scholarly journals First Report of Colletotrichum brevisporum Causing Anthracnose of Dalbergia odorifera in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xing Zhou Chen ◽  
Quan Yang ◽  
Zhi Wan ◽  
Guo Ying Zhou ◽  
Jun Ang Liu
Keyword(s):  
Management Practices ◽  
Aerial Mycelium ◽  
Ethanol Solution ◽  
Planting Density ◽  
Molecular Characteristics ◽  
Type Specimens ◽  
Koch’S Postulates ◽  
First Report ◽  
Dalbergia Odorifera ◽  
Koch's Postulates

Dalbergia odorifera T. Chen (family Fabaceae) is one of four prized species of mahogany plant in China. In June 2017, an investigation of the condition of anthracnose was carried out on apporximately 333 hectares of D. odorifera plantations in Haikou City, Hainan Province (110.19°E, 20.03°N). Approximately 40% of D. odorifera plants had disease symptoms. Lesions on leaves were brown to grayish-white containing black dots and dark-brown borders, occasionally surrounded by a yellowish-green halo. Leaf spots generally occurred along the edge of the leaf. Severely infected leaves became withered and died. Hyphal growth was recovered from symptomatic leaf tissue, surface-sterilized with a 75% ethanol solution for 30s, rinsed with sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 26°C in the dark. The representative isolate JXHTC19 was recovered by transferring a hyphal tip to a fresh PDA plate to obtain a pure culture. Fungal colonies had white aerial mycelium initially, turning pale gray after 3 days. At 7 days, colonies had a cottony appearance ranging from white to dark gray with orange masses of conidia. The colony surface was slimy and aerial mycelium was sparse. Isolates displayed single-celled, cylindrical, hyaline conidia that were rounded at both ends, and were 9.7 - 16.4 μm long (avg. 13.5 μm) × 3.6 - 6.2 μm wide (vg. 4.8 μm) (n = 100). To further identify the fungus, genomic DNA was extracted from single conidial cultures of JXHTC19. The rDNA internal transcribed spacer (ITS) region, glutamine synthetase (GS) gene, partial sequence of glyceraldeyde-3-phosphate dehydrogenase-like (GAPDH) gene, actin (ACT) gene, and beta-tubulin (TUB2) gene were amplified using the primer pairs ITS4/ITS5, GS-F/GS-R, GDF1/GDR1, ACT-512F/ACT-783R, and TUB2-T1/Bt-2b (Weir et al 2012), respectively. The results showed that the ITS, GS, GAPDH, ACT and TUB2 genes of the target strain (JXHTC19) have 100%, 95%, 100%, 97% and 98% sequence homology with C. brevisporum, respectively. The sequences obtained were deposited in GenBank (MF993572, MN737615, MN737614, MG515612, and MG515615[LJ1]). All five sequences were analyzed together with representative sequences from type or ex-type specimens of the Colletotrichum genus (Yang et al. 2011, Weir et al. 2012) and a phylogenetic tree was generated via the neighbor-joining method using MEGA6. The tree placed the isolate in the same group as C. brevisporum. Thus, both morphological and molecular characteristics identified the pathogen as C. brevisporum. To verify Koch's postulates, two-year-old leaves of healthy potted D. odorifera plants (n = 6) were inoculated with a spore suspensions of JXHTC19 that contained 105 conidia/ml. Plants were sprayed with water to serve as mock-inoculated controls [LJ2](Garibaldi et al, 2020). Six plants per treatment were used in each test. The test was repeated once.Plants were incubated in moist chambers at 26°C and monitored daily for symptom development. After five days, eleven of twelve isolates [LJ3]caused lesions on all inoculated plants, whereas no symptoms developed on the mock-inoculated controls. Koch’s postulates were fulfilled by reisolating the same fungus and verifying its colony and morphological characters as C. brevisporum. To our knowledge, this is the first report of this species causing anthracnose of D. odorifera in China. Corresponding measures must be adopted to manage this disease such as reducing the planting density of D. odorifera and increasing the species diversity of undergrowth vegetation. These results could help develop better monitoring and management practices for this disease.

scholarly journals First report of Stemphylium eturmiunum causing leaf spot and black spot on apple in Zhaotong, Yunnan, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Cong Zhou ◽  
Xin Long Pan ◽  
Bao Hua Kong ◽  
Yueqiu He ◽  
Jun Ma ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Yunnan Province ◽  
Management Practices ◽  
Black Spot ◽  
Parsimony Method ◽  
Koch’S Postulates ◽  
First Report ◽  
The World ◽  
Postharvest Rot ◽  
Koch's Postulates

Apple is the largest fruit tree crop in the world, and China is the largest apple-producing County in the world. Zhaotong, Yunnan Province is a typical cold and mountainous apple-producing area in China. However, apple production is threatened by diseases during the entire growing season, and among them, apple leaf spot and fruit black spot are severe. In previous reports, the main pathogen causing apple leaf spot and fruit black spot was Alternaria sp. (Lior, et al, 2017), while different pathogens were identified. In the current study, seven red Fuji apple fruit with typical black spot samples were collected randomly in Dongda company orchard, Sujiayuan town, Zhaotong, Yunnan on March 25, 2021. The spots on the surface of these apples appear rounded, the diseased parts turn brown or black in colour and the flesh became soften and rotten. The tissues of fruit epidermis at the edge between diseased and healthy parts were cut, soaked in 75% alcohol for 30 s, washed with sterile water three times, and air-dried. Five pieces of tissue were placed on PDA medium amended with rifampicin (50 mg/ml) and incubated in the dark at 25 ℃ for 3-5 days. After colonies grew, mycelial clumps were picked out from the edges of the colonies, transferred to new PDA plates, and incubated at 25 ℃ for 6 days. The diameter of the colonies reached up to 5.7 cm. A representative isolate was retained for further work and was named P6-3-1. The hyphae were white and dense at an early stage, the culture medium on the underside became yellow and the middle parts of the colonies were darker. With maturity, hyphae were clumped, became red with other colors interspersed, and the medium became dark red. Light brown spores were produced, with more vertical septa and fewer transverse septa. Two to three transverse septa were generally observed with obvious constriction at the transverse septa. Average spore size was 22.83 µm ± 2.04 µm × 14.58 µm ± 1.97 µm. DNA was extracted from mycelium, purified and amplified with two pairs of primers, ITS1/ITS4 (White et al. 1990) and gpdF/gpdR (Marcos P. S. Câmara, et al. 2002). The PCR products were sequenced and deposited in GenBank (accession NO.OK560128 and OK627661 ). The similarity of ITS sequences between the isolate and MH843733 (Stemphylium eturmiunum strain ST14) was 100%, and that of gpd sequences between the isolate and MH843728 (Stemphylium eturmiunum strain ST20) was 100%. The maximum parsimony method of Mega7.0 was used and demonstrated that the studied isolate converged to the same branch as Stemphylium eturmiunum. Koch's postulates was applied to identify the pathogenicity of this isolate. A disc of P6-3-1-culture on PDA (5 mm in diameter) was placed on apple leaves and fruit wounds. Sterile PDA was used as a control. All plants were kept in a growth chamber at 25-30 ℃. Four days after inoculation, the disease spot was observed on the inoculated sites and fruit, and with the extension of incubation time, the diseased spots continue to grow, and the leaf spots were not limited by the veins. The pathogen was re-isolated from the inoculated leaves and fruit, satisfying Koch’s postulates. This pathogen can also cause postharvest rot of sweet cherry (Alice Spadoni, et al, 2020), postharvest rot on tomato (Prencipe Simona, et al, 2021), etc. This is the first report that Stemphylium eturmiunum can cause apple leaf spot and fruit black spot in Yunnan province, China. The apple black spot caused by Stemphylium eturmiunum was accurately identified. By distinguishing between the two similar diseases mentioned above, resistance to the host and management practices can be accrued based on the characteristics of the pathogen, its epidemiological pattern and the choice of an effective chemical fungicide.

First Report of Pathogenicity of Fusarium sporotrichioides and Fusarium acuminatum on Sunflowers in the United States

2010 ◽  
Vol 11 (1) ◽  
pp. 42 ◽  
Author(s):  
F. Mathew ◽  
B. Kirkeide ◽  
T. Gulya ◽  
S. Markell
Keyword(s):  
United States ◽  
Helianthus Annuus ◽  
The United States ◽  
Fusarium Sporotrichioides ◽  
Charcoal Rot ◽  
Koch’S Postulates ◽  
First Report ◽  
Fusarium Acuminatum ◽  
Helianthus Annuus L ◽  
Koch's Postulates

Widespread infection of charcoal rot was observed in a commercial sunflower field in Minnesota in September 2009. Based on morphology, isolates were identified as F. sporotrichioides and F. acuminatum. Koch's postulates demonstrated pathogencity of both species. To our knowledge, this is the first report of F. sporotrichoides and F. acuminatum causing disease on Helianthus annuus L. in the United States. Accepted for publication 23 August 2010. Published 15 September 2010.

scholarly journals First Report of Stemphylium botryosum Causing Leaf Blight of Kiwi in the Province Imathia, Northern Greece

Plant Disease ◽  
2008 ◽  
Vol 92 (4) ◽  
pp. 650-650 ◽  
Author(s):  
T. Thomidis ◽  
T. J. Michailides
Keyword(s):  
Apical Cell ◽  
Morphological Characteristics ◽  
Leaf Blight ◽  
Width Ratio ◽  
Northern Greece ◽  
Cell Width ◽  
Koch’S Postulates ◽  
First Report ◽  
Stemphylium Botryosum ◽  
Koch's Postulates

In Greece, kiwi (Actinidia deliciosa) is mostly found in the northern part of the country where approximately 440,000 ha are grown. In the summer of 2006, a Stemphylium sp. was frequently isolated from leaves of kiwi (cv. Hayward) grown in the province of Imathia. Symptomatic leaves were covered with irregular, necrotic, brown areas. Lesions had a distinct margin that, in some cases, covered a wide part of the diseased leaves. Intense symptoms were frequently observed and associated with defoliation. This Stemphylium sp. was consistently isolated from diseased leaves onto potato dextrose agar (PDA) after surface sterilization with 0.1% chlorine solution. On the basis of morphological characteristics of mycelia, dimensions (length 20 to 29 μm and width 14 to 21 μm) and mean length/width ratio (1.42 μm) of conidia, and width and apical cell width of condiophores, the fungus was identified as Stemphylium botryosum (Wallr.) (2,3) Koch's postulates were completed in the laboratory by inoculating leaves of kiwi (cv. Hayward) with an isolate of S. botryosum originated from a symptomatic leaf of a Hayward kiwi. Twenty leaves were surface sterilized by dipping them into 0.1% chlorine solution for 2 to 3 min, washing in sterile distilled water, and allowing them to dry in a laminar flow hood. A leaf was then placed into a petri plate containing a wet, sterilized paper towel. Inoculation was made by transferring a 5-mm-diameter mycelial disc from the margins of a 7-day-old culture onto the center of each leaf surface. Petri plates were closed and incubated at 25°C with 12 h of light for 6 days. Koch's postulates were satisfied when the same S. botryosum was reisolated from 100% of inoculated leaves that developed symptoms similar to those observed in the vineyards. Leaves inoculated with a PDA plug alone (with no S. botryosum) did not develop any symptoms. Previously, Alternaria alternata was reported as the causal agent of a leaf spot pathogen of kiwi (1,4). To our knowledge, this is the first report of the occurrence of S. botryosum causing leaf blight of kiwi in Greece and worldwide. This pathogen can cause a high level of defoliation in diseased plants. References: (1) L. Corazza et al. Plant Dis. 83:487, 1999. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Mycology Institute. London, England, 1971. (3) E. G. Simmons. Mycologia 61:1, 1969. (4) C. Tsahouridou and C. C. Thanassoulopoulos. Plant Dis. 84:371, 2000

scholarly journals First Report of Root and Stem Rot Caused by Phytophthora nicotianae on Peperomia tetraphylla in China

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1171-1171 ◽  
Author(s):  
D. X. Zeng ◽  
X. L. Wu ◽  
Y. H. Li
Keyword(s):  
Southern China ◽  
Aerial Mycelium ◽  
Its Region ◽  
Soil Extract ◽  
Phytophthora Nicotianae ◽  
Stem Rot ◽  
Molecular Characteristics ◽  
Its Sequence ◽  
First Report ◽  
Pure Cultures

Peperomia tetraphylla, an evergreen herb, is becoming increasingly popular as a potted ornamental plant in southern China. In the summer of 2008, in some commercial flower nurseries in Shenzhen, Guangdong Province, P. tetraphylla showed extensive black stem and root rot, with leaves dropping from the rotten stem. Small pieces (approximately 3 mm2) of stems and leaves were excised from the margins of the black lesions, surface disinfected for 30 s to 1 min in 0.1% HgCl2, plated onto potato dextrose agar (PDA), and incubated at 25°C in the dark. All the plated samples yielded Phytophthora, and microscopic examination of pure cultures grown on PDA plates showed arachnoid colonies with abundant aerial mycelium, chlamydospores, and a few sporangia. Numerous sporangia were formed in sterile soil extract. Sporangia were ovoid or obpyriform, noncaducous, with prominent solitary papillae, and measured 31 to 52 μm (average 38 μm) × 21 to 34 μm (average 27 μm). Chlamydospores were spherical and 21 to 34 μm in diameter (average 28 μm). The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using primers ITS4/ITS5 and sequenced (2). The ITS sequence, when submitted for a BLAST search in the NCBI database, showed 100% homology with the sequences of two reference isolates of Phytophthora nicotianae (Accession Nos. AY833526 and EU433396) and the consensus ITS sequence was deposited in the NCBI as Accession No. GQ499373. The isolate was identified as Phytophthora nicotianae on the basis of morphological and molecular characteristics (1). Pathogenicity of the isolate was confirmed by inoculating 1-year-old plants of P. tetraphylla growing in pots. The isolate was grown for 7 days on PDA plates and mycelial plugs, 5 mm in diameter and taken from the advancing margins of the colonies, were buried approximately 1 cm deep near the base of the stem in such a way that the mycelium on the plugs was in contact with the surface of the stem, which had been wiped earlier with 70% ethanol and gently wounded with a needle. Plants treated the same way but inoculated with sterile PDA plugs served as control plants. Three plants in each pot were inoculated and there were five replications each for the treatment and the control. All plants were kept in a greenhouse at 22 to 32°C. After 6 to 7 days, the inoculated plants showed black lesions around the mycelial plugs; symptoms of root and stem rot developed rapidly thereafter and the plants collapsed within 2 weeks. All symptoms on the inoculated plants were identical to those observed in naturally diseased plants, whereas the control plants remained healthy. The same fungus was consistently reisolated from the inoculated plants. To our knowledge, this is the first report of Phytophthora nicotianae on P. tetraphylla in China. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) J. B. Ristaino et al. Appl. Environ. Microbiol. 64:948, 1998.

scholarly journals First report of Pestalotiopsis diospyri causing canker on persimmon trees

2011 ◽  
Vol 33 (3) ◽  
pp. 1019-1022 ◽  
Author(s):  
Giselda Alves ◽  
Francineia Silva Verbiski ◽  
Themis J. Michaelides ◽  
Louise Larissa May-de Mio
Keyword(s):  
Diospyros Kaki ◽  
Southern Brazil ◽  
Severe Damage ◽  
Santa Catarina ◽  
Koch’S Postulates ◽  
Canker Disease ◽  
First Report ◽  
Koch's Postulates

During 2006 to 2009 season symptoms of a canker disease were observed on twigs and branches of young and mature persimmon trees (Diospyros kaki L.) cv. Fuyu in the States of Santa Catarina and Paraná in the Southern Brazil. The cankers result in severe damage and reduced production. Isolations from the margins of these cankers revealed a genus of Pestalotiopsis. Koch's postulates were confirmed using two isolates of the pathogen which was identified as Pestalotiopsis diospyri.

Red Crown Rot of Hop in Oregon Caused by Phomopsis tuberivora

2013 ◽  
Vol 14 (1) ◽  
pp. 52
Author(s):  
David H. Gent ◽  
George Mueller-Warrant ◽  
Joanna L. Woods ◽  
Melodie L. Putnam ◽  
Megan C. Twomey
Keyword(s):  
Crown Rot ◽  
Management Implications ◽  
Koch’S Postulates ◽  
First Report ◽  
Red Crown Rot ◽  
Weak Growth ◽  
Koch's Postulates

During July 2007, symptoms including weak growth and death of plants of cultivar Fuggle were reported by a hop grower in Marion Co., OR. Phomopsis tuberivora H.T. Güssow & W.R. Foster 1932 was consistently recovered from affected plants. Koch's postulates were fulfilled with three isolates of the fungus, establishing the pathogen and the disease red crown rot as the cause of the damage. This is the first report of red crown rot on hop in Oregon, which may have important management implications for affected hop yards and farms. Accepted for publication 19 March 2013. Published 24 June 2013.

First Report of Phytophthora ramorum Infecting Grand fir in California

2011 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Kathleen L. Riley ◽  
Gary A. Chastagner ◽  
Cheryl Blomquist
Keyword(s):  
Phytophthora Ramorum ◽  
Christmas Tree ◽  
Native Range ◽  
Tree Plantation ◽  
Koch’S Postulates ◽  
First Report ◽  
Stem Lesions ◽  
Koch's Postulates

Phytophthora ramorum was detected on grand fir in 2003 and 2005 in a Christmas tree plantation near Los Gatos, CA, in association with infected California bay laurel. Isolates derived from stem lesions were used to inoculate grand fir seedlings in two tests. Isolations from lesions on inoculated plants were positive for P. ramorum in both tests. This work provides the completion of Koch's postulates to establish grand fir as a host of P. ramorum. The potential for grand fir to be infected within its native range is unknown. Accepted for publication 1 February 2011. Published 1 April 2011.

scholarly journals First Report of Lasiodiplodia theobromae Causing Dieback of Aquilaria sinensis in Taiwan

Plant Disease ◽  
2013 ◽  
Vol 97 (5) ◽  
pp. 690-690 ◽  
Author(s):  
M.-C. Fan ◽  
H.-C. Yeh ◽  
C.-F. Hong
Keyword(s):  
Uv Light ◽  
Aerial Mycelium ◽  
Molecular Characteristics ◽  
Width Ratio ◽  
Sodium Hypochlorite Solution ◽  
Aquilaria Sinensis ◽  
Lasiodiplodia Theobromae ◽  
First Report ◽  
Tree Survival ◽  
Pathogenicity Tests

Incense trees (Aquilaria sinensis (Lour.) Gilg) belong to a plant family used for alternative medicine in China and the production of wood. In the summer of 2012, at a nursery in Niaosong district, Kaohsiung City, Taiwan, more than 30% of a total of 400 incense trees had dieback symptoms on twigs with leaves attached, leading to eventual death of the entire plant. Symptomatic twigs and trunk pieces from six trees were collected and discolored tissues were excised, surface sterilized in 0.5% sodium hypochlorite solution, rinsed in sterilized distilled water, dried on sterilized filter paper, and then placed in petri dishes containing 2% water agar (WA). The dishes were incubated at room temperature for 1 to 2 days to obtain fungal strains from diseased tissues. The hyphal tips from developing fungal colonies were transferred to potato dextrose agar (PDA, Difco) dishes and placed under UV light (12 h/day) at 30°C. The purified colonies were used as inoculum in the pathogenicity tests. Pathogenicity tests were performed on 2-month-old A. sinensis seedlings, each treatment had three plants. Each plant was wounded by removing bark of the twigs with a disinfected scalpel enough to place a mycelium plug (about 5 × 10 mm2) of 7-day-old fungal isolate on the wound. The inoculated area was wrapped with a wet paper towel and Parafilm. Control plants were treated with PDA plugs. The symptoms described above were observed on inoculated plants 4 to 8 days after inoculation whereas control plants did not show symptoms. Diseased twigs were cut and placed in a moist chamber 21 days after inoculation and conidia oozing from pycnidia were observed. The same fungal pathogen was reisolated from inoculated plants, but not from the control. To identify the pathogen, the fungus was cultured as described above. The colonies were initially white with green to gray aerial mycelium after 5 to 6 days and eventually turned darker. Immature conidia were hyaline and one-celled, but mature conidia were dark brown, two-celled, thin-walled, and oval-shaped with longitudinal striations. The average size of 100 conidia was 25.23 ± 1.97 × 13.09 ± 0.99 μm with a length/width ratio of 1.92. For the molecular identification, the internal transcribed spacer (ITS) region of ribosomal DNA was PCR amplified with primers ITS1 and ITS4 (2) and sequenced. The sequences were deposited in GenBank (Accession No. JX945583) and showed 99% identity to Lasiodiplodia theobromae (HM346871, GQ469929, and HQ315840). Hence, both morphological and molecular characteristics confirmed the pathogen as L. theobromae (Pat.) Griffon & Maubl (1). To the best of our knowledge, this is the first report of L. theobromae causing dieback on Incense tree. This disease threatens tree survival and may decrease the income of growers. References: (1) W. H. Ko et al. Plant Dis. 88:1383, 2004. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

scholarly journals First Report of Leaf Spot Disease on Walnut Caused by Colletotrichum fioriniae in China

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 289-289 ◽  
Author(s):  
Y. Z. Zhu ◽  
W. J. Liao ◽  
D. X. Zou ◽  
Y. J. Wu ◽  
Y. Zhou
Keyword(s):  
Dna Sequences ◽  
Leaf Spot ◽  
Juglans Regia ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
Koch’S Postulates ◽  
First Report ◽  
Spot Disease ◽  
Leaf Spots ◽  
Koch's Postulates

In May 2014, a severe leaf spot disease was observed on walnut tree (Juglans regia L.) in Hechi, Guangxi, China. Leaf spots were circular to semicircular in shape, water-soaked, later becoming grayish white in the center with a dark brown margin and bordered by a tan halo. Necrotic lesions were approximately 3 to 4 mm in diameter. Diseased leaves were collected from 10 trees in each of five commercial orchards. The diseased leaves were cut into 5 × 5 mm slices, dipped in 75% ethanol for 30 s, washed three times in sterilized water, sterilized with 0.1% (w/v) HgCl2 for 3 min, and then rinsed five times with sterile distilled water. These slices were placed on potato dextrose agar (PDA), followed by incubating at 28°C for about 3 to 4 days. Fungal isolates were obtained from these diseased tissues, transferred onto PDA plates, and incubated at 28°C. These isolates produced gray aerial mycelium and then became pinkish gray with age. Moreover, the reverse of the colony was pink. The growth rate was 8.21 to 8.41 mm per day (average = 8.29 ± 0.11, n = 3) at 28°C. The colonies produced pale orange conidial masses and were fusiform with acute ends, hyaline, sometimes guttulate, 4.02 to 5.25 × 13.71 to 15.72 μm (average = 4.56 ± 0.31 × 14.87 ± 1.14 μm, n = 25). The morphological characteristics and measurements of this fungal isolate matched the previous descriptions of Colletotrichum fioriniae (Marcelino & Gouli) R.G. Shivas & Y.P. Tan (2). Meanwhile, these characterizations were further confirmed by analysis of the partial sequence of five genes: the internal transcribed spacer (ITS) of the ribosomal DNA, beta-tubulin (β-tub) gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene, chitin synthase 3(CHS-1) gene, and actin (ACT) gene, with universal primers ITS4/ITS5, T1/βt2b, GDF1/GDR1, CHS1-79F/CHS1-354R, and ACT-512F/ACT-783R, respectively (1). BLAST of these DNA sequences using the nucleotide database of GenBank showed a high identify (ITS, 99%; β-tub, 99%; GAPDH, 99%; CHS-1, 99%; and ACT, 100%) with the previously deposited sequences of C. fioriniae (ITS, KF278459.1, NR111747.1; β-tub, AB744079.1, AB690809.1; GAPDH, KF944355.1, KF944354.1; CHS-1, JQ948987.1, JQ949005.1; and ACT, JQ949625.1, JQ949626.1). Koch's postulates were fulfilled by inoculating six healthy 1-year-old walnut trees in July 2014 with maximum and minimum temperatures of 33 and 26°C. The 6-mm mycelial plug, which was cut from the margin of a 5-day-old colony of the fungus on PDA, was placed onto each pin-wounded leaf, ensuring good contact between the mycelium and the wound. Non-colonized PDA plugs were placed onto pin-wounds as negative controls. Following inoculation, both inoculated and control plants were covered with plastic bags. Leaf spots, similar to those on naturally infected plants, were observed on the leaves inoculated with C. fioriniae within 5 days. No symptoms were observed on the negative control leaves. Finally, C. fioriniae was re-isolated from symptomatic leaves; in contrast, no fungus was isolated from the control, which confirmed Koch's postulates. To our knowledge, this is the first report of leaf disease on walnut caused by C. fioriniae. References: (1) L. Cai et al. Fungal Divers. 39:183, 2009. (2) R. G. Shivas and Y. P. Tan. Fungal Divers. 39:111, 2009.

scholarly journals First Report of Aspergillus niger Causing Postharvest Fruit Rot of Cherry in the Prefectures of Imathia and Pella, Northern Greece

Plant Disease ◽  
2012 ◽  
Vol 96 (3) ◽  
pp. 458-458 ◽  
Author(s):  
T. Thomidis ◽  
E. Exadaktylou
Keyword(s):  
Aspergillus Niger ◽  
Fungal Spores ◽  
Morphological Characteristics ◽  
Fruit Rot ◽  
Northern Greece ◽  
Centraalbureau Voor ◽  
Koch’S Postulates ◽  
First Report ◽  
Postharvest Rot ◽  
Koch's Postulates

In June 2011, symptoms of postharvest rot were observed on approximately 3% of all cherries collected from commercial orchards of cultivars Lapen and Ferrovia in the prefectures of Imathia and Pella (northern Greece). Fruit were harvested in a timely manner to avoid overripeness. No wounds or other predisposing injuries were observed on the infected fruits. Lesions enlarged rapidly and separated easily from healthy tissue when pressure was applied. Infected tissues were pale and water soaked and the associated fungal spores were dark and powdery and easily liberated when mature. The fungus grew rapidly and produced black colonies on acidified potato dextrose agar (2.5 ml of 85% lactic acid per liter of nutrient medium) after 5 days at 24°C. Identification of the pathogen was based on morphological characteristics (1). The conidial head was radiate, vesicles were nearly spherical and covered with metulae and phialides (biseriate). Conidia were globose (3 to 5 μm in diameter) and usually very rough with irregular ridges, bars, and verrucae. Koch's postulates were completed in the laboratory by inoculating mature cherry fruits (cv. Lapen). The fruits were surface sterilized by dipping in 10% chloride bleach solution, allowed to dry in a laminar flow hood, and wounded with a sharp glass rod that was 2 mm in diameter. A 40-μl drop of a suspension containing 20,000 conidia per ml of water was placed on each wound. There were 20 inoculated and 20 control fruits (similarly wounded and inoculated with a 40-μl drop of sterile distilled water) in a randomized design and incubated at 24 to 26°C for 6 days. Koch's postulates were satisfied after reisolating the fungus from inoculated fruit that developed symptoms similar to those observed on fruit collected from orchards. Control fruits did not show any symptom of the disease. To our knowledge, this is the first report of the occurrence of Aspergillus niger as the causal agent of postharvest rots of cherries in Greece. Postharvest fruit rots caused by A. niger have been reported in cherry orchards of other countries around the world (2). Because this disease causes postharvest rots of cherry fruits, measures may need to be implemented to manage the pathogen. References: (1) M. A. Klich. Page 12 in: Identification of Common Aspergillus Species. Centraalbureau Voor Schimmelcultures, Utrecht, the Netherlands, 2002. (2) A. Valiuskaite et al. Phytopathol. Pol. 35:197, 2005.

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