First Report of Sour Rot Caused by Geotrichum citri-aurantii on Key Lime (Citrus aurantifolia) in Colima State, Mexico

Sour rot caused by Geotrichum citri-aurantii (Ferraris) R. Cif. & F. Cif. (synonym G. candidum Link) is a disease that causes postharvest losses of lemon (Citrus limon Burm, f.), mandarin (C. reticulata Blanco), and orange (C. sinensis (L.) Osbeck) (2–4) worldwide, but it has not been described on key lime (C. aurantifolia (Chistm.) Swingle) from the State of Colima, Mexico. During the agricultural cycle from 2005 to 2007, 300 fruits of key lime were analyzed. Symptoms observed on approximately 40% of the fruits were wounds with a sour, fermented smell with 30% of the softened area covered with white mycelium. A Geotrichum sp. was isolated on potato dextrose agar (PDA). On the basis of morphological criteria (1) and sequencing the internal transcribed spacer (ITS1-5.8s-ITS2) region of rDNA (GenBank Accession No. EU131181), the fungus was identified as G. citri-aurantii. A sample of the fungus was deposited in the Biology Collection of Yeast and Fungi (Reg. No. CLT20) of Centro de Investigaciones Biológicas del Noroeste, Mexico. Key limes were inoculated with G. citri-aurantii by placing three drops (20 μl each) of a sterile water suspension of 106 arthroconidia/ml in three punctured wounds of 3-mm diameter produced with a sterile scalpel on the fruit surface. Ten plastic boxes with five fruit each were stored for 2 weeks at 20°C and 85% relative humidity. Sour rot symptoms on key lime inoculated with G. citri-aurantii were identical to fruit in the field. The control fruit inoculated with sterile water did not develop symptoms. The fungus was reisolated, confirming Koch's postulates. The test was repeated three times to confirm our diagnosis. To our knowledge, this is the first report of G. citri-aurantii causing sour rot on key lime in Colima, Mexico. References: (1) S. Gente et al. J. Ind. Microbiol. Biotechnol. 33:1019, 2006. (2) P. Plaza et al. J. Hortic. Sci. Biotechnol. 79:935, 2004. (3) J. L. Smilanick et al. Post. Biol. Tech. 47:226, 2008. (4) V. H. Tournas and E. Katsoudas, J. Food. Microbiol. 105:11, 2005.

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First Report of Stem Rot and Wilt of Sunflower Caused by Sclerotinia minor in Spain

Plant Disease ◽

10.1094/pdis.2002.86.6.697d ◽

2002 ◽

Vol 86 (6) ◽

pp. 697-697

Author(s):

M. L. Molinero-Ruiz ◽

J. M. Melero-Vara

Keyword(s):

Helianthus Annuus ◽

Root Rot ◽

Mycelial Growth ◽

Disease Incidence ◽

Potato Dextrose Agar ◽

Stem Rot ◽

Sclerotinia Minor ◽

Stem Base ◽

First Report ◽

White Mycelium

In 2001, sunflower (Helianthus annuus L.) plants with symptoms of stem and root rot and wilt were observed in Soria, Spain. Light brown, water-soaked lesions developed on the collar of infected plants and extended along the stem, affecting the pith and causing early and sudden wilt. White mycelium and sclerotia (0.5 to 2 mm long) formed in the pith of stems. The sclerotia were disinfested in NaClO (10% vol/vol) for 1 min, transferred to potato dextrose agar (PDA), and incubated at 20°C. The fungus consistently obtained was identified as Sclerotinia minor Jagger (1). Pathogenicity was confirmed in a greenhouse experiment (15 to 25°C, 13 h light). Seven-week-old plants of six genotypes of sunflower (‘Peredovik’, HA89, HA821, HA61, RHA274, and HA337) were inoculated by placing one PDA disk with active mycelial growth adjacent to each basal stem just below the soil line and covering it with peat/sand/silt (2:2:1, vol/vol). Six plants of each genotype were inoculated without wounding, and another six were inoculated immediately after stem base wounding with a scalpel; six wounded and uninoculated plants were used as controls. First symptoms (wilting) appeared 4 days after inoculation in all genotypes. Two weeks after inoculation, the percentage of dead plants ranged from 33 to 92% (depending on cultivar), white mycelium was observed at the base of affected plants, and sclerotia were present in the pith of diseased plants. There was no effect of plant wounding on disease incidence or severity, and the fungus was reisolated from inoculated plants. To our knowledge, this is the first report of S. minor in Spain. Reference: (1) L. M. Kohn. Mycotaxon IX 2:365, 1979.

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First Report of Colletotrichum siamense Causing Leaf Drop and Fruit Spot of Citrus reticulata Blanco cv. Shiyue Ju in China

Plant Disease ◽

10.1094/pdis-04-13-0352-pdn ◽

2013 ◽

Vol 97 (11) ◽

pp. 1508-1508 ◽

Cited By ~ 7

Author(s):

B. P. Cheng ◽

Y. H. Huang ◽

X. B. Song ◽

A. T. Peng ◽

J. F. Ling ◽

...

Keyword(s):

Potato Dextrose Agar ◽

Citrus Reticulata ◽

Sterile Water ◽

Yield Losses ◽

First Report ◽

Citrus Reticulata Blanco ◽

Fruit Spot ◽

Wide Range ◽

Colletotrichum Siamense ◽

Leaf Drop

Citrus reticulata Blanco cv. Shiyue Ju, which produces one of China's most popular tropical fruits, is widely planted throughout southern China. In 2008, a new citrus disease was found in Zhaoqing City in Guangdong Province on about 20,000 ha. Yield losses averaged 15% on a wide range of different aged trees of C. reticulata cv. Shiyue Ju. No yield losses were observed on C. reticulata cv. Gong gan. Symptoms first appeared on young leaves as leaf lesions, which were reddish-brown, elliptical, and 2 to 5 mm in diameter. After several weeks, 20 to 70% of leaves dropped and 10 to 50% of fruits on the trees showed brown spots (5 to 40 mm in diameter). Leaves and fruit peels adjacent to and including lesions from different trees were surface disinfested with 1% sodium hypochlorite for 1 min and rinsed three times in sterile water. Then the tissues were plated on potato dextrose agar (PDA) in alternating light and dark at 28°C for 3 days. Twenty-three similar isolates of a fast-growing fungus were recovered from all samples. For identification, single-spore cultures were grown on potato dextrose agar (PDA) at 28°C. Initially, the colonies were white, but after 5 days, they became pale gray with concentric zones and greenish black beneath. No setae, acervuli, or ascocarp were observed in the PDA culture. Conidia formed in pink conidial masses, were hyaline, fusiform, straight, obtuse at the ends, sometimes slightly curved, and 14 to 20 × 4.5 to 6 μm (x¯ = 16.2 ± 1.5 × 4.9 ± 0.5, n = 100). The cultural and morphological characteristics of these isolates matched the description of Colletotrichum siamense (3), but not that of C. gloeosporioides or C. acutatum, which cause anthracnose on citrus plants (1,2). The actin, β-tubulin, CHS I, CAL, GPDH, and ITS regions of four representative isolates (GenBank KC524462, KC524463, KC524464, KC524465, KC524466, and KC524467) were identical and with almost 100% identity to those of the type specimen of C. hymenocallidis isolate CSSN3 (C. hymenocallidis is synonymous with C. siamense) (4), except for two inconsistent nucleotide bases in the GPDH gene. Four potted plants of C. reticulata cv. Shiyue Ju were used for pathogenicity tests. On each plant, 10 randomly selected leaves and four 6-month-old fruits were wound-inoculated with 20 μl of sterile water or conidial suspensions (1 × 105 conidia per ml). Plants were then maintained at 90% relative humidity with a 12-h photoperiod at 28°C. Symptoms resembling those in the field were observed on three inoculated plants after 14 days. In another similar experiment without wounding, three of 20 inoculated plants exhibited the symptoms after 14 days. Controls remained healthy throughout this period. The tests were performed three times. C. siamense was reisolated from all diseased inoculated plants, and the culture and fungus characteristics were the same as the original isolate. Thus, C. siamense was determined to be the pathogen causing leaf drop and fruit spot on C. reticulata cv. Shiyue Ju. To our knowledge, this is the first report of leaf drop and fruit spot on C. reticulata cv. Shiyue Ju caused by C. siamense. References: (1) H. Benyahia et al. Plant Pathol. 52:798, 2003. (2) N. A. Peres et al. Plant Dis. 89:784, 2005. (3) H. Prihastuti, et al. Fungal Diversity 39:89, 2009. (4) B. Weir et al. Stud Mycol. 73:115, 2012.

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First Report of Crown and Stem Rot of Orchid (Orchis palustris) Caused by Sclerotinia minor

Plant Disease ◽

10.1094/pd-89-0913c ◽

2005 ◽

Vol 89 (8) ◽

pp. 913-913

Author(s):

C. Eken ◽

S. Ercişli ◽

A. Eşitken ◽

E. Demirci ◽

G. Y. Yuen

Keyword(s):

Potato Dextrose Agar ◽

Stem Rot ◽

Eastern Anatolia ◽

Forage Production ◽

Sclerotinia Minor ◽

Transparent Plastic ◽

First Report ◽

Plastic Bags ◽

White Mycelium ◽

Plant Pathol

Orchis palustris Jacq. is a wild orchid native to wetlands in eastern Anatolia. During June of 2003, near Erzurum, Turkey, a decline of this orchid was observed in several meadows that had been irrigated for forage production. Stems were chlorotic, wilted, and collapsed. There was a soft, watery rot at the crowns and lower stems. White mycelium and black sclerotia formed on necrotic stem and crown tissues. The fungus was isolated from sclerotia on potato dextrose agar (PDA) and identified as Sclerotinia minor Jagger on the basis of small sclerotia (0.5 to 2.5 mm long) scattered throughout the colonies (2). Pathogenicity was confirmed by inoculating stems of 8-week-old plants with mycelial plugs from 5-day-old PDA cultures and enclosing inoculated plants in transparent plastic bags for 3 days. After 2 weeks, symptoms similar to those in the field were observed, and S. minor was reisolated from inoculated plants. Noninoculated control plants remained asymptomatic. The disease was previously observed on O. laxiflora Lam. in Turkey (1), but to our knowledge, this is the first report of S. minor infecting O. palustris References: (1) C. Eken et al. Plant Pathol. 52:802, 2003. (2) L.M. Kohn. Phytopathology 69:881, 1979.

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First Report of Septoria Blight of Parsley Caused by Septoria petroselini in the Mediterranean Region of Turkey

Plant Disease ◽

10.1094/pdis.2003.87.1.99a ◽

2003 ◽

Vol 87 (1) ◽

pp. 99-99 ◽

Cited By ~ 3

Author(s):

S. Kurt

Keyword(s):

Mediterranean Region ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

Distilled Water ◽

Conidial Suspension ◽

Sterile Water ◽

First Report ◽

Foliar Symptoms ◽

Polyethylene Bags ◽

The Mediterranean

During December 2001 to March 2002, Septoria blight of parsley was observed in approximately 500 ha of commercial parsley crops in Arsuz County, Hatay, in the Mediterranean Region of Turkey. Incidence of disease ranged from 42 to 80%. Symptoms included irregularly shaped, grayish brown spots (average 3 to 8 mm diameter) with a slightly darker brown margin of necrotic tissue that developed into tan-to-brown lesions surrounded by chlorotic halo on the leaves. Oval-shaped lesions were observed occasionally on petioles. Lesions contained erumpent, dark brown, flask-shaped pycnidia with the ostiole on the upper surface of the foliage. Thirty samples, consisting of diseased leaves and petioles of parsley, were collected from each field. Infected tissues were surface-sterilized in 1% NaOCl for 2 min, rinsed in sterile distilled water, placed on petri dishes containing potato dextrose agar (PDA), and incubated for 10 to 14 days at 25°C. The fungus formed long, multiseptate (0 to 4), hyaline, filiform conidia (14 to 29 μm × 0.5 to 1.9 μm), and short conidiophores within the pycnidia. Based on the morphological characteristics of the fungus, the pathogen was identified as Septoria petroselini Desm. (1). Monoconidial cultures of 18 isolates were prepared. Pathogenicity was confirmed by brush-inoculating slightly wounded foliage of 5- to 7- week-old parsley plants (cv. Kereviz yapragi) with a conidial suspension (106 conidia per ml of sterile water) of each isolate of S. petroselini. Control plants that were brush-inoculated with distilled water and inoculated plants were placed in clear polyethylene bags that were closed and incubated at 20°C for 48 h. The bags were removed, and plants were maintained in a dew chamber for 21 days at 65 to 70% relative humidity. Foliar symptoms developed 15 days after inoculation and appeared similar to lesions observed in the field. Yellowing and necrosis of leaves was also observed on >60% of inoculated plants. No lesions developed on the control plants. The pathogen was readily reisolated on PDA from inoculated plants. To our knowledge, this is the first report of Septoria blight of parsley in the Mediterranean Region of Turkey. Reference: (1) R. F. Cerkauskas and J. Uyenaka. Plant Dis. 74:1037, 1990.

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First Report of Myrothecium Leaf Spot of Common Bean in China Caused by Myrothecium roridum

Plant Disease ◽

10.1094/pdis-94-1-0127b ◽

2010 ◽

Vol 94 (1) ◽

pp. 127-127 ◽

Cited By ~ 4

Author(s):

Y.-J. Zhao ◽

B.-J. Li ◽

Y.-X. Shi ◽

X.-W. Xie

Keyword(s):

Common Bean ◽

Leaf Spot ◽

Potato Dextrose Agar ◽

Sterile Water ◽

Phaseolus Vulgaris L ◽

First Report ◽

Leaf Spots ◽

Myrothecium Roridum ◽

Beijing China ◽

Commercial Field

Common bean (Phaseolus vulgaris L.) is an economically important crop in China. In June 2008, a new foliar disease was observed on beans in Shunyi District, Beijing, China. The disease occurred in approximately 15% of the plants in a commercial field. Leaf spots were circular to irregular, reddish brown, zonate, and 8 to 20 mm in diameter. Black sporodochia with white tuffs were present on older lesions and black spore masses were present in moist weather. Ten isolates recovered from lesions produced white, floccose colonies and spore masses after 4 days on potato dextrose agar. The rod-shaped, hyaline conidia had rounded ends and averaged 6.8 × 2.5 μm. All characteristics were consistent with the description of Myrothecium roridum Tode ex Fr. (1). The internal transcribed spacer regions of one isolate were sequenced and deposited in GenBank (Accession No. GQ 381291). Sequences of the isolate from bean in China were 98% similar to sequences of M. roridum in GenBank. To determine pathogenicity, 30 healthy seedlings of common bean were inoculated by spraying a 1 × 105 conidia ml–1 suspension of M. roridum onto the foliage. Ten seedlings were sprayed with sterile water and served as controls. Plants were kept in a humid chamber at 27°C overnight and then placed in a growth chamber. After 6 days, the symptoms described above were observed on leaves in all inoculated plants, whereas symptoms did not develop on the control plants. The pathogen was reisolated from inoculated leaves, fulfilling Koch's postulates. There is one report of M. roridum on soybean in Korea (2). To our knowledge, this is the first report of Myrothecium leaf spot on common bean in China. References: (1) M. Fitton et al. CMI Mycol. Pap. No. 253, 1970. (2) K. J. Yum et al. Plant Pathol. J. 6:313, 1990.

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First Report of Pestalotiopsis clavispora Causing Dieback on Blueberry in Uruguay

Plant Disease ◽

10.1094/pdis-12-11-1070-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 914-914 ◽

Cited By ~ 14

Author(s):

P. González ◽

S. Alaniz ◽

M. J. Montelongo ◽

L. Rauduviniche ◽

J. Rebellato ◽

...

Keyword(s):

Vaccinium Corymbosum ◽

Harvard University ◽

Internal Transcribed Spacers ◽

Its2 Region ◽

Academic Press ◽

First Report ◽

Dieback Disease ◽

White Mycelium ◽

Cork Borer ◽

Concentric Circles

During the last 10 years, blueberry (Vaccinium corymbosum) production in Uruguay has increased to more than 850 ha. From 2005, symptoms of dieback characterized by the death of twigs and branches have been frequently observed in blueberry plants cv. O'Neal in orchards located in Uruguay. Symptomatic 4-year-old plants (cv. O'Neal) were collected and small pieces of necrotic tissues were surface disinfected and plated onto potato dextrose agar (PDA) with 0.2 g liter–1 of streptomycin sulfate. Plates were incubated at 25°C in the dark. All affected tissues consistently developed colonies with white and cottony mycelium, turning slightly yellow after 7 to 10 days. Black acervuli distributed in concentric circles were observed after 10 days. Conidia were fusiform, straight, and had five cells. Basal and apical cells were colorless while the three median cells were dark brown. Conidia (n = 50) had an average of 22.1 (16.5 to 28.2) × 6.6 (5.6 to 7.7) μm. All conidia had one basal appendage of 6.1 (3.9 to 14.3) μm and two to four (usually three) apical appendages of 22.8 (17.4 to 42.9) μm. According to colony and conidia morphology, the isolates were initially identified as Pestalotiopsis clavispora (G.F. Atk.) Steyaert (1). To identify, the internal transcribed spacers (ITS1, 5.8S, ITS2) region of rDNA of a representative isolate (Ara-1) was amplified with ITS1/ITS4 primers (4), sequenced, and compared with those deposited in GenBank. The isolate Ara-1 (Accession No. JQ008944) had 100% sequence identity with P. clavispora (Accession Nos. FJ517545 and EU342214). To confirm pathogenicity, isolate Ara-1 was inoculated onto asymptomatic 1-year-old blueberry plants (cv. O'Neal). Mycelial plugs (4 mm in diameter) from an actively growing colony on PDA were applied to same-size bark wounds made with a cork borer in the center of the stems previously disinfected with 70% ethanol and covered with Parafilm. Control plants were inoculated with sterile PDA plugs. Inoculated plants (five per treatment) were randomly distributed in a greenhouse and watered as needed. After 2 weeks, all stems inoculated with P. clavispora showed brown necrotic lesions 2 to 3 cm in length and 1 to 2 mm deep. White mycelium was observed over lesions. Control plants remained symptomless. The pathogen was reisolated from all necrotic lesions, thus fulfilling Koch's postulates. P. clavispora has been reported as associated with blueberry in Hawaii (3) and Chile (2). To our knowledge, this is the first report of P. clavispora causing dieback disease on blueberry in Uruguay. References: (1) E. F. Guba, Monograph of Pestalotia and Monocheatia. Harvard University Press, Cambridge, MA, 1961. (2) J. G. Espinoza et al. Plant Dis. 92:1407, 2008. (3) L. M. Keith et al. Plant Dis. 90:16, 2006. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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Blight Caused by Sclerotium rolfsii on Potted Ornamental Citrus in Sicily

Plant Disease ◽

10.1094/pdis-92-6-0977c ◽

2008 ◽

Vol 92 (6) ◽

pp. 977-977 ◽

Cited By ~ 1

Author(s):

A. Pane ◽

M. Magnano di San Lio ◽

F. Raudino ◽

S. O. Cacciola

Keyword(s):

Relative Humidity ◽

Sclerotium Rolfsii ◽

Soil Surface ◽

Morphological Characters ◽

Peat Moss ◽

Citrus Limon ◽

Pathogenicity Test ◽

Sterile Water ◽

Nursery Stock ◽

White Mycelium

Approximately 140,000 container-grown ornamental citrus plants are produced each year in the province of Catania (eastern Sicily). In the spring of 2006, a severe blight was observed in a commercial nursery in Catania on 2-month-old rooted cuttings of lemon (Citrus limon (L.) Burm.) and calamondin (× Citrofortunella mitis (Blanco) J. W. Ingram & H. E. Moore). Approximately 80% of the nursery stock of 2,000 cuttings was affected. Cuttings were grown in 7.5-cm2 pots made with compressed peat and wood pulp at 28 to 30°C with 95 to 100% relative humidity on benches in a greenhouse, The pot mix was composed of peat, perlite, and soil (2:1:2). Cuttings showed a dark brown necrotic lesion at the base of the stem that extended upward, resulting in chlorosis and wilting of the leaves. An invasive, white, cottony mycelium with a fan-like pattern and numerous, small, brown spherical sclerotia (0.5 to 4.0 mm in diameter) developed on infected tissues, in the potting mix as well as on the pot wall. Herbaceous cuttings collapsed within 2 weeks while woody cuttings gradually died. Symptomatic basal stem sections were disinfected for 1 min in 1% NaOCl, rinsed in sterile water, and plated on acidified (pH 4.5) potato dextrose agar (PDA). Isolations consistently yielded a fungus whose morphological characters corresponded to Sclerotium rolfsii Sacc. On PDA, it produced a septate mycelium with clamp connections and numerous olive brown-to-clove brown sclerotia (1 to 3 mm in diameter). Pathogenicity of two S. rolfsii isolates (IMI 396204 and IMI 396205) from citrus was confirmed on 3-month-old lemon cuttings grown in 10-cm-diameter plastic pots filled with a sterilized mix of peat moss and vermiculite (3:1) (10 cuttings for each isolate). Each pot was inoculated with 15 sclerotia harvested from 6-week-old cultures on PDA and placed on the soil surface around the base of the cutting. Ten noninoculated cuttings served as the control. Cuttings were kept in a growth chamber at 28°C and relative humidity at >95%. All inoculated cuttings showed wilting, blight, and stem rot within 3 weeks after inoculation. White mycelium and sclerotia were produced on the stem base and soil surface. Noninoculated controls remained symptomless. S. rolfsii was reisolated from infected cuttings. The pathogenicity test was repeated once with calamondin cuttings and the results were similar. Blight caused by S. rolfsii is widespread in nurseries of ornamentals in Italy (1). However, to our knowledge, this is the first report of this disease on potted ornamental citrus. Probably high temperature and moisture during rooting were conducive to the disease. References: (1) A. Garibaldi et al. Malattie Delle Piante Ornamentali. Calderini Edagricole, Bologna, Italy, 2000.

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First Report of Target Leaf Spot Caused by Corynespora cassiicola on Balsam Pear in China

Plant Disease ◽

10.1094/pdis-94-1-0127c ◽

2010 ◽

Vol 94 (1) ◽

pp. 127-127 ◽

Cited By ~ 1

Author(s):

B.-J. Li ◽

Y.-J. Zhao ◽

W. Gao ◽

Y.-X. Shi ◽

X.-W. Xie

Keyword(s):

Leaf Spot ◽

Its Region ◽

Potato Dextrose Agar ◽

Corynespora Cassiicola ◽

Sterile Water ◽

Exact Match ◽

First Report ◽

Humidity Chamber ◽

Plant Pathol ◽

Dark Green

Balsam pear (Momordica charantia L.) is an economically important vegetable in China with increasing interest as a medicinal plant. In December of 2006, a new foliar disease caused by Corynespora cassiicola was observed on balsam pear growing in greenhouses in Shouguang City, Shandong Province, China. The disease occurred on 35% or less of the plants. Leaves of affected plants developed off-white halos surrounding circular lesions that were 1 to 5 mm broad. The lesions became dark brown, necrotic with concentric rings, and up to 15 mm in diameter. Severely affected plants eventually wilted and defoliated. Pieces of tissue from the leading edges of lesions were disinfected in 1% NaOCl for 1 min, rinsed in sterile water, and plated on potato dextrose agar. Colonies of the fungus were gray to dark green. Conidiophores were erect and simple, pale brown to brown, and 100 to 450 μm long and 3 to 8 μm wide. Conidia were obclavate to cylindrical, pale olivaceous brown to dark brown, smooth, 35 to 100 × 8 to 12 μm, and were produced in chains. On the basis of these characteristics, the fungus was identified as Corynespora cassiicola (1). The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS1/ITS4 and deposited in GenBank (Accession No. GQ381292). It was an exact match for a sequence of C. cassiicola previously deposited (Accession No. EU364555). To confirm pathogenicity, 30 1-month-old healthy seedlings of balsam pear were inoculated by spraying a suspension of conidia (1 × 105 conidia per ml) of one isolate of C. cassiicola until runoff. Ten seedlings were sprayed with sterile water as controls. Plants were kept in a humidity chamber at 27°C overnight and then placed in a growth chamber at 27°C. After 7 days, symptoms identical to those described above were observed, while no symptoms developed on the control plants. The pathogen was reisolated from inoculated leaves. C. cassiicola causes foliar diseases on many plants, including tomato, eggplant, soybean, and cucumber (2). There is one report on balsam pear in Korea (3). To our knowledge, this is the first report of target leaf spot caused by C. cassiicola on balsam pear in China. References: (1) M. B. Ellis. CMI Mycol. Pap. No. 65, 1957. (2) M. B. Ellis et al. CMI Mycol. Pap. No. 303, 1971. (3) J. H. Kwon et al. Plant Pathol. J. 21:164, 2005.

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First Report of Formosan Michelia Seedling Root Rot Caused by Pythium splendens in Taiwan

Plant Disease ◽

10.1094/pd-89-1361a ◽

2005 ◽

Vol 89 (12) ◽

pp. 1361-1361 ◽

Cited By ~ 3

Author(s):

C. H. Fu ◽

C. M. Chen ◽

H. J. Hsieh

Keyword(s):

Root Rot ◽

Room Temperature ◽

Potato Dextrose Agar ◽

Malt Extract ◽

Sterile Water ◽

First Report ◽

Seedling Root ◽

Pythium Splendens ◽

Extract Medium ◽

Malt Extract Medium

Formosan michelia (Michelia compressa (Maxim.) Sargent) is a valuable evergreen tree in Taiwan that is distributed from low to medium (200 to 1,800 m) altitudes. In many nurseries in Taiwan, Formosan michelia seedlings grow poorly or wilt. The etiology of the disease observed in April 2004 in a nursery in Jinshan was investigated. Diseased seedlings with chlorotic leaves and decayed feeder roots lost leaves, died back, and then wilted. The putative pathogen, Pythium splendens Braun, was isolated and identified on a morphological basis (1). P. splendens was isolated from the roots of diseased seedlings on 2% water agar with 100 ppm of ampicillin. Isolates increased daily on potato dextrose agar at 24°C by 27 to 30 mm and on malt extract agar (MEA) by 23 to 25 mm. No zoosporangia and zoospores were produced. The main hyphae were as much as 9 μm wide on MEA. Hyphal swellings were abundant, globose, smooth, terminal, and 33 to 42 μm in diameter, often with dark, densely granulated contents. Attempted matings of four P. splendens isolates in V8 medium failed. To prove pathogenicity, the four isolates were cultured in 300-ml flasks containing 150 ml of 2% malt extract medium at room temperature for 14 days. The mycelia were homogenized in sterile water at 4,500 rpm for 5 min. The suspension was adjusted to 5 × 106 hyphal swellings per ml. Roots of the 2-month-old seedlings were immersed in the suspension for 2 h, whereas the control seedlings were immersed in sterilized water. Five seedlings of each of three replicates were inoculated with one of the four isolates for a total of 60 seedlings. Controls were replicated in the same way. The inoculated plants were transplanted into plastic flowerpots containing sterilized peat and moss and kept in the greenhouse at 20 to 24°C. After 14 days, inoculated seedlings developed symptoms like those of the original plants. The putative pathogen was reisolated from the roots of inoculated plants. Cultures are maintained at the Forest Pathology Lab of the National Taiwan University. To our knowledge, this is the first report of proof of pathogenicity of P. splendens on Formosan michelia seedlings. Reference: (1) A. J. Van der Plaats-Niterink. Stud. Mycol. 21:151, 1981.

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Unusual Stylar-End Breakdown and Sour Rot on Key Lime (Citrus aurantiifolia) in Pre-Harvest Condition in Italy

Plants ◽

10.3390/plants10050989 ◽

2021 ◽

Vol 10 (5) ◽

pp. 989

Author(s):

Giorgio Gusella ◽

Alberto Fiorenza ◽

Dalia Aiello ◽

Giancarlo Polizzi

Keyword(s):

Environmental Conditions ◽

Field Survey ◽

Physiological Disorder ◽

First Report ◽

Post Harvest ◽

Agronomic Practices ◽

Sour Rot ◽

Key Lime ◽

Citrus Aurantiifolia ◽

Citrus Spp

Key lime (Citrus aurantiifolia) is an emerging crop in Italy, especially in the Southern regions, where the environmental conditions are suitable for its cultivation. A field survey in Sicily in a commercial orchard of Key lime revealed the widespread presence of water-soaked spots and sunken/dry lesions at the stylar-end, mainly in pre-harvest condition. Water-soaked spots were attributed to Geotrichum citri-aurantii, an agent of sour rot on Citrus spp., whereas the sunken/dry lesion was attributed to the physiological disorder known as stylar-end breakdown. Sour rot and stylar-end breakdown are usually considered post-harvest diseases and rarely found in the field on fruit still attached to the tree. Although Geotrichum citri-aurantii is not responsible for the stylar-end breakdown, its association with this alteration reveals the importance of the environmental conditions and the agronomic practices in diseases/disorders development. In addition, to our knowledge, this is the first report of Geotrichum citri-aurantii on Key lime in Europe.

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