First Report of Gliocephalotrichum bulbilium Causing Cranberry Fruit Rot in New Jersey and Massachusetts

Cranberry (Vaccinium macrocarpon) fruit were collected as part of a fruit rot survey conducted in September 2010 on farms in New Jersey and Massachusetts. There are more than 20 fungal species reported as causing fruit rot (2) and symptoms are generally not diagnostic. The rotted fruit were surface sterilized in a 10% bleach solution for 5 min, sliced in half, and plated on V8 agar (nonclarified). A novel, fast-growing fungus that produced sporulating orange-brown colonies emerged from 5% of the fruit collected on three of the farms included in the survey. The fungus was notable as the only species present in the rotted fruit, suggesting it may be pathogenic. The conidia were produced as gloeoid masses on phialidic conidiogenous cells arranged in a polyverticillate penicillus. The conidiogenous cells were subtended at variable distances by zero to four sterile appendages that formed on the lightly pigmented conidiophore. On the basis of these characteristics, the fungus was identified as a species of Gliocephalotrichum (3). Further investigation of the growth medium revealed the presence of clustered, red-brown chlamydospores that were produced abundantly in all isolates. These structures, also known as bulbils, are restricted to two species in the genus, G. bulbilium and G. longibrachium (1). On average, the bulbils were 42.0 × 48.3 μm and conidia were 5.75 × 2.5 μm. On the basis of size and shape of conidia and presence of bulbils, the isolates were identified as G. bulbilium (1). To confirm the identity of the fungus, genomic DNA was extracted and ITS1-5.8S-ITS2 and the 5′ end of the β-tubulin gene were amplified and sequenced (1). The sequences (GenBank Accession Nos. HQ828060 and HQ828061) were compared with published sequences of Gliocephalotrichum isolates (1) and results confirmed the cranberry isolates were G. bulbilium. The isolates were tested for pathogenicity on harvested cranberry fruit. Fifty ripe cranberry fruit (cv. Stevens) were inoculated by injecting approximately 20 μl (using a 26G 9.5-mm needle) of conidia (1 × 105 ml–1) into the side of each berry. As a comparison, isolates of two common cranberry fruit rot pathogens, Colletotrichum acutatum and C. gloeosporioides, were inoculated on to fruit using the same technique. A water-only inoculation was used as the control. Fruit rot developed on all inoculated fruit except the water control. In the case of G. bulbilium, all fruit rotted within 2 days, whereas the other two species developed symptoms within 4 to 7 days. G. bulbilium and both species of Colletotrichum were consistently reisolated from all of the respectively inoculated fruit. To our knowledge, this is the first report of G. bulbilium causing fruit rot on cranberry. The species has been reported as an important postharvest fruit rot (4) on rambutan (Nephelium lappaceum) in Thailand, rambutan and guava (Psidium guajava) in Hawaii, and durian (Durio spp.) in Brunei Darussalam. This report of G. bulbilium extends the range within the United States to include Louisiana, Hawaii, Wisconsin, West Virginia, New Jersey, and Massachusetts (2). References: (1) C. Decock et al. Mycologia 98:488, 2006. (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/ , 16 December 2010. (3) A. Rossman et al. Mycologia, 85:685, 1993. (4) A. Sivapalan et al. Australas. Plant Pathol. 27:274, 1998.

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First Report of Anthracnose Caused by Colletotrichum acutatum on Persimmon Fruit in the United States

Plant Disease ◽

10.1094/pdis-94-5-0634a ◽

2010 ◽

Vol 94 (5) ◽

pp. 634-634 ◽

Cited By ~ 7

Author(s):

S. M. Williamson ◽

T. B. Sutton

Keyword(s):

United States ◽

Filter Paper ◽

The United States ◽

Grocery Store ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Diospyros Kaki ◽

Japanese Persimmon ◽

First Report ◽

Persimmon Fruit

Persimmon trees are important for their fruit as well as their colorful fruit and foliage in the fall. Persimmon fruit (Japanese persimmon, Diospyros kaki cv. Fuyu) were collected in November 2008 from a tree in Windsor, NC, located in the Coastal Plain. Fruit were not symptomatic on the tree but developed dark lesions after harvest. Isolations from six fruit yielded seven isolates of Colletotrichum acutatum J. H. Simmonds. After incubation at 25°C under continuous light for 15 days on potato dextrose agar (PDA), all isolates had gray aerial mycelium, but the inverse sides of the plates of six isolates were maroon and one was beige. Masses of salmon-colored conidia were formed first in the center of the colonies, then were observed scattered across the colonies in older cultures. Conidia were hyaline, one-celled, elliptic with one or both ends pointed, and measured 8.1 to 16.3 × 3.1 to 5 μm. Setae and sclerotia were not observed. There were also dark structures measuring 1 to 10 mm that were partially embedded in the agar that contained conidia. Cultural and conidial characteristics of the isolates were similar to those of C. acutatum (3). PCR amplification was performed with the species-specific primer pair CaInt2/ITS4 (2) and genomic DNA from the original isolates and isolates obtained from inoculated fruit. An amplification product of approximately 490 bp, which is specific for C. acutatum, was observed. To fulfill Koch's postulates, persimmon fruit obtained from the grocery store were surface disinfested with 0.5% sodium hypochlorite and sterile filter paper disks dipped in conidial suspensions (1 × 105 conidia/ml) of two C. acutatum isolates (maroon and beige reverse) or sterile, deionized water were placed on the fruit. Three fruit were inoculated per treatment and the disks were placed on four locations on each fruit. Parafilm was wrapped around the diameter of the fruit to keep the filter paper disks moist and in place. Fruit were placed in moist chambers and incubated at 25°C. After 3 days, the Parafilm was removed and the fruit returned to the moist chambers. Small, dark lesions were observed on fruit inoculated with each isolate of C. acutatum when the filter paper disks were removed. Ten days after inoculation, dark lesions and acervuli with salmon-colored masses of conidia were observed on fruit inoculated with both isolates of C. acutatum and the fruit were soft. After 12 days, there were abundant masses of conidia and the inoculated areas were decayed. Control fruit remained firm and did not develop symptoms. Cultures obtained from the fruit and the conidia produced were typical of the isolates used to inoculate the fruit. C. acutatum has been reported to cause fruit rot on persimmon fruit in New Zealand (1). To our knowledge, this is the first report of C. acutatum on persimmon fruit in the United States. References: (1) R. Lardner et al. Mycol. Res. 103:275, 1999. (2) S. Sreenivasaprasad et al. Plant Pathol. 45:650, 1996. (3) B. C. Sutton. Page 523 in: Coelomycetes. Commonwealth Agricultural Bureaux, Great Britain. 1980.

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First Report of Lasmenia sp. and Two Species of Gliocephalotrichum on Rambutan in Hawaii

Plant Disease ◽

10.1094/pdis.2002.86.1.71c ◽

2002 ◽

Vol 86 (1) ◽

pp. 71-71 ◽

Cited By ~ 4

Author(s):

K. A. Nishijima ◽

P. A. Follett ◽

B. C. Bushe ◽

M. A. Nagao

Keyword(s):

The United States ◽

Psidium Guajava ◽

Fruit Rot ◽

Fluorescent Light ◽

Tropical Fruit ◽

Centraalbureau Voor ◽

First Report ◽

Culture Characteristics ◽

Decaying Wood ◽

Branch Dieback

Rambutan (Nephelium lappaceum L.) is a tropical fruit grown in Hawaii for the exotic fruit market. Fruit rot was observed periodically during 1998 and 1999 from two islands, Hawaii and Kauai, and severe fruit rot was observed during 2000 in orchards in Kurtistown and Papaikou on Hawaii. Symptoms were characterized by brown-to-black, water-soaked lesions on the fruit surface that progressed to blackening and drying of the pericarp, which often split and exposed the aril (flesh). In certain cultivars, immature, small green fruits were totally mummified. Rambutan trees with high incidence of fruit rot also showed symptoms of branch dieback and leaf spot. Lasmenia sp. Speg. sensu Sutton, identified by Centraalbureau voor Schimmelcultures (Baarn, the Netherlands), was isolated from infected fruit and necrotic leaves. Also associated with some of the fruit rot and dieback symptoms were Gliocephalotrichum simplex (J.A. Meyer) B. Wiley & E. Simmons, and G. bulbilium J.J. Ellis & Hesseltine. G. simplex was isolated from infected fruit, and G. bulbilium was isolated from discolored vascular tissues and infected fruit. Identification of species of Gliocephalotrichum was based on characteristics of conidiophores, sterile hairs, and chlamydospores (1,4). Culture characteristics were distinctive on potato dextrose agar (PDA), where the mycelium of G. bulbilium was light orange (peach) without reverse color, while G. simplex was golden-brown to grayish-yellow with dark brown reverse color. Both species produced a fruity odor after 6 days on PDA. In pathogenicity tests, healthy, washed rambutan fruits were wounded, inoculated with 30 μl of sterile distilled water (SDW) or a fungus spore suspension (105 to 106 spores per ml), and incubated in humidity chambers at room temperature (22°C) under continuous fluorescent light. Lasmenia sp. (strain KN-F99-1), G. simplex (strain KN-F2000-1), and G. bulbilium (strains KN-F2001-1 and KN-F2001-2) produced fruit rot symptoms on inoculated fruit and were reisolated from fruit with typical symptoms, fulfilling Koch's postulates. Controls (inoculated with SDW) had lower incidence or developed less severe symptoms than the fungus treatments. Inoculation tests were conducted at least twice. To our knowledge, this is the first report of Lasmenia sp. in Hawaii and the first report of the genus Gliocephalotrichum on rambutan in Hawaii. These pathogens are potentially economically important to rambutan in Hawaii. G. bulbilium has been reported previously on decaying wood of guava (Psidium guajava L.) in Hawaii (2), and the fungus causes field and postharvest rots of rambutan fruit in Thailand (3). References: (1) J. J. Ellis and C. W. Hesseltine. Bull. Torrey Bot. Club 89:21, 1962. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (3) N. Visarathanonth and L. L. Ilag. Pages 51–57 in: Rambutan: Fruit Development, Postharvest Physiology and Marketing in ASEAN. ASEAN Food Handling Bureau, Kuala Lumpur, Malaysia, 1987. (4) B. J. Wiley and E. G. Simmons. Mycologia 63:575, 1971.

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First Report of Gliocephalotrichum bulbilium Causing Fruit Rot of Posthavest Mangosteen in China

Plant Disease ◽

10.1094/pdis-09-13-0917-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 994-994 ◽

Cited By ~ 1

Author(s):

Y. X. Li ◽

W. X. Chen ◽

A. Y. Liu ◽

Q. L. Chen ◽

S. J. Feng

Keyword(s):

Its Region ◽

The United States ◽

Psidium Guajava ◽

Morphological Characters ◽

Fruit Rot ◽

Diseased Plant ◽

Garcinia Mangostana ◽

Single Spore ◽

Tropical Fruit ◽

First Report

Mangosteen (Garcinia mangostana L., Guttiferae) is a tropical fruit renowned for its pleasant taste, rich nutrition, and medicinal value. Little research about mangosteen diseases during storage and transport has been reported. In June of 2012, fruit rots on mangosteens imported from Thailand were observed in Guangzhou, China. In infected fruits, pericarps showed an increased firmness, were discolored to deep pink, and the edible aril became brown and rotten. In order to search for the etiological agent of this rot symptom, infected mangosteens were analyzed. Diseased mangosteen tissues were surface-sterilized with 70% alcohol, then with 0.1% HgCl2, dipped in sterilized water three times, and placed onto potato dextrose agar (PDA) at 26°C. The fungi isolated from tissues of the pericarp and aril were similar in morphology and grew rapidly, covering the plate surface (9 mm diameter) after 2 to 3 days of incubation at 26°C. The morphological characters of 10 single-spore isolates were observed. These isolates showed light yellow to light brown fertile colonies on PDA. On corn meal agar (CMA), conidiophores were erect, arising from wide hyphae; they were composed of a basal stipe ending in a penicillate conidiogenous apparatus with directly subtending sterile stipe extensions ranging from 74.5 to 195.0 μm long. Conidia were unicellular, smooth, oblong to elliptical, 6.3 to 8.5 × 2.5 to 3.0 μm, and accumulated in a mucilaginous mass. Chlamydospores were multicellular, dark brown, regular in shape and thick-walled, and 40.0 to 52.5 μm in diameter. On the basis of these morphological characters, these isolates were identified as Gliocephalotrichum bulbilium (2). To confirm the identity of this fungus, genomic DNA of two isolates was extracted, and fragments of ITS region and β-tubulin gene were amplified by PCR, sequenced, and compared with sequences of Gliocephalotrichum species available in NCBI GenBank. Both DNA regions (GenBank Accession Nos. KF716166 and KF716168) had sequence similarities of 99% and 97%, respectively, to other G. bulbilium sequences at GenBank. Pathogenicity tests were conducted on three detached fruits for two isolates. Fruits were inoculated using 5-mm mycelial disks with conidia taken from 3-day-old cultures of G. bulbilium isolate Gb1 and Gb10 grown on PDA. Controls were inoculated with PDA disks only. All treated fruits were kept individually in a humid chamber at 26°C. Tests were repeated twice. Three days after inoculation, white mycelial growth for Gb was observed at inoculation sites. Eight days after inoculation, mycelium of Gb nearly covered the fruit, causing fruit rot, and the pericarp became hard and light in color. The control fruit did not rot. G. bulbilium was re-isolated from diseased plant tissue, thus fulfilling Koch's postulates. G. bulbilium has been reported causing postharvest fruit rot of rambutan (Nephelium lappaceum) and guava (Psidium guajava) in some locations (3,4). Moreover, the fungus caused cranberry fruit rot in the United States (1). To our knowledge, this is the first report of G. bulbilium causing postharvest fruit rot of mangosteen in China. It is uncertain whether the fungus infected mangosteen in Thailand and was carried to China due to commercial relationship. References: (1) C. Constantelos et al. Plant Dis. 95:618, 2011. (2) C. Decock et al. Mycologia 98:488, 2006. (3) L. M. Serrato-Diaz et al. Plant Dis. 96:1225, 2012. (4) A. Sivapalan et al. Australas. Plant Pathol. 27:274, 1998.

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First Report of Neoscytalidium dimidiatum Causing Fruit Rot on Guava (Psidium guajava) in Malaysia

Plant Disease ◽

10.1094/pdis-06-20-1267-pdn ◽

2021 ◽

Vol 105 (1) ◽

pp. 220

Author(s):

S. I. Ismail ◽

K. Ahmad Dahlan ◽

S. Abdullah ◽

D. Zulperi

Keyword(s):

Psidium Guajava ◽

Fruit Rot ◽

First Report ◽

Neoscytalidium Dimidiatum

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First Report of Anthracnose Fruit Rot Caused by Colletotrichum fioriniae on Red Raspberry (Rubus idaeus) in the Mid-Atlantic Region of the United States

Plant Disease ◽

10.1094/pdis-10-19-2256-pdn ◽

2020 ◽

Vol 104 (6) ◽

pp. 1855

Author(s):

A. Schoeneberg ◽

M.-J. Hu

Keyword(s):

United States ◽

The United States ◽

Rubus Idaeus ◽

Fruit Rot ◽

Red Raspberry ◽

Atlantic Region ◽

First Report

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First Report of Guignardia psidii, an Ascigerous State of Phyllosticta psidiicola, Causing Fruit Rot on Guava in Venezuela

Plant Disease ◽

10.1094/pd-89-0773c ◽

2005 ◽

Vol 89 (7) ◽

pp. 773-773 ◽

Cited By ~ 1

Author(s):

M. S. González ◽

A. Rondón

Keyword(s):

Psidium Guajava ◽

Potato Dextrose Agar ◽

Fruit Rot ◽

Symptom Development ◽

First Report ◽

Guava Fruit ◽

Pathogenicity Tests ◽

Apical Appendage ◽

Ascigerous State ◽

Gelatinous Envelope

During August 2003, guava fruit (Psidium guajava L.) cv. Red Dominicana from Cojedes state in Venezuela showed circular, purple-to-brown lesions (0.5 to 1.0 cm) that spread over all surfaces and became black and shrunken on severely affected fruit. Symptomatic tissues were plated aseptically on potato dextrose agar (PDA). Colonies that were initially gray and turned black with age were consistently isolated. The fungus was characterized by dense, submerged, brown-to-black mycelium with septate hyphae. Ascocarps were perithecial, abundant, granulose, subglobose to cylindric obpyriform, solitary or aggregated, mostly unilocular with prominent long necks; ascocarp walls were stromatic, composed of several layers of cells, thick walled, and deeply pigmented on the outside. Asci were subclavate to cylindrical, stipitate, 44 to 84 × 7 to 9 μm, and eight-spored; asci walls were thick and bitunicate. Ascospores were unicellular, hyaline, guttulate, fusiform ellipsoid, widest in the mid-region with rounded ends and gelatinous plugs, and 12 to 17 × 4.5 μm. Conidiomata were pycnidial, intermixed among ascocarps, variable in shape, dark brown, solitary or aggregated, ostiolate, and with long necks up to 1 mm. Pycnidial walls were pseudoparenchymatic, multicellular, and composed of many layers of brown compressed cells. Conidiogenous cells were hyaline, subglobose to cylindrical, and smooth, and holoblastic. Conidia were hyaline, unicellular, obovate, 6 to 12 (7.5) × 5 to 8 μm, slightly truncate at the bases, rounded at apices, guttulate, and provided a gelatinous envelope and apical appendage. Appendages were hyaline, tubular, smooth, and 3.0 to 4.5 × 0.5 μm. The fungus is homothallic because single ascospores and single conidia developed ascigerous states. The ascigerous state was identified as Guignardia psidii (1) and the anamorph as Phyllosticta psidiicola (1,2). Pathogenicity tests were conducted on detached fruits inoculated with monosporic cultures. Pathogenesis and symptom development only occurred when a mixture of mycelium, ascospores, and conidia was used as inoculum. The fungus was reisolated from symptomatic fruit tissues. To our knowledge, this is the first report of Guignardia psidii, an ascigerous state of Phyllosticta psidiicola from guava fruits in Venezuela. References: (1) B. A. Ullasa and R. D. Rawal. Curr. Sci. 53:435, 1984. (2) H. A. van der Aa. Page 95 in: No. 5, Stud. Mycol., 1973.

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First Report of Colletotrichum fructicola and C. queenslandicum Causing Fruit Rot of Rambutan (Nephelium lappaceum)

Plant Disease ◽

10.1094/pdis-11-16-1557-pdn ◽

2017 ◽

Vol 101 (6) ◽

pp. 1043 ◽

Cited By ~ 3

Author(s):

L. M. Serrato-Diaz ◽

L. I. Rivera-Vargas ◽

R. Goenaga ◽

E. D. Navarro ◽

R. D. French-Monar

Keyword(s):

Fruit Rot ◽

First Report ◽

Nephelium Lappaceum ◽

Colletotrichum Fructicola

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First Report of Postharvest Fruit Rot in Persimmon Caused by Phacidiopycnis washingtonensis in Italy

Plant Disease ◽

10.1094/pdis-94-6-0788b ◽

2010 ◽

Vol 94 (6) ◽

pp. 788-788 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. T. Amatulli ◽

M. L. Gullino

Keyword(s):

United States ◽

Its Region ◽

The United States ◽

Fruit Rot ◽

Diospyros Kaki ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report ◽

Pathogenicity Tests ◽

Phacidiopycnis Washingtonensis

Persimmon (Diospyros kaki L.) is widely grown in Italy, the leading producer in Europe. In the fall of 2009, a previously unknown rot was observed on 3% of fruit stored at temperatures between 5 and 15°C in Torino Province (northern Italy). The decayed area was elliptical, firm, and appeared light brown to dark olive-green. It was surrounded by a soft margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. On the decayed tissue, black pycnidia that were partially immersed and up to 0.5 mm in diameter were observed. Light gray conidia produced in the pycnidia were unicellular, ovoid or lacriform, and measured 3.9 to 6.7 × 2.3 to 3.5 (average 5.0 × 2.9) μm. Fragments (approximately 2 mm) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at temperatures between 23 and 26°C under alternating light and darkness. Colonies of the fungus initially appeared ash colored and then turned to dark greenish gray. After 14 days of growth, pycnidia and conidia similar to those described on fruit were produced. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 502-bp segment showed a 100% similarity with the sequence of Phacidiopycnis washingtonensis Xiao & J.D. Rogers (GenBank Accession No. AY608648). The nucleotide sequence has been assigned the GenBank Accession No. GU949537. Pathogenicity tests were performed by inoculating three persimmon fruits after surface disinfesting in 1% sodium hypochlorite and wounding. Mycelial disks (10 mm in diameter), obtained from PDA cultures of one strain were placed on wounds. Three control fruits were inoculated with plain PDA. Fruits were incubated at 10 ± 1°C. The first symptoms developed 6 days after the artificial inoculation. After 15 days, the rot was very evident and P. washingtonensis was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice. Since P. washingtonensis was first identified in the United States on decayed apples (2), ‘Fuji’, ‘Gala’, ‘Golden Delicious’, ‘Granny Smith’, ‘Red Chief’, and ‘Stark Delicious’, apple fruits also were artificially inoculated with a conidial suspension (1 × 106 CFU/ml) of the pathogen obtained from PDA cultures. For each cultivar, three surface-disinfested fruit were wounded and inoculated, while three others served as mock-inoculated (sterile water) controls. Fruits were stored at temperatures ranging from 10 to 15°C. First symptoms appeared after 7 days on all the inoculated apples. After 14 days, rot was evident on all fruit inoculated with the fungus, and P. washingtonensis was consistently reisolated. Controls remained symptomless. To our knowledge, this is the first report of the presence of P. washingtonensis on persimmon in Italy, as well as worldwide. The occurrence of postharvest fruit rot on apple caused by P. washingtonensis was recently described in the United States (3). In Italy, the economic importance of the disease on persimmon fruit is currently limited, although the pathogen could represent a risk for apple. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) Y. K. Kim and C. L. Xiao. Plant Dis. 90:1376, 2006. (3) C. L. Xiao et al. Mycologia 97:473, 2005.

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First report of preharvest fruit rot of ‘Pink Lady’ apples caused by Colletotrichum fructicola in Italy

Plant Disease ◽

10.1094/pdis-11-20-2404-pdn ◽

2021 ◽

Author(s):

Marcel Wenneker ◽

Khanh Pham ◽

Engelien Kerkhof ◽

Dalphy O.C. Harteveld

Keyword(s):

Species Complex ◽

Management Strategies ◽

Morphological Characteristics ◽

Late Summer ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Apple Orchards ◽

First Report ◽

Bitter Rot ◽

Colletotrichum Fructicola

In late summer 2019, a severe outbreak of fruit rot was observed in commercial ‘Pink Lady’ apple orchards (>20 ha in total) in the region Emilia-Romagna (Northern Italy). The symptoms on the fruit appeared as small circular red to brown lesions. Disease incidences of over 50% of the fruits were observed. To isolate the causal agent, 15 affected apples were collected and small portions of fruit flesh were excised from the lesion margin and placed on potato dextrose agar (PDA). The plates were incubated at 20°C in the dark, and pure cultures were obtained by transferring hyphal tips on PDA. The cultures showed light to dark gray, cottony mycelium, with the underside of the culture being brownish and becoming black with age. Conidia (n=20) were cylindrical, aseptate, hyaline, rounded at both ends, and 12.5 to 20.0 × 5.0 to 7.5 μm. The morphological characteristics were consistent with descriptions of Colletotrichum species of the C. gloeosporioides species complex, including C. fructicola (Weir et al. 2012). The identity of two representative isolates (PinkL2 & PinkL3) from different apples was confirmed by means of multi-locus gene sequencing. Genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Molecular identification was conducted by sequencing the ITS1/ITS4 region and partial sequences of four other gene regions: chitin synthase (CHS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), and beta-tubulin (TUB). The sequences have been deposited in GenBank under accession numbers MT421924 & MT424894 (ITS), MT424612 & MT424613 (CHS), MT424616 & MT424617 (GAPDH), MT424614 & MT424615 (ACT), and MT424620 & MT424621 (TUB). MegaBLAST analysis revealed that our ITS sequences matched with 100% identity to Colletotrichum fructicola (Genbank JX010177). The CHS, GAPDH, ACT and TUB sequences of both isolates were 100% identical with C. fructicola culture collection sequences in Genbank (JX009807, JX009923, JX009436 and JX010400, respectively), confirming the identity of these isolates as C. fructicola. Koch's postulates were performed with 10 mature ‘Pink Lady’ apples. Surface sterilized fruit were inoculated with 20 μl of a suspension of 105 conidia ml–1 after wounding with a needle. The fruits were incubated at 20˚C at high relative humidity. Typical symptoms appeared within 4 days on all fruit. Mock-inoculated controls with sterile water remained symptomless. The fungus was reisolated and confirmed as C. fructicola by morphology and sequencing of all previously used genes. Until recently the reported causal agents of bitter rot of apple in Europe belong to the Colletotrichum acutatum species complex (Grammen et al. 2019). C. fructicola, belonging to C. gloeosporioides species complex, is known to cause bitter rot of apple in the USA, Korea, Brazil, and Uruguay (Kim et al. 2018; Velho et al. 2015). There is only one report of bitter rot associated with C. fructicola on apple in Europe (France) (Nodet et al. 2019). However, C. fructicola is also the potential agent of Glomerella leaf spot (GLS) of apple (Velho et al. 2015; 2019). To the best of our knowledge this is the first report of C. fructicola on apples in Italy. It is important to stress that the C. gloeosporioides species complex is still being resolved and new species on apple continue to be identified, e.g. C. chrysophilum that is very closely related to C. fructicola (Khodadadi et al. 2020). Given the risks of this pathogen the presence of C. fructicola in European apple orchards should be assessed and management strategies developed.

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First Report of Calonectria hongkongensis Causing Fruit Rot of Rambutan (Nephelium lappaceum)

Plant Disease ◽

10.1094/pdis-01-13-0008-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1117-1117 ◽

Cited By ~ 2

Author(s):

L. M. Serrato-Diaz ◽

E. I. Latoni-Brailowsky ◽

L. I. Rivera-Vargas ◽

R. Goenaga ◽

P. W. Crous ◽

...

Keyword(s):

Mycelial Growth ◽

Elongation Factor ◽

Type Specimen ◽

Fruit Rot ◽

Fluorescent Light ◽

Mycelium Growth ◽

Tropical Fruit ◽

First Report ◽

Nephelium Lappaceum ◽

Pure Cultures

Fruit rot of rambutan is a pre- and post-harvest disease problem of rambutan orchards. In 2011, fruit rot was observed at USDA-ARS orchards in Mayaguez, Puerto Rico. Infected fruit were collected and 1 mm2 tissue sections were surface disinfested with 70% ethanol followed by 0.5% sodium hypochlorite. Infected fruit were rinsed with sterile, deionized, double-distilled water and transferred to acidified potato dextrose agar (APDA). Plates were incubated at 25 ± 1°C for 6 days. Three isolates of Calonectria hongkongensis (Cah), CBS134083, CBS134084, and CBS134085, were identified morphologically using taxonomic keys (2,3). In APDA, colonies of Cah produced raw sienna to rust-colored aerial mycelial growth. Conidiophores of Cah had a penicillate arrangement of primary to quaternary branches of 2 to 6 phialides. Conidia (n = 50) were cylindrical, hyaline, 1-septate, rounded at both ends, and 44 to 52 μm × 3.5 to 4.5 μm. Conidiophores produced terminal and lateral stipe extensions with terminal sphaeropedunculate vesicles that were 8 to 12 μm wide. Subglobose to ovoid perithecia, 300 to 500 μm × 200 to 350 μm and orange to red-brown, were produced in groups of 3. Asci were clavate and contained 8 ascospores aggregated at the top of the ascus. Ascospores (n = 50) were hyaline, guttulate, fusoid with rounded ends, straight to curved, 1-septate with constriction at the septum, and 28 to 36 μm × 4 to 7 μm. For molecular identification, the ITS rDNA, fragments of β-tubulin (BT), histone H3 (HIS3), and elongation factor (EF1-α) genes were amplified by PCR, sequenced, and compared using BLASTn with Calonectria spp. submitted to the NCBI GenBank. The sequences of Cah submitted to GenBank include accessions KC342208, KC342206, and KC342207 for ITS; KC342217, KC342215, and KC342216 for BT; KC342211, KC342209, and KC342210 for HIS3; and KC342214, KC342212, and KC342213 for EF1α. The sequences were >99% or identical with the ex-type specimen of Cah CBS 114828 for all genes used. Pathogenicity tests were conducted on 5 healthy superficially sterilized fruits per isolate. Both scalpel-wounded and unwounded fruit tissues were inoculated with 5-mm mycelial disks from 8-day-old pure cultures grown in APDA. Untreated controls were inoculated with APDA disks only. Fruits were kept in a humid chamber for 8 days at 25°C under 12 h of fluorescent light. The test was repeated once. Three days after inoculation (DAI), white mycelial growth was observed on the fruit. Five DAI, the fruit changed color from red to brown and yellowish mycelia colonized 50 to 62% of the fruit surface. Eight DAI, all the fruit turned brown, the mycelium growth covered the entire fruit, and conidiophores were produced on spinterns (hairlike appendages). Fruit rot of spinterns, exocarp (skin), endocarp (aril), and light brown discoloration were observed inside the fruit. Untreated controls showed no symptoms of fruit rot and no fungi were reisolated from tissue. Cah was reisolated from diseased tissue, fulfilling Koch's postulates. Calonectria spp. (or their Cylindrocladium asexual states) have been associated with lychee decline syndrome in North Vietnam (1). Both fruits belong to the Sapindaceae family. To our knowledge, this is the first report of Cah causing fruit rot of rambutan. References: (1) L. M. Coates et al. Diseases of Longan, Lychee and Rambutan. Pages 307-325 in: Diseases of Tropical Fruit Crops. R. C. Ploetz, ed. CABI Publishing, Cambridge, MA, 2003. (2) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. APS Press, St Paul, MN, 2002. (3) P. W. Crous, et al. Stud. Mycol. 50:415, 2004.

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