Characterisation and Pathogenicity of Aspergillus tamarii Causing Banana Fruit Rot

Banana fruit rot is a common postharvest disease of the banana fruit. The appearance of rot symptoms on the surface of the fruits reduces the quality and marketability of banana. From rot lesions on banana fruits, three Aspergillus isolates were isolated. Based on morphological characteristics and sequences of Internal Transcribed Spacer, β-tubulin and calmodulin, the isolates were identified as A. tamarii. Pathogenicity tests of the isolates, conducted using mycelial plugs with wounded and unwounded treatments, showed A. tamarii as the pathogen of banana fruit rot. Rot symptoms were highly severe on wounded banana fruits compared to unwounded fruits, and therefore, wounded banana fruits are more susceptible to A. tamarii infection. To the best of our knowledge, this is the first report of A. tamarii as a causal pathogen of banana fruit rot. This study indicated A. tamarii is one of postharvest rot pathogens of banana.

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Outbreak of Leaf Spot and Fruit Rot in Florida Strawberry Caused by Neopestalotiopsis spp.

Plant Disease ◽

10.1094/pdis-06-20-1290-re ◽

2021 ◽

pp. PDIS-06-20-1290

Author(s):

Juliana S. Baggio ◽

Bruna B. Forcelini ◽

Nan-Yi Wang ◽

Rafaela G. Ruschel ◽

James C. Mertely ◽

...

Keyword(s):

Internal Transcribed Spacer ◽

Phylogenetic Analyses ◽

Morphological Characteristics ◽

Taxonomic Status ◽

Spore Production ◽

Potato Dextrose Agar ◽

Fruit Rot ◽

Low Genetic Diversity ◽

Pathogenicity Tests ◽

A New Species

Pestalotiopsis-like species have been reported affecting strawberry worldwide. Recently, severe and unprecedented outbreaks have been reported in Florida commercial fields where leaf, fruit, petiole, crown, and root symptoms were observed, and yield was severely affected. The taxonomic status of the fungus is confusing because it has gone through multiple reclassifications over the years. Morphological characteristics, phylogenetic analyses, and pathogenicity tests were evaluated for strawberry isolates recovered from diseased plants in Florida. Phylogenetic analyses derived from the combined internal transcribed spacer, β-tub, and tef1 regions demonstrated that although there was low genetic diversity among the strawberry isolates, there was a clear separation of the isolates in two groups. The first group included isolates recovered over a period of several years, which was identified as Neopestalotiopsis rosae. Most isolates recovered during the recent outbreaks were genetically different and may belong to a new species. On potato dextrose agar, both groups produced white, circular, and cottony colonies. From the bottom, colonies were white to pale yellow for Neopestalotiopsis sp. and pale luteous to orange for N. rosae. Spores for both groups were five-celled with three median versicolored cells. Mycelial growth and spore production were higher for the new Neopestalotiopsis sp. isolates. Isolates from both groups were pathogenic to strawberry roots and crowns. However, the new Neopestalotiopsis sp. proved more aggressive in fruit and leaf inoculation tests, confirming observations from the recent outbreaks in commercial strawberry fields in Florida.

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A polyphasic approach to characterise two novel species of Phoma (Didymellaceae) from China

Phytotaxa ◽

10.11646/phytotaxa.197.4.4 ◽

2015 ◽

Vol 197 (4) ◽

pp. 267-281 ◽

Cited By ~ 17

Author(s):

Qian Chen ◽

KE ZHANG ◽

GUOZHEN ZHANG ◽

LEI CAI

Keyword(s):

Rna Polymerase Ii ◽

Internal Transcribed Spacer ◽

Novel Species ◽

Large Subunit ◽

Morphological Characteristics ◽

Polyphasic Approach ◽

Nrdna Its ◽

Two New Species ◽

Viburnum Odoratissimum ◽

Β Tubulin

Phoma odoratissimi sp. nov. on Viburnum odoratissimum and Syringa oblate, and Phoma segeticola sp. nov. on Cirsium segetum from China are introduced and described, employing a polyphasic approach characterising morphological characteristics, host association and phylogeny. Both species are the first records of Phoma species on their respective hosts. Multi-locus phylogenetic tree was inferred using combined sequences of the internal transcribed spacer regions 1 & 2 and 5.8S nrDNA (ITS), and partial large subunit 28S nrDNA region (LSU), β-tubulin (TUB) region and RNA polymerase II (RPB2) region. The two new species clustered in two separate and distinct lineages, and are distinct from their allied species.

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

Plant Disease ◽

10.1094/pdis-07-11-0620 ◽

2012 ◽

Vol 96 (3) ◽

pp. 458-458 ◽

Cited By ~ 1

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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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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Mucor Rot—An Emerging Postharvest Disease of Mandarin Fruit Caused by Mucor piriformis and other Mucor spp. in California

Plant Disease ◽

10.1094/pdis-10-15-1173-re ◽

2016 ◽

Vol 100 (6) ◽

pp. 1054-1063 ◽

Cited By ~ 3

Author(s):

S. Saito ◽

T. J. Michailides ◽

C. L. Xiao

Keyword(s):

Internal Transcribed Spacer ◽

Mycelial Growth ◽

Morphological Characteristics ◽

Central Valley ◽

Lesion Size ◽

The Other ◽

Postharvest Disease ◽

First Report ◽

Mucor Piriformis

In recent years, an emerging, undescribed postharvest disease was observed on mandarin fruit after extended storage in California. We collected decayed mandarin fruit from three citrus packinghouses in the Central Valley of California in 2015 and identified this disease as Mucor rot caused by Mucor spp. Mucor rot occurred in 11 of the 15 grower lots sampled, and the percentage of Mucor rot in the total decayed fruit varied among affected grower lots, ranging from 3.3 to 93.1% with an average of 49.2%. In total, 197 isolates of Mucor spp. were obtained from decayed mandarin fruit and identified based on internal transcribed spacer sequence and morphological characteristics. Of the 197 isolates, 182 (92.4%) were identified as Mucor piriformis, 7 (3.6%) were M. circinelloides (6 M. circinelloides f. lusitanicus and 1 M. circinelloides f. circinelloides), 4 (2%) were M. racemosus f. racemosus, 3 (1.5%) were M. hiemalis, and 1 (0.5%) was M. mucedo. All species grew at 0 and 5°C, except M. circinelloides, which did not grow at 0°C. Mycelial growth was arrested at 27°C for M. piriformis; 35°C for M. racemosus f. racemosus, M. circinelloides f. lusitanicus, M. hiemalis and M. mucedo; and 37°C for M. circinelloides f. circinelloides. Optimal mycelial growth occurred at 20°C for M. piriformis and M. mucedo, 25°C for M. racemosus f. racemosus and M. hiemalis, 27°C for M. circinelloides f. lusitanicus, and 30°C for M. circinelloides f. circinelloides. M. piriformis grew significantly faster than the other four species at 5 and 20°C, and M. mucedo was the slowest in growth among the five species. Sporangiospores of M. piriformis, M. racemosus f. racemosus, and M. hiemalis germinated at both 5 and 20°C. M. circinelloides germinated at 20°C but did not germinate at 5°C after incubation for 48 h. All five Mucor spp. caused decay on mandarin fruit inoculated with the fungi, and the lesion size caused by M. piriformis was significantly larger than that caused by other species at both 5 and 20°C. Our results indicated that Mucor rot in mandarin fruit in California is caused by Mucor spp. consisting of M. piriformis, M. circinelloides, M. racemosus f. racemosus, M. hiemalis, and M. mucedo, with M. piriformis being the dominant and most virulent species. Previously, M. racemosus was reported on citrus. This is the first report of Mucor rot in citrus caused by M. piriformis, M. circinelloides, M. hiemalis, and M. mucedo.

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First Report of Gliocephalotrichum bacillisporum Causing Fruit Rot of Rambutan (Nephelium lappaceum) in Malaysia

Plant Disease ◽

10.1094/pdis-09-12-0831-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1110-1110

Author(s):

M. A. Intan Sakinah ◽

Z. Latiffah

Keyword(s):

Morphological Characteristics ◽

Culture Collection ◽

Fruit Rot ◽

Tropical Fruit ◽

First Report ◽

Surface Sterilization ◽

Nephelium Lappaceum ◽

Its Regions ◽

Mycelial Plug ◽

Β Tubulin

Rambutan (Nephelium lappaceum L.) is among the tropical fruit grown in Malaysia and the demand for export rose in 2011. A fruit rot was observed between August and December 2011 from several areas in the states of Pulau Pinang and Perak, Malaysia. The symptoms initially appeared as light brown, water-soaked lesions that developed first in the pericarp and pulp, later enlarging and becoming dark brown. Greyish brown mycelia were observed on infected areas that turned yellowish at later stages of infection. Gliocephalotrichum bacillisporum was isolated from infected fruit by surface sterilization techniques. Conidia were mass-transferred onto potato dexstrose agar (PDA) plates and incubated at 27 ± 1°C. Tissue pieces (5 × 5 mm) excised from the margins between infected and healthy areas were then surface sterilized in 1% sodium hypochlorite for 3 to 5 min before being rinsed with distilled water, plated on PDA, and incubated at 27 ± 1°C for 7 days. Ten isolates of G. bacillisporum were obtained. Colonies on PDA were initially white before turning yellow with a feathery appearance. Microscopic characteristics on carnation leaf agar (CLA) consisted of hyaline conidia that were slightly ellipsoid to bacilliform with rounded apex ranging from 6.0 to 8.5 μm long and 2.0 to 2.5 μm wide. Conidiophores (70 to 130 μm long) were mostly single arising from large hypha approximately 13 to 16 μm. The conidiogenous structures were mostly quadriverticillate with dense, short, penicillate branches. The phialides were cylindrical and finger-like. Chlamydospores were present singly, in groups of 2 to 4, or in occasionally branched short chains and were brown in color with thick walls ranging from 11 to 13 μm. The cultural and morphological characteristics of G. bacillisporum isolates in the present study were very similar to previously published descriptions (1) except the conidiophores formed without sterile stipe extensions. All the G. bacillisporum isolates were deposited in culture collection at the Plant Pathology Lab, University Sains Malaysia, Penang. Molecular identification was accomplished from the ITS regions using ITS1 and ITS2 primers, and the β-tubulin gene using Bt2a and Bt2b primers (2). BLAST results from the ITS regions showed a 98 to 99% similarity with sequences of G. bacillisporum isolates reported in GenBank. Accession numbers of G. bacillisporum ITS regions: JX484850, JX484852, JX484853, JX484856, JX484858, JX484860, JX484862, JX484866, JX484867, and JX484868. The identity of G. bacillisporum isolates infecting rambutan was further confirmed by β-tubulin sequences (KC683909, KC683911, KC683912, KC683916, KC683919, KC683920, KC683923, KC683926, and KC683927), which showed 92 to 95% similarity with sequences of G. bacillisporum. Pathogenicity tests were also performed using mycelial plug (5 mm) and sprayed conidial suspensions (20 μl suspension of 106 conidia/ml) prepared from 7-day-old cultures. Inoculated fruits were incubated at 27 ± 1°C and after 10 days, similar rotting symptoms appeared on the fruit surface. The pathogen was reisolated from fruit rot lesions, thus fulfilling Koch's postulates, and tests were repeated twice. To our knowledge, this is the first report of G. bacillisporum causing fruit rot of rambutan (N. lappaceum L.) in Malaysia. References: (1) C. Decock et al. Mycologia 98:488, 2006. (2) N. L. Glass and G. C. Donaldson. Appl. Environ Microbiol. 61:1323, 1995.

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First Report of Fusarium solani Fruit Rot of Pumpkin (Cucurbita pepo) in Trinidad

Plant Disease ◽

10.1094/pdis-93-5-0547b ◽

2009 ◽

Vol 93 (5) ◽

pp. 547-547

Author(s):

S. N. Rampersad

Keyword(s):

Fusarium Solani ◽

Cucurbita Pepo ◽

Morphological Characteristics ◽

Soft Rot ◽

The United States ◽

Fruit Rot ◽

Laboratory Manual ◽

First Report ◽

Pathogenicity Tests ◽

Negative Controls

Trinidad is a major exporter of pumpkins (Cucurbita pepo L.) to other Caribbean countries, Canada, and the United States. Producers and exporters have reported 50 to 80% yield losses because of soft rot and overnight collapse of fruit at the pre- and postharvest stages. Severe fruit rot occurred in fields in Victoria County in South Trinidad between April and May 2006 (mid-to-late dry season) with an increase in the severity and number of affected fruit in the rainy season (July to December). Symptoms began as water-soaked lesions on the fruit of any age at the point of contact with the soil. The disease progressed to a soft rot with leakage and whole fruit collapse. A dark brown, soft decay also developed at the base of the main vines. Fusarium solani was isolated on selective fusarium agar and potato dextrose agar (PDA) (1) after 7 to 10 days of incubation at 25°C. The pathogen was identified by morphological characteristics and pathogenicity tests. Colonies were fast growing with white aerial mycelia and a cream color on the reverse side; hyphae were septate and hyaline, conidiophores were unbranched, and microconidia were abundant, thin walled, hyaline, fusiform to ovoid, generally one to two celled, and 8 to 10 × 2 to 4 μm. Macroconidia were hyaline, two to three celled, moderately curved, thick walled, and 25 to 30 × 4 to 6 μm. Pathogenicity tests for 10 isolates were conducted on 2-week-old pumpkin seedlings (cv. Jamaican squash; seven plants per isolate) and mature pumpkin fruit (2). Briefly, seedlings were inoculated by dipping their roots in a spore suspension (1 × 104 spores per ml) for 20 min. The plants were repotted in sterile potting soil. For negative controls, plant roots were dipped in sterile water. After the rind of fruit was swabbed with 70% ethanol followed by three rinses with sterile distilled water, 0.4-cm-diameter agar plugs of the isolates were inserted into wounds made with a sterile 1-cm-diameter borer. Sterile PDA plugs served as negative controls. Fruit were placed in sealed, clear, plastic bags. Inoculated plants and fruit were placed on greenhouse benches (30 to 32°C day and 25 to 27°C night temperatures) and monitored over a 30-day period. Tests were repeated once. Inoculated fruit developed a brown, spongy lesion that expanded from the initial wound site over a period of approximately 17 days after inoculation. White mycelia grew diffusely over the lesion. Inoculated plants developed yellow and finally necrotic leaves and lesions developed on stems at the soil line approximately 21 days after inoculation. No symptoms developed on the control plants. The fungus was reisolated from symptomatic tissue, fulfilling Koch's postulates. To my knowledge, this is the first report of Fusarium fruit rot of pumpkin in Trinidad. References: (1) J. Leslie and B. Summerell. Page 1 in: The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, 2006. (2) W. H. Elmer. Plant Dis. 80:131, 1996.

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First Report of Lasidiplodia theobromae and Cryptovalsa ampelina Associated with Grapevine Decline from Castilla y León, Spain

Plant Disease ◽

10.1094/pdis-93-5-0545c ◽

2009 ◽

Vol 93 (5) ◽

pp. 545-545 ◽

Cited By ~ 4

Author(s):

M. T. Martin ◽

L. Martin ◽

M. T. de-Francisco ◽

R. Cobos

Keyword(s):

Dna Sequences ◽

Morphological Characteristics ◽

Tubulin Gene ◽

Current Season ◽

First Report ◽

Grapevine Decline ◽

Eutypa Dieback ◽

Castilla Y Leon ◽

Pathogenicity Tests ◽

Β Tubulin

Symptoms of grapevine decline were surveyed. Samples from mature vines exhibiting external symptoms of Eutypa dieback and Esca were collected, as were young plants with and without external symptoms, and fungal isolations were performed. In 2007, 3-year-old grapevines (cv. Tempranillo grafted onto 110R rootstock) with low vigor, reduced foliage, and vascular streaking in the wood were observed. Small pieces of discolored wood were placed onto malt extract agar supplemented with 0.25 g/liter of chloramphenicol, incubated at 25°C, and resulting colonies were transferred to potato dextrose agar (PDA). Isolates were characterized by abundant aerial and fast-growing mycelium covering the plate surface after 3 days, mycelium became dark green. Pycnidia contained thick-walled, aseptate conidia 15 to 35 × 10 to 15 μm. Lasidiplodia theobromae was identified based on morphological characteristics (3) and confirmed by banding patterns obtained after the digestion of the 1,200-bp amplicon generated with ITS1 and NL4 primers (2) using restriction endonucleases (2). Single-spore cultures were generated and DNA sequences of the rDNA internal transcribed spacer region, partial sequence of the 5′ end of the β-tubulin gene, and a fragment of the elongation factor further confirmed the identification and revealed genetic similarity with other isolates of L. theobromae. A sequence of each fragment was deposited in GenBank with Accession Nos. EU600925, EU597297, and EU597298, respectively. Pathogenicity tests were conducted on four replicate rootstocks (110R) and 15 canes of current-season growth (cv. Tempranillo). Plants were inoculated with an agar plug containing L. theobromae; controls were treated with agar only. Grapevines were maintained in a greenhouse at 20 to 25°C. After 3 months, L. theobromae was reisolated from internal vascular lesions in 100 and 66% of inoculated rootstocks and canes, respectively. Control plants were asymptomatic and L. theobromae was not recovered. Using the same methodology, a fungus identified based on morphological characteristics in culture as Cryptovalsa ampelina (1) was isolated from grapevines (cv. Tempranillo) planted in 1987. Cultures in PDA were white to creamy white and cottony with diffuse margins. Colonies covered the 90-mm-diameter petri dish surface in 5 days. Conidia were 20 to 23 × 1 to 1.5 μm, unicellular, hyaline, and filiform. PCR amplifications of the DNA extracts of C. ampelina with Camp-1 and Camp-2R primers gave a characteristic DNA fragment of 300 bp (3) and DNA sequences of the ITS4-ITS5 amplicons (GenBank Accession No. EU597296) confirmed the identification. For the first time, the 5′ end of the β-tubulin gene was sequenced and deposited in GenBank (Accession No. EU600926). Pathogenicity tests were conducted as described above for L. theobromae. Both pathogens were examined in the same experiment. C. ampelina was reisolated from internal brown streaking lesions in 25% of the rootstocks and 33% of the canes. Control plants exhibited no symptoms. L. theobromae appeared to be a more aggressive pathogen than C. ampelina on grapevine with more internal brown streaking and greater recovery of pathogen from inoculated samples. To our knowledge, this is the first report of L. theobromae and C. ampelina causing grapevine decline in Castilla y León. References: (1) J. Luque et al. Phytopathol. Mediterr. 45:S101, 2006. (2) M. T. Martin and R. Cobos. Phytopathol. Mediterr. 46:18, 2007. (3) D. Pavlic et al. Stud. Mycol. 50:313, 2004.

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First Report of Fruit Rot in Pear Caused by Botryosphaeria dothidea in Italy

Plant Disease ◽

10.1094/pdis-02-12-0130-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 910-910 ◽

Cited By ~ 9

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

A. Poli ◽

M. L. Gullino

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Fruit Rot ◽

Pathogenicity Test ◽

Botryosphaeria Dothidea ◽

First Report ◽

Irregular Margin ◽

Pyrus Communis L ◽

Pathogenicity Tests

Pear (Pyrus communis L.) is widely grown in Italy, the leading producer in Europe. In summer 2011, a previously unknown rot was observed on fruit of an old cultivar, Spadoncina, in a garden in Torino Province (northern Italy). The decayed area of the fruit was soft, dark brown, slightly sunken, circular, and surrounded by an irregular margin. The internal decayed area appeared rotten and brown and rotted fruit eventually fell. To isolate the causal agent, fruits were soaked in 1% NaOCl for 30 s and fragments (approximately 2 mm) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at temperatures between 20 and 28°C under alternating light and darkness. Colonies of the fungus initially appeared whitish, then turned dark gray. After about 30 days of growth, unicellular elliptical hyaline conidia were produced in pycnidia. Conidia measured 16 to 24 × 5 to 7 (average 20.1 × 5.7) μm (n = 50). The morphological characteristics are similar to those of the fungus Botryosphaeria dothidea (Moug.: Fr.) Ces. & De Not. (4). The internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 473-bp segment showed a 100% similarity with the sequence of the epitype of B. dothidea AY236949. The nucleotide sequence has been assigned the GenBank Accession No. JQ418493. Pathogenicity tests were performed by inoculating six pear fruits of the same cultivar (Spadoncina) after surface disinfesting in 1% sodium hypochlorite and wounding. Mycelial disks (8 mm diameter), obtained from 10-day-old PDA cultures of one strain, were placed on wounds. Six control fruits were inoculated with plain PDA. Fruits were incubated at 25 ± 1°C in plastic boxes. The first symptoms developed 3 days after inoculation. After 5 days, the rot was very evident and B. dothidea was consistently reisolated. Noninoculated fruits remained healthy. The pathogenicity test was performed twice. B. dothidea was identified on decayed pears in the United States (2), South Africa, New Zealand, Japan, and Taiwan (3). To our knowledge, this is the first report of the presence of B. dothidea on pear in Italy, as well as in Europe. In Italy, the economic importance of the disease on pear fruit is at present limited, although the pathogen could represent a risk for this crop. References: (1) S. F. Altschul et al. Nucleic Acids Res., 25:3389, 1997. (2) L. F. Grand. Agr. Res. Serv. Techn. Bull. 240:1, 1985. (3) Y. Ko et al. Plant Prot. Bull. (Taiwan) 35:211, 1993. (4) B. Slippers et al. Mycologia 96:83, 2004.

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First Report of Postharvest Fruit Rot in Avocado (Persea americana) Caused by Lasiodiplodia theobromae in Italy

Plant Disease ◽

10.1094/pdis-10-11-0886 ◽

2012 ◽

Vol 96 (3) ◽

pp. 460-460 ◽

Cited By ~ 6

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. T. Amatulli ◽

J. Cardinale ◽

M. L. Gullino

Keyword(s):

Plant Pathogens ◽

Morphological Characteristics ◽

The United States ◽

Disease Diagnosis ◽

Persea Americana ◽

Fruit Rot ◽

Pathogenicity Test ◽

Lasiodiplodia Theobromae ◽

First Report ◽

Pathogenicity Tests

Avocado (Persea americana Mill.) is grown in some areas of southern Italy. In spring 2011, a previously unknown rot was observed on fruit that was marketed in Torino (northern Italy). The decayed area started from the stalk, appeared irregular and soft, and was surrounded by a dark brown margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. Fragments (approximately 3 mm) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at temperatures between 21 and 25°C under alternating conditions of light and dark. Colonies of the fungus initially appeared whitish, later turning mouse gray to black. Mature mycelium was septate and produced a dark pigment. The fungus, grown on oat agar (2) and incubated at temperatures between 21 and 25°C under alternating light and darkness, produced grayish colonies with a fluffy aerial mycelium that became dark with age and produced black pigments. After 18 days of incubation, such colonies produced pycnidia aggregated into stromatic masses, emerging from decayed tissues, and up to 3 to 4 mm in diameter. Conidia produced in the pycnidia were initially unicellular, hyaline, granulose, ovoid to ellipsoidal, and measured 20.8 to 26.9 × 12.5 to 16.1 (average 24.4 × 13.5) μm. After 7 days, mature conidia became darker, uniseptate, and longitudinally striate. Paraphyses produced within the tissues of pycnidia were hyaline, cylindrical, nonseptate, and up to 63 μm long. Morphological characteristics of mycelia, pycnidia, and conidia observed with a light microscope permitted identify of the fungus as Lasiodiplodia theobromae (3). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 488-bp segment showed a 100% similarity with the corresponding sequence (GenBank Accession No. GQ502453) of L. theobromae Pat. Griffon & Maubl. The nucleotide sequence of the strain used for pathogenicity tests was submitted to GenBank (Accession No. JN849098). Pathogenicity tests were performed by inoculating 10 avocado fruits after surface disinfesting in 1% sodium hypochlorite and then wounding. Mycelial disks (8 mm in diameter) obtained from PDA cultures of one strain were placed on wounds. Ten control fruits were inoculated with plain PDA. Fruits were incubated at 15 ± 1°C. The first symptoms developed 4 days after the artificial inoculation. After 7 days, the rot was evident and L. theobromae was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice. To our knowledge, this is the first report of the presence of L. theobromae causing postharvest fruit rot on avocado in Italy, as well as in Europe. The occurrence of postharvest fruit rot on avocado caused by L. theobromae was described in many avocado-producing areas such as the United States (4), South Africa, and Israel. In Italy, the economic importance of avocado cultivation is currently limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2). P. Narayanasamy. Microbial Plant Pathogens. Detection and Disease Diagnosis: Fungal Pathogens. Springer, Dordrecht, 2011. (3) E. Punithalingam. Sheet 519. CMI Description of Fungi and bacteria, 1976. (4) H. E. Stevens and R. B. Piper. Circular No. 582, USDA, 1941.

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