First Report of Anthracnose Fruit Rot Caused by Colletotrichum acutatum on Pepper and Tomato in Bulgaria

In the late summer of 2005, sporadic and unusual damage was observed on pepper (Capsicum annuum cv. Kurtovska kapia and local cv. Ribka) on two farms and tomato (Lycopersicon esculentum cv. Florida 47) fruits on one farm in the Plovdiv Region of Bulgaria. Dry, round, sunken zones (10 to 20 mm) were observed on pepper fruits that preserved their natural skin color even after black acervuli containing orange masses of conidia appeared. Eventually, the lesions turned brown, coalesced, and the fruits mummified on the plants. Tomato fruits developed similar symptoms, with less prominent discoloration and fewer acervuli. The pathogen was easily isolated from both hosts on potato dextrose agar where it formed white-to-gray colonies with salmon orange pigmentation on the reverse side of the plates. Conidia that formed were hyaline, fusiform, aseptate, and measured 13.3 to 17.4 × 3.5 to 5.5 μm and 11.6 to 15.5 × 4.1 to 5.0 μm for pepper and tomato isolates, respectively. Both cultural and morphological characteristics of the isolates were similar to those described for Colletotrichum acutatum (3). Koch's postulates were performed with two representative isolates from each host by artificial inoculation of healthy, green pepper and ripe tomato fruits from the respective cultivars. Fruits were wound inoculated with a sterile scalpel, and small agar plugs (3 to 4 mm) containing 7-day-old sporulating cultures were placed on each wound (five fruits per isolate), or by pipette tip-pricking and pipetting a 5-μl droplet of a conidial suspension (5 × 106 conidia ml–1) on each wound. The same number of wounded, noninoculated fruits was used as a control. Fruits were maintained in a humidity chamber at 22 to 25°C, and 4 days later, sunken necrotic zones were observed around the wounds of inoculated fruit, whereas control fruits remained symptomless. The pathogen was subsequently reisolated from the inoculated diseased tissues but not from the control fruits. Species-specific PCR (using primer pair CaInt2/ITS4) (2,4) of genomic DNA from three representative isolates (two from pepper and one from tomato) resulted in an amplification product of 490 bp, specific for C. acutatum, further confirming the identity of the pathogen. To our knowledge, this is the second report of C. acutatum in Bulgaria (1), and the first occurrence of that agent on tomato and pepper in this country. References: (1) S. G. Bobev et al. Plant Dis. 86:1178, 2002. (2) S. Freeman et al. Phytopathology 91:586, 2001. (3) P. S. Gunnell and W. D. Gubler. Mycologia 84:157, 1992. (4) M. L. Lewis Ivey et al. Plant Dis. 88:1198, 2004.

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First report of preharvest fruit rot of ‘Pink Lady’ apples caused by Colletotrichum fructicola in Italy

Plant Disease ◽

10.1094/pdis-11-20-2404-pdn ◽

2021 ◽

Author(s):

Marcel Wenneker ◽

Khanh Pham ◽

Engelien Kerkhof ◽

Dalphy O.C. Harteveld

Keyword(s):

Species Complex ◽

Management Strategies ◽

Morphological Characteristics ◽

Late Summer ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Apple Orchards ◽

First Report ◽

Bitter Rot ◽

Colletotrichum Fructicola

In late summer 2019, a severe outbreak of fruit rot was observed in commercial ‘Pink Lady’ apple orchards (>20 ha in total) in the region Emilia-Romagna (Northern Italy). The symptoms on the fruit appeared as small circular red to brown lesions. Disease incidences of over 50% of the fruits were observed. To isolate the causal agent, 15 affected apples were collected and small portions of fruit flesh were excised from the lesion margin and placed on potato dextrose agar (PDA). The plates were incubated at 20°C in the dark, and pure cultures were obtained by transferring hyphal tips on PDA. The cultures showed light to dark gray, cottony mycelium, with the underside of the culture being brownish and becoming black with age. Conidia (n=20) were cylindrical, aseptate, hyaline, rounded at both ends, and 12.5 to 20.0 × 5.0 to 7.5 μm. The morphological characteristics were consistent with descriptions of Colletotrichum species of the C. gloeosporioides species complex, including C. fructicola (Weir et al. 2012). The identity of two representative isolates (PinkL2 & PinkL3) from different apples was confirmed by means of multi-locus gene sequencing. Genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Molecular identification was conducted by sequencing the ITS1/ITS4 region and partial sequences of four other gene regions: chitin synthase (CHS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), and beta-tubulin (TUB). The sequences have been deposited in GenBank under accession numbers MT421924 & MT424894 (ITS), MT424612 & MT424613 (CHS), MT424616 & MT424617 (GAPDH), MT424614 & MT424615 (ACT), and MT424620 & MT424621 (TUB). MegaBLAST analysis revealed that our ITS sequences matched with 100% identity to Colletotrichum fructicola (Genbank JX010177). The CHS, GAPDH, ACT and TUB sequences of both isolates were 100% identical with C. fructicola culture collection sequences in Genbank (JX009807, JX009923, JX009436 and JX010400, respectively), confirming the identity of these isolates as C. fructicola. Koch's postulates were performed with 10 mature ‘Pink Lady’ apples. Surface sterilized fruit were inoculated with 20 μl of a suspension of 105 conidia ml–1 after wounding with a needle. The fruits were incubated at 20˚C at high relative humidity. Typical symptoms appeared within 4 days on all fruit. Mock-inoculated controls with sterile water remained symptomless. The fungus was reisolated and confirmed as C. fructicola by morphology and sequencing of all previously used genes. Until recently the reported causal agents of bitter rot of apple in Europe belong to the Colletotrichum acutatum species complex (Grammen et al. 2019). C. fructicola, belonging to C. gloeosporioides species complex, is known to cause bitter rot of apple in the USA, Korea, Brazil, and Uruguay (Kim et al. 2018; Velho et al. 2015). There is only one report of bitter rot associated with C. fructicola on apple in Europe (France) (Nodet et al. 2019). However, C. fructicola is also the potential agent of Glomerella leaf spot (GLS) of apple (Velho et al. 2015; 2019). To the best of our knowledge this is the first report of C. fructicola on apples in Italy. It is important to stress that the C. gloeosporioides species complex is still being resolved and new species on apple continue to be identified, e.g. C. chrysophilum that is very closely related to C. fructicola (Khodadadi et al. 2020). Given the risks of this pathogen the presence of C. fructicola in European apple orchards should be assessed and management strategies developed.

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First Report of Strawberry Fruit Rot Caused by Alternaria tenuissima in Korea

Plant Disease ◽

10.1094/pdis.2001.85.5.563b ◽

2001 ◽

Vol 85 (5) ◽

pp. 563-563 ◽

Cited By ~ 5

Author(s):

H. B. Lee ◽

C.-J. Kim ◽

S. H. Yu

Keyword(s):

Fruits And Vegetables ◽

Morphological Characteristics ◽

West Germany ◽

Fruit Rot ◽

Conidial Suspension ◽

Strawberry Fruit ◽

Alternaria Tenuissima ◽

First Report ◽

The Usa ◽

Dark Green

A strawberry (Fragaria × ananassa Duch.) fruit rot disease has been observed in several vinyl-house fields at Nonsan and Taejon, Chungnam district, Korea, especially following moist and cool conditions in the spring and again in September. Over the past 7 years, incidence of the disease has ranged from 0.2 to 2.0%. Early symptoms on fruits were characterized by small, irregular lesions, which were slightly sunken and appeared light green to black in color as sporulation began. Conidia were 25 to 55 μm long by 10 to 17 μm wide; beaks, when present, were 2 to 3 μm wide and up to 40 μm long; and conidiophores were 20 to 110 μm long by 3 to 5 μm wide. Older lesions were circular, largely sunken, firm, and dark-green to almost black because of abundant sporulation. The fungus isolated from infected fruit tissues was identified as Alternaria tenuissima (Fries) Wiltshire, based on the morphological characteristics of the conidia and conidiophores. Pathogenicity tests were conducted by inoculating slightly wounded, ripe (red) and immature (green) fruits with a conidial suspension (1 × 106 conidia/ml). Twenty-four ripe and immature fruits were inoculated with each of six isolates in duplicate and placed in a moist chamber for 48 h at 25°C and then transferred to vinyl-house field. After 7 to 10 days fruit rot symptoms were visible on the inoculated fruits and appeared nearly identical to lesions observed in the field, although there were differences in aggressiveness among isolates. Control fruits sprayed with distilled water did not develop any symptoms. Green fruits were generally more resistant to infection than ripe ones. The causal fungus was easily reisolated from lesions on inoculated strawberries. Alternaria fruit rot of strawberries has been reported from the USA, UK, and West Germany (2). Howard and Albregts (1) first reported a strawberry fruit rot caused by A. tenuissima in Florida, but the disease is generally not considered important. However, occasionally losses from this disease have been extensive in Korea. To the authors' knowledge, this is the first report of strawberry fruit rot caused by Alternaria tenuissima in Korea. References: (1) C. M. Howard and E. E. Albregts. Phytopathology 63:638–639, 1973. (2) A. L. Snowdon. Pages 250–252 in: A Color Atlas of Post-Harvest Diseases and Disorders of Fruits and Vegetables. Vol. 1. 1990. Wolfe Scientific, London.

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First Report of Colletotrichum acutatum in Blueberry Plants in Spain

Plant Disease ◽

10.1094/pdis.2001.85.12.1285a ◽

2001 ◽

Vol 85 (12) ◽

pp. 1285-1285 ◽

Cited By ~ 3

Author(s):

C. Barrau ◽

B. de los Santos ◽

F. Romero

Keyword(s):

Pink Salmon ◽

Morphological Characteristics ◽

Vaccinium Corymbosum ◽

Fungal Species ◽

Colletotrichum Acutatum ◽

Enzyme Linked Immunosorbent Assay ◽

Conidial Suspension ◽

First Report ◽

Small Areas ◽

Leaf Tissues

An anthracnose disease was observed affecting leaves of high-bush blueberry plants (Vaccinium corymbosum L. ‘Sharpblue’) in small areas within two production fields in Huelva Province of Andalucía, in southwestern Spain. The first symptoms observed in late spring were circular, necrotic lesions, red to salmon in color, and ranging from 3 to 20 mm in diameter. Later, lesions became salmon colored in the center with a brilliant red halo. Fungal isolations were made from the lesions. Infected tissues were surface-disinfected in 1% sodium hypochlorite for 1 min, blotted dry on sterile filter paper, and plated on 2% water agar. The plates were incubated at 25°C for 5 to 10 days. Fungal colonies isolated from the tissues were transferred to potato dextrose yeast agar (PDYA). Only one fungal species was consistently isolated from affected leaf tissues and was identified as Colletotrichum acutatum J.H. Simmonds based on morphological characteristics (2) and enzyme-linked immunosorbent assay (1). Colonies of the fungus on PDYA showed a white-to-gray dense mycelium covered with salmon-colored spore masses. The reverse of the plates was a pink-salmon color. Colony diameter on PDYA averaged 50 mm after 7 days at 25°C. Conidia were hyaline, aseptate, fusiform to cylindrical, and 12.5 × 3.2 μm. Inoculation of leaves and fruits of blueberry cv. Misty with a conidial suspension (106 conidia per ml) of C. acutatum produced lesions on the leaves and fruits similar to those observed on diseased plants in the field. The pathogen was isolated from lesions on inoculated plants. To our knowledge, this is the first report of C. acutatum in high-bush blueberry plants in Spain. References: (1) T. A. Cooke et al. EPPO Bull. 25:57, 1995. (2) B. C. Sutton. The Coelomycetes. CMI, Kew, England, 1980.

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First report of Fusarium incarnatum causing fruit rot of litchi in China

Plant Disease ◽

10.1094/pdis-11-20-2393-pdn ◽

2021 ◽

Author(s):

Zhaoyin Gao ◽

Jiaobao Wang ◽

Zhengke Zhang ◽

Min Li ◽

Deqiang Gong ◽

...

Keyword(s):

Southern China ◽

Fusarium Species ◽

Morphological Characteristics ◽

Fruit Rot ◽

Conidial Suspension ◽

Single Spore ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Litchi Fruit ◽

His3 Gene

Litchi (Litchi chinensis Sonn.) is an indigenous tropical and subtropical fruit in Southern China with an attractive appearance, delicious taste, and good nutritional value (Jiang et al. 2003). In March 2020, brown rots were observed on nearly ripe litchi fruits (cv. Guihuaxiang) in an orchard of Lingshui county, Hainan province of China (18.615877° N, 109.948871° E). About 5% fruits were symptomatic in the field, and the disease caused postharvest losses during storage. The initial infected fruits had no obvious symptoms on the outer pericarp surfaces, but appeared irregular, brown to black-brown lesions in the inner pericarps around the pedicels. Then lesions expanded and became brown rots. Small tissues (4 mm × 4 mm) of fruit pericarps were cut from symptomatic fruits, surface-sterilized in 1% sodium hypochlorite for 3 min, rinsed in sterilized water three times, plated on potato dextrose agar (PDA) and incubated at 28℃ in the darkness. Morphologically similar colonies were isolated from 85% of 20 samples after 4 days of incubation. Ten isolates were purified using a single-spore isolation method. The isolates grown on PDA had abundant, fluffy, whitish to yellowish aerial mycelia, and the reverse side of the Petri dish was pale brown. Morphological characteristics of conidia were further determined on carnation leaf-piece agar (CLA) (Leslie et al. 2006). Macroconidia were straight to slightly curved, 3- to 5-septates with a foot-shaped basal cell, tapered at the apex, 2.70 to 4.43 µm × 18.63 to 37.58 µm (3.56 ± 0.36 × 28.68 ± 4.34 µm) (n = 100). Microconidia were fusoid to ovoid, 0- to 1-septate, 2.10 to 3.57 µm × 8.18 to 18.20 µm (2.88 ± 0.34 × 11.71 ± 1.97 µm) (n = 100). Chlamydospores on hyphae singly or in chains were globose, subglobose, or ellipsoidal. Based on cultural features and morphological characteristics, the fungus was identified as a Fusarium species (Leslie et al. 2006). To further confirm the pathogen, DNA was extracted from the 7-day-old aerial mycelia of three isolates (LZ-1, LZ-3, and LZ-5) following Chohan et al. (2019). The sequences of the internal transcribed spacer region of rDNA (ITS), translation elongation factor-1 alpha (tef1) gene, and histone H3 (his3) gene were partially amplified using primers ITS1/ITS4, EF1-728F/EF1-986R, and CYLH3F/CYLH3R, respectively (Funnell-Harris et al. 2017). The nucleotide sequences were deposited in GenBank (ITS: 515 bp, MW029882, 533 bp, MW092186, and 465 bp, MW092187; tef1: 292 bp, MW034437, 262 bp, MW159143, and 292 bp, MW159141; his3: 489 bp, MW034438, 477 bp, MW159142, and 474 bp, MW159140). The ITS, tef1, and his3 genes showed 99-100% similarity with the ITS (MH979697), tef1 (MH979698), and his3 (MH979696) genes, respectively of Fusarium incarnatum (TG0520) from muskmelon fruit. The phylogenetic analysis of the tef1 and his3 gene sequences showed that the three isolates clustered with F. incarnatum. Pathogenicity tests were conducted by spraying conidial suspension (1×106 conidia/ml) on wounded young fruits in the orchid. Negative controls were sprayed with sterilized water. Fruits were bagged with polythene bags for 24 hours and then unbagged for 10 days. Each treatment had 30 fruits. The inoculated fruits developed symptoms similar to those observed in the orchard and showed light brown lesions on the outer pericarp surfaces and irregular, brown to black-brown lesions in the inner pericarps, while the fruits of negative control remained symptomless. The same fungus was successfully recovered from symptomatic fruits, and thus, the test for the Koch’s postulates was completed. F. semitectum (synonym: F. incarnatum) (Saha et al. 2005), F. oxysporum (Bashar et al. 2012), and F. moniliforme (Rashid et al. 2015) have been previously reported as pathogens causing litchi fruit rots in India and Bangladesh. To our knowledge, this is the first report of Fusarium incarnatum causing litchi fruit rot in China.

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Extreme Susceptibility of Primosole Mandarin to Alternaria Fruit Rot in Italy

Plant Disease ◽

10.1094/pdis.2001.85.12.1291b ◽

2001 ◽

Vol 85 (12) ◽

pp. 1291-1291

Author(s):

P. Bella ◽

R. La Rosa ◽

V. Catara ◽

G. Polizzi

Keyword(s):

Morphological Characteristics ◽

Fruit Rot ◽

Total Production ◽

Conidial Suspension ◽

Single Spore ◽

The Core ◽

Fruit Drop ◽

Plastic Bags ◽

Citrus Diseases ◽

Pathogenicity Tests

Primosole mandarin is a promising mandarin-like hybrid of Satsuma Miho and Carvalhais mandarin that ripens very early, at the beginning of October, in southern Italy (2). During August and September 1999 and 2000 in Sicily, widespread fruit rot, affecting from 80 to 95% of the total production, was observed in a 4-year-old Primosole mandarin orchard. The fruits developed color prematurely and light brown-to-black discoloration of the rind at the stylar end. Internal symptoms consisted of a black rot of the fruit core. Sometimes the exterior of the fruits appeared healthy. No premature fruit drop was observed, and infected fruits became mummified and remained attached on the trees. Alternaria citri Ellis & N. Pierce in N. Pierce was consistently isolated from infected tissues, and the identification of the fungus was based on morphological characteristics of the conidia (1). Pathogenicity tests of single-spore isolates were carried out on surface-sterilized Primosole fruits and were repeated twice. Either a conidial suspension (2 × 104 conidia per ml) was injected into the core of fruits, or fruits were pricked at the stylar end near or through growth cracks in poorly formed navels, and the conidial suspension was placed on the wound. Thirty fruits were used per treatment, and thirty noninoculated fruits were used for controls. Following inoculation, the fruits were placed in plastic bags and kept at 30°C for 15 days. No external symptoms were observed on any of the fruits, but when cut in half, decay of the core was observed in all inoculated fruits. A. citri was reisolated from inoculated fruits, fulfilling Koch's postulates. No symptoms were observed on fruits used as controls. We believe that infection is facilitated by growth cracks at the stylar end and the sensitivity to sunburn of Primosole mandarin. To our knowledge, this is the first report of the extreme susceptibility of Primosole mandarin to Alternaria fruit rot. References: (1) G. E. Brown and J. W. Eckert. Postharvest fungal diseases. Page 37 in: Compendium of Citrus Diseases, 2nd ed. L. W. Timmer, S. M. Garnsey, and J. H. Graham, eds. The American Phytopathological Society, St. Paul, MN, 2000. (2) E. Tribulato and G. La Rosa. Italus Hortus 1:21, 1993.

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First Report of Leaf Blight on Rubus brasiliensis Caused by Colletotrichum acutatum in Brazil

Plant Disease ◽

10.1094/pdis-06-10-0441 ◽

2010 ◽

Vol 94 (11) ◽

pp. 1378-1378 ◽

Cited By ~ 1

Author(s):

U. P. Lopes ◽

L. Zambolim ◽

H. S. S. Duarte ◽

P. G. C. Cabral ◽

O. L. Pereira ◽

...

Keyword(s):

Native Species ◽

Morphological Characteristics ◽

Minas Gerais ◽

Leaf Blight ◽

Colletotrichum Acutatum ◽

Conidial Suspension ◽

Specific Primer ◽

First Report ◽

Young Leaves ◽

Necrotic Spots

There are more than 300 blackberry (Rubus) species worldwide. Rubus brasiliensis Mart. is a native Brazilian species found in tropical forests. In January 2009, samples of R. brasiliensis with severe leaf blight were collected from an area of rain forest in the city of São Miguel do Anta, State of Minas Gerais, Brazil. Dark spots began developing in the young leaves and progressed to necrotic spots with occasional twig dieback. From the spots, a fungus was isolated with the following morphology: acervuli that were 20 to 50.0 × 50 to 125.0 μm and hyaline amerospores that were ellipsoid and fusiform and 7.5 to 23.75 × 2.5 to 5.0 μm. On the basis of these morphological characteristics, the fungus was identified as Colletotrichum acutatum. In Brazil, C. acutatum is reported in apple, citrus, strawberry, peach, plum, nectarine, olive, medlar, and yerba-mate, but it was not reported as the causal agent of leaf blight in R. brasiliensis. A sample was deposited in the herbarium at the Universidade Federal de Viçosa, Minas Gerais, Brazil (VIC 31210). One representative isolate, OLP 571, was used for pathogenicity testing and molecular studies. Identity was confirmed by amplifying the internal transcribed spacer (ITS) regions of the ribosomal RNA with primers ITS4 (3), CaInt2 (a specific primer for C. acutatum [2]) and CgInt (a specific primer for C. gloeosporioides [1]). Isolates of C. acutatum (DAR78874 and DAR78876) and C. gloeosporioides (DAR78875) obtained from Australian olive trees were used as positive controls. The primers ITS4 and CaInt2 amplified a single DNA product of 500 bp expected for C. acutatum. OLP 571 was grown for 7 days on potato dextrose agar. Young leaves of R. brasiliensis were inoculated with a conidial suspension (106 conidia/ml) on young leaves. Inoculated plants were maintained in a moist chamber for 2 days and subsequently in a greenhouse at 25°C. Necrotic spots similar to those described were detected on young leaves 3 days after the inoculation. Control leaves, on which only water was sprayed, remained healthy. The same fungus was reisolated from the inoculated symptomatic tissues. To our knowledge, this is the first report of C. acutatum causing leaf blight in the native species of R. brasiliensis in Brazil. References: (1) P. R. Mills et al. FEMS Microbiol. Lett. 98:137, 1999. (2) S. Sreenivasaprasad et al. Plant Pathol. 45:650, 1996. (3) 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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First Report of Lentil Ascochyta Blight Caused by Ascochyta lentis in Italy

Plant Disease ◽

10.1094/pdis.1999.83.1.77c ◽

1999 ◽

Vol 83 (1) ◽

pp. 77-77

Author(s):

C. Cappelli ◽

R. Buonaurio ◽

R. Torricelli

Keyword(s):

Lens Culinaris ◽

Ascochyta Blight ◽

Central Italy ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

Conidial Suspension ◽

First Report ◽

Ascochyta Lentis ◽

Humidity Chamber ◽

Dry Conditions

In May 1997, ascochyta blight incited by Ascochyta lentis Vassiljevsky was observed at an incidence of less than 5% in lentil (Lens culinaris Medik.) fields in Umbria (Central Italy). Symptoms appeared on leaves and stems as tan spots surrounded by a dark margin. Small black pycnidia that produced a pink exudate containing hyaline, 1 septate, 14.2 to 15.8 × 3.5 μm conidia under high humidity were visible in the center of the spots. The fungus was consistently isolated on potato dextrose agar from diseased leaves or stems. To satisfy Koch's postulates, a conidial suspension (106 conidia per ml) of the fungus was sprayed on leaves of 20-day-old lentil plants (landrace Castelluccio) that were maintained in a humidity chamber for 96 h after inoculation. Lesions resembling symptoms that occurred in the field were observed on plants 3 weeks after inoculation. Symptoms were not observed on control plants sprayed with water. The fungus reisolated from the diseased plants was identical to the original isolates. Based on morphological characteristics of pycnidia and conidia as well as pathogenicity, the fungus was identified as A. lentis. A deep-freeze blotter method (2) was used to detect A. lentis in lentil seeds of 20 local landraces used by Umbrian farmers and two accessions from Canada and Turkey, as well as in seed collected from infected fields. The fungus was present only in the two lentil accessions with an incidence of about 5%. Although the fungus had been isolated from Italian seed germplasm in 1986 (1), this is the first report of ascochyta blight occurring in lentil crops in Italy. The heavy rainfalls that characterize the first stage of lentil cultivation in Umbria are favorable for disease development while hot and dry conditions that usually occur during flowering and maturation prevent the dissemination of inoculum and the infection of the seeds. For these reasons, some Umbrian areas could be more suitable for production of ascochyta-free lentil seeds. References: (1) W. J. Kaiser and R. M. Hannan. Phytopathology 76:355, 1986. (2) T. Limonard. Proc. Int. Seed Test. Assoc. 33:343, 1968.

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First Report of Anthracnose Fruit Rot of Strawberry Caused by Colletotrichum acutatum in Montenegro

Plant Disease ◽

10.1094/pdis-02-12-0108-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1066-1066 ◽

Cited By ~ 1

Author(s):

J. Latinovic ◽

N. Latinovic ◽

J. Tiodorovic ◽

A. Odalovic

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Pathogenicity Test ◽

Centraalbureau Voor ◽

First Report ◽

Strawberry Anthracnose ◽

Production Area ◽

Ascigerous Stage

Strawberries (Fragaria × ananassa) in Montenegro have become an increasingly important economic crop in recent years. During May 2011, severe fruit damage in strawberry cv. Clery was observed in two fields in the Podgorica region. Fruit symptoms were typical for strawberry anthracnose: sunken, dark brown to black circular lesions appeared on maturing fruits. However, no stem, crown, or foliar symptoms were observed. Under wet conditions, orange masses of conidia were produced in acervuli in the center of lesions. Conidia were hyaline, aseptate, cylindrical, with pointed ends, measuring 9.8 to 17.2 (mean 14.3) × 2.5 to 6.1 (mean 4.4) μm. Colonies on potato dextrose agar (PDA) were initially white, then turned gray as conidia formed in orange to salmon pink masses around the center of the culture. Setae or an ascigerous stage were never observed in culture or on the host. Koch's postulates were fulfilled by inoculating ripe and unripe asymptomatic fruits (20 of each, removed from strawberry plants cv. Clery) with the isolated fungus. Fruits were sprayinoculated (106 conidia/ml). An equal number of noninoculated fruits were used as a control. After incubation time of 2 to 3 days at 25°C in a moist chamber, symptoms appeared on inoculated ripe fruits. On unripe fruits, the lesions developed only 3 to 4 days after the inoculation. No symptoms were found on control fruits. The fungus was reisolated from fruits, after which typical morphological characteristics developed in culture as described above. On the basis of the symptoms, the morphological and cultural characteristics of the fungus, and the pathogenicity test, the disease was identified as strawberry anthracnose caused by Colletotrichum acutatum, which is in accordance with previous reports (1,2,3,4). The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 131813). The internal transcribed spacer (ITS) region of the fungal DNA was amplified with ITS1F and ITS4 primers, sequenced, and submitted to NCBI GenBank (Accession No. JQ424934). BLASTn searches of GenBank using the ITS sequence revealed 99% similarity with database sequences of C. acutatum. Since the pathogen was found in the main Montenegrin strawberry production area, it poses a threat to strawberry production in Montenegro. To our knowledge, this is the first report of anthracnose fruit rot of strawberry in Montenegro. References: (1) S. G. Bobev et al. Plant Dis. 86:1178, 2002. (2) F. M. Dai et al. Plant Dis. 90:1460, 2006. (3) U. Nilsson et al. Plant Dis. 89:1242, 2005. (4) A. Stensvand et al. Plant Dis. 85:558, 2001.

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First Report of Penicillium olsonii Bainier & Sartory Causing Postharvest Fruit Rot of Grape (Vitis vinifera L.) in China

Plant Disease ◽

10.1094/pdis-10-21-2354-pdn ◽

2021 ◽

Author(s):

Jian Zou ◽

Tingfu Zhang ◽

Guoqin Wen ◽

Bo Song ◽

Shijiao Jiang

Keyword(s):

Vitis Vinifera ◽

Morphological Characteristics ◽

Grape Berry ◽

Fruit Rot ◽

Vitis Vinifera L ◽

Grocery Stores ◽

Conidial Suspension ◽

Single Spore ◽

Isolation Technique ◽

Initial Symptoms

Grapes (Vitis vinifera L.) are very popular in China as fresh fruit. Due to its storability, some grape varieties can be kept fresh until winter, increasing the popularity of fruit grapes. However, in 2019, rot symptoms were observed on cv. Crimson in Wuhan, Hubei (30°52′N, 114°31′E), and Chengdu, Sichuan (30°67′N, 104°06′E). Subsequently, from 2019 to 2021, Liangshan (28°33′N, 102°42′E, cv.Crimson), Ya’an (29°40′N, 102°66′E, cv. Red globe), and Nanchong (30°80′N, 106°06′E, cv. Victoria), Sichuan also experienced the same decay symptoms. Initial symptoms of this disease were slightly sunken lesions on the berries 5 to 7 days in storage at 28℃, and then white mycelial growth on the surface of lesions. The growth became bluish-green following the occurrence of abundant sporulation, along with softening and collapsing the whole berry (Fig. 1a). Twenty symptomatic berries from each city were collected (100 samples in total) and twenty isolates were obtained using the single spore isolation technique developed by Chomnunti et al. (2014). The colony on PDA media initially appeared as white mycelium, and later developed into greenish-gray to grayish-green sporulation with white margins, the colony diameter reached 32.5 to 34.5 mm after ten days of incubation at 28±1℃. The reverse side of the colony was oblive-brown or grayish-yellow. Morphological characteristics of the twenty isolates showed that the conidiophores were broom-shaped and verticillate, the stipes smooth-walled and measured 120 to 300 × 2.5 to 4.0 μm; the ramus (n = 2 to 3) measured 6.0 to 15 × 2.5 to 3.6 μm; the metulas (n = 2 to 4) were verticillate, with sizes ranging from 8.7 to 9.8 × 2.0 to 3.2 μm; the phialides (n = 3 to 7) were elongate and ampulliform, with sizes ranging from 2.0 to 3.5 × 2.0 to 2.4 μm; the conidia (2.0 to 3.5 × 2.0 to 2.4 μm) were sub-globose to ellipsoidal in shape, with thick and finely roughened walls. Based on these cultural and morphological characteristics, the isolates were identified as Penicillium olsonii Bainier & Sartory (Frisvad et al., 1990). A multi-locus approach was performed to accurately identify a representative WHG5 isolate. The internal transcribed spacer regions (ITS), calmodulin (CaM,), beta tubulin (BenA), and 18S ribosomal RNA (18S) of isolate WHG5 were amplified and sequenced as described by Walker et al. (2012). The pairwise alignments of ITS, CaM, BenA, and 18S sequences was nearly 100% identical to Penicillium olsonii with GenBank accession numbers KX056230.1 (524/524 bp, 100%), DQ645807.1 (570/572 bp, 99%), AY674444.1 (472/472 bp, 99%), and FJ717701.1 (1299/1301 bp, 99%), respectively. The resulting sequences were deposited in GenBank (Accession no. ITS: MW192867; CaM: MZ936474; BenA: MZ936475; and 18S: MZ936476). The phylogenetic analysis performed with the Neighbor-Joining method classified WGH5 into the P. olsonii clade with a posterior probability of 100% based on the concatenated sequences of the ITS CaM, BenA, and 18S (Fig. 2). Combined with the above morphological characteristics, we finally confirmed the identity of isolate WGH5 as P. olsonii. To fulfill Koch’s postulates and confirm the pathogenicity of WGH5, a 10 μL conidial suspension (1 × 106 spores/mL) aliquot was inoculated into the healthy grape berry (cv. Crimson) while using sterile distilled water as a control. Thirty berries were surface disinfected with 2% sodium hypochlorite then artificially wounded prior to inoculation with the conidial suspension. The artificial wound was made using a sterilized steel needle with a diameter of 0.5 mm and a depth of 0.3 cm. All the inoculated fruits were placed in sealed and sterilized Petri dishes and incubated at 28±1℃. The experiments were done in triplicate. After five days, the inoculated grape berries showed typical symptoms (Fig. 1b) while the control remained asymptomatic. Using the same protocol as above, the fungus P. olsonii was re-isolated from the symptomatic inoculated berries but not successfully from mock-inoculated berries. Previously, P. olsonii has been reported from Portuguese wine grapes (Serra et al., 2007). This study is the first time that P. olsonii was reported as a plant pathogen in China. Since the grapes were collected from grocery stores, details of post-harvest management that could have affected disease presence and progression of rotting were not available.

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First report of Colletotrichum fructicola and Colletotrichum nymphaeae causing leaf spot on Rubus corchorifolius in Zhejiang province, China

Plant Disease ◽

10.1094/pdis-01-21-0198-pdn ◽

2021 ◽

Author(s):

Ju Wu ◽

Hanrong Wang ◽

Li Fang ◽

Yunye Xie ◽

Lianping Wang

Keyword(s):

Leaf Spot ◽

Type Strain ◽

Disease Incidence ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Zhejiang Province ◽

Colletotrichum Acutatum ◽

Leaf Spot Disease ◽

Conidial Suspension ◽

First Report

Rubus corchorifolius is one of the most economically important fruit trees, (Tian et al. 2021). A severe leaf spot disease on leaves of R. corchorifolius was observed in Longquan county, Zhejiang province (118°42’E, 27°42’N) in 2019, with disease incidence of more than 20% on affected plants. The symptoms on leaves of the naturally affected plants were early necrotic lesion with white centers, surrounded by yellow halos (< 5 mm). Later, lesions were expanded with yellowish-brown centers, surrounded by yellow halos (< 5 mm). Putative pathogenic fungi were isolated as described by Fang (1998) and two pure single-colony fungal strains (FPZ1 and FPZ2) were selected for further analysis. The fungi was cultured on potato dextrose agar (PDA) medium for 6 days, at 25°C. The colonies had gray-green centers, white aerial mycelium and gelatinous orange conidial masses. The conidia were unicellular, smooth-walled, hyaline, cylindrical with obtuse to rounded ends, the size 10.15 to 14.09 µm (mean = 12.95 µm, n = 50) × 4.36 to 6.19 µm (mean = 5.19 µm, n = 50) were single, brown to dark brown, ovoid or irregular in shape, and 5.59 to 12.99 µm (mean = 8.77 µm, n = 50) × 4.68 to 10.36 µm (mean = 6.50 µm, n = 50). The characteristics of FPZ1 were consistent with the description of species in the Colletotrichum gloeosporioides complex (Weir et al. 2012). The conidia of FPZ2 were hyaline, smooth-walled, one-celled, fusiform, the size 9.34 to 14.09 µm (mean = 11.92 µm, n = 50) × 3.26 to 6.15 µm (mean = 4.89 µm, n = 50). Appressoria were single, darker brown, elliptical or irregular in outline, and 4.49 to 15.06 µm (mean = 9.88 µm, n = 50) × 3.23 to 7.42 µm (mean = 5.72 µm, n = 50) in size. The characteristics of FPZ2 were consistent with species of the Colletotrichum acutatum complex (Damn et al. 2012). For molecular identification of strains, the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-tubulin (TUB), chitin synthase (CHS-1), and actin (ACT) genes were sequenced (Weir et al. 2012). For the strain FPZ1, the five sequences obtain were deposited in GenBank (MT846907, MT849313, MT849317, MT849315 and MT849319, respectively). A BLAST search of FPZ1 sequences showed 99% identity with the five loci sequences of type strain C. fructicola ICMP 18581 (JX010165, JX010033, JX010405, JX009866 and FJ907426) (Jayawardena et al. 2016). Similarly, for the strain FPZ2, the five sequences (MT846885, MT849314, MT849318, MT849316 and MT849320, respectively) had 99% identity with the five loci sequences of type strain C. nymphaeae CBS 515.78 (JQ948197, JQ948527, JQ949848, JQ948858 and JQ949518, respectively) (Jayawardena et al. 2016). Based on morphological characteristics and phylogenetic analysis, FPZ1 was identified as C. fructicola and FPZ2 as C. nymphaeae, respestively. For pathogenicity tests, 10 μL conidial suspension (1 × 106 conidia per ml) of FPZ1 was used to inoculate five healthy, non-wounded detached leaves, while five leaves inoculated with sterilized water served as control. The experiment was repeated three times, and all leaves were kept on a mist bench at 27°C and relative humidity 80% for 6 days. The inoculation sites of both FPZ1 and FPZ2 became brown and necrotic, while control leaves developed no symptoms. C. fructicola and C. nymphaeae were re-isolated from the lesions of inoculated leaves, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. fructicola and C. nymphaeae causing leaf spot on Rubus corchorifolius in China, and reports on the prevalence of C. gloeosporioides and C. acutatum species complexes will be beneficial to management of anthracnose in R. corchorifolius.

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