scholarly journals First Report of Verticillium Wilt Caused by Verticillium dahliae on Coleus verschaffeltii in Italy

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 878-878 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
The United States ◽  
Peat Moss ◽  
Conidial Suspension ◽  
First Report ◽  
Vascular Tissues ◽  
Initial Symptoms ◽  
Bedding Plant

Coleus verschaffeltii Lem. (synonym C. blumei Benth., Plectranthus scutellaroides (L.) R. Br., and Solenostemon scutellarioides (L.) Codd), a perennial plant belonging to the Lamiaceae family, is used as a bedding plant for public gardens. The most popular cultivars produce speckled leaves of various colors. In October 2010, severe outbreaks of a previously unknown wilt were observed in a public garden at Torino (northern Italy) on 50 8-month-old plants. Plants were sprinkle irrigated. Initial symptoms were withering of leaves starting from the collar and brown streaks in the vascular tissue of roots, crown, and stem. Subsequently, infected tissues wilted and plants became stunted. Early leaf drop was observed and plants appeared bare, keeping few leaves only at the end of stems. Infected plants did not die but they lost the original ornamental aspect. Seventy percent of the plants were affected. Stems of 10 plants were disinfected with 1% sodium hypochlorite. Cross-sections through symptomatic vascular tissues were plated on potato dextrose agar amended with 25 ppm of streptomycin sulfate. After 10 days at 20 to 23°C, a fungus was consistently recovered from 90% of stems. Irregular, black microsclerotia, 29 to 76 × 14 to 52 (average 49 × 28) μm, developed in hyaline hyphae after 15 days of growth. Hyaline, elliptical, single-celled conidia, 3.9 to 7.2 × 1.7 to 2.8 (average 5.1 × 2.2) μm, developed on verticillate conidiophores with three phialides at each node. On the basis of these morphological characteristics, the fungus was identified as Verticillium dahliae (3). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (4) and sequenced. BLASTn analysis (1) of the 491-bp segment showed a 99% homology with the sequence of V. dahliae (Accession No. GU461634). The ITS nucleotide sequence of our isolate has been assigned the GenBank Accession No. JF704205. Pathogenicity tests were performed twice using 45-day-old plants obtained from seeds of C. verschaffeltii grown in 1-liter pots containing a 50:20:20:10 steamed mix of peat moss/pumice/pine bark/clay. Roots of 10 healthy plants were immersed in a conidial suspension (1.7 × 107 ml–1) of one culture of V. dahliae isolated from infected plants. Ten plants immersed in sterile water served as controls. Plants were maintained in a glasshouse at daily average temperatures between 20 and 28°C and relative humidity between 50 and 80%. First wilt symptoms and vascular discoloration in the roots, crown, and stems developed 20 days after inoculation. V. dahliae was consistently reisolated from infected vascular tissues of crown and stems of symptomatic plants. Noninoculated plants remained healthy. To our knowledge, this is the first report of Verticillium wilt on C. verschaffeltii in Italy. Verticillium wilt had been previously reported on S. scutellaroides in the United States (2). At this time, the economic importance of Verticillium wilt on C. verschaffeltii in Italy is limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society. St Paul, MN, 1989. (3) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Verticillium Wilt Caused by Verticillium dahliae on Rudbeckia fulgida (Orange Coneflower) in Italy

Plant Disease ◽  
2008 ◽  
Vol 92 (9) ◽  
pp. 1367-1367 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Vascular Tissue ◽  
Morphological Characteristics ◽  
Its Region ◽  
The United States ◽  
Conidial Suspension ◽  
First Report ◽  
Initial Symptoms

Rudbeckia fulgida (common name orange coneflower) is an herbaceous perennial (Asteraceae) grown in full sun in perennial borders in gardens. At the end of the summer of 2007, in a public garden located in Turin (northern Italy), symptoms of vascular wilt and stunting were observed on approximately 80% of the plants grown in a mixed border. Initial symptoms were yellowing of external leaves and brown or black streaks in the vascular tissue of roots, crown, and leaves. A fungus was consistently and readily isolated on potato dextrose agar from symptomatic vascular tissue previously disinfested in 1% sodium hypochloride. Ovoid, dark microsclerotia, 41 to 108 μm, developed in hyaline hyphae after 10 days of growth at 23°C (12 h of light and 12 h of dark). Hyaline, elliptical, single-celled conidia, 3.2 to 7.3 × 2.1 to 3.7 (average 4.7 × 2.8) μm, developed on verticillate conidiophores. On the basis of these morphological characteristics, the fungus was identified as Verticillium dahliae (4). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 530 bp showed a 100% homology with the sequence of V. dahliae. The nucleotide sequence has been assigned GenBank Accession No. EU 627007. Healthy, 30-day-old R. fulgida plants were grown in a steam-disinfested mix of sphagnum peat:pomix:pine bark:clay (50:20:20:10) infested with a conidial suspension (1.5 × 106/ml) of three isolates of V. dahliae isolated from infected plants. Noninoculated plants served as controls. Plants (16 per treatment) were grown in pots (3 liter vol) and maintained in a glasshouse at temperatures between 22 and 25°C and relative humidity between 50 and 70%. First wilt symptoms and vascular discoloration in the roots, crown, and veins developed 17 days after inoculation. Noninoculated plants remained healthy. The pathogenicity tests were carried out twice. To our knowledge, this is the first report in Italy of Verticillium wilt on R. fulgida. Wilts caused by V. dahliae on R. laciniata in Poland (3) and V. albo-atrum on R. hirta in the United States (2) were previously reported. The importance and economic impact of this disease is currently limited but may increase because of the popularity of Rudbeckia spp. in private and public parks. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. F. Farr et al. Fungi on Plants and Their Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) B. Leski. Rocz. Nauk Roln. 253, 1974. (4) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002.

scholarly journals First Report of Verticillium Wilt of Grapevine (Vitis vinifera) Caused by Verticillium dahliae in China

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 841-841 ◽  
Author(s):  
L. Zhang ◽  
G. L. Zhang ◽  
X. Qian ◽  
G. Y. Li
Keyword(s):  
Vitis Vinifera ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Sequential Analysis ◽  
Vascular Tissue ◽  
Tap Water ◽  
The United States ◽  
Conidial Suspension ◽  
First Report ◽  
5.8S Rdna

Verticillium dahliae Kleb. causes Verticillium wilt in large numbers of crops all over the world. Common symptoms caused by the pathogen include yellowing, wilting of leaves, and discoloration in vascular tissue of the stem. In June 2007, symptoms of Verticillium wilt were observed in a grapevine (Vitis vinifera) field in the Shihezi Region of Xinjiang. To isolate the pathogen, stem segments (0.5 cm long) were surface sterilized with 1% HgCl2 for 1 min and then dipped in 70% ethanol for 10 s. The sterilized tissues were rinsed with sterile water and incubated in the dark for 7 days at 25°C on potato dextrose agar (PDA) medium. The fungus growing from the diseased tissue showed dark colonies that produced verticillate conidiophores with two to three layers with colorless, ovoid, unicellular conidia and small, black microsclerotia, which are characteristics of V. dahliae (3). To confirm its identity, ribosomal DNA fragments (regions ITS1, 5.8S rDNA, and ITS4) were PCR amplified with primer pair ITS1/ITS4 (4) and sequenced (GenBank Accession No. FJ475122). Sequential analysis revealed that the rDNA region of the fungus isolated from grapevine was identical to that of a Greek strain of V. dahliae (GenBank Accession No. AF104926). Furthermore, the specific fragment (1,500 bp) of nondefoliating pathotype of V. dahliae (1) was PCR amplified from 24 grapevine isolates of V. dahliae collected in Xinjiang, indicating that the V. dahliae pathogen from Xinjiang is a nondefoliating pathotype. To verify the causal role of the isolated fungus, pathogenicity assays were conducted on 1-year-old seedlings of the Centennial seedless cultivar. Trimmed roots were submerged in a conidial suspension (1 × 106 conidia/ml) for 30 min and sterile tap water was used as a control. The seedlings were transplanted into a pot containing 2:1 sterile mixture of peat/perlite (vol/vol). Plants were grown in a greenhouse at 25°C. Six Verticillium isolates were found to cause the same symptoms as in fields 50 days after inoculation. V. dahliae was successfully reisolated from the stems of inoculated plants. Control seedlings inoculated in sterile tap water remained healthy. Because grapevine (Vitis vinifera) is an economically important crop for fruit and winemaking material in Xinjiang, Verticillium wilt poses a threat. The disease has been previously reported in the United States (2), but to our knowledge, this is the first report from China. References: (1) E. Pérez Artés et al. Eur. J. Plant Pathol. 106:507, 2000. (2) W. C. Schnathorst and A. C. Goheen. Plant Dis. Rep. 61:909, 1977. (3) H. C. Smith. N. Z. J. Agric. Res. 8:450, 1965. (4) T. J. White et al. PCR Protocols. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of Verticillium Wilt Caused by Verticillium dahliae on Figmarigold in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 129-129
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
P. Pensa ◽  
M. L. Gullino
Keyword(s):  
Verticillium Wilt ◽  
Cross Sections ◽  
Vascular Tissue ◽  
Morphological Characteristics ◽  
Ground Cover ◽  
Its Region ◽  
Peat Moss ◽  
Conidial Suspension ◽  
First Report ◽  
Initial Symptoms

Lampranthus spp. N.B. Brown (figmarigold) belongs to the Aizoaceae family and is grown as a ground cover in gardens or as a potted plant. In January 2009, severe outbreaks of a previously unknown wilt were observed at a commercial farm in Liguria (northern Italy) where 7-month-old potted plants were grown outdoors in a mix of peat/clay/pumice at pH 6.5. In cultivars with pink flowers, 12% of plants were affected, while only a few cultivars with red flowers were diseased. Initial symptoms were yellowing of external leaves and brown or black streaks in the vascular tissue of roots, crown, and leaves. Subsequently, infected tissues wilted and stopped growing, stems and leaves appeared desiccated, and infected plants died. Stems of 10 pink-flowered plants were severed with a knife, cut ends sealed with wax, and surfaces disinfected with 1% sodium hypochlorite. Cross-sections (1 mm long) through symptomatic vascular tissue were plated onto potato dextrose agar. After 10 days at 22°C, 90% of the stems tested positive for Verticillium. Irregular, dark microsclerotia, 22 to 128 × 13 to 66 (average 51 × 29) μm, developed in hyaline hyphae after 10 days of growth at 22 ± 1°C (12-h photoperiod). Hyaline, elliptical, single-celled conidia, 2.9 to 4.8 × 1.3 to 2.4 (average 4.1 × 1.7) μm, developed on verticillate conidiophores. On the basis of these morphological characteristics, the fungus was identified as V. dahliae (3). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 (2) and sequenced. BLASTn analysis (1) of the 476-bp segment showed a 100% homology with the sequence of V. dahliae. The nucleotide sequence has been assigned GenBank Accession No. GQ 149479. Pathogenicity tests were performed twice using five 40-day-old plants of a pink-flower cultivar of a Lampranthus sp. grown in 1-liter pots containing a 50:20:20:10 mix of peat moss/pumice/pine bark cortex/clay. The substrate was infested with a conidial suspension (1.0 × 107/ml) of one isolate of V. dahliae recovered from infected plants. Inoculum (50 ml) were added to each pot, drenching the top of the soil. Noninoculated plants served as controls. Plants (five per treatment) were maintained in a glasshouse at daily average temperatures between 20 and 26°C and at 50 to 70% relative humidity. The first wilt symptoms and a vascular discoloration in the roots, crown, and veins developed 30 days after inoculation. V. dahliae was consistently reisolated. Noninoculated plants remained healthy. In a second test, the susceptibility of purple-, white-, yellow-, red-, and orange-flowered cultivars was tested. Ten rooted cuttings of each cultivar were inoculated as described above. The severity of Verticillium wilt was evaluated and each cultivar was classified as resistant, partially resistant, average susceptible, susceptible, or highly susceptible. All tested cultivars were susceptible or highly susceptible to Verticillium. Only the purple cultivar showed an average susceptibility. To our knowledge, this is the first report of Verticillium wilt on Lampranthus spp. in Italy as well as worldwide. Today, the economic importance of Verticillium wilt on figmarigold in Italy is still limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) M. A. Innis et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (3) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002.

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

Plant Disease ◽  
2007 ◽  
Vol 91 (6) ◽  
pp. 770-770 ◽  
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.

scholarly journals First Report of Sclerotinia sclerotiorum on Campanula carpatica and Schizanthus × wisetonensis in Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (1) ◽  
pp. 71-71
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Sclerotinia Sclerotiorum ◽  
Ornamental Plants ◽  
Soil Surface ◽  
The United States ◽  
First Report ◽  
Potted Plants ◽  
Initial Symptoms ◽  
Stem Necrosis ◽  
Campanula Carpatica

The production of potted ornamental plants is very important in the Albenga Region of northern Italy, where plants are grown for export to central and northern Europe. During fall 2000 and spring 2001, sudden wilt of tussock bellflower (Campanula carpatica Jacq.) and butterfly flower (Schizanthus × wisetonensis Hort.) was observed on potted plants in a commercial greenhouse. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of the lower leaves. As stem necrosis progressed, infected plants growing in a peat, bark compost, and clay mixture (70-20-10) wilted and died. Necrotic tissues were covered with whitish mycelia that produced dark, spherical (2 to 6 mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from symptomatic stem pieces of both plants disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with streptomycin sulphate at 100 ppm. Pathogenicity of three isolates obtained from each crop was confirmed by inoculating 45- to 60-day-old C. carpatica and Schizanthus × wisetonensis plants grown in containers (14 cm diameter). Inoculum that consisted of wheat kernels infested with mycelia and sclerotia of each isolate was placed on the soil surface around the base of previously artificially wounded or nonwounded plants. Noninoculated plants served as controls. All plants were maintained outdoors where temperatures ranged between 8 and 15°C. Inoculated plants developed symptoms of leaf yellowing, followed by wilt, within 7 to 10 days, while control plants remained symptomless. White mycelia and sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of stem blight of C. carpatica and Schizanthus × wisetonensis caused by S. sclerotiorum in Italy. The disease was previously observed on C. carpatica in Great Britain (2) and on Schizanthus sp. in the United States (1). References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) J. Rees. Welsh J. Agric. 1:188, 1925.

scholarly journals First Report of Stem Blight Caused by Calonectria colhounii (Anamorph Cylindrocladium colhounii) on Greenhouse-Grown Blueberries in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1187-1187
Author(s):  
J. J. Sadowsky ◽  
T. D. Miles ◽  
A. M. C. Schilder
Keyword(s):  
United States ◽  
North Carolina ◽  
Root Rot ◽  
The United States ◽  
Vaccinium Corymbosum ◽  
Conidial Suspension ◽  
Centraalbureau Voor ◽  
First Report ◽  
Stem Lesions ◽  
Β Tubulin

Necrotic stems and leaves were observed on 2- to 4-month-old, rooted microshoot plants (Vaccinium corymbosum L. ‘Liberty’ and ‘Bluecrop’, V. angustifolium Aiton ‘Putte’, and V. corymbosum × V. angustifolium ‘Polaris’) in a Michigan greenhouse in 2008 and 2009. As the disease progressed, leaves fell off and 80 to 100% of the plants died in some cases. Root rot symptoms were also observed. A fungus was isolated from stem lesions. On potato dextrose agar (PDA), cultures first appeared light tan to orange, then rusty brown and zonate with irregular margins. Chains of orange-brown chlamydospores were abundant in the medium. Macroconidiophores were penicillately branched and had a stipe extension of 220 to 275 × 2.5 μm with a narrowly clavate vesicle, 3 to 4 μm wide at the tip. Conidia were hyaline and cylindrical with rounded ends, (1-)3-septate, 48 to 73 × 5 to 7 (average 60 × 5.5) μm and were held together in parallel clusters. Perithecia were globose to subglobose, yellow, 290 to 320 μm high, and 255 to 295 μm in diameter. Ascospores were hyaline, 2- to 3-septate, guttulate, fusoid with rounded ends, slightly curved, and 30 to 88 × 5 to 7.5 (average 57 × 5.3) μm. On the basis of morphology, the fungus was identified as Calonectria colhounii Peerally (anamorph Cylindrocladium colhounii Peerally) (1,2). The internal transcribed spacer region (ITS1 and ITS2) of the ribosomal DNA and the β-tubulin gene were sequenced (GenBank Accession Nos. HQ909028 and JF826867, respectively) and compared with existing sequences using BLASTn. The ITS sequence shared 99% maximum identity with that of Ca. colhounii CBS 293.79 (GQ280565) from Java, Indonesia, and the β-tubulin sequence shared 97% maximum identity with that of Ca. colhounii CBS 114036 (DQ190560) isolated from leaf spots on Rhododendron sp. in North Carolina. The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 129628). To confirm pathogenicity, 5 ml of a conidial suspension (1 × 105/ml) were applied as a foliar spray or soil drench to four healthy ‘Bluecrop’ plants each in 10-cm plastic pots. Two water-sprayed and two water-drenched plants served as controls. Plants were misted intermittently for 2 days after inoculation. After 7 days at 25 ± 3°C, drench-inoculated plants developed necrotic, sporulating stem lesions at the soil line, while spray-inoculated plants showed reddish brown leaf and stem lesions. At 28 days, three drench-inoculated and one spray-inoculated plant had died, while others showed stem necrosis and wilting. No symptoms were observed on control plants. Fungal colonies reisolated from surface-disinfested symptomatic stem, leaf, and root segments appeared identical to the original isolate. Cy. colhounii was reported to cause a leaf spot on blueberry plants in nurseries in China (3), while Ca. crotalariae (Loos) D.K. Bell & Sobers (= Ca. ilicicola Boedijn & Reitsma) causes stem and root rot of blueberries in North Carolina (4). To our knowledge, this is the first report of Ca. colhounii causing a disease of blueberry in Michigan or the United States. Because of its destructive potential, this pathogen may pose a significant threat in blueberry nurseries. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) L. Lombard et al. Stud. Mycol. 66:31, 2010. (3) Y. S. Luan et al. Plant Dis. 90:1553, 2006. (4) R. D. Milholland. Phytopathology 64:831, 1974.

scholarly journals First Report of Alternaria tenuissima Causing Postharvest Decay on Apple Fruit from Cold Storage in the United States

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 690-690 ◽  
Author(s):  
L. P. Kou ◽  
V. L. Gaskins ◽  
Y. G. Luo ◽  
W. M. Jurick
Keyword(s):  
United States ◽  
South Africa ◽  
Cold Storage ◽  
Fungal Pathogens ◽  
The United States ◽  
Apple Fruit ◽  
Conidial Suspension ◽  
Single Spore ◽  
Alternaria Tenuissima ◽  
First Report

Apples are grown and stored for 9 to 12 months under controlled atmosphere conditions in the United States. During storage, apples are susceptible to various fungal pathogens, including several Alternaria species (2). Alternaria tenuissima (Nees) Wiltshire causes dry core rot (DCR) on apples during storage and has recently occurred in South Africa (1). Losses range widely, but typically occur at 6 to 8% annually due to this disease (2). In February 2013, ‘Nittany’ apples with round, dark-colored, dry, spongy lesions were obtained from wooden bins in a commercial cold storage facility located in Pennsylvania. Symptomatic fruits were transported to the lab, rinsed with sterile water, and the lesions were sprayed with 70% ethanol until runoff and wiped dry. The skin was aseptically removed with a scalpel, and asymptomatic tissue was placed onto potato dextrose agar (PDA) and incubated at 25°C. Two single-spore isolates were propagated on PDA and permanent cultures were maintained as slants and stored at 4°C. The fungus produced a cottony white mycelium that turned olive-green to brown with abundant aerial hyphae and had a dark brown to black reverse on PDA. Isolates were identified as Alternaria based on conidial morphology as the spores were slightly melanized and obclavate to obpyriform catentulate with longitudinal and transverse septa attached in unbranched chains on simple short conidiophores. Conidia ranged from 10 to 70 μm long (mean 27.7 μm) and 5 to 15 μm wide (mean 5.25 μm) (n = 50) with 1 to 6 transverse and 0 to 2 longitudinal septa. Conidial beaks, when present, were short (5 μm or less) and tapered. Mycelial genomic DNA was extracted, and a portion of the histone gene (357 bp) was amplified via gene specific primers (Alt-His3-F/R) using conventional PCR (Jurick II, unpublished). The forward and reverse sequences were assembled into a consensus representing 2× coverage and MegaBLAST analysis showed that both isolates were 100% identical to Alternaria tenuissima isolates including CR27 (GenBank Accession No. AF404622.1) that caused DCR on apple fruit during storage in South Africa. Koch's postulates were conducted using 10 organic ‘Gala’ apple fruit that were surface sterilized with soap and water, sprayed with 70% ethanol, and wiped dry. The fruit were aseptically wounded with a nail to a 3 mm depth, inoculated with 50 μl of a conidial suspension (1 × 104 conidia/ml), and stored at 25°C in 80 count boxes on paper trays for 21 days. Mean lesion diameters on inoculated ‘Gala’ apple fruit were 19.1 mm (±7.4), water only controls (n = 10 fruit) were symptomless, and the experiment was repeated. Symptoms observed on artificially inoculated ‘Gala’ apple fruit were similar to the decay observed on ‘Nittany’ apples from cold storage. Based on our findings, it is possible that A. tenuissima can cause decay that originates from wounded tissue in addition to dry core rot, which has been reported (1). Since A. tenuissima produces potent mycotoxins, even low levels of the pathogen could pose a health problem for contaminated fruit destined for processing and may impact export to other countries. To the best of our knowledge, this is the first report of alternaria rot caused by A. tenuissima on apple fruit from cold storage in the United States. References: (1) J. C. Combrink et al. Decid. Fruit Grow. 34:88, 1984. (2) M. Serdani et al. Mycol. Res. 106:562, 2002. (3) E. E. Stinson et al. J. Agric. Food Chem. 28:960, 1980.

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

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 788-788 ◽  
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.

scholarly journals First Report of Myrothecium roridum Causing Myrothecium Leaf Spot on Salvia spp. in the United States

Plant Disease ◽  
2007 ◽  
Vol 91 (6) ◽  
pp. 772-772 ◽  
Author(s):  
J. A. Mangandi ◽  
T. E. Seijo ◽  
N. A. Peres
Keyword(s):  
United States ◽  
Leaf Spot ◽  
Pathogenic Fungi ◽  
Lower Surface ◽  
The United States ◽  
Plant Diseases ◽  
Control Measures ◽  
Conidial Suspension ◽  
First Report ◽  
Myrothecium Roridum

The genus Salvia includes at least 900 species distributed worldwide. Wild species are found in South America, southern Europe, northern Africa, and North America. Salvia, commonly referred to as sage, is grown commercially as a landscape plant. In August 2006, pale-to-dark brown, circular leaf spots 5 to 20 mm in diameter with concentric rings were observed on Salvia farinacea ‘Victoria Blue’. Approximately 5% of the plants in a central Florida nursery were affected. Lesions were visible on both leaf surfaces, and black sporodochia with white, marginal hyphal tuffs were present mostly on the lower surface in older lesions. Symptoms were consistent with those of Myrothecium leaf spot described on other ornamentals such as gardenia, begonia, and New Guinea impatiens (4). Isolations from lesions on potato dextrose agar produced white, floccose colonies with sporodochia in dark green-to-black concentric rings. Conidia were hyaline and cylindrical with rounded ends and averaged 7.4 × 2.0 μm. All characteristics were consistent with the description of Myrothecium roridum Tode ex Fr. (2,3). The internal transcribed spacer regions ITS1, ITS2, and the 5.8s rRNA genomic region of one isolate were sequenced (Accession No. EF151002) and compared with sequences in the National Center for Biotechnology Information (NCBI) database. Deposited sequences from M. roridum were 96.3 to 98.8% homologous to the isolate from salvia. To confirm pathogenicity, three salvia plants were inoculated by spraying with a conidial suspension of M. roridum (1 × 105 conidia per ml). Plants were covered with plastic bags and incubated in a growth chamber at 28°C for 7 days. Three plants were sprayed with sterile, distilled water as a control and incubated similarly. The symptoms described above were observed in all inoculated plants after 7 days, while control plants remained symptomless. M. roridum was reisolated consistently from symptomatic tissue. There are more than 150 hosts of M. roridum, including one report on Salvia spp. in Brunei (1). To our knowledge, this is the first report of Myrothecium leaf spot caused by M. roridum on Salvia spp. in the United States. Even the moderate level disease present caused damage to the foliage and reduced the marketability of salvia plants. Therefore, control measures may need to be implemented for production of this species in ornamental nurseries. References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2006, (2) M. B. Ellis. Page 449 in: Microfungi on Land Plants: An Identification Handbook. Macmillan Publishing, NY, 1985. (3) M. Fitton and P. Holliday. No. 253 in: CMI Descriptions of Pathogenic Fungi and Bacteria. The Eastern Press Ltd. Great Britain, 1970. (4) M. G. Daughtrey et al. Page 19 in: Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society. St. Paul, MN, 1995.

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