes (4). P. sterilum Belbahri & Lefort only reproduces asexually (1). Our isolate was similar but did not produce sporangia in water or on PDA, V8 juice agar, Rye A agar, or water agar. Roots of 10 2-month-old ‘Bluecrop’ cuttings were placed in an aqueous suspension of rinsed mycelium (0.1 g/ml) from 21-day-old cultures grown in V8 broth or in sterile deionized water (control). After 1 h, plants were potted in peat moss/perlite (2:1) or autoclaved sand (five each) and placed in a glasshouse at 25°C. After 7 days, inoculated plants in both soil types had wilted or collapsed with significant necrosis on the roots and primary shoot. Control plants showed no symptoms. In a similar experiment with 6-month-old plants in sand, symptoms appeared after 10 to 12 days. The pathogen was recovered from surface-disinfested root and stem sections of all inoculated plants but not control plants and its identity was confirmed by sequencing of the ITS region. To our knowledge, this is the first report of P. sterilum on blueberries in the United States. While this disease appears to be uncommon in Michigan, it is a potential cause of plant decline, the diagnosis of which may be complicated by cross reactivity in ELISA testing. References: (1) L. Belbahri et al. FEMS Microbiol. Lett. 255:209, 2006. (2) D. R. Bryla and R. G. Linderman. HortScience 43:260, 2008. (3) F. N. Martin. Mycologia 92:711, 2000. (4) S. Sabaratnam. BC Plant Health Fund Final Report. B.C. Retrieved from http://www.agf.gov.bc.ca/cropprot/phf_final_report.pdf , 2008.

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First Report of Colletotrichum coccodes Causing Leaf and Neck Anthracnose on Onions (Allium cepa) in Michigan and the United States

Plant Disease ◽

10.1094/pdis-01-12-0022-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 769-769 ◽

Cited By ~ 2

Author(s):

L. M. Rodriguez-Salamanca ◽

T. B. Enzenbacher ◽

M. L. Derie ◽

L. J. du Toit ◽

C. Feng ◽

...

Keyword(s):

Its Region ◽

The United States ◽

Distilled Water ◽

Conidial Suspension ◽

Water Control ◽

First Report ◽

Plastic Bags ◽

Pathogenicity Tests ◽

Colletotrichum Spp ◽

Water Plants

In July of 2010, dry, oval lesions, each with a salmon-colored center and bleached overall appearance, were observed on the leaves and neck of onions plants growing in production fields of Newaygo, Ottawa, Kent, and Ionia counties, Michigan. Acervuli and setae that are characteristic of Colletotrichum spp. were observed with a dissecting microscope, and elliptical conidia (8 to 23 × 3 to 12 μm) with attenuated ends were observed with a compound microscope. Symptomatic tissues were excised and cultured onto potato dextrose agar amended with 30 and 100 ppm of rifampicin and ampicillin, respectively. The cultures produced pale salmon-colored sporulation after growing for 5 days at 22 ± 2°C and black microsclerotia after 2 weeks. Six isolates were confirmed as C. coccodes based on sequence analysis of the internal transcribed (ITS) region of the ribosomal DNA and a 1-kb intron of the glutamine synthase gene (GS) (2). Sequences were submitted to GenBank (Accession Nos. JQ682644 and JQ682645 for ITS and GS, respectively). Pathogenicity tests were conducted on two- to three-leaved ‘Stanley’ and ‘Cortland’ onion seedlings. Prior to inoculation, seedlings were enclosed in clear plastic bags overnight to provide high relative humidity. The bags were removed, and seedlings were sprayed inoculated with a C. coccodes conidial suspension (5 × 105 conidia/ml and 25 ml/plant) in sterile double-distilled water. Control seedlings were sprayed with sterile double-distilled water. Tween (0.01%) was added to the conidial suspension and the water. Plants were enclosed in bags for 72 h postinoculation and incubated in growth chambers at 28°C day/23°C night with a 12-h photoperiod. Sunken, oval lesions were observed on the foliage of the onion seedlings inoculated with C. coccodes 4 days postinoculation. Lesions coalesced and foliage collapsed 7 days postinoculation. Control plants remained asymptomatic. When five leaf samples per replication were detached and incubated in a moist chamber for 3 days at 21 ± 2°C, abundant acervuli and setae were observed on the symptomatic tissue but not on control tissue. C. coccodes was consistently recovered from the onion seedling lesions. Six different Colletotrichum spp. have been reported to cause diseases on onions worldwide (1,4). C. circinans, which causes smudge, is an occasional onion pathogen in Michigan, while C. gloeosporioides has only been reported to be infecting onions in Georgia (3). To our knowledge, this is the first report of C. coccodes infecting and causing disease in onions plants. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , August 6, 2010. (2) J. C. Guerber et al. Mycologia 95:872. 2003. (3) C. Nischwitz et al. Plant Dis. 92:974. 2008. (4) H. F. Schwartz, and K. S. Mohan. Compendium of Onion and Garlic Diseases and Pests, 2nd ed. The American Phytopathological Society, St. Paul, MN. 1995.

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First Report of Alternaria alternata Causing a Leaf Spot on Philodendron ‘con-go’ in China

Plant Disease ◽

10.1094/pdis-07-14-0726-pdn ◽

2014 ◽

Vol 98 (11) ◽

pp. 1588-1588 ◽

Cited By ~ 3

Author(s):

Z. Zhou ◽

Y. L. Li ◽

C. Y. Yuan ◽

P. L. Duan

Keyword(s):

Alternaria Alternata ◽

Leaf Spot ◽

Its Region ◽

Control Treatment ◽

Distilled Water ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Potted Plants ◽

Similar Disease ◽

Residential District

Philodendron ‘con-go’ is widely cultivated indoors in China as an evergreen potted plant. In October 2013, a leaf spot on Philodendron ‘con-go’ was observed in the residential district of Luoyang (112.46° E, 34.62° N), Henan Province, China. The disease was characterized by oval-shaped, 10 to 20 × 25 to 55 mm, yellow to brown lesions with darker brown borders. Fifty potted plants were surveyed, and less than 2% of the leaves were infected. Lesions appeared mostly in old leaves. The symptomatic leaves affected on the plants' ornamental value, but had little impact on their health. Some lesions merged to form a large irregular lesion that could cover a whole leaf. Two infected leaves from one plant were selected randomly for the isolation of the pathogen. Lesions were cut into 1 cm2 pieces, soaked in 70% ethanol for 30 s, sterilized with 1% sodium hypochlorite for 5 min, then washed three times in sterilized distilled water. The pieces were incubated at 25°C on potato dextrose agar (PDA) for 4 to 5 days. A fungus was consistently isolated. Colonies of the fungus were deep green with white mycelium borders. Conidiophores were light brown with 2 to 4 septa. Conidia were obclavate, 14.6 to 49.1 × 8.3 to 16.4 μm, with a short beak, and with 1 to 5 transverse septa and 0 to 3 longitudinal septa, light brown to olive-brown. Based on morphology, the pathogen was identified as Alternaria alternata. Three isolates were selected randomly for further identification. To confirm pathogenicity, eight leaves of potted Philodendron ‘con-go’ plants were wounded with a sterile pin after wiping each leaf surface with 70% ethanol and washing each leaf with sterilized distilled water three times. The isolates were grown on PDA for 7 days and suspended in sterile distilled water to produce a final concentration of 2 × 105 spores/ml. A 5-μl drop of spore suspension was placed on each pin-wounded leaf. Each of three fungal isolates was inoculated on two leaves, and the control treatment (water inoculated) was done similarly on two leaves. The plants were placed in a growth chamber at 28°C with 80% relative humidity, 50 to 60 klx/m2 light intensity, and a 10-h photoperiod. After 7 days, lesions appeared on inoculated leaves, but the control leaves remained symptomless. Pathogenicity tests were repeated three times. Similar disease symptoms and re-isolation of A. alternata fulfilled Koch's postulates. To confirm the fungal identification, the rDNA of the internal transcribed spacer region in three isolates were amplified using primers ITS1 and ITS4 (1) and sequenced. The nucleotide sequence of the ITS region was submitted to GenBank under accession KJ829535 and showed 100% sequence identity with the strain A. alternata LPSC 1187 (KF753947.1). To our knowledge, this is the first report of a leaf spot of Philodendron ‘con-go’ by A. alternate in China. Reference: (1) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

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First Report of Sclerotinia Rot on Blueberry Caused by Sclerotinia sclerotiorum in Argentina

Plant Disease ◽

10.1094/pdis-01-11-0074 ◽

2011 ◽

Vol 95 (6) ◽

pp. 774-774 ◽

Cited By ~ 3

Author(s):

B. A. Perez ◽

O. M. Farinon ◽

M. F. Berretta

Keyword(s):

Sclerotinia Sclerotiorum ◽

Continuous Light ◽

Pathogenic Fungi ◽

Vaccinium Corymbosum ◽

Universal Primers ◽

Highbush Blueberry ◽

Buenos Aires Province ◽

Laboratory Manual ◽

First Report ◽

Sclerotinia Rot

In October 2007, blighted shoots were observed on highbush blueberry (Vaccinium corymbosum L. cv. O'Neal) plants in La Plata, Buenos Aires Province, Argentina. Isolations from surface-disinfested shoots onto carrot agar and Spezieller Nahrstoffarmer Agar (SNA) consistently yielded white colonies that produced black sclerotia, mainly near the edge of the culture plates, after 7 days. Sclerotia were transferred to SNA tubes and kept at 5°C for several months. The germination of sclerotia produced numerous 6 mm long initials, stipitate pale brown cup-shaped apothecia (10 × 6 mm) with eight-spored asci (137 × 7 μm) at 18°C and continuous light conditions. Asci with uniseriate ascospores were cylindrical and narrow at the base. Ascospores (11 to 12 × 4 μm) were hyaline, unicellular, smooth, and ellipsoid. This isolated fungus was morphologically identified as Sclerotinia sclerotiorum (Lib.) de Bary (2,3). The isolate was deposited in the IMYZA Microbial Collection as INTA-IMC 87. Mycelium was cultured in 100 ml of Czapek's-Dox medium, supplemented with sucrose, peptone, yeast extract, sodium nitrate, and vitamins (1), for 3 days and fungal DNA was obtained using a DNA extraction kit. ITS1 and ITS2 of ribosomal genes were amplified by PCR using universal primers (4) and the PCR product was sequenced. A BLAST algorithm search revealed 100% identity of the sequence with 12 GenBank entries for S. sclerotiorum. The nucleotide sequence was deposited in the GenBank with Accession No. JF277567. Pathogenicity testing was achieved by placing detached leaves of cvs. Emerald, Misty, and Start on water agar (WA) plates, inoculating with 9-mm2 mycelial blocks, and incubating at 20°C with 12 h of light. Young shoots of highbush blueberry, Misty and O'Neal, were inoculated by the cut shoot method with micropipette tips filled with mycelium and kept under greenhouse conditions at 24°C and 14 h of light. On control plants, WA blocks or WA-filled micropipette tips were used. Leaf blight was observed after 5 to 6 days and sclerotia appeared after 7 days on inoculated tissues. Shoot blight was recorded on inoculated plants after 5 days. The fungus was reisolated from inoculated tissues, with no symptoms showing on controls. To our knowledge, this is the first report of Sclerotinia rot caused by S. sclerotiorum in blueberry in Argentina. References: (1) J.F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Hoboken, NJ, 2006. (2). J. E. M. Mourde and P. Holliday. No. 513 in: CMI Descriptions of Pathogenic Fungi and Bacteria. Kew, Surrey, UK, 1976. (3) S. Umemoto et al. Gen. Plant Pathol. 73:290, 2007. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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First report of Colletotrichum siamense Causing Blossom Blight on Thai basil (Ocimum basilicum L.) in Malaysia

Plant Disease ◽

10.1094/pdis-06-20-1371-pdn ◽

2020 ◽

Author(s):

Siti Izera Ismail ◽

Nur Adlina Rahim ◽

Dzarifah Zulperi

Keyword(s):

Disease Incidence ◽

Its Region ◽

Ocimum Basilicum ◽

Distilled Water ◽

Single Spore ◽

First Report ◽

Plastic Bags ◽

Colletotrichum Siamense ◽

Primer Sets ◽

Acca Sellowiana

Thai basil (Ocimum basilicum L.) is widely cultivated in Malaysia and commonly used for culinary purposes. In March 2019, necrotic lesions were observed on the inflorescences of Thai basil plants with a disease incidence of 60% in Organic Edible Garden Unit, Faculty of Agriculture in the Serdang district (2°59'05.5"N 101°43'59.5"E) of Selangor province, Malaysia. Symptoms appeared as sudden, extensive brown spotting on the inflorescences of Thai basil that coalesced and rapidly expanded to cover the entire inflorescences. Diseased tissues (4×4 mm) were cut from the infected lesions, surface disinfected with 0.5% NaOCl for 1 min, rinsed three times with sterile distilled water, placed onto potato dextrose agar (PDA) plates and incubated at 25°C under 12-h photoperiod for 5 days. A total of 8 single-spore isolates were obtained from all sampled inflorescence tissues. The fungal colonies appeared white, turned grayish black with age and pale yellow on the reverse side. Conidia were one-celled, hyaline, subcylindrical with rounded end and 3 to 4 μm (width) and 13 to 15 μm (length) in size. For fungal identification to species level, genomic DNA of representative isolate (isolate C) was extracted using DNeasy Plant Mini Kit (Qiagen, USA). Internal transcribed spacer (ITS) region, calmodulin (CAL), actin (ACT), and chitin synthase-1 (CHS-1) were amplified using ITS5/ITS4 (White et al. 1990), CL1C/CL2C (Weir et al. 2012), ACT-512F/783R, and CHS-79F/CHS-345R primer sets (Carbone and Kohn 1999), respectively. A BLAST nucleotide search of ITS, CHS-1, CAL and ACT sequences showed 100% similarity to Colletotrichum siamense ex-type cultures strain C1315.2 (GenBank accession nos. ITS: JX010171 and CHS-1: JX009865) and isolate BPDI2 (CAL: FJ917505, ACT: FJ907423). The ITS, CHS-1, CAL and ACT sequences were deposited in GenBank as accession numbers MT571330, MW192791, MW192792 and MW140016. Pathogenicity was confirmed by spraying a spore suspension (1×106 spores/ml) of 7-day-old culture of isolate C onto 10 healthy inflorescences on five healthy Thai basil plants. Ten infloresences from an additional five control plants were only sprayed with sterile distilled water and the inoculated plants were covered with plastic bags for 2 days and maintained in a greenhouse at 28 ± 1°C, 98% relative humidity with a photoperiod of 12-h. Blossom blight symptoms resembling those observed in the field developed after 7 days on all inoculated inflorescences, while inflorescences on control plants remained asymptomatic. The experiment was repeated twice. C. siamense was successfully re-isolated from the infected inflorescences fulfilling Koch’s postulates. C. siamense has been reported causing blossom blight of Uraria in India (Srivastava et al. 2017), anthracnose on dragon fruit in India and fruits of Acca sellowiana in Brazil (Abirami et al. 2019; Fantinel et al. 2017). This pathogen can cause a serious threat to cultivation of Thai basil and there is currently no effective disease management strategy to control this disease. To our knowledge, this is the first report of blossom blight caused by C. siamense on Thai basil in Malaysia.

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