First Report of Root and Basal Rot of Angelica acutiloba Caused by Fusarium solani in Taiwan

Angelica (Angelica acutiloba (Siebold. & Zucc.) Kitag.) is one of the most important traditional Chinese medicines in Taiwan. The medicinal herb has been mainly imported from China, but cultivation at a commercial scale has also been established in recent years in Hualien County, Taiwan. In September 2008, angelica plants in a field at Liou-shih-dan Mountain displayed symptoms of yellowing, stunting, rotting of roots and basal stem, and wilting. A severe brown discoloration of vascular tissue along the stems of infected plants was observed. One or more Fusarium spp. was consistently isolated from the roots and stems of diseased plants. Isolates R3, R4, and R5 were incubated for 14 days on celery tissues to produce chlamydospores, and 33 g of celery tissue with chlamydospores were mixed with 500 ml of soil per pot as inoculum. One 4-month-old angelica seedling was planted per pot. Three angelica plants were inoculated with each isolate in the first test and nine plants were inoculated with each isolate in the second test. Other seedlings were inoculated with water as checks. Pathogenicity tests were conducted twice. Incidence of diseased plants was 66, 100, and 33% in the first test, and 66, 100, and 44% in the second test for the R3, R4, and R5 isolates, respectively. Symptoms similar to those on the diseased plants in the field were produced, with leaves turning yellow starting 7 days after inoculation and wilt and discoloration of roots 14 days after inoculation. Fusarium spp. also were reisolated from the diseased plants. Genomic DNA was extracted from mycelium with a fungal genomic DNA purification kit, and the internal transcribed spacer (ITS) rDNA region was amplified and sequenced with primers ITS-4 and ITS-5. The sequence of the resulting ~550-bp amplicon was compared with those in GenBank. The ITS sequences of the R3, R4, and R5 isolates shared 98.7, 98.7, and 97.9% similarity with F. solani isolate AF129104 (3), respectively. Phylogenetic analysis also showed that the three isolates were closer to F. solani than to other Fusarium species. Both macroconidia and microconidia of the R4 isolate were produced on potato dextrose agar. Macroconidia were three to five septate and 27.2 to 37.8 × 4.4 to 6.2 μm; microconidia were zero to one septate and 9.3 to 14.7 × 2.9 to 4.8 μm. Chlamydospores produced on celery juice agar were terminal or intercalary, solitary, in pairs or in chains, and 9.3 to 12.1 μm. Morphological characteristics identified the three isolates as F. solani (Martius) Snyder & Hansen according to Fu and Chang (2) and Chung et al. (1), which agrees with the ITS comparison. To our knowledge, this is the first report of root and basal rot caused by F. solani on angelica in Taiwan. References: (1) W. C. Chung et al. Plant Prot. Bull. 40:177, 1998. (2) C. H. Fu and T. T. Chang. Taiwan J. For. Sci. 14:223, 1999. (3) H. Suga et al. Mycol. Res. 104:1175, 2000.

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First report of Fusarium commune causing root and crown rot on maize in Italy

Plant Disease ◽

10.1094/pdis-01-21-0075-pdn ◽

2021 ◽

Author(s):

Monica Mezzalama ◽

Vladimiro Guarnaccia ◽

Ilaria Martino ◽

Giulia Tabome ◽

Maria Lodovica GULLINO

Keyword(s):

Plant Disease ◽

Tap Water ◽

Morphological Characteristics ◽

Plant Diseases ◽

Crown Rot ◽

Conidial Suspension ◽

Fusarium Spp ◽

First Report ◽

Root And Crown Rot ◽

Pathogenicity Tests

Maize (Zea mays L.) is a cereal crop of great economic importance in Italy; production is currently of 62,587,469 t, with an area that covers 628,801 ha, concentrated in northern Italy (ISTAT 2020). Fusarium species are associated with root and crown rot causing failures in crop establishment under high soil moisture. In 2019 maize seedlings collected in a farm located in San Zenone degli Ezzelini (VI, Italy) showed root and crown rot symptoms with browning of the stem tissues, wilting of the seedling, and collapsing due to the rotting tissues at the base of the stem. The incidence of diseased plants was approximately 15%. Seedlings were cleaned thoroughly from soil residues under tap water. Portions (about 3-5 mm) of tissue from roots and crowns of the diseased plants were cut and surface disinfected with a water solution of NaClO at 0.5% for 2 minutes and rinsed in sterile H20. The tissue fragments were plated on Potato Dextrose Agar (PDA) amended with 50 mg/l of streptomycin sulfate and incubated for 48-72 hours at 25oC. Over the 80 tissue fragments plated, 5% were identified as Fusarium verticillioides, 60% as Fusarium spp., 35% developed saprophytes. Fusarium spp. isolates that showed morphological characteristics not belonging to known pathogenic species on maize were selected and used for further investigation while species belonging to F. oxysporum were discarded. Single conidia of the Fusarium spp. colonies were cultured on PDA and Carnation Leaf Agar (CLA) for pathogenicity tests, morphological and molecular identification. The colonies showed white to pink, abundant, densely floccose to fluffy aerial mycelium. Colony reverse showed light violet pigmentation, in rings on PDA. On CLA the isolates produced slightly curved macronidia with 3 septa 28.1 - 65.5 µm long and 2.8-6.3 µm wide (n=50). Microconidia were cylindrical, aseptate, 4.5 -14.0 µm long and 1.5-3.9 µm wide (n=50). Spherical clamydospores were 8.8 ± 2.5 µm size (n=30), produced singly or in pairs on the mycelium, according to the description by Skovgaard et al. (2003) for F. commune. The identity of two single-conidia strains was confirmed by sequence comparison of the translation elongation factor-1α (tef-1α), and RNA polymerase II subunit (rpb2) gene fragments (O’Donnell et al. 2010). BLASTn searches of GenBank, and Fusarium-ID database, using the partial tef-1α (MW419921, MW419922) and rpb2 (MW419923, MW419924) sequences of representative isolate DB19lug07 and DB19lug20, revealed 99% identity for tef-1α and 100% identity to F. commune NRRL 28387(AF246832, AF250560). Pathogenicity tests were carried out by suspending conidia from a 10-days old culture on PDA in sterile H2O to 5×104 CFU/ml. Fifty seeds were immersed in 50 ml of the conidial suspension of each isolate for 24 hours and in sterile water (Koch et al. 2020). The seeds were drained, dried at room temperature, and sown in trays filled with a steamed mix of white peat and perlite, 80:20 v/v, and maintained at 25°C and RH of 80-85% for 14 days with 12 hours photoperiod. Seedlings were extracted from the substrate, washed under tap water, and observed for the presence of root and crown rots like the symptoms observed on the seedlings collected in the field. Control seedlings were healthy and F. commune was reisolated from the symptomatic ones and identified by resequencing of tef-1α gene. F. commune has been already reported on maize (Xi et al. 2019) and other plant species, like soybean (Ellis et al. 2013), sugarcane (Wang et al. 2018), potato (Osawa et al. 2020), indicating that some attention must be paid in crop rotation and residue management strategies. To our knowledge this is the first report of F. commune as a pathogen of maize in Italy. References Ellis M L et al. 2013. Plant Disease, 97, doi: 10.1094/PDIS-07-12-0644-PDN. ISTAT. 2020. http://dati.istat.it/Index.aspx?QueryId=33702. Accessed December 28, 2020. Koch, E. et al. 2020. Journal of Plant Diseases and Protection. 127, 883–893 doi: 10.1007/s41348-020-00350-w O’Donnell K et al. 2010. J. Clin. Microbiol. 48:3708. https://doi.org/10.1128/JCM.00989-10 Osawa H et al. 2020. Journal of General Plant Pathology, doi.org/10.1007/s10327-020-00969-5. Skovgaard K 2003. Mycologia, 95:4, 630-636, DOI: 10.1080/15572536.2004.11833067. Wang J et al. 2018. Plant Disease, 102, doi/10.1094/PDIS-07-17-1011-PDN Xi K et al. 2019. Plant Disease, 103, doi/10.1094/PDIS-09-18-1674-PDN

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First Report of Vascular Wilt Caused by Fusarium redolens on Lentil in Italy

Plant Disease ◽

10.1094/pdis-92-7-1132c ◽

2008 ◽

Vol 92 (7) ◽

pp. 1132-1132 ◽

Cited By ~ 5

Author(s):

L. Riccioni ◽

A. Haegi ◽

M. Valvassori

Keyword(s):

Vascular Tissue ◽

Fusarium Species ◽

Elongation Factor ◽

Morphological Characteristics ◽

Its Region ◽

Its Sequences ◽

Homology Search ◽

Control Treatment ◽

Pathogenicity Test ◽

First Report

Lentil (Lens culinaris Medik.) is a traditional crop in Sicily, Italy. Near Villalba (Caltanissetta), a local lentil landrace, “Lenticchia di Villalba”, is commonly grown. From 2002 to 2004, wilt was observed in five lentil fields (≈1 ha each) at rates from 5 to 20%. Affected plants were yellow and stunted with discoloration in the vascular tissue of stems and crowns. Pieces of brown vascular tissue from stems were disinfested in 2% sodium hypochlorite for 2 min, rinsed with sterile distilled water, placed on potato dextrose agar, and incubated at 23°C. Isolates with morphological characteristics of Fusarium oxysporum Schlecht.:Fr. (2) were consistently recovered from affected plants. For molecular identification of five isolates, the rDNA internal transcribed spacer (ITS) region and a portion of the elongation factor EF-1α were sequenced using ITS5/4 and EF1/2 primers, respectively (1). Two sequences of the ITS region were obtained: a 468-bp sequence from isolates ER1259, ER1260, and ER1275 (submitted as GenBank Accession No. EU159118) and a 483-bp sequence from isolates ER1274 and ER1276 (submitted as GenBank Accession No. EU281661). The two sequences shared 93% similarity. A sequence homology search using the NCBI BLAST program revealed that the first sequence had 100% homology with the ITS sequences of more than 50 F. oxysporum isolates of various formae speciales in GenBank and the second shared 100% homology with the ITS sequences of five isolates of F. redolens Wollenw. (e.g., GenBank Accession No. X94169 of the strain CBS 360.87). Amplification of the EF-1α produced a sequence from isolates ER1274 and ER1276 (submitted as GenBank Accession No. EU281660) with 99 to 100% homology to sequences of F. redolens and a sequence from strains ER1259, ER1275, and ER1260 (submitted as GenBank Accession No. EU281659) with 100% homology to that of more than 50 F. oxysporum strains in GenBank. Although F. redolens and F. oxysporum are morphologically similar, recent molecular studies have shown that they are distinct and phylogenetically distant species (3). On the basis of genetic sequences, isolates ER1274 and ER1276 were identified as F. redolens. These isolates were evaluated for pathogenicity on lentil. For each isolate, 10 2-week-old seedlings of “Lenticchia di Villalba” were inoculated by submerging roots in a suspension of 2.5 × 106 conidia/ml for 10 min. Plants were put into separate tubes containing 70 ml of a nutritional liquid medium (7 ml of HydroPlus Olikani per liter; Yara, Nanterre, France) and incubated in a growth chamber at 20°C with 12 h of light per day. Seedlings dipped in sterile water served as the control treatment. The pathogenicity test was repeated twice. Inoculated seedlings started to wilt 1 week after inoculation and developed root rot and vascular discoloration. After 2 weeks, 70% of the inoculated plants were affected by both isolates and 40 and 10% died when inoculated with ER1274 and ER1276 isolates, respectively. F. redolens was consistently reisolated from the stems of wilted plants. Noninoculated plants remained healthy. Currently, only F. oxysporum f. sp. lentis Vasud. and Sriniv. has been reported as the cause of Fusarium wilt of lentil. To our knowledge, this is the first report of F. redolens as a pathogen on lentil. References: (1) R. P. Baayen et al. Phytopathology 91:1037, 2001. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, 1983. (3) K. O'Donnell et al. Mycologia 90:465, 1998.

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First Report of Lavender Wilt Caused by Fusarium sporotrichioides in Croatia

Plant Disease ◽

10.1094/pdis-12-11-1046-pdn ◽

2012 ◽

Vol 96 (4) ◽

pp. 591-591 ◽

Cited By ~ 4

Author(s):

J. Cosic ◽

K. Vrandecic ◽

D. Jurkovic ◽

J. Postic ◽

L. Orzali ◽

...

Keyword(s):

Vascular Tissue ◽

Soil Surface ◽

Fusarium Sporotrichioides ◽

Artificial Infection ◽

Sterile Soil ◽

Laboratory Manual ◽

First Report ◽

Soil Inoculum ◽

Brown Discoloration ◽

Pathogenicity Tests

In May 2011, samples of lavender plants (Lavandula × intermedia) showing wilt symptoms were collected from two commercial plantings in Slavonia County. Disease was observed on 20 to 30% of the plants. Symptoms of the disease consisted of chlorosis, stunting, wilting, and death. Vascular tissue of stems and roots exhibited brown discoloration. Isolations of the pathogen were made from the discolored tissues on potato dextrose agar (PDA). Colonies were initially white, but with age became red, and red pigments were produced in agar. Microconidia were pear shaped, oval, and fusoid, and ranged from 4.5 to 14.0 × 2.8 to 4.7 μm. Macroconidia were curved, mostly three septate, and ranged from 21.8 to 24.3 × 2.9 to 3.9 μm. Morphology of colonies and conidia matched the description of Fusarium sporotrichioides Sherb. (1). Identity of the fungus was confirmed by examining a portion of the EF1-α gene using the degenerated primers EF1 and EF2 (2). BLAST searches of the obtained sequences showed a 100% homology with several isolates of F. sporotrichioides from GenBank. Pathogenicity tests were conducted on 20 4-month-old rooted cuttings under greenhouse conditions. Each plant was planted in a separate pot containing 0.7 liter of sterile soil. Inoculum for artificial infection was prepared with sterilized mixtures of wheat and barley seeds (10 g of each). Seeds were inoculated with a F. sporotrichioides spore suspension (106 conidia/ml) and incubated at 22°C for 10 days. Noninoculated seeds served as controls. Ten seeds were placed under the soil surface around the root of each plant. Plants were irrigated and placed in a greenhouse (22°C and a 12-h day/night photoperiod). Sixteen days after inoculation, 80% of inoculated plants were wilted. Symptoms on infected plants were similar to those observed in the field. The pathogen was reisolated and confirmed from the infected vascular tissue, thus fulfilling Koch's postulates. A previous paper reported lavender as host of F. solani in China (4) and F. oxysporum in Saudi Arabia (3). To our knowledge, this is the first report of Fusarium wilt of lavender caused by F. sporotrichioides. References: (1) J. F. Leslie and B. A. Summerell. Page 256 in: The Fusarium Laboratory Manual. Blackwell Publishing Professional, Hoboken, NJ, 2006. (2) K. O'Donnell et al. Appl Biol. Sci. 95:2044, 1998. (3) K. Perveen and N. Bokhari. Plant Dis. 94:1163, 2010. (4) Y. Z. Ren et al. New Dis. Rep. 15:55, 2007.

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First Report of Cylindrocarpon macrodidymum Associated with Black Foot Diseases of Grapevine in Turkey

Plant Disease ◽

10.1094/pdis-05-11-0393-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 762-762 ◽

Cited By ~ 5

Author(s):

S. Özben ◽

F. Demirci ◽

K. Değirmenci ◽

S. Uzunok

Keyword(s):

Vascular Tissue ◽

Morphological Characteristics ◽

First Report ◽

Foot Diseases ◽

Vascular Elements ◽

Pathogenicity Tests ◽

Foot Disease ◽

Water Plants ◽

Black Foot ◽

Black Foot Disease

Grape (Vitis vinifera) is widely planted and is an economically important crop in Turkey for domestic consumption and export. Black foot disease, caused by Cylindrocarpon macrodidymum Halleen, Schroers & Crous, is a recently identified but worsening problem in vineyards worldwide (3,4). Symptomatic grapevines show reduced vigor, shortened internodes, small leaves with interveinal chlorosis, and necrosis frequently leading to the death of the plants (1). Roots of symptomatic grapevines exhibit black, sunken, necrotic lesions with a reduction in root biomass. Pith of affected vines is discolored (4). During the summers of 2009 and 2010, a survey was carried out in 63 vineyards (4 to 15 years old) in six locations of Ankara Province. We collected 44 samples from roots and crowns of grapevines exhibiting black foot symptoms. In cross section, extensive necrosis at the base of the trunk and brown-black spots in xylem vessels were observed, resembling those previously reported for black foot disease (2,4). Isolations were made from roots, vascular elements, and pith tissue. In this study, 26 isolates were identified as C. macrodidymum on the basis of morphological characteristics. Isolates identified as C. macrodidymum had a dark orange-brown colony color and abundant aerial mycelia when grown on potato dextrose agar. Isolates produced ellipsoid or ovoid microconidia. The macroconidia were one to three septate, straight, and cylindrical. One-septate macroconidia were 24 to 32 × 5 to 7 μm; three-septate macroconidia were 26 to 40 × 5 to 6 μm. Chlamydospores developed in short, intercalary chains. Conidiophores were simple or complex and sporodochial. Isolate identities were confirmed by sequence analysis of the ribosomal DNA internal transcribed spacer (GenBank Accession No. HM245331) with primers ITS1 and ITS4 (4). Isolates had 99% genetic identity with other isolates of C. macrodidymum present in GenBank. In pathogenicity tests, one representative isolate was used to inoculate five grapevine plants. Tests were completed by drench inoculation onto 3-month-old rooted cuttings of cv. Sultana with 25 ml of a conidia suspension (106 conidia ml–1). Controls were inoculated with an equal volume of sterile distilled water. Plants were incubated for 4 months in a controlled environment facility at 25°C. After 3 to 4 months, inoculations resulted in reduction of root mass, and C. macrodidymum was reisolated from regions of brown streaking in wood and discolored vascular tissue in all inoculated plants, fulfilling Koch's postulates. Control plants were asymptomatic and C. macrodidymum was not recovered from control plants. To our knowledge, this is the first report of the presence of C. macrodidymum causing black foot disease on grapevine in Turkey. References: (1) S. Alaniz et al. Plant Dis. 93:821, 2009. (2) F. Hallen et al. Stud. Mycol. 50:431, 2004. (3) F. Halleen et al. Phytopathol. Mediterr. 45:S55, 2006. (4) E. Petit and W. D. Gubler. Plant Dis. 89:1051, 2005.

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First Report of Verticillium Wilt Caused by Verticillium dahliae on Lettuce in Italy

Plant Disease ◽

10.1094/pdis-91-6-0770c ◽

2007 ◽

Vol 91 (6) ◽

pp. 770-770 ◽

Cited By ~ 8

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

M. L. Gullino

Keyword(s):

Verticillium Wilt ◽

Verticillium Dahliae ◽

Vascular Tissue ◽

Morphological Characteristics ◽

The United States ◽

Conidial Suspension ◽

First Report ◽

Lactuca Sativa L ◽

Northeastern Italy ◽

Pathogenicity Tests

Lettuce (Lactuca sativa L.) is an important crop used for fresh and processing markets in Italy and is grown on more than 21,000 ha. During October and November of 2006, wilt symptoms were observed on field-grown lettuce, cv. Estelle, in Forlì, Emila Romagna (northeastern Italy) and on cv. Ballerina grown under plastichouses in Piedmont (northwestern Italy). Both lettuce cultivars were of a butterhead type. Affected plants were stunted and developed yellow leaves with brown or black streaks in the vascular tissue. Yellowing started from the external leaves. Discoloration was observed in the vascular tissue of roots, crown, and leaves. A fungus was consistently and readily isolated from symptomatic vascular tissue, previously disinfested in 1% sodium hypochlorite, when cultured on potato dextrose agar (PDA). Microscopic observations revealed hyaline hyphae with many ovoid, dark microsclerotia measuring 32 to 43 × 16 to 26 μm developing after 15 days of growth at 18°C in the dark. Conidiophores showed two verticils of three elements. Conidia were hyaline, elliptical, single celled, and measured 3.5 to 8.5 × 1.8 to 4.3 μm (average 5.5 × 2.5 μm). According to its morphological characteristics, the fungus was identified as Verticillium dahliae (2). Healthy, 20-day-old lettuce plants, cvs. Principessa and Maxima, both belonging to the butterhead type, were separately inoculated by root dip with a conidial suspension (106/ml) of two isolates of V. dahliae isolated, respectively, at Forlì and Torino. Noninoculated lettuce plants served as control treatments. Plants (10 per treatment) were grown in pots (10-liter vol.) in a steam-disinfested peat/perlite/sand (3:1:1 vol/vol) substrate and were maintained in a glasshouse at temperatures ranging between 17 and 22°C and relative humidity ranging between 60 and 70%. First wilt symptoms and vascular discoloration in the roots, crown, and veins developed 40 days after the artificial inoculation. Forty percent of the plants were affected in the case of cv. Maxima and 30% for cv. Principessa. Noninoculated plants remained healthy. The pathogenicity tests were repeated twice. To our knowledge, this is the first report in Italy of Verticillium wilt on lettuce. The disease has been previously reported in Greece (1) and the United States (3). Currently, Verticillium wilt of lettuce seems restricted in Italy to very few farms in the two locations; moreover, its incidence is very low (0.05%). References: (1) E. K. Ligoxigakis et al. Phytoparasitica 30:141, 2002. (2) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002. (3) G. E. Vallad et al. Plant Dis. 89:317, 2005.

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Identification of Fusarium Species Isolated From Stored Apple Fruit in Croatia / Identifikacija Vrsta Roda Fusarium Izoliranih S Plodova Jabuke Nakon Skladištenja

Archives of Industrial Hygiene and Toxicology ◽

10.2478/10004-1254-63-2012-2227 ◽

2012 ◽

Vol 63 (4) ◽

pp. 463-470 ◽

Cited By ~ 12

Author(s):

Zdravka Sever ◽

Dario Ivić ◽

Tomislav Kos ◽

Tihomir Miličević

Keyword(s):

Fusarium Species ◽

Morphological Characteristics ◽

Molecular Data ◽

Apple Fruit ◽

Fusarium Avenaceum ◽

Human Consumption ◽

Low Oxygen ◽

Fusarium Rot ◽

Pathogenicity Tests ◽

Apple Fruits

AbstractSeveral species of the genus Fusarium can cause apple fruit to rot while stored. Since Fusarium taxonomy is very complex and has constantly been revised and updated over the last years, the aim of this study was to identify Fusarium species from rotten apples, based on combined morphological characteristics and molecular data.We identified 32 Fusarium isolates from rotten apple fruit of cultivars Golden Delicious, Jonagold, Idared, and Pink Lady, stored in Ultra Low Oxygen (ULO) conditions. Fusarium rot was detected in 9.4 % to 33.2 % of naturally infected apples, depending on the cultivar. The symptoms were similar in all four cultivars: a soft circular brown necrosis of different extent, with or without visible sporulation. Fusarium species were identified by the morphology of cultures grown on potato-dextrose agar (PDA) and carnation leaf agar (CLA). Twenty one isolates were identified as Fusarium avenaceum and confirmed as such with polymerase chain reaction (PCR) using specific primer pair FA-ITSF and FA-ITSR. F. pseudograminearum,F. semitectum, F. crookwellense, and F. compactum were identified by morphological characteristics. F.avenaceum can produce several mycotoxins and its dominance in Fusarium rot points to the risk of mycotoxin contamination of apple fruit juices and other products for human consumption. Pathogenicity tests showed typical symptoms of Fusarium rot in most of the inoculated wounded apple fruits. In this respect Fusarium avenaceum, as the dominant cause of Fusarium rot in stored apple fruits is a typical wound parasite.

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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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Current Classification and Diversity of Fusarium Species Complex, the Causal Pathogen of Fusarium Wilt Disease of Banana in Malaysia

Agronomy ◽

10.3390/agronomy11101955 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1955

Author(s):

Anysia Hedy Ujat ◽

Ganesan Vadamalai ◽

Yukako Hattori ◽

Chiharu Nakashima ◽

Clement Kiing Fook Wong ◽

...

Keyword(s):

Fusarium Oxysporum ◽

Fusarium Wilt ◽

Species Complex ◽

Phylogenetic Trees ◽

Fusarium Species ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Fusarium Spp ◽

Specific Primers ◽

Fusarium Oxysporum Species Complex

The re-emergence of the Fusarium wilt caused by Fusarium odoratissimum (F. odoratissimum) causes global banana production loss. Thirty-eight isolates of Fusarium species (Fusarium spp.) were examined for morphological characteristics on different media, showing the typical Fusarium spp. The phylogenetic trees of Fusarium isolates were generated using the sequences of histone gene (H3) and translation elongation factor gene (TEF-1α). Specific primers were used to confirm the presence of F. odoratissimum. The phylogenetic trees showed the rich diversity of the genus Fusarium related to Fusarium wilt, which consists of F. odoratissimum, Fusarium grosmichelii, Fusarium sacchari, and an unknown species of the Fusarium oxysporum species complex. By using Foc-TR4 specific primers, 27 isolates were confirmed as F. odoratissimum. A pathogenicity test was conducted for 30 days on five different local cultivars including, Musa acuminata (AAA, AA) and Musa paradisiaca (AAB, ABB). Although foliar symptoms showed different severity of those disease progression, vascular symptoms of the inoculated plantlet showed that infection was uniformly severe. Therefore, it can be concluded that the Fusarium oxysporum species complex related to Fusarium wilt of banana in Malaysia is rich in diversity, and F. odoratissimum has pathogenicity to local banana cultivars in Malaysia regardless of the genotype of the banana plants.

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First Report of Occurrence of Eggplant Wilt Caused by Verticillium dahliae in Korea

Plant Disease ◽

10.1094/pdis.2000.84.10.1152a ◽

2000 ◽

Vol 84 (10) ◽

pp. 1152-1152

Author(s):

S. K. Kim ◽

S. S. Hong ◽

K. W. Kim ◽

E. W. Park

Keyword(s):

Verticillium Dahliae ◽

Solanum Melongena ◽

Morphological Characteristics ◽

Wilt Disease ◽

Potato Dextrose Agar ◽

First Report ◽

Vascular Tissues ◽

Fungal Isolates ◽

Pathogenicity Tests ◽

Root Cutting

A wilt disease occurred on greenhouse-grown eggplants (Solanum melongena L.) at Hanam and Yeojoo, Korea, in 1997. Lower leaves on the 2-month-old wilted eggplants exhibited gradual yellowing, interveinal necrosis, and marginal crinkling and dropped prematurely. Vascular tissues of diseased stems were discolored and turned black. Vertical sections of the stems revealed that the pith had been colonized by the fungus. The disease progressed from lower parts of the plants upward. Incidence of diseased eggplants in greenhouses was 5% on 23 May 1997. Although the incidence increased to 10% on 13 June, it remained constant through early July. Fungal isolates from discolored vascular tissues were initially whitish to cream color on potato-dextrose agar, which turned black due to the formation of microsclerotia. The fungus also produced abundant verticillate conidiophores with phialides and conidia. Based on these cultural and morphological characteristics, the fungus was identified as Verticillium dahliae Klebahn. Pathogenicity tests by root cutting, root dipping, or soil drenching resulted in similar symptoms observed in the naturally infected eggplants. Symptoms were first observed on lower leaves of each eggplant 3 weeks after inoculation. Isolation from symptomatic leaves of the inoculated eggplants yielded V. dahliae. This is the first report of occurrence of Verticillium wilt of eggplant in Korea.

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Isolation and Identification of Fusarium spp., the Causal Agents of Onion (Allium cepa) Basal Rot in Northeastern Israel

Biology ◽

10.3390/biology9040069 ◽

2020 ◽

Vol 9 (4) ◽

pp. 69

Author(s):

Ben Kalman ◽

Dekel Abraham ◽

Shaul Graph ◽

Rafael Perl-Treves ◽

Yael Meller Harel ◽

...

Keyword(s):

Allium Cepa ◽

Fusarium Species ◽

Germination Rate ◽

Post Inoculation ◽

Fusarium Spp ◽

Isolation And Identification ◽

Preventive Program ◽

Onion Bulbs ◽

Basal Rot

Over the past decade, there have been accumulating reports from farmers and field extension personnel on the increasing incidence and spread of onion (Allium cepa) bulb basal rot in northern Israel. The disease is caused mainly by Fusarium species. Rotting onion bulbs were sampled from fields in the Golan Heights in northeastern Israel during the summers of 2017 and 2018. Tissue from the sampled onion bulbs was used for the isolation and identification of the infecting fungal species using colony and microscopic morphology characterization. Final confirmation of the pathogens was performed with PCR amplification and sequencing using fungi-specific and Fusarium species-specific primers. Four Fusarium spp. isolates were identified in onion bulbs samples collected from the contaminated field: F. proliferatum, F. oxysporum f. sp. cepae, and two species less familiar as causative agents of this disease, F. acutatum and F. anthophilium. Phylogenetic analysis revealed that these species subdivided into two populations, a northern group isolated from white (Riverside cv.) onion bulbs, and a southern group isolated from red (565/505 cv.) bulbs. Pathogenicity tests conducted with seedlings and bulbs under moist conditions proved that all species could cause the disease symptoms, but with different degrees of virulence. Inoculating seeds with spore suspensions of the four species, in vitro, significantly reduced seedlings’ germination rate, hypocotyl elongation, and fresh biomass. Mature onion bulbs infected with the fungal isolates produced typical rot symptoms 14 days post-inoculation, and the fungus from each infected bulb was re-isolated and identified to satisfy Koch’s postulates. The onion bulb assay also reflected the degree of sensitivity of different onion cultivars to the disease. This work is the first confirmed report of the direct and primary cause of Fusarium onion basal rot disease in northeastern Israel. These findings are a necessary step towards uncovering the mycoflora of the diseased onion plants and developing a preventive program that would reduce the disease damage.

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