First Report of Stagonosporiopsis cucurbitacearum Causing Fruit Rot of Luffa cylindrica in Brazil

Luffa cylindrica (Cucurbitaceae) is an Asian vine widely known as the source of loofah (4). In Brazil (local name bucha), it is cultivated by small scale producers as a cash crop. In January 2012, samples of fruits were collected in three areas in the municipality of Cipotânea, state of Minas Gerais (Brazil) bearing rot symptoms. These had large necrotic areas with a grayish epidermis and slightly sunken tissue. Internally, the fibrous parts were necrosed, darkened, and unmarketable. Isolations by surface sterilization of necrotic tissue with 10% bleach and plating onto potato dextrose agar yielded colonies with consistent morphology. A representative culture was deposited in the culture collection of the Universidade Federal de Viçosa (UFV) as COAD1119. Inoculations of seven healthy-appearing L. cylindrica fruits were performed with culture disks obtained from 4-day-old cultures grown on PDA, which were placed onto two points on the epidermis of each of seven fruits. Each point was either intact or previously injured with a sterile needle. Controls consisted of two fruits treated equally but with tap water agar disks in place of fungal inoculum. Fruits were then placed on trays with water-soaked cotton and the trays were wrapped in plastic bags and left over a bench at room temperature for 2 days. The plastic bags were then removed. After 5 days, necrosis was evident and fungal fruit bodies appeared at points with injury. No symptoms appeared on controls. Isolation from diseased tissue yielded colonies identical to those of the inoculated fungus. A dried sample was deposited in the local herbarium at UFV (VIC 32053). Slides were mounted in lactophenol and observed. The fungus had subepidermal perithecia, globose to subglobose, from 75.5 to 134 μm diam.; asci bitunicate, cylindrical, 8-spored; pseudoparaphyses filiform; ascospores fusoid to ellipsoidal, from 26 to 45 μm long and 8 to 11.5 μm wide, one septate, and hyaline. This morphology is consistent with Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae) (3), a broad spectrum pathogen of cucurbits. Genomic DNA was extracted from the isolate growing in pure culture and ITS and LSU sequences were generated and deposited in GenBank under the accession numbers KC582022 and KC582021, respectively. Sequences were compared in BLASTn with other entries in GenBank, and the closest match for each region were S. cucurbitacearum strain CAP14C and D. bryoniae strain CBS 133.96 (JQ936326 and GU456335) with 100% of nucleotide homology for ITS and 100% of nucleotide homology for LSU. Cercospora citrullina and C. cucurbitae have been reported in Brazil on L. cylindrica and mistakenly indicated as synonyms of D. bryoniae (2). To our knowledge, this is the first valid report of S. cucurbitacearum causing fruit rot of loofah in Brazil and the first time pathogenicity to this host has been demonstrated. Losses due to the disease on the crop were reported to be high by growers and management to be difficult since there are no fungicides registered for this crop in Brazil. References: (1) M. M. Aveskamp et al. Stud. Mycol 65:1, 2010. (2) M. A. S. Mendes and A. F. Urben. Fungos em Plantas no Brasil. Brasília, Brazil: EMBRAPA-SPI. Retrieved from http://pragawall.cenargen.embrapa.br/aiqweb/michtml/micbanco01a.asp , 2012. (3) E. Puithalingam and P. Holliday. CMI Descriptions of Pathogenic Fungi and Bacteria 332:1, 1972. (4) J. W. Purseglove. Tropical Crops – Dicotyledons. Longman Group, London, 1968.

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First Report of Phytophthora Fruit Rot on Bitter Gourd (Mormodica charantia) and Sponge Gourd (Luffa cylindrica) Caused by Phytophthora capsici

Plant Health Progress ◽

10.1094/php-br-15-0005 ◽

2015 ◽

Vol 16 (2) ◽

pp. 93-94 ◽

Cited By ~ 3

Author(s):

Chandrasekar S. Kousik ◽

Camilo Parada ◽

Lina Quesada-Ocampo

Keyword(s):

Phytophthora Capsici ◽

Management Strategies ◽

Fruit Rot ◽

Bitter Gourd ◽

Small Scale ◽

Molecular Tools ◽

Luffa Cylindrica ◽

Sponge Gourd ◽

Luffa Sponge ◽

The U.S

Luffa sponge (smooth gourd) and bitter gourds (bitter melon) are specialty vegetables grown in the U.S. on a small scale for select markets. Luffa gourds are also grown for sponges. In Sept. 2014, heavy rainfall resulted in rot of >50% of bitter gourd and >25% on sponge gourd in a field in Charleston, SC. The microbe causing the fruit rot was identified using microscopy and molecular tools. Prior to this study it was not known if this microbe could cause fruit rot of bitter gourd. This knowledge will be useful to suggest management strategies. Accepted for publication 17 March 2015. Published 6 May 2015.

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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 Didymella bryoniae Causing Gummy Stem Blight of Chayote in Taiwan

Plant Disease ◽

10.1094/pdis-02-12-0185-pdn ◽

2012 ◽

Vol 96 (10) ◽

pp. 1578-1578 ◽

Cited By ~ 2

Author(s):

Y. C. Tsai ◽

J. F. Chen

Keyword(s):

Morphological Characteristics ◽

Pathogenic Fungi ◽

Molecular Data ◽

Pathogenicity Test ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Plastic Bags ◽

Pathogenicity Tests ◽

Stems And Leaves

Chayote (Sechium edule (Jacq.) Swartz, Cucurbitaceae), originally native to Mexico, is an important vegetable known as “dragon-whisker vegetable” and is cultivated for its shoots in Ji-an, Hualien County in eastern Taiwan. In June 2010, 70 to 80% of the chayote plants grown in Ji-an developed necrotic spots on stems, leaves, and fruits. The disease was severe during the warm and rainy season from June to August. The symptoms on stems, leaves, and fruits were water-soaked lesions that eventually dried up, cracked, and produced perithecia on necrotic tissues. A single ascospore was isolated from perithecia harvested from diseased stems and cultured on potato dextrose agar (PDA) at 25°C for 1 month. Colonies of three isolates (SE5, SE6, and SE7) were white to olivaceous green bearing unicellular conidia measuring 2 to 5 × 3 to 10 μm, which is consistent with the morphological characteristics of Didymella bryoniae (Auersw.) Rehm (anamorph Phoma cucurbitacearum (Fr.:Fr.) Sacc.) (1,2,3). DNA of SE5, SE6, and SE7 isolates were obtained using microwave-based method (4). The internal transcribed spacer (ITS) rDNA (GenBank accessions AB714984, AB714985, and AB714986), PCR-amplified using primers ITS1 and ITS4, had 98 to 99% nucleotide sequence identity with D. bryoniae (GenBank Accession Nos. GU045304 and GU592001). A pathogenicity test was conducted in a greenhouse with temperature ranging from 20 to 30°C. Three-day-old mycelial plugs (5 × 5 mm) of the three isolates were placed on the needle-pricked wounds of stems and leaves of 36 4-month-old potted chayote plants wrapped in plastic bags to maintain 100% relative humidity for 2 days. Six days after inoculation, water-soaked lesions formed on the stems and leaves. Controls inoculated with sterile water had no symptoms. The fungus reisolated from the lesions of diseased stems and leaves had morphological characteristics of D. bryoniae. Based on the results of morphology, molecular data, and pathogenicity tests, we reported for the first time to our knowledge that gummy stem blight of chayote is caused by D. bryoniae in Taiwan. References: (1) J. W. Huang and W. R. Hsieh. Plant Prot. Bull. 27:325, 1985. (2) A. P. Keinath et al. Phytopathology 85:364, 1995. (3) E. Punithalingam and P. Holliday. P. 332 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1972. (4) S. R. Tendulkar et al. Biotechnol. Lett. 22:1941, 2003.

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First Report of Phytophthora cactorum Causing Fruit Rot on Avocado in Spain

Plant Disease ◽

10.1094/pd-89-1363b ◽

2005 ◽

Vol 89 (12) ◽

pp. 1363-1363

Author(s):

C. J. López-Herrera ◽

R. M. Pérez-Jiménez ◽

T. Zea-Bonilla

Keyword(s):

Tap Water ◽

Pathogenic Fungi ◽

Persea Americana ◽

Southern Spain ◽

Fruit Rot ◽

Sterile Water ◽

Phytophthora Cactorum ◽

First Report ◽

Apical Necrosis ◽

Mycelial Suspension

The area of avocado (Persea americana Mill.) orchards in southern Spain has increased recently and is currently at 8,063 ha. Avocado production in this part of Spain was 72,581 t during 2003. During February 2004, apical necrosis was observed on avocado fruits (cv. Hass) in one orchard in Vélez-Málaga, Málaga Province, southern Spain. Dark brown lesions and necrotic flecking of the flesh also were observed on fruits. Isolations from the skin of the fruit previously washed with tap water and disinfested with 20% sodium hypochlorite on potato dextrose agar (PDA) consistently resulted in mycelial colonies. Sporangia produced on V8 juice by successive washing of mycelia with saline solution (1) measured 31 to 37.2 (33.3) × 21.7 to 28.8 (24.2) μm in size. The pathogen was identified as Phytophthora cactorum on the basis of morphological structures (mycelia, sporangia, chlamydospores, and oospores) formed when grown on V8 juice and PDA (2). To confirm pathogenicity, a mycelial suspension was obtained by blending mycelia grown for 1 week on PDA in 200 ml of sterile water. Three healthy avocado fruits were inoculated with the suspension by injection; three other fruits were inoculated by placing a drop of suspension on the unbroken skin of the fruit. The same number of fruit was inoculated as controls using sterile water instead of mycelial suspension. The inoculated fruits were incubated for 5 days in a moist chamber at 24°C in darkness. Spots appeared on all fruits for both inoculation methods, and the pathogen was isolated and identified as P. cactorum. No symptoms appeared on the control fruits. To our knowledge, this is the first report of P. cactorum causing fruit rot on avocado in Spain. References: (1) D. Chen and G. A. Zentmeyer. Mycologia 62:397, 1970. (2) G. M. Waterhouse and J. M. Waterston. No. 111 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1966.

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First Report of Gummy Stem Blight Caused by Didymella bryoniae on Watermelon and Confirmation of the Disease on Pumpkin in Tanzania

Plant Disease ◽

10.1094/pdis-01-11-0044 ◽

2011 ◽

Vol 95 (6) ◽

pp. 768-768 ◽

Cited By ~ 7

Author(s):

B. D. Jensen ◽

A. Massawe ◽

I. S. Swai

Keyword(s):

Citrullus Lanatus ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Weather Conditions ◽

Fruit Rot ◽

Didymella Bryoniae ◽

First Report ◽

Stem Blight ◽

Gummy Stem Blight ◽

Specific Pcr

Foliar, stem, and fruit lesions were observed on watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) and pumpkin (Cucurbita maxima Duchesne) in two separate research fields in the district of Arusha, Tanzania during the warm, rainy season from February to April 2010. Similar symptoms were observed in commercial watermelon fields and intercropped pumpkin fields in Same and Moshi districts with as much as 100% fruit loss in watermelon. Disease symptoms on watermelon were dark brown, V-shaped leaf lesions. On pumpkin, V-shaped leaf lesions were light brown. On both hosts, stems showed water-soaked lesions after rain, which dried up and cracked. On pumpkin, a gummy, amber exudate was seen after rain on stem and fruit lesions. Flowers and fruits of both hosts developed black rot spots and aborted. Isolation of the causal agent on potato dextrose agar (PDA) from leaf and stem pieces of watermelon and pumpkin plants in Arusha showed white-to-olivaceous green mycelium. Pycnidia formed on one-quarter-strength PDA and produced hyaline, oblong conidia mainly with two guttules, nonseptate, 5 to 11 × 3 to 5 μm. Pathogenicity was tested with three isolates from watermelon and one from pumpkin on four 1-month-old plants per watermelon cvs. Sugar Baby and Charleston Grey and pumpkin cv. Small Sugar per isolate. The test was repeated on the watermelon cultivars. One site on the main stem and two leaves per plant were misted, pricked with a scalpel, inoculated with 3-day-old mycelial plugs (5 × 5 mm), and kept humid at 20 to 30°C in cellophane bags for 3 days. All plants developed leaf and/or stem lesions. Detached, misted leaves were also laid on 2% water agar and inoculated as above. Water-soaked lesions developed around inoculation sites and microscopy of infected tissue revealed pycnidia with conidia as described above. All isolates infected both hosts. A set of control plants and detached leaves, mock inoculated with agar plugs, remained symptomless. The fungus was reisolated from infected leaves and stems of both hosts. On the basis of the morphological characteristics, the fungus was identified as Didymella bryoniae (Auersw.) Rehm (anamorph Phoma cucurbitacearum (Fr.:Fr.) Sacc.) (1,3) and this was confirmed by amplification of species-specific PCR products. The isolates from both hosts were cultured in liquid medium, and DNA was extracted using a DNeasy Plant Mini Kit (Qiagen, Valencia, CA). PCR and multiplex PCR involving D. bryoniae-unique primer sequences D6 and D7S, in combination with primer UNLO28S22, produced the expected band sizes (2). To our knowledge, this is the first report of gummy stem blight and black fruit rot of watermelon caused by D. bryoniae in Tanzania, which confirms a previous report of leaf spot on pumpkin (4), and the first report of black fruit rot on pumpkin. The disease was previously an unidentified problem in watermelon and the severe outbreak was associated with favorable weather conditions. References: (1) A. P. Keinath et al. Phytopathology 85:364, 1995. (2) C. A. Koch and R. S. Utkhede. Can. J. Plant Pathol. 26:291, 2004. (3) E. Punithalingam and P. Holliday. No. 332 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1972. (4) E. A. Riley. Mycol. Pap. 75:1, 1960.

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First Report of Anthracnose Caused by Colletotrichum liaoningense on Trichosanthes kirilowii in China

Plant Disease ◽

10.1094/pdis-07-21-1363-pdn ◽

2021 ◽

Author(s):

Lixin Zhang ◽

Yifan Lin ◽

Lei Zhang ◽

Xia Wang ◽

Jianghua Song

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Culture Collection ◽

Central China ◽

Fruit Rot ◽

First Report ◽

Plastic Bags ◽

Fruit Samples ◽

Pathogenicity Tests ◽

Trichosanthes Kirilowii

Trichosanthes kirilowii Maxim (T. kirilowii) is widely grown in central China for its medicinal and edible value. In August 2020, an anthracnose-like disease was observed on fruit of T. kirilowii (cv. Wanlou9) in four fields (0.9 ha) located in Taihu county, Anhui Province of China. Approximately 60% of the T. kirilowii plants were affected in the fields. The symptoms initially consisted of small off-white necrotic spots, and later became larger, irregular gray necrotic lesions on green fruit, causing fruit rot and sometimes fruit drop. More than 10 symptomatic fruits were sampled, and small pieces of diseased tissue were surface sterilized in 0.1% HgCl2 for 2 min, 75% ethanol for 45 s, rinsed three times with sterile distilled water, then placed on potato dextrose agar (PDA) and incubated at 25℃in the dark. A fungus was consistently (80%) isolated from symptomatic fruit samples. Aerial mycelia were light gray, and radially black with white in reverse medium. Conidia were rarely produced on PDA, but prolific on water agar. The conidia were cylindrical to clavate, both ends rounded, had obvious circular granule in the center, and ranged from 14.6 to 19.9 μm × 5.4 to 7.3 μm. The morphological characteristics were similar to the descriptions of C. liaoningense by Diao et al. (2017). For molecular identification, representative isolates LG5-4 and LG9-6 were selected. Genomic DNA was extracted, and the internal transcribed spacer (ITS) region, actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-tubulin (TUB2) genes were amplified by PCR (White et al. 1990; Duan et al. 2018), and sequenced bidirectionally. A BLAST search of GenBank revealed the ACT and TUB sequences had 95.83% (KP890097), 99.20%, 95.33% (KP890111) and 99.84%, respectively, to C. liaoningense CAUOS2. A phylogenetic analysis was conducted using MEGA7 based on concatenated sequences of the four genes, indicating that the isolates were closely clustered with reference strains of C. liaoningense (98% bootstrap value). The two strains were deposited in the China General Microbiological Culture Collection Center as CGMCC3.20344 and CGMCC3.20345, and their sequences deposited in GeneBank (Accession nos. MW082811-12, MW117926-31), respectively. Pathogenicity tests were conducted on healthy fruit of T. kirilowii (cv. Wanlou9) using the wound inoculation by pinpricking and droplet (106 conidia/mL) on fruit surface. The experiments were done with three fruit per isolate (LG5-4 and LG9-6), and replicated three times. The controls were inoculated with sterile water. The fruit were covered with plastic bags and kept in a chamber (>90% RH, 28 to 30°C) for 14 days. Typical symptoms of yellow-brown lesions appeared 14 days after inoculation. No symptoms were observed on the controls. The fungus was re-isolated from the diseased tissues and identified as C. liaoningense by sequencing of the four genes, confirming Koch’s postulates. C. liaoningense has been reported to cause anthracnose of mango and chili in China (Diao et al. 2017; Li et al. 2019). To our knowledge, this is the first report of C. liaoningense causing anthracnose on T. kirilowii. Due to cultivation of T. kirilowii in the region, further studies are required to develop management strategy of this disease.

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Biocontrol potential of Streptomyces sp. CACIS-1.5CA against phytopathogenic fungi causing postharvest fruit diseases

Egyptian Journal of Biological Pest Control ◽

10.1186/s41938-020-00319-9 ◽

2020 ◽

Vol 30 (1) ◽

Author(s):

Zahaed Evangelista-Martínez ◽

Erika Anahí Contreras-Leal ◽

Luis Fernando Corona-Pedraza ◽

Élida Gastélum-Martínez

Keyword(s):

Pathogenic Fungi ◽

Phytopathogenic Fungi ◽

Antagonistic Activity ◽

Fruit Rot ◽

Main Body ◽

Type I ◽

Tropical Fruit ◽

Habanero Pepper ◽

Antagonistic Microorganisms

Abstract Background Fungi are one of the microorganisms that cause most damage to fruits worldwide, affecting their quality and consumption. Chemical controls with pesticides are used to diminish postharvest losses of fruits. However, biological control with microorganisms or natural compounds is an increasing alternative to protect fruits and vegetables. In this study, the antifungal effect of Streptomyces sp. CACIS-1.5CA on phytopathogenic fungi that cause postharvest tropical fruit rot was investigated. Main body Antagonistic activity was evaluated in vitro by the dual confrontation over fungal isolates obtained from grape, mango, tomato, habanero pepper, papaya, sweet orange, and banana. The results showed that antagonistic activity of the isolate CACIS-1.5CA was similar to the commercial strain Streptomyces lydicus WYEC 108 against the pathogenic fungi Colletotrichum sp., Alternaria sp., Aspergillus sp., Botrytis sp., Rhizoctonia sp., and Rhizopus sp. with percentages ranging from 30 to 63%. The bioactive extract obtained from CACIS-1.5 showed a strong inhibition of fungal spore germination, with percentages ranging from 92 to 100%. Morphological effects as irregular membrane border, deformation, shrinkage, and collapsed conidia were observed on the conidia. Molecularly, the biosynthetic clusters of genes for the polyketide synthase (PKS) type I, PKS type II, and NRPS were detected in the genome of Streptomyces sp. CACIS-1.5CA. Conclusions This study presented a novel Streptomyces strain as a natural alternative to the use of synthetic fungicides or other commercial products having antagonistic microorganisms that were used in the postharvest control of phytopathogenic fungi affecting fruits.

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Characterizing CMN1308, a Novel Strain of Bacillus amyloliquefaciens, for Potential Biological Control Application

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha44110054 ◽

2016 ◽

Vol 44 (1) ◽

pp. 60-66

Author(s):

Xuehua ZHANG ◽

Linling LI ◽

Shuiyuan CHENG ◽

Hua CHENG

Keyword(s):

Biological Control ◽

Antimicrobial Activity ◽

Bacillus Amyloliquefaciens ◽

Spatial Competition ◽

Pathogenic Fungi ◽

Cryphonectria Parasitica ◽

Fruit Rot ◽

Penicillium Expansum ◽

Antibiotic Compounds ◽

Plant Disease Management

Fungal diseases of plants continue to contribute to heavy crop losses in spite of the best control efforts of plant pathologists. Breeding for disease-resistant varieties and the application of synthetic chemical fungicides are the most widely accepted approaches in plant disease management. CMN1308 strain of Bacillus amyloliquefaciens was isolated from healthy Chinese chestnut fruit, which has antibiosis and induced resistance to the prevention mechanism of pathogenic bacterium after picking. In order to evaluate the antibiosis mechanism, CMN1308 was fostered with the method of confrontÂ culture. The antimicrobial components were also isolated from the culture of CMN1308, and their stability and antimicrobial activity was tested under different treatments such as temperature, pH and UV. The results showed that CMN1308 displays advantages in regard to spatial competition against the major pathogens of chestnut, Rhizopus stolonifer, Fusarium solani, Stachybotrys chartarum, Cryphonectria parasitica, Lasiodiplodia theobromae, Penicillium expansum and Aspergillus niger. Among this, CMN1308 had the best antimicrobial activity against P. expansum, with the inhibitionÂ zoneÂ diameter ofÂ 27.1 mm. The antimicrobial material isolated from CMN1308 culture showed a strong inhibition to the growth of P. expansum hyphal and also had a good stability to high temperature, alkali media and UV, but was sensitive to acidic conditions. Furthermore, CMN1308 increased the peroxidase, polyphenol oxidase activity and reduced the MDA content in chestnuts after infecting by pathogenic fungi. Thus, producing antibiotic compounds and inducible resistance are the main factors that may explain the antibacterial mechanism of CMN1308 on chestnut pathogenic. The results of this study might help to optimize the practical use of CMN1308 in the biological control of chestnut rot or other fruit rot infected by pathogenic fungi.

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First Report of Stigmina palmivora Causing Leaf Spots on Phoenix roebelenii in Brazil

Plant Disease ◽

10.1094/pdis-10-13-1030-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 849-849 ◽

Cited By ~ 1

Author(s):

A. Colmán ◽

R. A. da Silva ◽

R. Alves ◽

M. Silva ◽

R. W. Barreto

Keyword(s):

Pure Culture ◽

Leaf Surface ◽

The United States ◽

Culture Collection ◽

Commonwealth Mycological Institute ◽

First Report ◽

Leaf Spots ◽

Nucleotide Homology ◽

Query Coverage ◽

Representative Samples

Phoenix roebelenii (Arecaceae), known as dwarf date (tamareira-anã in Brazil), is a palm native to Southeast Asia and widely cultivated worldwide because of its ornamental value and ease of adaptation to a broad range of climates and soil types (4). In June 2012, some individuals were observed in a private garden in the municipality of Viçosa (state of Minas Gerais, Brazil) bearing numerous necrotic lesions on its leaves. Representative samples were taken, dried in a plant press, and brought to the laboratory for examination. A fungus was regularly associated with the leaf spots. Fungal structures were mounted in lactophenol and slides were examined under a microscope (Olympus BX 51). Spores were taken from sporulating colonies with a sterile fine needle and plated on PDA for isolation. A pure culture was deposited in the culture collection of the Universidade Federal de Viçosa (accession COAD1338). A dried herbarium sample was deposited in the local herbarium (VIC39741). The fungus had the following morphology: conidiophores grouped on sporodochia, cylindrical, 12 to 29 × 5 to 6 μm, dark brown; conidiogenous cells, terminal, proliferating percurrently (annellidic), 8 to 20 × 5 to 6 μm, pale to dark brown; conidia obclavate to subcylindrical, straight, 58 to 147 × 5 to 6 μm, 6 to 16 septate, hila thickened and darkened with a thin-walled projecting papilla, dark brown, and verrucose. The morphology of the Brazilian collections agrees well with the description of Stigmina palmivora (2), a species known to cause leaf spots on P. roebelenii in the United States (Florida) and Japan (3). Pathogenicity was demonstrated through inoculation of leaves of healthy plants by placing 6 mm diameter cuture disks of COAD1338 on the leaf surface followed by incubation in a moist chamber for 48 h and then transferred to a greenhouse bench at 21 ± 3°C. Typical leaf spots were observed 15 days after inoculation. DNA was extracted from the isolate growing in pure culture and ITS and LSU sequences were generated and deposited in GenBank under the accession numbers KF656785 and KF656786, respectively. These were compared by BLASTn with other entries in GenBank, and the closest match for each region were Mycosphaerella colombiensis strain X215 and M. irregulariamosa strain CPC 1362 (EU514231, GU2114441) with 93% of nucleotide homology (over 100% query coverage) for ITS and 98% of nucleotide homology (over 100% query coverage) for LSU. There are no sequences for S. palmivora deposited in public databases for comparison, but for Stigmina platani, the type species in this genus, 86% and 96% nucleotide homology for ITS and LSU with S. palmivora were found. The genus Stigmina is regarded as being polyphyletic (1) and this is probably reflected by these low homology levels found in the BLASTn search. To our knowledge, this is the first report of Stigmina palmivora in Brazil. References: (1) P. W. Crous et al. Stud. Mycol. 75:37, 2012. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, UK, 1971. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab. ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 2013. (4) H. Lorenzi et al. Palmeira no Brasil: Exóticas e Nativas, 2nd ed. Editora Plantarum, Nova Odessa, Brazil, 2005.

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First Report of Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽

10.1094/pdis-09-11-0813 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287

Author(s):

K. S. Han ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

United States ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

First Report ◽

Cornell University ◽

Plastic Bags ◽

Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

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