First report of Colletotrichum fioriniae and C. nymphaeae as Causal Agents of anthracnose on walnut in Italy

English walnut (Juglans regia L.) is species grown either for high quality wood or fruit production. In Italy walnut cultivation occupies an area of about 4600 ha (FAOSTAT, http://www.fao.org/faostat, 2020). In 2019-2020, walnut fruits (cv Lara) with anthracnose symptoms were collected from walnut orchards in Province of Venice (Northern Italy). Affected fruits showed necrotic and circular lesions with acervuli in the center causing the complete mummification of the fruit as described by Da Lio et al., 2018. Orange conidial masses appeared under wet conditions. The fungus was isolated from necrotic tissues and conidial masses were put on potato dextrose agar (PDA) medium. Plates were incubated at 25°C for 5 to 7 days. The colonies were white to pink on the upper side and pink with black spots on the reverse. Acervuli formed and produced conidial masses on PDA after 6 days. Culture and conidial morphology were in concordance with published descriptions of C. acutatum sensu lato (Damm et al., 2012). To confirm the identity, internal transcribed spacers (ITS), (glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT) and beta-tubulin (TUB2) genes were amplified and sequenced using the primer pairs ITS1/ITS4 (White at al. 1990), GDF1/GDR1 (Guerber et al., 2003), ACT512F/ACT783R and BT2Fd/BT4R primers (Da Lio et al., 2018). The isolates belonged to two different species of Colletotrichum acutatum complex: C. fioriniae (Marcelino & Gouli) and C. nymphaeae (Pass). Sequences of two representative isolates C. fioriniae CREADC-F2317 and C. nymphaeae CREADC-F2372 were deposited in GenBank with accession numbers MZ153170 and MZ191794 (ITS), MZ203522 and MZ224013 (GAPDH), MZ203521 and MZ224012 (ACT), and MZ203523 and MZ224014 (TUB2). For all the genes, isolates had a 100% similarity to multiple C. fioriniae and C. nymphaeae accessions, respectively. Maximum likelihood trees based on concatenated sequences of the four genes were constructed using MEGA 6.0 (Tamura et al., 2013). The phylogenetic analysis grouped the isolates in the C. fioriniae and nymphaeae clusters respectively. The two isolates CREADC-F2317 and CREADC-F2372 were used to confirm pathogenicity on walnut fruits. Fruits of cv Lara were surface disinfected by dipping in 3% NaOCl for 1 min, rinsed in sterile distilled water, and arranged in sterile humid chambers. Fruits were wounded with a sterile needle then inoculated with 20 μl of 106 conidia/ml suspensions of each isolate (one wound per fruit). Fruit treated with sterile distilled water served as a control. Inoculations were conducted on three fruits per replicate and three replicates per treatment arranged in a complete block randomized design. After 7 days incubation at 25 ± 1°C, all the inoculated fruits showed typical anthracnose symptoms and lesions with cream to salmon pink acervuli, whereas the controls remaied healthy. The species C. nymphaeae and C. fioriniae were reisolated from the rotted fruit. Pathogenicity tests were repeated twice with the same results. The morphology of the reisolated fungi was consistent with the inoculated one, fulfilling Koch’s postulates. The species C. fioriniae and C. nymphaeae have been described affecting numerous species worldwide (Damm et al., 2012). C. fioriniae and C. nymphaeae have been previously reported to cause severe anthracnose on walnut, C. fioriniae in France (Da Lio et al., 2018) and Hungary (Varjas et al., 2019) and C. nymphaeae in France (Da Lio et al., 2018) and Brazil (Savian et al., 2019). To our knowledge, this is the first report of C. fioriniae and C. nymphaeae as causal agents of walnut anthracnose in Italy.

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First Report of Anthracnose of Papaya (Carica papaya L.) Caused by Colletotrichum siamense in China

Plant Disease ◽

10.1094/pdis-10-20-2154-pdn ◽

2021 ◽

Author(s):

Yujie Zhang ◽

Wenxiu Sun ◽

Ping Ning ◽

Tangxun Guo ◽

SuiPing Huang ◽

...

Keyword(s):

Carica Papaya ◽

Disease Incidence ◽

Aerial Mycelium ◽

Postharvest Disease ◽

Distilled Water ◽

First Report ◽

Surface Samples ◽

Initial Symptoms ◽

Colletotrichum Siamense ◽

Pathogenicity Tests

Papaya (Carica papaya L.) is a rosaceous plant widely grown in China, which is economically important. Anthracnose caused by Colletotrichum sp. is an important postharvest disease, which severely affects the quality of papaya fruits (Liu et al., 2019). During April 2020, some mature papaya fruits with typical anthracnose symptoms were observed in Fusui, Nanning, Guangxi, China with an average of 30% disease incidence (DI) and over 60% DI in some orchards. Initial symptoms of these papayas appeared as watery lesions, which turned dark brown, sunken, with a conidial mass appearing on the lesions under humid and warm conditions. The disease severity varied among fruits, with some showing tiny light brown spots, and some ripe fruits presenting brownish, rounded, necrotic and depressed lesions over part of their surface. Samples from two papaya plantations (107.54°E, 22.38°N) were collected, and brought to the laboratory. Symptomatic diseased tissues were cut into 5 × 5 mm pieces, surface sterilized with 2% (v/v) sodium hypochlorite for 1 minute, and rinsed three times with sterilized water. The pieces were then placed on potato dextrose agar (PDA). After incubation at 25°C in the dark for one week, colonies with uniform morphology were obtained. The aerial mycelium on PDA was white on top side, and concentric rings of salmon acervuli on the underside. A gelatinous layer of spores was observed on part of PDA plates after 7 days at 28°C. The conidia were elliptical, aseptate and hyaline (Zhang et al., 2020). The length and width of 60 conidia were measured for each of the two representative isolates, MG2-1 and MG3-1, and these averaged 13.10 × 5.11 μm and 14.45 × 5.95 μm. DNA was extracted from mycelia of these two isolates with the DNA secure Plant Kit (TIANGEN, Biotech, China). The internal transcribed spacer (ITS), partial actin (ACT), calmodulin (CAL), chitin synthase (CHS), β-tubulin 2 (TUB2) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) regions were amplified by PCR and sequenced. The sequences were deposited into GenBank with accessions MT904003, MT904004, and MT898650 to MT898659. BLASTN analyses against the GenBank database showed that they all had over 99% identity to the type strain of Colletotrichum siamense isolate ICMP 18642 (GenBank accession numbers JX010278, GQ856775, JX009709, GQ856730, JX010410, JX010019) (Weir et al., 2012). A phylogenetic tree based on the combined ITS, ACT, CAL, CHS, TUB2 and GAPDH sequences using the Neighbor-joining algorithm also showed that the isolates were C. siamense. Pathogenicity tests were conducted on 24 mature, healthy and surface-sterilized papaya fruits. On 12 papaya fruits, three well separated wounded sites were made for inoculation, and for each wounded site, six adjacent pinhole wounds were made in a 5-mm-diameter circular area using a sterilized needle. A 10 µl aliquot of 1 × 106 conidia/ml suspension of each of the isolates (MG2-1 and MG3-1) was inoculated into each wound. For each isolate, there were six replicate fruits. The control fruits were inoculated with sterile distilled water. The same inoculation was applied to 12 non-wound papaya fruits. Fruits were then placed in boxes which were first washed with 75% alcohol and lined with autoclaved filter paper moistened with sterilized distilled water to maintain high humidity. The boxes were then sealed and incubated at 28°C. After 10 days, all the inoculated fruits showed symptoms, while the fruits that were mock inoculated were without symptoms. Koch's postulates were fulfilled by re-isolation of C. siamense from diseased fruits. To our knowledge, this is the first report of C. siamense causing anthracnose of papaya in China. This finding will enable better control of anthracnose disease caused by C. siamense on papaya.

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First Report of Colletotrichum acutatum on Tomato and Apple Fruits in the Czech Republic

Plant Disease ◽

10.1094/pdis-10-11-0849-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 769-769 ◽

Cited By ~ 4

Author(s):

J. Víchová ◽

B. Staňková ◽

R. Pokorný

Keyword(s):

Czech Republic ◽

Tomato Fruit ◽

Colletotrichum Acutatum ◽

Distilled Water ◽

Species Determination ◽

Specific Primers ◽

The Czech Republic ◽

First Report ◽

Pcr Products ◽

Apple Fruits

Apple (Malus domestica Borkh.) is a fruit traditionally grown in the Czech Republic, and tomatoes (Solanum lycopersicum Mill.), too, are widely raised in this region. Colletotrichum acutatum J. H. Simmonds is a polyphagous fungal plant pathogen. Earlier, this pathogen caused disease on strawberry in the Czech Republic (2), and now it has become an important pathogen on safflower (4). During the 2010 harvest, anthracnose symptoms were noticed on the fruits of apple and tomato. Infected apples fruits (localities Velká Bíteš and Znojmo) and tomatoes (localities Velká Bíteš and Žabčice) were collected. Typical symptoms on fruit surfaces were round, brown, shriveled and sunken spots, 1.2 to 2.0 cm, with orange conidial masses appearing on the spots. A fungus was isolated from each host on potato dextrose agar and cultured at 25 ± 2°C for 10 days. Mycelium was superficial, partly immersed, and white to gray with occurrence of orange conidial masses. Conidia of the tomato and apple isolates were colorless and fusiform. The size of conidia from the apple and tomato isolates, respectively, ranged from 11 to 15 × 2.5 to 3.5 μm and 11 to 16 × 2.5 to 4 μm. Morphological characteristics suggested that the isolated fungi was a Colletotrichum sp. To fulfill Koch's postulates, healthy tomato and apple fruits were disinfected with 3% sodium hypochlorite for 2 min and rinsed in sterile distilled water. Fruits were pinpricked with a sterile needle and 10 μl of a spore suspension (1 × 105 conidia ml–1) was inoculated by pipetting into the wound. Control fruits were treated with sterile distilled water. The fruits were transferred to a growth cabinet and maintained at a temperature of 25 ± 2°C, relative humidity of 70 ± 5%, and a photoperiod of 12 h. Similar disease symptoms as in the collected fruits were observed on tomato fruits at 7 days and apple fruits at 20 days after inoculation, while no symptoms appeared on control fruits. The pathogen was reisolated from infected fruits. Species determination of the isolates was confirmed by PCR. Specific primers designed in region ITS1, the 5.8S RNA gene, and region ITS2 of the pathogen DNA were selected. Specific primers CaInt2 and ITS4 were used to identify C. acutatum (3), and primers CgInt and ITS4 were used to determine C. gloeosporioides isolate CCM 177 (1), which was used as a control. Our isolates yielded PCR products (490 bp) only with primers designed for C. acutatum. The C. gloeosporioides isolate yielded a PCR product (450 bp) only with CgInt and ITS4 primers. PCR products were sequenced and identified with the BLAST program. The sequence of the tomato fruit isolate (Accession No. JN676199) and apple fruit isolate (Accession No. JN676198) matched with 100% similarity to the C. acutatum sequences in GenBank. The control isolate of C. gloeosporioides matched 100% to sequences AJ749682 and AJ749692. To our knowledge, this is the first report of C. acutatum on tomato and apple fruits in the Czech Republic. This pathogen can endanger the production and storage of apples and tomatoes in this region. References: (1) P. R. Mills et al. FEMS Microbiol. Lett. 98:137, 1992. (2) D. Novotný et al. Plant Dis. 91:1516, 2007. (3) S. Sreenivasaprasad et al. Plant Pathol. 45:650, 1996. (4) J. Víchová et al. Plant Dis. 95:79, 2011.

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First Report of Pythium splendens Associated with Severe Wilt of Muskmelon (Cucumis melo) in Oman

Plant Disease ◽

10.1094/pdis-92-2-0313c ◽

2008 ◽

Vol 92 (2) ◽

pp. 313-313 ◽

Cited By ~ 8

Author(s):

A. M. Al-Sa'di ◽

M. L. Deadman ◽

F. A. Al-Said ◽

I. Khan ◽

M. Al-Azri ◽

...

Keyword(s):

Cucumis Melo ◽

Morphological Characteristics ◽

Fruit Production ◽

Maturation Stage ◽

Vegetable Crops ◽

First Report ◽

Sultan Qaboos University ◽

Pythium Splendens ◽

Pathogenicity Tests ◽

Cucumis Melo L

Muskmelon (Cucumis melo L.) is one of the most important vegetable crops in Oman. In the fall of 2004, sudden wilt was observed in muskmelon grown in a field at Sultan Qaboos University, Muscat. The disease was characterized by rapid collapse of vines and muskmelon plants at the fruit production to maturation stage, associated with brown-to-dark brown rotted primary and secondary roots. The disease resulted in death of more than 85% of muskmelon plants in that field. On potato dextrose agar (PDA), with published methods (1), Pythium spp. were consistently isolated from crowns and roots of plants showing wilt symptoms. Further identification of five isolates of Pythium with sequences of the internal transcribed spacer (ITS) of the ribosomal DNA (1) using ITS1 and ITS4 primers produced a nucleotide sequence 806 bp long, which was identical among all isolates. Comparison with sequences deposited at the National Center for Biotechnology Information revealed 100% nucleotide similarity to a previously published sequence (Accession No. DQ381808) of isolate P091 of P. splendens from cucumber from Oman, for which identification has also been confirmed by morphological characteristics. The sequence of one isolate of P. splendens (P222) was assigned GenBank Accession No. EF546436 and deposited at CBS under Accession No. CBS121855. In pathogenicity tests conducted in a greenhouse, P. splendens induced damping-off symptoms on 7-day-old muskmelon seedlings and also reproduced the same wilt symptoms observed in the field when 2-month-old muskmelon plants were inoculated with 3-day-old P. splendens grown in PDA. To our knowledge, this is the first report of association of P. splendens with wilt of muskmelon in Oman. Reference: (1) A. M. Al-Sa'di et al. Plant Pathol. 56:140, 2007.

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First Report of Colletotrichum acutatum sensu lato Causing Anthracnose on Gooseberry Fruits in the Czech Republic

Plant Disease ◽

10.1094/pdis-01-13-0080-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1249-1249 ◽

Cited By ~ 1

Author(s):

J. Víchová ◽

B. Jílková ◽

R. Pokorný

Keyword(s):

Czech Republic ◽

Morphological Characteristics ◽

Colletotrichum Acutatum ◽

Species Determination ◽

Specific Primers ◽

The Czech Republic ◽

First Report ◽

Sterile Needle ◽

Pcr Products ◽

Pathogen Dna

Gooseberry (Ribes uva-crispa L.) is a commonly grown fruit tree or bush in the Czech Republic. Colletotrichum acutatum J. H. Simmonds is a polyphagous fungal plant pathogen. This pathogen has been reported causing anthracnose on strawberry in the Czech Republic (2), and recently it has become an important pathogen on the fruits of apple and tomato (4). In 2012, anthracnose symptoms were noticed on fruits of gooseberry (locality Pribyslavice, near Brno). The symptoms on fruit surfaces were round, brown, shriveled, sunken spots of 1.2 to 2.0 cm, with orange conidial masses on the spots. The pathogen was isolated from symptomatic fruits on PDA and cultured at 25 ± 2°C. The color of colonies varied with age from white to gray with occurrence of orange conidial masses. Conidia were colorless and fusiform, size 13 to 17 × 4 to 5 μm (n = 100). The morphological characteristics classified the pathogen as a Colletotrichum sp. To fulfill Koch's postulates, 25 disinfested healthy gooseberry fruits were pinpricked by sterile needle and 10 μl of spore suspension (1 × 105 conidia ml–1) was inoculated by pipetting into the wound. Control fruits were treated with sterile distilled water. The fruits were transferred to a growth cabinet and maintained at a temperature of 25 ± 2°C, relative humidity 70 ± 5%. Similar anthracnose symptoms were observed on all of gooseberry fruits a week after inoculation, whereas no symptoms appeared on control fruits. The pathogen was reisolated from infected fruits. Species determination of the isolates was confirmed by PCR. Specific primers designed in region ITS1, the 5.8S RNA gene, and region ITS2 of the pathogen DNA were selected. Specific primers CaInt2 and ITS4 were used to identify C. acutatum (3), and primers CgInt and ITS4 were used to determine C. gloeosporioides isolate CCM 177 (1), which was used as a control. Our isolates yielded PCR products (size 490 bp) only with primers designed for C. acutatum. The C. gloeosporioides isolate yielded PCR product (size 450 bp) only with CgInt and ITS4 primers. PCR products were sequenced and identified with the BLAST program. The sequence of the gooseberry fruit isolates (Accession No. JX843763 and JX843764) matched with 100% similarity to the C. acutatum sequences in GenBank. To our knowledge, this is the first report of C. acutatum sensu lato on gooseberry fruits in the Czech Republic. This pathogen can endanger the production of gooseberry fruits in this region. References: (1) P. R. Mills et al. FEMS Microbiol. Lett., 98:137, 1992. (2) D. Novotný et al. Plant Dis. 91:1516, 2007. (3) S. Sreenivasaprasad et al. Plant Pathol. 45:650, 1996. (4) J. Víchová et al. Plant Dis. 96:769, 2012.

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First Report of Walnut Canker Caused by Fusarium incarnatum from India

Plant Disease ◽

10.1094/pdis-04-11-0352 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1587-1587

Author(s):

B. Singh ◽

C. S. Kalha ◽

V. K. Razdan ◽

V. S. Verma

Keyword(s):

Fusarium Species ◽

Juglans Regia ◽

Infected Plant ◽

Distilled Water ◽

Conidial Suspension ◽

State University ◽

Single Spore ◽

Jammu And Kashmir ◽

First Report ◽

Branch Dieback

While screening newly introduced cultivars of walnut (Juglans regia) at Bhaderwah (Mini Kashmir), Jammu and Kashmir, India in September 2008, 60% of grafted plants were found to be dying because of a cankerous growth observed on seedling stems. Later, these symptoms extended to lateral branches. In the surveyed nurseries, cvs. SKU 0002 and Opex Dachaubaria were severely affected by the disease. Cankers were also observed in all walnut nurseries in the area with several wild seedlings also being observed to be exhibiting similar cankerous symptoms on stem and branches. Necrotic lesions from cankerous tissues on seedling stems were surface disinfested with 0.4% NaOCl for 1 min and these disinfected cankerous tissues were grown on potato dextrose agar (potato-250 g, dextrose-15 g, agar-15 g, distilled water-1 liter). A Fusarium sp. was isolated consistently from these cankerous tissues, which was purified using single-spore culture. Carnation leaf agar was used for further culture identification (2,3). The fungal colony was floccose, powdery white to rosy in appearance when kept for 7 days at 25 ± 2°C. Macroconidia were straight to slightly curved, four to eight septate and 30 to 35 × 3.5 to 5.7 μm. These are characteristics consistent with Fusarium incarnatum (3). Pathogenicity was confirmed by spraying a conidial suspension (1 × 106 conidia/ml) onto bruised branches of 1-year-old walnut plants (cv. Opex Dachaubaria) while sterile distilled water sprays were used for the controls. Inoculated plants were incubated at 20 ± 2°C and 85% relative humidity for 48 h. Fifty days following inoculation, branch dieback followed by canker symptoms developed on inoculated plants. Control plants remained healthy with no symptoms of canker. F. incarnatum (Roberge) Sacc. was repeatedly isolated from inoculated walnut plants, thus satisfying Koch's postulates. Infected plant material has been deposited at Herbarium Crytogamae Indiae Orientalis (ITCC-6874-07), New Delhi. To our knowledge, this is the first report of walnut canker caused by F. incarnatum (Roberge) Sacc. from India. This fungus was previously reported to be affecting walnut in Italy (1) and Argentina (4). References: (1) A. Belisario et al. Informatore Agrario 21:51, 1999. (2) J. C. Gilman. A Manual of Soil Fungi. The Iowa State University Press, Ames, 1959. (3) P. E. Nelson et al. Fusarium Species. An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, 1983. (4) S. Seta et al. Plant Pathol. 53:248, 2004.

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First Report of Colletotrichum nymphaeae Causing Anthracnose on Almond in Hungary

Plant Disease ◽

10.1094/pdis-08-21-1847-pdn ◽

2021 ◽

Author(s):

Virág Varjas ◽

Sámuel László Szilágyi ◽

Tamás Lakatos

Keyword(s):

Species Complex ◽

Prunus Dulcis ◽

Colletotrichum Acutatum ◽

Valid Species ◽

Bootstrap Support ◽

First Report ◽

Pathogenicity Tests ◽

Buda Hills ◽

Genebank Collection

Almond (Prunus dulcis [Mill.] D. A. Webb) is cultivated in commercial orchards in southwestern Hungary while numerous backyard orchards predominate in Buda Hills and central Hungary. In July 2019, anthracnose symptoms and necrotic twigs were observed across almond genotypes in a meadow orchard of Óbuda and in the genebank collection of the Hungarian University of Agriculture and Life Sciences. Fruits of some genotypes were damaged 100%, whereas others to a lesser degree or asymptomatic. Orange slightly sunken lesions on fruits produced gum. Near the diseased fruits the young shoots shriveled, the stalks became necrotized, on twigs necrosis developed. Isolates obtained from orange conidial masses from epicarp, necrotized tissues from twigs, and stalks were grown on PDA for 7 days at 25 ֯C in the dark. Upper surfaces of the colonies were white to pale gray, black solid mycelial structures were formed, the reverse side varied white to salmon. Acervuli were not formed, but conidia were produced from hyphae. Conidia were unicellular, hyaline, smooth-walled, cylindrical, predominant with both end rounded, or one end acute. Morphometric measurements of conidia showed mean length ± SD × width ± SD = 18.0 ± 2.2 × 4.7 ± 0.6 μm (n = 100). The isolates were morphologically identified as Colletotrichum acutatum sensu lato (Damm et al. 2012). Sexual morph was not observed. Three monosporic isolates were used for molecular identification. Partial nucleotide sequences were amplified from three loci, internal transcribed spacer (ITS), β-tubulin (TUB2) and calmodulin (CAL) after White et al. (1990); Glass and Donaldson (1995) and Weir et al. (2012), respectively. The ITS sequences (GenBank accessions MW425388 to MW425390) of the three isolates revealed that they belong to the C. acutatum species complex while BLAST results showed that TUB2 sequences (GenBank accessions MW428285 to MW428287) had 99.3% identity with C. nymphaeae strain CBS515.78, whereas the CAL sequences (GenBank accessions MW428288 to MW428290) had 100% with C. nymphaeae strain FREC138. The phylogenetic tree containing all the valid species of C. acutatum species complex confirmed that the isolates clustered to C. nymphaeae with high bootstrap support. The fungus was identified as Colletotrichum nymphaeae (Pass) Aa based on morphometric and molecular biological evidence. In vivo pathogenicity tests were conducted on ten healthy fruits, and ten twigs by inserting mycelial agar plugs (5 mm in diameter) onto wounded pericarp and phloem tissues, which were then wrapped in wet cotton and Parafilm®. The control treatments received sterile PDA discs. After 15 days, necrotic lesions 12 to 19 mm in diameter developed on fruit, 9 to 18 mm on twig. Control fruits, and twigs were asymptomatic. Koch’s postulates were fulfilled with the reisolation of the pathogen from symptomatic tissues. The ITS, ACT and CAL sequences of the reisolated Colletotrichum were determined and found identical to the original isolates. Anthracnose symptoms are known on almond fruits in several almond growing regions all over the word caused by Colletotrichum acutatum, C. godetiae, C. fioriniae, C. simmondsii, and C. gloeosporioides (Adaskaveg et al. 1997; López-Moral et al. 2000; de Silva et al. 2021; Shabi et al. 1983;). To our knowledge, this is the first report of Colletotrichum nymphaeae causing anthracnose of almond globally.

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First Report of Leaf Spot of Dieffenbachia picta and Aglaonema commutatum Caused by Burkholderia gladioli in Argentina

Plant Disease ◽

10.1094/pdis-93-5-0550c ◽

2009 ◽

Vol 93 (5) ◽

pp. 550-550 ◽

Cited By ~ 1

Author(s):

A. M. Alippi ◽

A. C. López

Keyword(s):

Burkholderia Cepacia ◽

Disease Incidence ◽

Soft Rot ◽

Distilled Water ◽

First Report ◽

Burkholderia Gladioli ◽

Sterile Needle ◽

Pcr Products ◽

Humidity Chamber ◽

Physiological Tests

During May of 2008 (austral autumn), an uncharacterized disease was observed on Dieffenbachia picta (Lodd.) Schott and Aglaonema commutatum Schott in commercial greenhouses in Pontevedra (34°45′6″S, 58°42′42″W), Argentina. Affected plants showed irregular, brown lesions on leaves, approximately 15 to 20 mm in diameter, surrounded by water-soaked haloes that progressed inward from the margins. Water-soaked rotting symptoms were also observed in petioles. Disease incidence approached 80%. Abundant bacterial streaming was observed from lesions when examined at ×100. Bacteria consistently isolated from lesions formed cream-colored, glistening, convex colonies on sucrose peptone agar and produced a yellowish green, diffusible, nonfluorescent pigment on King's medium B. Four isolates from different symptomatic plants were selected for further study. All were aerobic, gram-negative rods that accumulated poly-β-hydroxybutyrate inclusions. In LOPAT tests, all induced a hypersensitive response in tobacco plants, caused soft rot of potato tubers, and were positive for levan, negative for arginine dihydrolase, and variable for oxidase. All isolates oxidized glucose, did not hydrolyze starch and were able to rot onion slices. Colonies developed at 41°C but not at 4°C. With the API 20NE test strips and database (bioMerieux, Buenos Aires, Argentina), all isolates matched (99% identity) Burkholderia cepacia, but their inability to metabolize cellobiose and sucrose further identified them as B. gladioli. For molecular identification, 23S rDNA was amplified by PCR using B. gladioli-specific primers LP1 and LP4, which yielded a 700-bp product (3), and PCR-restriction fragment length polymorphism of 16S rDNA using AluI (2). PCR products were identical to those from the type strain for B. gladioli, ICMP 3950, isolated from Gladiolus spp. that had been included in all tests for comparison. Pathogenicity was verified on D. picta and A. commutatum by spraying the plants with bacterial suspensions in sterile distilled water at 108 CFU/ml with and without wounding the leaves with a sterile needle and also by injection-infiltration of bacterial suspensions at 105 CFU/ml. In addition, another host plant, Gladiolus communis L., was inoculated in the same manner. Controls were sprayed or infiltrated with sterile distilled water. After 48 h in a humidity chamber, plants were kept at 25 ± 3°C in a greenhouse. In all hosts, symptoms were first detected 3 days after inoculation and lesions expanded to resemble natural infections within 4 to 7 days. All strains caused necrosis around the inoculation sites and lesions were identical to those induced by the ICMP reference strain. Bacteria were reisolated from each host tested and then the original and reisolated strains were compared by enterobacterial repetitive intergeneric consensus-PCR (1); DNA fingerprints of the reisolated strains were identical to those of the original strains, thereby fulfilling Koch's postulates. No lesions were observed on controls or on plants inoculated by spraying without wounding, suggesting that bacteria gain entry through wounds. On the basis of PCR and physiological tests the pathogen was identified as B. gladioli (2–4). To our knowledge, this is the first report of B. gladioli on Dieffenbachia and Aglaonema spp. References: (1) F. J. Louws et al. Appl. Environ. Microbiol. 60:2286, 1994. (2) C. Van Pelt et al. J. Clin. Microbiol. 37:2158, 1999. (3) P. W. Whitby et al. J. Clin. Microbiol. 38:282, 2000. (4) E. Yabuuchi et al. Microbiol. Immunol. 36:1251, 1992.

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First Report of Colletotrichum acutatum on Strawberry in Northwestern Argentina

Plant Disease ◽

10.1094/pdis.2000.84.6.706b ◽

2000 ◽

Vol 84 (6) ◽

pp. 706-706 ◽

Cited By ~ 5

Author(s):

C. J. Ramallo ◽

L. D. Ploper ◽

M. Ontivero ◽

M. P. Filippone ◽

A. Castagnaro ◽

...

Keyword(s):

Colletotrichum Acutatum ◽

Conidial Suspension ◽

Disease Symptoms ◽

Northwestern Argentina ◽

First Report ◽

Surface Control ◽

Detached Leaves ◽

Strawberry Anthracnose ◽

Pathogenicity Tests ◽

Necrotic Spots

Isolates were obtained from strawberry tissue with anthracnose symptoms from several locations near Tucumán, Argentina. Isolates were characterized using several criteria. Isolates produced fusiform conidia, tapered to a point at both ends, and averaged 13.5 × 4.9 μm. On potato dextrose agar, colonies produced a white cottony mycelial colony that turned orange in older cultures. Compared with Colletotrichum fragariae, the new isolates produced fewer appressoria. Pathogenicity tests were conducted on detached leaves and plants in the greenhouse and field. Detached immature leaves of cvs. Chandler, Fern, and Sweet Charlie were inoculated with a 20-μl droplet of an aqueous conidial suspension (106 conidia per ml) placed on the adaxial surface. Control leaves were inoculated with sterile distilled water. Leaves were maintained under white light (2,000 lux, 12 h/day) at 26°C, and 100% relative humidity. Necrotic spots were visible 4 days after inoculation. Greenhouse and field plants were spray-inoculated and covered for 48 h. Disease symptoms were mainly observed on petioles and runners 9 days after inoculation. No lesions were observed on control detached leaves or plants. Koch's postulates were confirmed in all cases. Based on morphological and cultural characteristics, isolates were identified as C. acutatum Simmonds (1). This is the first report of C. acutatum causing strawberry anthracnose in northwestern Argentina. Reference: (1) B. Smith and L. L. Black. Plant Dis. 74:69, 1990.

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First Report of Anthracnose Caused by Colletotrichum gloeosporioides on Schefflera actinophylla in China

Plant Disease ◽

10.1094/pdis-12-12-1205-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 998-998

Author(s):

J. Huang

Keyword(s):

Dna Sequence ◽

Species Complex ◽

Colletotrichum Gloeosporioides ◽

Conidial Suspension ◽

First Report ◽

Leaf Spots ◽

Black Spots ◽

Pathogenicity Tests ◽

Colletotrichum Gloeosporioides Species Complex ◽

And Control

In China, in mild to warm climates, Schefflera actinophylla is commonly grown as a decorative tree in gardens. When mature, it has bright red flowers in inflorescences with up to 20 racemes that develop in summer or early autumn. From 2008 to 2011, lesions were observed on young and mature leaves in several locations in Guangzhou, China. The first symptoms were circular, necrotic areas that usually developed into irregular, dry, brown to reddish brown or black spots. Spots often first appeared at or near the margins of leaves. Reproductive bodies of the pathogen appeared as black specks in leaf spots. Under a 10× magnification, black, needle-like fungal structures (setae) were observed in the centers of spots on the upper leaf surface. A fungus was isolated from the lesion and was identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. based on cultural characteristics and conidial morphology (1). The voucher isolates were deposited in the Institute of Plant Pathology, Zhongkai University of Agriculture and Engineering. C. gloeosporioides is a species complex (2) and there is a degree of unresolved aspects of taxonomy in this species complex. Cultures on potato dextrose agar (PDA) had aerial white mycelium that turned gray to grayish black after 10 days at 25°C and a 12-h photoperiod and produced salmon to orange conidial masses. Brown, 80 to 120 μm long setae were observed in the acervulus. Conidia 14.1 to 18.0 × 4.0 to 6.1 μm in size were hyaline, thin-walled, aseptate, granular inside, clavate to slightly navicular in shape with an obtuse apex and a truncate base. To identify the fungus, a 588-bp segment of the ITS1-5.8S-ITS2 rDNA region was amplified by PCR and sequenced. The DNA sequence was submitted to GenBank as KC207404. A BLAST search of the DNA sequence showed 99% identity with accessions AY266389.1, EF423519.1, and HM575258.1 of C. gloeosporioides. Pathogenicity tests were conducted under greenhouse conditions at 25 ± 2°C. A total of 15 leaves from three 1-year-old S. actinophylla plants were inoculated with mycelial PDA plugs that were placed on 0.5-cm2 leaf wounds and then wrapped with Parafilm. Control leaves were treated similarly except that they were inoculated with PDA plugs without the fungus. No symptoms developed on control leaves after 10 days. Foliar lesions on inoculated leaves closely resembled those observed in the field. C. gloeosporioides was reisolated consistently from inoculated leaves. Pathogenicity was also tested by spraying leaves of potted S. actinophylla plants about 30 cm in height with 10 ml of a conidial suspension (1 × 105 conidia/ml) prepared from 7-day-old PDA cultures grown at 25°C. Leaves sprayed with distilled water were used as controls. Three plants were inoculated in each of two experiments and were incubated at 25°C and 90% relative humidity in a growth chamber. Tiny brown spots started to develop on all inoculated leaves 5 days after inoculation and the progression of symptom development was similar to that observed in the field. Control leaves remained asymptomatic. C. gloeosporioides was reisolated from inoculated leaves. To my knowledge, this is the first report of C. gloeosporioides causing anthracnose on S. actinophylla in China. References: (1) B. C. Sutton. The genus Glomerella and its anamorph Colletotrichum. In: Colletotrichum Biology, Pathology and Control. CAB International, Wallingford, UK, 1992. (2) B. S. Weir et al. The Colletotrichum gloeosporioides species complex. Stud. Mycol. 73:115, 2012.

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First Report of Phaeoacremonium krajdenii Causing Petri Disease of Grapevine in Spain

Plant Disease ◽

10.1094/pdis-11-10-0808 ◽

2011 ◽

Vol 95 (5) ◽

pp. 615-615 ◽

Cited By ~ 3

Author(s):

D. Gramaje ◽

M. I. Aguilar ◽

J. Armengol

Keyword(s):

Tap Water ◽

Vitis Vinifera L ◽

Sodium Hypochlorite Solution ◽

Malt Extract ◽

First Report ◽

Worldwide Distribution ◽

Black Spots ◽

Pathogenicity Tests ◽

Weak Growth ◽

Human Infections

In September 2009, symptoms of grapevine (Vitis vinifera L.) decline were observed on 3-year-old grapevines in a vineyard in Roquetas de Mar (Almeria Province, southern Spain). Affected vines were weak with reduced foliage and chlorotic leaves. Black spots and dark streaking of the xylem vessels could be seen in cross- or longitudinal sections of the rootstock trunk. Symptomatic plants were collected and sections (10 cm long) were cut from the basal end of the rootstocks, washed under running tap water, surface disinfested for 1 min in a 1.5% sodium hypochlorite solution, and washed twice with sterile distilled water. The sections were split longitudinally and small pieces of discolored tissues were plated onto malt extract agar (MEA) supplemented with 0.5 g liter–1 of streptomycin sulfate. Dishes were incubated at 25 to 26°C in the dark for 14 to 21 days, and all colonies were transferred to potato dextrose agar (PDA). A Phaeoacremonium sp. was consistently isolated from necrotic tissues. Single conidial isolates were obtained and grown on PDA and MEA in the dark at 25°C for 2 to 3 weeks until colonies produced spores (2). Colonies were grayish brown on PDA and dark brown on MEA. Conidiophores were short and unbranched and 11.5 to 46 (25.5) μm long. Phialides were often polyphialidic. Conidia were hyaline, oblong-ellipsoidal or allantoid, 2.5 to 5 (4.2) μm long, and 1 to 1.7 (1.2) μm wide. On the basis of these characters, the isolates were identified as Phaeoacremonium krajdenii L. Mostert, Summerb. & Crous (1,2). DNA sequencing of a fragment of the beta-tubulin gene of the isolate (Pkr-1) using primers T1 and Bt2b (GenBank Accession No. HM637892) matched P. krajdenii GenBank Accession No. AY579330. Pathogenicity tests were conducted using isolate Pkr-1. Ten 1-year-old callused and rooted cuttings of 110 R rootstock grown in pots with sterile peat were wounded at the uppermost internode with an 8-mm cork borer. A 5-mm mycelium PDA plug from a 2-week-old culture was placed in the wound before being wrapped with Parafilm. Ten control plants were inoculated with 5-mm noncolonized PDA plugs. Plants were maintained in a greenhouse at 25 to 30°C. Within 3 months, shoots on all Phaeoacremonium-inoculated cuttings had weak growth with small leaves and short internodes and there were black streaks in the xylem vessels. The vascular necroses that developed on the inoculated plants were 5.5 ± 1.2 cm long, significantly greater than those on the control plants (P < 0.01). Control plants did not show any symptoms. The fungus was reisolated from discolored tissue of all inoculated cuttings, completing Koch's postulates. P. krajdenii has a worldwide distribution, although these reports are from human infections (1). P. krajdenii was first reported as a pathogen of grapevines in South Africa (1). To our knowledge, this is the first report of P. krajdenii causing young grapevine decline in Spain or any country in Europe. References: (1) L. Mostert et al. J. Clin. Microbiol. 43:1752, 2005. (2) L. Mostert et al. Stud. Mycol. 54:1, 2006.

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