First Report of Neopestalotiopsis mesopotamica causing root and crown rot on strawberry in Ecuador

In Ecuador, strawberry production is located in the Andean region with an area of 1000 ha. Albion is the most popular cultivar due to its conical fruit shape, fruit size, bright red color, and sweetness. Since June 2014, farmers reported a reduction in the production cycle from 24 months to 6-8 months and a decreased yield of around 50% due to an unknown soil pathogen. Plant symptoms presented a reddish discoloration on new leaves, coming through the leaf apex to the petiole until turning wholly brown in old leaves leading to plant death. Additionaly, a brown-reddish spot inside the strawberry crown and root rot were reported (Fig. S1). In 2020, in Ecuador's most extensive production area, called Yaruqui (Pichincha province), 25 diseased plants were collected for pathogen isolation. The pathogen was isolated on water agar medium from the crowns internal tissue using 0.5 cm diseased plant fragments, previously disinfected with 2% sodium hypochlorite, and rinsed with sterile water. After two days, single hyphal tip was reisolated on potato dextro agar (PDA). A total of 18 pure isolates were grown at 25°C for 12 days, then 3-7 days of blacklight treatment was applied to induce sporulation. All the isolates presented a cottony beige mycelium with undulate edges. The conidia were ellipsoidal (range between 20.73 to 29 µm in length and 6.2 to 8.77 µm in width; n=60), multiseptated (4 segments) showing hyaline apical (3.8 to 5 µm) and basal (4.87 to 8 µm) cells, and three brown median cells, the second and third were darker than the fourth one, with one basal and 2 to 4 apical appendages (26.09 to 38.7 µm; Fig. S1). According to colony and conidia morphology, the isolates were identified as Neopestalotiopsis sp. (Dung et al. 2016; Essa et al. 2018; Maharachchikumbura et al. 2011). Five isolates were select randomly for DNA extraction and sequencing of the internal transcribed spacer (ITS) region (ITS4/ITS5), β-tubulin (Bt2b/ T1), and translation elongation factor 1-alpha (TEF-1a) region (EF1-728/ EF1-986) (Maharachchikumbura et al. 2014). DNA sequences obtained from each marker were identical for all isolates. Consensus sequences and alignment were built using ClustalX in MEGA X (Kumar et al. 2018). The consensus sequences were deposited in GenBank with the following accession numbers: ITS, MZ047602; β-tubulin, MZ054301; and TEF-1a, MZ054302. A multilocus Bayesian inference phylogenetic tree was constructed using the concatenated sequences in the Beast software (version 1.8.4)(Drummond et al. 2012; Maharachchikumbura et al. 2014). The isolate in our study clustered with isolates of Neopestalotiopsis mesopotamica with a posterior probability of 1, confirming its identity (Fig. S2). For Koch's postulates, healthy plants were grown in sterile soil for four months. Conidia of the pathogen were suspended in potato dextro broth (PDB) (1 x 104 conidia/ml), and it was sprayed on 15 healthy plants that previously had their crowns wounded with a sterile needle (0.6 cm deep) at the four cardinal points. The control treatment (15 plants) was wounded and sprayed with PDB alone. The plants were maintained at 25°C and more than 85% relative humidity (Sigillo et al. 2020). Twelve days after inoculation, plants showed reddish discoloration on new leaves, and old leaves presented low-level wilt, rusty color, and necrotic petioles. Forty-one days later, 75% of the treated plants had severe wilt or were dead, showing root and crown rot. Control plants presented no symptoms of the disease. Reisolation of the pathogen from the disease crown tissues was done on water agar and PDA as previously described. The isolates presented the exact morphology of pure cultures obtained from field diseased strawberry crowns. The pathogenicity test was performed twice. To our knowledge, this is the first report of Neopestalotiopsis mesopotamica being the causal agent of root and crown rot on strawberries in Ecuador. N. iranensis and N. mesopotamica have been reported as causal agents of strawberries fruit rot and leaf lesions in Iran (Ayoubi and Soleimani, 2016), and N. clavispora was reported to be causing root and crown rot on strawberry plants in Argentina (Obregon et al. 2018). Disease diagnosis contributes to providing strategies against this new disease. Further investigations are needed to find biological/chemical techniques or cultivar resistance to control this pathogen in strawberries in Ecuador.

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First Report of Phytophthora citrophthora on Penstemon barbatus in Italy

Plant Disease ◽

10.1094/pd-90-1260a ◽

2006 ◽

Vol 90 (9) ◽

pp. 1260-1260 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

D. Minerdi ◽

M. L. Gullino

Keyword(s):

Its Region ◽

The United States ◽

Phytophthora Species ◽

Crown Rot ◽

Pathogenicity Test ◽

Phytophthora Citrophthora ◽

First Report ◽

Blastn Analysis ◽

Root And Crown Rot ◽

Pathogenicity Tests

Penstemon barbatus (Cav.) Roth (synonym Chelone barbata), used in parks and gardens and sometimes grown in pots, is a plant belonging to the Scrophulariaceae family. During the summers of 2004 and 2005, symptoms of a root rot were observed in some private gardens located in Biella Province (northern Italy). The first symptoms resulted in stunting, leaf discoloration followed by wilt, root and crown rot, and eventually, plant death. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on a semiselective medium for Oomycetes (4). The microorganism consistently isolated from infected tissues, grown on V8 agar at 22°C, produced hyphae with a diameter ranging from 4.7 to 5.2 μm. Sporangia were papillate, hyaline, measuring 43.3 to 54.4 × 26.7 to 27.7 μm (average 47.8 × 27.4 μm). The papilla measured from 8.8 to 10.9 μm. These characteristics were indicative of a Phytophthora species. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 800 bp obtained showed a 100% homology with Phytophthora citrophthora (R. & E. Sm.) Leonian. The nucleotide sequence has been assigned GenBank Accession No. DQ384611. For pathogenicity tests, the inoculum of P. citrophthora was prepared by growing the pathogen on autoclaved wheat and hemp kernels (2:1) at 25°C for 20 days. Healthy plants of P. barbatus cv. Nano Rondo, 6 months old, were grown in 3-liter pots (one plant per pot) using a steam disinfested substrate (peat/pomix/pine bark/clay 5:2:2:1) in which 200 g of kernels per liter of substrate were mixed. Noninoculated plants served as control treatments. Three replicates were used. Plants were maintained at 15 to 20°C in a glasshouse. The first symptoms, similar to those observed in the gardens, developed 21 days after inoculation, and P. citrophthora was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice with similar results. A nonspecified root and crown rot of Penstemon spp. has been reported in the United States. (2). To our knowledge, this is the first report of P. citrophthora on P. barbatus in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) F. E. Brooks and D. M. Ferrin. Plant Dis. 79:212, 1995. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) H. Masago et al. Phytopathology 67:425, 1977.

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First Report of Crown and Root Rot Caused by Phytophthora capsici on Hydroponically Grown Cucumbers in Norway

Plant Disease ◽

10.1094/pdis-92-7-1138c ◽

2008 ◽

Vol 92 (7) ◽

pp. 1138-1138 ◽

Cited By ~ 3

Author(s):

M. L. Herrero ◽

M. B. Brurberg ◽

A. Hermansen

Keyword(s):

Mating Type ◽

Phytophthora Capsici ◽

Crown Rot ◽

Yield Reduction ◽

Cox1 Gene ◽

Pathogenicity Test ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Leaf Stage ◽

Root And Crown Rot

In December 2004, symptoms of root and crown rot were observed on cucumbers (Cucumis sativus L.) in a greenhouse in Norway. Cucumbers were the only crop of the greenhouse that used rockwool as a growing substrate in a hydroponical system. The first symptoms were detected in propagation material. One week after planting, symptoms of root and crown rot were observed and approximately 10% of the plants died. Later, losses of 50% in some greenhouses were observed. A yield reduction as much as 65% was estimated in the winter period (January and February). The two main cucumber cultivars planted were Armada and Lopez. In February 2005, Phytophthora capsici (Leonian) (1) was isolated on potato dextrose agar from a sample of cv. Lopez. The isolate produced deciduous, papillate sporangia (occasionally with two or three papilla) and pedicels that were sometimes longer than the sporangia. Sequencing of amplicons of the internal transcribed spacer region (ITS) rDNA and of the mitochondrial cytochrome c oxidase subunit 1 (Cox1) gene (2) confirmed the identification. Three isolates collected through 2005 from the same greenhouse were crossed with tester strains of P. cryptogea. Formation of oogonia and amphigynous antheridia was always observed in crosses with mating type A2; thus, all isolates were the A1 mating type. All three isolates grew well at 35°C and did not produce chlamydospores. A pathogenicity test was performed with one isolate of P. capsici. Four plants of cucumber cvs. Indira and Jessica were grown in a growth chamber at 24°C. Plants at the two-leaf stage were drenched with 20 ml of a zoospore suspension of 106 zoospores per ml per plant. After 18 days, all plants of both cultivars developed symptoms of crown rot or wilted and died. P. capsici was reisolated from inoculated plants of both cultivars. The pathogenicity test was repeated in the same way, but in a greenhouse with temperatures that ranged between 18 and 29°C. In addition, four plants of both cultivars at the four-leaf stage were inoculated with a suspension of 105 zoospores per ml. After 1 week, all plants developed crown rot or were irreversibly wilted, independently of the plant age or the zoospore concentration. To our knowledge, this is the first report of P. capsici in Norway. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society St. Paul MN, 1996. (2) L. P. N. M. Kroon et al. Phytopathology 94:613, 2004.

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First Report of Postharvest Fruit Rot in Avocado (Persea americana) Caused by Lasiodiplodia theobromae in Italy

Plant Disease ◽

10.1094/pdis-10-11-0886 ◽

2012 ◽

Vol 96 (3) ◽

pp. 460-460 ◽

Cited By ~ 6

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. T. Amatulli ◽

J. Cardinale ◽

M. L. Gullino

Keyword(s):

Plant Pathogens ◽

Morphological Characteristics ◽

The United States ◽

Disease Diagnosis ◽

Persea Americana ◽

Fruit Rot ◽

Pathogenicity Test ◽

Lasiodiplodia Theobromae ◽

First Report ◽

Pathogenicity Tests

Avocado (Persea americana Mill.) is grown in some areas of southern Italy. In spring 2011, a previously unknown rot was observed on fruit that was marketed in Torino (northern Italy). The decayed area started from the stalk, appeared irregular and soft, and was surrounded by a dark brown margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. Fragments (approximately 3 mm) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at temperatures between 21 and 25°C under alternating conditions of light and dark. Colonies of the fungus initially appeared whitish, later turning mouse gray to black. Mature mycelium was septate and produced a dark pigment. The fungus, grown on oat agar (2) and incubated at temperatures between 21 and 25°C under alternating light and darkness, produced grayish colonies with a fluffy aerial mycelium that became dark with age and produced black pigments. After 18 days of incubation, such colonies produced pycnidia aggregated into stromatic masses, emerging from decayed tissues, and up to 3 to 4 mm in diameter. Conidia produced in the pycnidia were initially unicellular, hyaline, granulose, ovoid to ellipsoidal, and measured 20.8 to 26.9 × 12.5 to 16.1 (average 24.4 × 13.5) μm. After 7 days, mature conidia became darker, uniseptate, and longitudinally striate. Paraphyses produced within the tissues of pycnidia were hyaline, cylindrical, nonseptate, and up to 63 μm long. Morphological characteristics of mycelia, pycnidia, and conidia observed with a light microscope permitted identify of the fungus as Lasiodiplodia theobromae (3). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 488-bp segment showed a 100% similarity with the corresponding sequence (GenBank Accession No. GQ502453) of L. theobromae Pat. Griffon & Maubl. The nucleotide sequence of the strain used for pathogenicity tests was submitted to GenBank (Accession No. JN849098). Pathogenicity tests were performed by inoculating 10 avocado fruits after surface disinfesting in 1% sodium hypochlorite and then wounding. Mycelial disks (8 mm in diameter) obtained from PDA cultures of one strain were placed on wounds. Ten control fruits were inoculated with plain PDA. Fruits were incubated at 15 ± 1°C. The first symptoms developed 4 days after the artificial inoculation. After 7 days, the rot was evident and L. theobromae was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice. To our knowledge, this is the first report of the presence of L. theobromae causing postharvest fruit rot on avocado in Italy, as well as in Europe. The occurrence of postharvest fruit rot on avocado caused by L. theobromae was described in many avocado-producing areas such as the United States (4), South Africa, and Israel. In Italy, the economic importance of avocado cultivation is currently limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2). P. Narayanasamy. Microbial Plant Pathogens. Detection and Disease Diagnosis: Fungal Pathogens. Springer, Dordrecht, 2011. (3) E. Punithalingam. Sheet 519. CMI Description of Fungi and bacteria, 1976. (4) H. E. Stevens and R. B. Piper. Circular No. 582, USDA, 1941.

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First Report of Gliocephalotrichum bulbilium and G. simplex Causing Fruit Rot of Rambutan in Puerto Rico

Plant Disease ◽

10.1094/pdis-02-12-0210-pdn ◽

2012 ◽

Vol 96 (8) ◽

pp. 1225-1225 ◽

Cited By ~ 3

Author(s):

L. M. Serrato-Diaz ◽

E. I. Latoni-Brailowsky ◽

L. I. Rivera-Vargas ◽

R. Goenaga ◽

R. D. French-Monar

Keyword(s):

Puerto Rico ◽

Sri Lanka ◽

Mycelial Growth ◽

Fruit Rot ◽

Its2 Region ◽

Research Station ◽

Diseased Plant ◽

Tubulin Gene ◽

First Report ◽

Β Tubulin

Post-harvest disease losses of rambutan (Nephelium lappaceum L.) have been reported worldwide and several pathogens have been associated with fruit rot (3,4). In 2011, fruit rot of rambutan was observed on 11-year-old trees at the USDA-ARS Tropical Agriculture Research Station in Mayaguez, Puerto Rico. Infected fruit sections (1 mm2) were surface-sterilized, rinsed with sterile deionized-distilled water, and transferred to acidified potato dextrose agar (APDA). Gliocephalotrichum bulbilium J.J. Ellis & Hesseltine (Gb) and G. simplex (J.A. Meyer) B. Wiley & E. Simmons (Gs) were identified using a taxonomic key (1). In corn meal agar (CMA), five isolates of Gb were light yellow-to-light brown. Conidiophores had sterile stipe extensions ranging from 120 to 150 μm long and were produced contiguous to the erect conidiogenous penicilli. Conidia were unicellular, smooth, oblong to elliptical, and 5.5 to 7.5 μm long by 2.0 to 2.5 μm wide. Bulbilloid aggregates were observed and averaged 70 μm long. In CMA, five isolates of Gs were light brown-to-chestnut brown. Conidiophores had sterile stipe extensions 130 to 180 μm long that were produced approximately 15 to 30 μm away from the conidiogenous penicilli. Conidia were unicellular, smooth, cylindrical to elliptical, and with slightly curved ends ranging from 6.5 to 8.5 μm long by 2.0 to 2.5 μm wide. Chlamydospores were unicellular, brown, smooth and thick-walled, averaging 35 μm long. Pathogenicity tests were conducted on five detached fruits per isolate. Five isolates of each Gliocephalotrichum spp. were inoculated on fruits using 5-mm mycelial disks of 8-day-old pure cultures grown in APDA. Untreated controls were inoculated with APDA disks only. Inoculated fruit was kept in a humid chamber for 8 days at 25°C under 12 hours of fluorescent light. Test was repeated once. Five days after inoculation (DAI), white mycelial growth for Gb and golden mycelial growth for Gs were observed on rambutan fruits. Eight DAI, fruit rot, and aril (flesh) rot symptoms were observed on fruits inoculated with isolates of Gb and Gs. Infected fruit changed in color from red to brown, and, on average, mycelia of Gb and Gs covered 50 and 60% of the fruit, respectively. Conidiophores were observed on spintems (hair-like appendages). Control fruit did not rot. Both species were reisolated from diseased plant tissue, thus fulfilling Koch's postulates. For molecular identification of these species of Gliocephalotrichum, the ITS1-5.8S-ITS2 region of the rDNA and a fragment of the β-tubulin gene were amplified by PCR and aligned with other Gb and Gs sequences in NCBI GenBank for comparison. The sequences submitted to GenBank included Gs Accession Nos. JQ688045 and JQ688046 and Gb Accession Nos. JQ688044 and JQ68847 for the ITS sequences. For the β-tubulin gene, Gs Accession Nos. JQ688049 and JQ688050 and Gb Accession Nos. JQ688048 and JQ688051. Both DNA regions had 99.9 to 100% sequence identity to other isolates of Gb and Gs reported in GenBank (1). Gliocephalotrichum spp. have been associated with rambutan fruit rot in Hawaii, Sri Lanka and Thailand (2,4). To our knowledge, this is the first report of G. bulbilium and G. simplex causing fruit rot of rambutan in Puerto Rico. References: (1) C. Decock et al. Mycologia 98:488, 2006. (2) K. A. Nishijima and P. A. Follett. Plant Dis. 86:71, 2002. (3) L. M. Serrato et al. Phytopathology 100:S176, 2010. (4) D. Sivakumar et al. J. Natn. Sci. Coun. Sri Lanka 25:225, 1997.

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First Report of Rhizoctonia solani AG 4 on Lamb's Lettuce in Italy

Plant Disease ◽

10.1094/pd-90-1109c ◽

2006 ◽

Vol 90 (8) ◽

pp. 1109-1109 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

M. L. Gullino

Keyword(s):

Rhizoctonia Solani ◽

Morphological Characteristics ◽

Northern Italy ◽

Crown Rot ◽

Pathogenicity Test ◽

First Report ◽

Pathogenicity Tests ◽

Hyphal Diameter ◽

Wheat Kernels ◽

Extensive Necrosis

Lamb's lettuce or corn salad (Valerianella olitoria) is increasingly grown in Italy and used primarily in the preparation of mixed processed salad. In the fall of 2005, plants of lamb's lettuce, cv Trophy, exhibiting a basal rot were observed in some commercial greenhouses near Bergamo in northern Italy. The crown of diseased plants showed extensive necrosis, progressing to the basal leaves, with plants eventually dying. The first symptoms, consisting of water-soaked zonate lesions on basal leaves, were observed on 30-day-old plants during the month of October when temperatures ranged between 15 and 22°C. Disease was uniformly distributed in the greenhouses, progressed rapidly in circles, and 50% of the plants were affected. Diseased tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with 100 μg/liter of streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani was consistently and readily isolated and maintained in pure culture after single-hyphal tipping (3). The five isolates of R. solani, obtained from affected plants successfully anastomosed with tester isolate AG 4, no. RT 31, received from R. Nicoletti of the Istituto Sperimentale per il Tabacco, Scafati, Italy (2). The hyphal diameter at the point of anastomosis was reduced, and cell death of adjacent cells occurred (1). Pairings were also made with AG 1, 2, 3, 5, 7, and 11 with no anastomoses observed between the five isolates and testers. For pathogenicity tests, the inoculum of R. solani (no. Rh. Vale 1) was grown on autoclaved wheat kernels at 25°C for 10 days. Plants of cv. Trophy were grown in 10-liter containers (20 × 50 cm, 15 plants per container) on a steam disinfested substrate (equal volume of peat and sand). Inoculations were made on 20-day-old plants by placing 2 g of infected wheat kernels at each corner of the container with 3 cm as the distance to the nearest plant. Plants inoculated with clean wheat kernels served as controls. Three replicates (containers) were used. Plants were maintained at 25°C in a growth chamber programmed for 12 h of irradiation at a relative humidity of 80%. The first symptoms, consisting of water-soaked lesions on the basal leaves, developed 5 days after inoculation with crown rot and plant kill in 2 weeks. Control plants remained healthy. R. solani was consistently reisolated from infected plants. The pathogenicity test was carried out twice with similar results. This is, to our knowledge, the first report of R. solani on lamb's lettuce in Italy as well as worldwide. The isolates were deposited at the AGROINNOVA fungal collection. The disease continues to spread in other greenhouses in northern Italy. References: (1) D. Carling. Rhizoctonia Species: Pages 37–47 in: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. B. Sneh et al., eds. Kluwer Academic Publishers, the Netherlands, 1996. (2) J. Parmeter et al. Phytopathology, 59:1270, 1969. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN, 1996.

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First Report of Fusarium pernambucanum Causing Fruit Rot of Muskmelon in China

Plant Disease ◽

10.1094/pdis-07-21-1520-pdn ◽

2021 ◽

Author(s):

Xianping Zhang ◽

Jiwen Xia ◽

Jiakui Liu ◽

Dan Zhao ◽

Lingguang Kong ◽

...

Keyword(s):

Phylogenetic Analyses ◽

Apical Cell ◽

Morphological Characteristics ◽

Fruit Rot ◽

Likelihood Method ◽

Correct Identification ◽

Pathogenicity Test ◽

First Report ◽

The Core ◽

Representative Isolate

Muskmelon (Cucumis melo L.) is one of the most widely cultivated and economically important fruit crops in the world. However, many pathogens can cause decay of muskmelons; among them, Fusarium spp. is the most important pathogen, affecting fruit yield and quality (Wang et al. 2011). In May 2017, fruit rot symptoms were observed on ripening muskmelons (cv. Jipin Zaoxue) in several fields in Liaocheng of Shandong Province, China. Symptoms appeared as brown, water-soaked lesions, irregularly circular in shape, with the lesion size ranging from a small spot (1 to 2 cm) to the decay of the entire fruit. The core and the surface of the infected fruit were covered with white to rose-reddish mycelium. Two infected muskmelons were collected from each of two fields, 10 km apart. Tissues from the inside of the infected fruit were surface disinfected with 75% ethanol for 30 s, and cultured on potato dextrose agar (PDA) at 25 °C in the dark for 5 days. Four purified cultures were obtained using the single spore method. On carnation leaf agar (CLA), macroconidia had a pronounced dorsiventral curvature, falcate, 3 to 5 septa, with tapered apical cell, and foot-shaped basal cell, measuring 19 to 36 × 4 to 6 μm. Chlamydospores were abundant, 5.5–7.5 μm wide, and 5.5–10.5 μm long, ellipsoidal or subglobose. No microconidia were observed. These morphological characteristics were consistent with the descriptions of F. pernambucanum (Santos et al. 2019). Because these isolates had similar morphology, one representative isolate was selected for multilocus phylogenetic analyses. DNA was extracted from the representative isolate using the CTAB method. The nucleotide sequences of the internal transcribed spacers (ITS) (White et al. 1990), translation elongation factor 1-α gene (TEF1), RNA polymerase II second largest subunit gene (RPB2), calmodulin (CAM) (Xia et al. 2019) were amplified using specific primers, sequenced, and deposited in GenBank (MN822926, MN856619, MN856620, and MN865126). Based on the combined dataset of ITS, TEF1, RPB2, CAM, alignments were made using MAFFT v. 7, and phylogenetic analyses were processed in MEGA v. 7.0 using the maximum likelihood method. The studied isolate (XP1) clustered together with F. pernambucanum reference strain URM 7559 (99% bootstrap). To perform pathogenicity test, 10 μl of spore suspensions (1 × 106 conidia/ml) were injected into each muskmelon fruit using a syringe, and the control fruit was inoculated with 10 μl of sterile distilled water. There were ten replicated fruits for each treatment. The test was repeated three times. After 7 days at 25 °C, the interior of the inoculated muskmelons begun to rot, and the rot lesion was expanded from the core towards the surface of the fruit, then white mycelium produced on the surface. The same fungus was re-isolated from the infected tissues and confirmed to fulfill the Koch’s postulates. No symptoms were observed on the control muskmelons. To our knowledge, this is the first report of F. pernambucanum causing of fruit rot of muskmelon in China. Considering the economic value of the muskmelon crop, correct identification can help farmers select appropriate field management measures for control of this disease.

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First Report of Neopestalotiopsis clavispora Causing Root and Crown Rot on Strawberry in Italy

Plant Disease ◽

10.1094/pdis-03-19-0673-pdn ◽

2019 ◽

Vol 103 (11) ◽

pp. 2959-2959 ◽

Cited By ~ 1

Author(s):

G. Gilardi ◽

F. Bergeretti ◽

M. L. Gullino ◽

A. Garibaldi

Keyword(s):

Crown Rot ◽

First Report ◽

Root And Crown Rot

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First Report of Lasiodiplodia theobromae Causing Inflorescence Blight and Fruit Rot of Longan (Dimocarpus longan L.) in Puerto Rico

Plant Disease ◽

10.1094/pdis-05-13-0473-pdn ◽

2014 ◽

Vol 98 (2) ◽

pp. 279-279 ◽

Cited By ~ 4

Author(s):

L. M. Serrato-Diaz ◽

L. I. Rivera-Vargas ◽

R. Goenaga ◽

R. D. French-Monar

Keyword(s):

Puerto Rico ◽

Fruit Rot ◽

Fluorescent Light ◽

Its2 Region ◽

Tropical Fruit ◽

Lasiodiplodia Theobromae ◽

First Report ◽

Wide Range ◽

Dimocarpus Longan ◽

Β Tubulin

Dimocarpus longan L., commonly known as longan, is a tropical fruit tree of the Sapindaceae family. From 2008 to 2010, a disease survey for longan was conducted in March and October in Puerto Rico. Fruit rot and inflorescence blight (rotting of the rachis, rachilla, and flowers) were observed in fields of longan at the USDA-ARS Research Farm in Isabela, and two commercial orchards in Puerto Rico. Tissue sections (1 mm2) of diseased inflorescences and surface of the fruit were disinfested with 70% ethanol, rinsed with sterile water, and transferred to acidified potato dextrose agar (APDA). Three isolates of Lasiodiplodia theobromae (Pat.) Griffon & Maubl. (Lt) were isolated from symptomatic tissue and identified morpho-molecularly using a taxonomic key for the Botryosphaeriaceae and DNA sequence analysis (1). In APDA, colonies of Lt had initial greenish-gray aerial mycelia that turned dark brown with age. Pycnidia were dark brown to black. Immature conidia were sub-ovoid to ellipsoid, apex rounded, truncate at the base, thick-walled, hyaline, and one-celled, becoming dark brown, two-celled, and with irregular longitudinal striations when mature. Conidia (n = 50) for all the isolates averaged 26.9 μm long by 13 μm wide. For molecular identification, the ITS1-5.8S-ITS2 region and fragments of the β-tubulin and elongation factor 1-alpha (EF1-α) genes were sequenced and BLASTn searches done in GenBank. Accession numbers of gene sequences of Lt submitted to GenBank were KC964546, KC964547, and KC964548 for ITS region; KC964549, KC964550, and KC964551 for β-tubulin; and KC964552, KC964553, and KC964554 for EF1-α. For all genes used, sequences were 99 to 100% identical to reference isolate CBS164.96 of Lt reported in GenBank (accessions AY640255, EU673110, and AY640258). Pathogenicity tests were conducted on six random healthy non-detached inflorescences of longan and six healthy detached fruits per isolate. Unwounded inflorescences and fruit were inoculated with 5-mm mycelial disks from 8-day-old pure cultures grown in APDA. Inflorescences were enclosed in plastic bags for 5 days under field conditions while fruits were kept in a humid chamber using plastic boxes for 5 days under laboratory conditions of 25°C and 12 h of fluorescent light. Untreated controls were inoculated with APDA disks only. The experiment was repeated once. Five days after inoculation, isolates of Lt caused inflorescence blight, fruit rot, and aril (flesh) rot. Inflorescences turned brown and flower mummification was observed on the inflorescences. The exocarp (peel) and endocarp (aril) turned dark brown and mycelial growth and pycnidia of Lt were observed on fruits. Untreated controls did not show any symptoms and no fungi were re-isolated from tissue. In diseased inflorescences and fruits, Lt was re-isolated from diseased tissue and identified using morphological and molecular parameters, thus fulfilling Koch's postulates. Lt has been reported to cause dieback, stem end rot, and fruit rot on a wide range of plants host (2,4). In longan, Lt has been reported causing fruit rot in Thailand (3). To our knowledge, this is the first time that Lt has been reported causing inflorescence blight in longan and the first report of Lt causing fruit rot in Puerto Rico. References: (1) A. J. L. Phillips. Key to the various lineages in “Botryosphaeria” Version 01 2007. Retrieved from http://www.crem.fct.unl.pt/botryosphaeria_site/key.htm , 26 November 2013. (2) B. Slippers et al. Mycologia 97:99, 2005. (3) P. Suwanakood et al. Asian J. Biol. Ed. 3:47, 2007. (4) A. F. Wright and P. F. Harmon. Plant Dis. 93:962, 2009.

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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 Fruit Rot Caused by Fusarium luffae in Muskmelon in China

Plant Disease ◽

10.1094/pdis-12-21-2666-pdn ◽

2022 ◽

Author(s):

Xianping Zhang ◽

Xuedong Cao ◽

Qingqing Dang ◽

Yongguang Liu ◽

Xiaoping Zhu ◽

...

Keyword(s):

Phylogenetic Analyses ◽

Apical Cell ◽

Morphological Characteristics ◽

Fruit Rot ◽

Likelihood Method ◽

Correct Identification ◽

Pathogenicity Test ◽

Fusarium Spp ◽

First Report ◽

The Core

Muskmelon (Cucumis melo L.) is one of the most widely cultivated and economically important fruit crops in the world. However, many pathogens can cause decay of muskmelon fruit, including Fusarium spp.. Fusarium spp. are the most important pathogen, affecting muskmelon fruit yield and quality (Wang et al. 2011). In August 2020, fruit rot symptoms were observed on ripening muskmelons (cv. Tianbao) in several fields in Jiyang District, Jinan City of Shandong Province, China. The incidences of infected muskmelon ranged from 15% to 30% and caused an average 20% yield loss. Symptoms appeared as pale brown, water-soaked lesions that were irregular in shape, with the lesion sizes ranging from a small spot (1 to 2 cm) to decay of the entire fruit. The core and surface of infected fruit were colonized and covered with white mycelia. Two infected muskmelons were collected from two fields, 3.5 km apart. Tissues removed from inside the infected fruit were surface disinfected with 75% ethanol for 30 s, and cultured on potato dextrose agar (PDA) at 25°C in the dark for 5 days. Four purified cultures were obtained using the single spore method. On carnation leaf agar (CLA), 3 to 5 septate, falcate, with a pronounced dorsiventral curvature macroconidia with tapered apical cell, and foot-shaped basal cell, measuring 20 to 40 × 3.5 to 4.5 μm. Microconidia and chlamydospores were not observed. These morphological characteristics were consistent with the description of F. luffae (Wang et al., 2019). Because these isolates had similar morphology, two representative isolates (XP11 and XP12) were selected for multilocus phylogenetic analyses. DNA was extracted from the representative isolates using a CTAB method. Nucleotide sequences of the internal transcribed spacers (ITS) (White et al. 1990), calmodulin (CAM), RNA polymerase II second largest subunit (RPB2), translation elongation factor 1-α gene (TEF1) (Xia et al. 2019) were amplified using specific primers, sequenced, and deposited in GenBank (ITS: MW391509 and MW391510, CAM: MW392789 and MW392790, RPB2: MW392797 and MW392798, TEF1: MW392793 and MW392794). Alignments of a combined dataset of ITS, CAM, RPB2 and TEF1 were made using MAFFT v. 7, and phylogenetic analyses were conducted in MEGA v. 7.0 using the maximum likelihood method. The muskmelon isolates (XP11 and XP12) clustered together with the F. luffae reference strain LC12167 (99% bootstrap). To perform a pathogenicity test, 10 μl of conidial suspensions (1 × 106 conidia/ml) were injected into each muskmelon fruit using a syringe, and the control fruit was inoculated with 10 μl of sterile distilled water. There were ten replicated fruits for each treatment. The test was repeated three times. After 7 days at 25°C, the interior of the inoculated muskmelons begun to rot, and the rot lesion expanded from the core towards the surface of the fruit, then white mycelia were produced on the surface. Ten isolations were re-isolated from the infected tissues and confirmed to fulfill Koch’s postulates. No symptoms were observed on the control muskmelons. To our knowledge, this is the first report of fruit rot caused by F. luffae in muskmelon in China. Considering the economic value of the muskmelon crop, correct identification can help farmers select appropriate field management measures for control of this disease.

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