First Report of Phomopsis Fruit Rot of Strawberry in Ohio

During spring (May and June) 1999, ≈30% of the fruit in a 0.5-ha commercial planting of strawberry (Fragaria × ananassa ‘Allstar’) was lost to an unknown fruit rot. The planting was established on black plastic (plasticulture) during summer 1998. Plasticulture is a relatively new system of perennial strawberry production in Ohio that is rapidly gaining popularity among growers (2). It was observed that the plastic beneath the plants in the plasticulture planting was covered with a layer of dead leaves from the previous season's growth, and virtually all rotted fruits were in contact with dead leaves. Fruit rot was rarely observed on fruits that were not in direct contact with dead leaves, and fruits of the same cultivar grown in the traditional matted-row system in an adjacent field did not show rot symptoms. It was postulated that infested dead leaf material could serve as an inoculum source for infection. Fruit rot symptoms were identical to those described for Phomopsis soft rot (1). Isolations were made from infected berries. Berries were soaked in 70% ethanol for 60 s, and tissue sections were placed on potato dextrose agar and incubated at room temperature (≈20 to 22°C). A fungus was isolated consistently from infected tissue. The fungus produced pycnidia in culture, and the fruiting structure and conidia conformed to the description of Phomopsis obscurans (Ellis & Everh.) Sutton (synamorph Dendrophoma obscurans (Ellis & Everh.) H.W. Anderson). Pathogenicity studies were conducted by placing one drop (20 μl) of a conidial suspension (9 × 106 conidia per ml) obtained from 2-week-old cultures on each of five ripe (red) and five immature (pink) detached strawberry fruits. Inoculated fruits were placed on screens in plastic moisture chambers. Five uninoculated fruits served as controls. Within 3 days, whitish lesions appeared on all inoculated fruit; within 8 days, the symptoms observed in the field were reproduced, and lesions were covered by pycnidia. No fruit rot developed on control fruit. The fungus was reisolated from infected fruit to complete Koch's postulates. Although the incidence of Phomopsis leaf blight is increasing in many Ohio strawberry plantings and is becoming a concern to growers, this is the first observation and report of Phomopsis fruit rot in Ohio. Unlike leaf blight, for which it is difficult to directly relate economic loss to disease incidence or severity, losses due to fruit rot can be high, as in this field. As the number of strawberry plantings under plasticulture continues to increase, the importance of Phomopsis leaf blight and fruit rot also may increase. References: (1) J. L. Maas, ed. 1998. Compendium of Strawberry Diseases, 2nd ed. The American Phytopathological Society, St. Paul, MN. (2) E. B. Poling. HortTechnology 3:384, 1993.

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First Report of Leaf Blight on Duying Caused by Phyllosticta anacardiacearum in China

Plant Disease ◽

10.1094/pdis-93-5-0546b ◽

2009 ◽

Vol 93 (5) ◽

pp. 546-546 ◽

Cited By ~ 2

Author(s):

B. G. Lou ◽

Y. D. Xu ◽

C. Sun ◽

X. M. Lou

Keyword(s):

Southern China ◽

Disease Incidence ◽

Its Region ◽

Culture Collection ◽

Leaf Blight ◽

Its Sequences ◽

Dead Leaf ◽

Conidial Suspension ◽

First Report ◽

Branch Dieback

Duying (Elaeocarpus glabripetalus Merr.; Elaeocarpaceae) is widely cultivated as an ornamental tree of commercial importance in southern China. From 2003 to 2008, severe outbreaks of Duying leaf blight occurred in the Hangzhou area, Zhejiang Province. Disease incidence was greater than 20% and mainly infected young leaves and shoots in the spring and autumn. Severely infected leaves and shoots died and eventually led to branch dieback. The overall growth decline of affected trees occurs over 4 to 6 years before tree death. Infection symptoms are characterized by grayish, round, semicircular- or irregular-shaped spots (5 mm to 5 cm long) with dark brown borders and the appearance of black, granular pycnidia within the dead leaf tissues. The primary infection zones are commonly observed on the leaf margins and apices, are brown, up to 2 mm in diameter, and often surrounded by a yellow zone. Pycnidia were globose and 122 to 127 μm (average 123.5 μm) in diameter. A fungus was consistently isolated from symptomatic tissues on potato dextrose agar (PDA). Ash-black pycnidia appeared on PDA after 10 days. Ascospores developed on modified PDA (1 liter of PDA + 20 g of Duying leaves) after 18 days. Conidiogenous cells were cylindrical to obpyriform. The hyaline conidia were obovoid and guttulate, 10 to 13 × 6 to 8 μm (average 11.5 × 7.5 μm), and usually surrounded by a mucilaginous sheath with a hyaline apical appendage that was 5 to 8 μm long. Pseudothecia were solitary and subglobose with long necks. Asci were 45 to 70 × 7.5 to 12 μm (average 62.5 × 10.8 μm). Ascospores were 12 to 13 × 4 to 5 μm with rounded apices and hyaline, mucilaginous, apical caps. The fungus was morphologically identified as Phyllosticta anacardiacearum van der Aa (teleomorph Guignardia mangiferae A. J. Roy). This identification was also confirmed by the China General Microbiological Culture Collection Center (CGMCC). Six representative fungal isolates were identified by sequencing the internal transcribed spacer (ITS) region of the rDNA and comparing the sequences with those in GenBank using BLAST searches. The ITS sequences of six cultures (GenBank Accession Nos. EU821356–EU821361) showed 100% identity with the ITS sequences of an isolate of a Phyllosticta sp. (GenBank Accession No. AF532314) (2) and G. mangiferae (GenBank Accession No. AY277717) (1). To fulfill Koch's postulates, a conidial suspension (106 conidia per ml) collected from PDA cultures (isolate phy01) was used to spray inoculate leaves of potted 3-year-old Duying trees. Inoculated trees were kept for 48 h under a polyethylene sheet cover and grown at 10 to 15°C in a greenhouse. A total of 30 leaves of five healthy trees were inoculated with the pathogen. In addition, five 3-year-old trees were sprayed with sterile water to serve as uninoculated controls. After 10 to 14 days, inoculated leaves showed infection symptoms resembling those observed on Duying trees naturally infected with P. anacardiacearum. The pathogen was reisolated from the margins of necrotic tissues, but not from controls. To our knowledge, this is the first report of leaf blight on E. glabripetalus caused by P. anacardiacearum in China. Reference: (1) F. R. Katia et al. Mycol. Res. 108:45, 2004. (2) A. K. Pandey et al. Mycol. Res. 107:439, 2003.

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First report of Alternaria alternata causing leaf blight on little millet (Panicum sumatrense) in India.

Plant Disease ◽

10.1094/pdis-06-20-1373-pdn ◽

2020 ◽

Author(s):

Boda Praveen ◽

A. Nagaraja ◽

M. K. Prasanna Kumar ◽

Devanna Pramesh ◽

K. B. Palanna ◽

...

Keyword(s):

Crop Yields ◽

Disease Incidence ◽

Leaf Blight ◽

Post Inoculation ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Pcr Assay ◽

Causal Organism ◽

First Report ◽

Little Millet

Little millet (LM) is a minor cereal crop grown in the Indian sub-continent. During October 2018, dark brown, circular to oval necrotic spots surrounded by concentric rings were observed on the upper leaf surface of the LM (cv. VS-13) grown in the fields of the University of Agricultural Sciences, Bengaluru, India (13.0784oN, 77.5793oE). As the disease progressed, infected leaves became blighted. Disease incidence up to 53% was recorded in 3 fields of 0.4-hectare area each. Thirty symptomatic leaves were collected to isolate the associated causal organism. The margins of diseased tissue were cut into 5 × 5-mm pieces, surface-sterilized in 75% ethanol for 45 seconds followed by 1% sodium hypochlorite for 1 min, finally rinsed in sterile distilled water five times and placed on PDA. After 7 days of incubation at 25°C, greyish fungal colonies appeared on PDA. Single-spore isolations were performed to obtain ten isolates. Pure cultures of the fungus initially produced light gray aerial mycelia that later turned to dark grey. All isolates formed obclavate to pyriform conidia measured 22.66-48.97μm long and 6.55-13.79µm wide with 1-3 longitudinal and 2-7 transverse septa with a short beak (2.55-13.26µm) (n=50). Based on the conidial morphology, the fungus was identified as Alternaria sp. Further, the taxonomic identity of all ten isolates was confirmed as A. alternata using species-specific primers (AAF2/AAR3, Konstantinova et al. 2002) in a PCR assay. Later, one of the isolate UASB1 was selected, and its internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh), major allergen Alt a 1 (Alt a 1), major endo-polygalacturonase (endoPG), OPA10-2, and KOG1058 genes were amplified in PCR (White et al. 1990; Berbee et al. 1999; Woudenberg et al. 2015), and the resultant products were sequenced and deposited in the NCBI GenBank (ITS, MN919390; gapdh, MT637185; Alt a 1, MT882339; endoPG, MT882340; OPA10-2, MT882341; KOG1058, MT882342). Blastn analysis of ITS, gapdh, Alt a 1, endoPG, OPA10-2, KOG1058 gene sequences showed 99.62% (with AF347031), 97.36% (with AY278808), 99.58% (with AY563301), 99.10% (with JQ811978), 99.05% (with KP124632) and 99.23% (with KP125233) respectively, identity with reference strain CBS916.96 of A. alternata, confirming UASB1 isolate to be A. alternata. For pathogenicity assay, conidial suspension of UASB1 isolate was spray inoculated to ten healthy LM (cv. VS-13) plants (45 days old) maintained under protected conditions. The spore suspension was sprayed until runoff on healthy leaves, and ten healthy plants sprayed with sterile water served as controls. Later, all inoculated and control plants were covered with transparent polyethylene bags and were maintained in a greenhouse at 28±2 ◦C and 90% RH. The pathogenicity test was repeated three times. After 8 days post-inoculation, inoculated plants showed leaf blight symptoms as observed in the field, whereas no disease symptoms were observed on non-inoculated plants. Re-isolations were performed from inoculated plants, and the re-isolated pathogen was confirmed as A. alternata based on morphological and PCR assay (Konstantinova et al. 2002). No pathogens were isolated from control plants. There is an increasing acreage of LM crop in India, and this first report indicates the need for further studies on leaf blight management and the disease impacts on crop yields.

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First Report of Leaf Blight Caused by Septoria allii on Garlic Chives in Korea

Plant Disease ◽

10.1094/pdis-08-12-0809-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 147-147

Author(s):

J. H. Park ◽

S. E. Cho ◽

K. S. Han ◽

H. D. Shin

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Leaf Blight ◽

Plant Diseases ◽

Cultivated Plants ◽

Sequence Information ◽

Conidial Suspension ◽

Korean Society ◽

First Report

Garlic chives, Allium tuberosum Roth., are widely cultivated in Asia and are the fourth most important Allium crop in Korea. In June 2011, a leaf blight of garlic chives associated with a Septoria spp. was observed on an organic farm in Hongcheon County, Korea. Similar symptoms were also found in fields within Samcheok City and Yangku County of Korea during the 2011 and 2012 seasons. Disease incidence (percentage of plants affected) was 5 to 10% in organic farms surveyed. Diseased voucher specimens (n = 5) were deposited at the Korea University Herbarium (KUS). The disease first appeared as yellowish specks on leaves, expanding to cause a leaf tip dieback. Half of the leaves may be diseased within a week, especially during wet weather. Pycnidia were directly observed in leaf lesions. Pycnidia were amphigenous, but mostly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, separate, unilocular, 50 to 150 μm in diameter, with ostioles of 20 to 40 μm in diameter. Conidia were acicular, straight to sub-straight, truncate at the base, obtuse at the apex, hyaline, aguttulate, 22 to 44 × 1.8 to 3 μm, mostly 3-septate, occasionally 1- or 2-septate. These morphological characteristics matched those of Septoria allii Moesz, which is differentiated from S. alliacea on conidial dimensions (50 to 60 μm long) (1,2). A monoconidial isolate was cultured on potato dextrose agar (PDA). Two isolates have been deposited in the Korean Agricultural Culture Collection (Accession Nos. KACC46119 and 46688). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequence of 482-bp was deposited in GenBank (JX531648 and JX531649). ITS sequence information was at least 99% similar to those of many Septoria species, however no information was available for S. allii. Pathogenicity was tested by spraying leaves of three potted young plants with a conidial suspension (2 × 105 conidia/ml), which was harvested from a 4-week-old culture on PDA. Control leaves were sprayed with sterile water. The plants were placed in humid chambers (relative humidity 100%) for the first 48 h. After 7 days, typical leaf blight symptoms started to develop on the leaves of inoculated plants. S. allii was reisolated from the lesions of inoculated plants, confirming Koch's postulates. No symptoms were observed on control plants. The host-parasite association of A. tuberosum and S. allii has been known only from China (1). S. alliacea has been recorded on several species of Allium, e.g. A. cepa, A. chinense, A. fistulosum, and A. tuberosum from Japan (4) and A. cepa from Korea (3). To the best of our knowledge, this is the first report of S. allii on garlic chives. No diseased plants were observed in commercial fields of garlic chives which involved regular application of fungicides. The disease therefore seems to be limited to organic garlic chive production. References: (1) P. K. Chi et al. Fungous Diseases on Cultivated Plants of Jilin Province, Science Press, Beijing, China, 1966. (2) P. A. Saccardo. Sylloge Fungorum Omnium Hucusque Congnitorum. XXV. Berlin, 1931. (3) The Korean Society of Plant Pathology. List of Plant Diseases in Korea, Suwon, Korea, 2009. (4) The Phytopathological Society of Japan. Common Names of Plant Diseases in Japan, Tokyo, Japan, 2000.

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First Report of a Leaf Blight of Onion Caused by Xanthomonas spp. in Georgia

Plant Disease ◽

10.1094/pdis.2003.87.6.749b ◽

2003 ◽

Vol 87 (6) ◽

pp. 749-749 ◽

Cited By ~ 11

Author(s):

F. H. Sanders ◽

D. B. Langston ◽

J. H. Brock ◽

R. D. Gitaitis ◽

D. E. Curry ◽

...

Keyword(s):

Disease Incidence ◽

Methyl Esters ◽

Economic Loss ◽

Leaf Blight ◽

Identification System ◽

Sterile Water ◽

Disease Symptoms ◽

First Report ◽

Microbial Identification ◽

Dry Conditions

In October of 2001 and 2002, a leaf blight was reported affecting Vidalia onion (Allium cepa) cvs. Pegasus and Sweet Vidalia, respectively, in one field each. Lesions on onion seedlings began as a water-soaked, tip dieback that gradually blighted the entire leaf. Symptoms on onion transplants appeared as elongated, water-soaked lesions that typically collapsed at the point of initial infection. In both cases, disease was very severe on seedlings, and disease incidence was 50% or more in both fields. Warm temperatures combined with overhead irrigation and above average rainfall likely enhanced the severity and spread of disease. Disease was not detected on more mature onions once cool, dry conditions occurred later in the season, and no significant economic loss occurred. Seed was tested from seed lots of the aforementioned cultivars and Xanthomonas spp. were not found. Diseased tissue was macerated in sterile, phosphate-buffered saline, and 10 μl of the resulting suspension was streaked on nutrient agar plates. Yellow-pigmented, gram-negative, rod-shaped bacteria were isolated routinely from diseased tissue. Bacteria were catalase-positive, cellulolytic, oxidase-negative, amylolytic, proteolytic, and utilized glucose in an oxidative manner. Analysis of whole cell, fatty acid methyl esters (FAME) using the Microbial Identification System (MIS, Sherlock version 3.1; MIDI, Inc., Newark, DE) identified four representative strains of the bacterium as a pathovar of Xanthomonas axonopodis (similarity indices 0.75 to 0.83). Known Xanthomonas spp. from onion from Colorado and Texas (1,2) had similar FAME profiles when analyzed by the MIDI system. Onion plants were grown under greenhouse conditions for 2 months and inoculated by injecting the base of a quill with 1.0 ml of bacterial suspensions (1 × 107 CFU ml-1) of the Xanthomonas sp. isolated from Georgia, and negative controls were inoculated with 1 ml of sterile water. Disease symptoms developed on plants inoculated with bacterial suspensions in 4 to 7 days and Xanthomonas sp. was isolated from the lesions produced. Disease symptoms occurred when the same suspension was sprayed on onion foliage. No symptoms occurred on plants inoculated with 1 ml of sterile water. To our knowledge, this is the first report of Xanthomonas spp. affecting Vidalia onions. References: (1) T. Isakeit et al. Plant Dis. 84:201, 2000. (2) H. F. Schwartz and K. Otto. Plant Dis. 84:922, 2000.

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First Report of Alternaria petroselini Causing Leaf Blight of Fennel in Spain

Plant Disease ◽

10.1094/pdis-01-12-0059-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 907-907 ◽

Cited By ~ 2

Author(s):

D. D. M. Bassimba ◽

J. L. Mira ◽

C. Baixauli ◽

A. Vicent

Keyword(s):

Disease Incidence ◽

Leaf Blight ◽

Conidial Suspension ◽

Morphological Examination ◽

Foeniculum Vulgare ◽

Medicinal Uses ◽

First Report ◽

Plastic Bags ◽

Water Plants ◽

Production Areas

Fennel (Foeniculum vulgare Mill.) is an aromatic herb widely cultivated in Mediterranean areas for culinary and medicinal uses. In 2010, symptoms consisting of leaf blight and necrosis were observed in commercial organic fennel production areas in Valencia Province in east-central Spain. Disease incidence in affected fields was approximately 20%. Symptomatic leaves from four fields were surface disinfected with 0.5% NaOCl for 2 min, and small fragments from necrotic lesions were then plated on potato dextrose agar (PDA) amended with 0.5 g of streptomycin sulfate/liter. After 7 days at 25°C, isolates of the genus Alternaria were consistently isolated. Single conidium cultures were grown on PDA and V8 agar for morphological examination. On both agar media, colonies were dark olive brown without production of pigments. On V8 agar, conidia were solitary, darkly pigmented, and predominantly ovoid-subsphaeroid. Mature conidia were 25 to 59 × 12 to 23 μm with up to six to seven transepta and one to three longisepta. The 5.8S, ITS2, and 28S ribosomal RNA (rRNA) regions were amplified with the primers ITS3 and ITS4 (3) from DNA extracted from the isolate IVIA-A029, and sequenced (GenBank Accession No. JQ240204). The sequence had 100% identity (total score 399, 97% coverage) with that of Alternaria petroselini (Neergard) Simmons strain EGS 09-159 (GenBank Accession No. AF229454.1) (1). Pathogenicity tests were conducted on four 3-month-old fennel plants (cv. Giotto) by spraying a conidial suspension of the fungus (10 ml/plant, 103 conidia/ml of water). Four control plants were sprayed with sterile, distilled water. Plants were covered with plastic bags and incubated in a growth chamber for 72 h at 25°C. Leaf necrosis was visible on inoculated plants after 4 days, but symptoms were not observed on control plants. The fungus was reisolated from leaf lesions on inoculated plants, but not from leaves of control plants, confirming Koch's postulates. On the basis of the morphological (2), molecular, and pathogenicity data, the disease was identified as Alternaria leaf blight of fennel caused by A. petroselini. To our knowledge, this is the first report of A. petroselini in Spain. References: (1) B. M. Pryor and R. L. Gilbertson. Mycol. Res. 104:1312, 2000. (2) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007. (3) T. J. White et al. Pages 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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First Report of Leaf Blight on Parthenium hysterophorus Caused by Nigrospora sphaerica in Malaysia

Plant Disease ◽

10.1094/pdis-02-21-0411-pdn ◽

2021 ◽

Author(s):

Azim Syahmi Zafri ◽

Rita Muhamad ◽

Aswad Wahab ◽

Anis Syahirah Mokhtar ◽

Erneeza Mohd Hata

Keyword(s):

Disease Incidence ◽

Leaf Blight ◽

Parthenium Hysterophorus ◽

Morphological Identification ◽

Distilled Water ◽

Conidial Suspension ◽

Accession Number ◽

First Report ◽

Weed Host ◽

Parthenium Weed

Weeds may act as inoculum reservoirs for fungal pathogens that could affect other economically important crops (Karimi et al. 2019). In February 2019, leaves of the ubiquitous invasive weed, Parthenium hysterophorus L. (parthenium weed) exhibiting symptom of blight were observed at Ladang Infoternak Sg. Siput (U), a state–owned livestock center in Perak, Malaysia. Symptoms appeared as irregularly shaped, brown–to–black necrotic lesions across the entire leaf visible from both surfaces, and frequently on the older leaves. The disease incidence was approximately 30% of 1,000 plants. Twenty symptomatic parthenium weed leaves were collected from several infested livestock feeding plots for pathogen isolation. The infected tissues were sectioned and surface–sterilized with 70% ethyl alcohol for 1 min, rinsed three times with sterile distilled water, transferred onto potato dextrose agar, and incubated at 25°C under continuous dark for 7 days. Microscopic observation revealed fungal colonies with similar characteristics. Mycelium was initially white and gradually changed to pale orange on the back of the plate but later turned black as sporulation began. Conidia were spherical or sub–spherical, single–celled, smooth–walled, 12 to 21 μm diameter (mean = 15.56 ± 0.42 μm, n= 30) and were borne on a hyaline vesicle. Based on morphological features, the fungus was preliminarily identified as Nigrospora sphaerica (Sacc) E. W. Mason (Wang et al. 2017). To confirm identity, molecular identification was conducted using isolate 1SS which was selected as a representative isolate from the 20 isolates obtained. Genomic DNA was extracted from mycelia using a SDS–based extraction method (Xia et al. 2019). Amplification of the rDNA internal transcribed spacer (ITS) region was conducted with universal primer ITS1/ITS4 (White et al. 1990; Úrbez–Torres et al. 2008). The amplicon served as a template for Sanger sequencing conducted at a commercial service provider (Apical Scientific, Malaysia). The generated sequence trace data was analyzed with BioEdit v7.2. From BLASTn analysis, the ITS sequence (GenBank accession number. MN339998) had at least 99% nucleotide identity to that of N. sphaerica (GenBank accession number. MK108917). Pathogenicity was confirmed by spraying the leaf surfaces of 12 healthy parthenium weed plants (2–months–old) with a conidial suspension (106 conidia per ml) collected from a 7 day–old culture. Another 12 plants served as a control treatment and received only sterile distilled water. Inoculation was done 2 h before sunset and the inoculated plants were covered with plastic bags for 24 h to promote conidial germination. All plants were maintained in a glasshouse (24 to 35°C) for the development of the disease. After 7 days, typical leaf blight symptoms developed on the inoculated plants consistent with the symptoms observed in the field. The pathogen was re–isolated from the diseased leaves and morphological identification revealed the same characteristics as the original isolate with 100% re–isolation frequency, thus, fulfilling Koch’s postulates. All leaves of the control plants remained symptomless and the experiment was repeated twice. In Malaysia, the incidence of N. sphaerica as a plant pathogen has been recorded on several important crops such as watermelon and dragon fruit (Kee et al. 2019; Ismail and Abd Razak 2021). To our knowledge, this is the first report of leaf blight on P. hysterophorus caused by N. sphaerica from this country. This report justifies the significant potential of P. hysterophorus as an alternative weed host for the distribution of N. sphaerica. Acknowledgement This research was funded by Universiti Putra Malaysia (UPM/GP–IPB/2017/9523402). References Ismail, S. I., and Abd Razak, N. F. 2021. Plant Dis. 105:488. Karimi, K., et al. 2019. Front Microbiol. 10:19. Kee, Y. J., et al. 2019. Crop Prot. 122:165. Úrbez–Torres, J. R., et al. 2008. Plant Dis. 92:519. Wang, M., et al. 2017. Persoonia 39:118. White, T. J. et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Xia, Y., et al. 2019. Biosci Rep. 39:BSR20182271.

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First Report of Botrytis Leaf Blight and Fruit Rot on Schisandra chinensis Caused by Botrytis cinerea in China

Plant Disease ◽

10.1094/pdis-02-11-0086 ◽

2011 ◽

Vol 95 (6) ◽

pp. 769-769

Author(s):

R. H. Yu ◽

J. Gao ◽

J. Wang ◽

X. Wang

Keyword(s):

Botrytis Cinerea ◽

Morphological Characteristics ◽

Gray Mold ◽

Leaf Blight ◽

Jilin Province ◽

Fruit Rot ◽

Conidial Suspension ◽

Schisandra Chinensis ◽

Mycelium Growth ◽

First Report

Schisandra (Schisandra chinensis (Turcz.) Baill) is a perennial plant belonging to Magnoliaceae. It is a very important medicinal herb in China and is mainly used for treatment of insomnia and memory decay. From July to September 2008, an unknown leaf blight and fruit rot on schisandra were first observed at Jingyu County, Jilin Province. The same symptoms were detected in other areas of Jilin Province, such as Ji'an City, Baishan City, and Hunchun City. Initially, some small, brown spots appeared on the tip or margin of the leaves. Light brown or brown necrotic lesions developed and eventually covered entire leaves. Seriously affected leaves were rolled or distorted and eventually became completely dry and brittle. Small spots appeared on the surface of mature fruits, coalesced, and the fruits finally dropped. Gray mycelia and conidiophores developed on the diseased leaves and fruits. To isolate the causal agent, conidia and conidiophores were scraped aseptically from the internal tissues, suspended in sterile water, and streaked onto the surface of potato dextrose agar (PDA). Single-hyphal tips were transferred on PDA and the isolated fungus was identified as Botrytis cinerea Pers.: Fr. on the basis of its morphological characteristics and internal transcribed spacer (ITS) sequence. Colonies of B. cinerea on PDA were colorless at first and became gray to brown 20 days later with the mycelium growth and conidia producing in cultures. Conidia are single celled, lemon shaped, colorless to a light color, and 4.4 to 15.0 × 7.0 to 10.0 μm. Sclerotia formed about 1 week later, were black-brown and varied in size (2.0 to 5.0 × 2.0 to 4.0 mm) and shape. The ITS region of rDNA was amplified from DNA extracted from single-spore isolate BC12 of B. cinerea using primers ITS4/ITS5 and sequenced (GenBank Accession No. GU724512), BLAST analysis (1) of the 535-bp segment showed 99% similarity with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). Pathogenicity tests were carried out on healthy schisandra plants that were 4 years old. After the surface of the leaves and fruits was disinfected with 5% sodium hypochlorite, a conidial suspension of 105 conidia/ml was sprayed on 10 schisandra leaves, and plugs of the fungus obtained from the colony margins were transferred onto a 3- × 3-mm wound on the surface of disinfected fruit. Ten control schisandra leaves and 10 fruits were inoculated at the same time. Plants were covered with polyethylene bags and incubated at 25°C in a greenhouse with relative humidity of 85% for 3 days. Similar symptoms to those observed on diseased leaves and fruits in the field were observed on inoculated schisandra leaves and fruits 7 days after inoculation, whereas control leaves and fruits showed no symptoms. The pathogen was successfully reisolated. The gray mold disease caused by B. cinerea was reported in many plants, such as Lavandula stoechas and Chamelaucium uncinatum in Italy (2,3). However, to our knowledge, this is the first report of gray mold disease of schisandra caused by B. cinerea in China. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) A. Garibaldi et al. Plant Dis. 94:968, 2009. (3) A. Garibaldi et al. Plant Dis. 94:380, 2010.

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First Report of Fruit Rot of Grapes (Vitis vinifera) Caused by Cladosporium cladosporioides in Xinjiang, China

Plant Disease ◽

10.1094/pdis-01-21-0080-pdn ◽

2021 ◽

Author(s):

Zheng Liu ◽

Rui-Lian Jiao ◽

Si-Ying Chen ◽

Yuzhong Ren ◽

Li Zhang ◽

...

Keyword(s):

Vitis Vinifera ◽

Disease Incidence ◽

Evolutionary Relationship ◽

Light Condition ◽

Cladosporium Cladosporioides ◽

Fruit Rot ◽

Common Disease ◽

Conidial Suspension ◽

Grape Quality ◽

Pcr Targeting

Xinjiang Province accounts for nearly 20% of the total grape (Vitis Vinifera L.), proles orientalis) (wine, table and raisin combined) production, being the largest production area in China. Fruit rot is the most common disease that impacts grape quality and yield. A new disease where the ripe grape berry surfaces were coated with brownish mildew was observed, and the disease mainly occurred on whole clusters or most of the berries in the cluster. In September 2019 and 2020, 125 diseased grape clusters were collected from 10 locations in northern Xinjiang where the disease incidence was 15.3% − 27.4% ((diseased clusters/ total clusters)*100). To identify the pathogen, symptomatic grape berries were disinfected with 1% NaClO for 2 min, followed by 70% ethanol for 30 s, and rinsed thrice in sterile distilled water. Three pieces of ~0.5 cm2 diseased grape skin with partial exocarp were placed on potato dextrose agar (PDA) amended with streptomycin sulfate and kanamycin (50 µg/mL each). The PDA plates were then incubated at 25℃ under light condition with the luminous intensity 3500 Lux for 7 days. Fungal colonies emerging from the plated tissue were subcultured and single-spored three times to obtain pure cultures. From 20 strains with similar colony phenotype and grey olive hue, flocculent, felt-like surface, six (Cc-Vivi-3, 7, 9, 11, 13 and 19) isolates were chosen for further characterization after 7 days of incubation. Conidia were either single or grew in chains, with around 4 conidia per chain. Conidia were ovoid, nearly spindle or globose with slightly smooth or irregular reticulate surface. Conidiophores were solitary, smooth, septate, erect or geniculate. These characteristics were consistent with the descriptions for Cladosporium cladosporioides. To confirm this identification, PCR was performed on the genomic DNA of the selected strains using primers for internal transcribed spacer (ITS) region ITS1/ITS4, actin (ACT) and translation elongation factor (TEF) (Schubert et al., 2007; Braun et al., 2003). Amplified ITS sequences provided a 100% match to C. cladosporioides (AY213641) in NCBI. Homology of ACT sequences to C. cladosporioides (HM148527 and MH047330) was 99.57% and 100%, respectively; and the homology of TEF sequences with C. cladosporioides (HM148258, HM148289, HM148260 and HM148266) was 97.56% ~ 100%. To further confirm the evolutionary relationship of strains from grapes with Cladosporium spp., phylogenetic analyses based on ITS, ACT and TEF conjoint sequences from the six experimental isolates, five C. cladosporioides strains, eight proximal Cladosporium species were analyzed. The phylogenetic tree showed that the six isolates from grapes clustered with C. cladosporioides strains, but not other proximal Cladosporium species. This confirmed that all six isolates evaluated were C. cladosporioides. Pathogenicity tests with one C. cladosporioides isolate (Cc-Vivi-3; accession No. ITS: MW556429, ACT: MW567144, TEF: MW567143) were carried out as follows: ripe and healthy grape clusters from cultivars Xinyu and Munag when total soluble solids were 20-21°Bx and 19-20 °Bx, respectively, were detached from the vines. Five berries of three clusters of each cultivar were punctured with a sterile syringe, then inoculated with a 20 μL conidial suspension (107 conidia/mL). And uninoculated, punctured berries in clusters treated with sterilized water served as controls. The experiment was repeated three times. Symptoms were recorded 15 days after incubation at 80% relative humidity and 25℃ with a 14 h light/10 h dark cycle. The olive green or blackish green mildew layer was produced on all inoculated berries. No symptoms were observed on the uninoculated berries. Koch’s postulates were fulfilled by reisolating C. cladosporioides from all symptomatic tissues and identifying them by PCR targeting the ACT gene. This is the first description of C. cladosporioides causing grape fruit rot in Xinjiang, China. In recent years, worldwide reports of Cladosporium spp. damaging crops are increasing (Briceño et al., 2008; Walker et al., 2016; Meneses et al., 2018; Robles-Yerena et al., 2019; Ding et al., 2019; Yang et al., 2021). However, relatively few methods of management including some fungicides and biocontrol agents are available in different crops (Wang et al., 2018; Addrah et al., 2019). In view of the important role of Xinjiang in China agricultural production, that should arouse strong attention.

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First Report of Nigrospora osmanthi causing leaf blight on Orthosiphon stamineus in Malaysia

Plant Disease ◽

10.1094/pdis-12-20-2668-pdn ◽

2021 ◽

Author(s):

Siti Izera Ismail ◽

Nida Athirah Mat Norzaki ◽

Mohammad Effendy Ya'acob ◽

Syari Jamian

Keyword(s):

Maximum Likelihood ◽

Type Strain ◽

Disease Incidence ◽

Leaf Blight ◽

Likelihood Method ◽

Herbaceous Plant ◽

Distilled Water ◽

Conidial Suspension ◽

Orthosiphon Stamineus ◽

Initial Symptoms

Orthosiphon stamineus (Java tea) is a perennial herbaceous plant in the family Lamiaceae and is cultivated extensively in Southeast Asia for its medicinal value (Arifullah et al. 2014). During October 2018, leaf blight symptoms were observed on leaves of ~210 plants O. stamineus grown in experimental plots of a research farm at Faculty of Engineering, Serdang, Selangor, Malaysia (3°00'30.4"N 101°43'19.9"E) with 80% disease incidence. Initial symptoms were brown-to-black lesions on the leaves that enlarged and coalesced until the leaf withered and abscissed. Diseased tissues (4 × 4 mm) of six infected leaves were excised, surface disinfected with 0.5% NaOCl for 1 min, rinsed twice with sterile distilled water, placed onto potato dextrose agar (PDA) plates, and incubated at 25°C with a 12-h photoperiod under fluorescent light for 7 days. A total of six single-spore isolates were obtained from sampled leaves. All isolates exhibited similar morphology and two representative isolates, MK and MK1, were characterized further. Colonies on PDA were initially white then turned dark gray with age and had a pale green underside. Hyphae were branched, septate and hyaline to pale brown. The conidia were one-celled, black, smooth-walled, spherical to subspherical in shape measuring 11.0 μm × 16.5 μm in diameter (n=30) and which are borne on hyaline vesicles at the tip of each conidiophore or formed directly from the mycelia. Based on morphological characteristics, the fungal isolates were identified as Nigrospora osmanthi (Wang et al. 2017). Total genomic DNA of the isolates was extracted from fresh mycelium using DNeasy Plant Mini kit (Qiagen, USA) and the internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF1) and Beta-tubulin (TUB2) gene regions were amplified using ITS5/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999) and Bt-2a/Bt-2b primer set (Glass and Donaldson 1995), respectively. BLASTn analysis showed that the ITS, TEF1 and TUB sequences of the isolates shared 99%-100% identity with Nigrospora osmanthi ex-type strain CGMCC 3.18126 (GenBank accession nos. KX986010, KY019421, KY019461). The sequences of two representative isolates (MK and MK1) were deposited in GenBank (ITS: accession nos. MT645782, MW363019; TEF1: MW366861, MW366862; TUB: MW366863, MW366864). Phylogenetic analysis by the maximum likelihood method based on the concatenated ITS-TEF1-TUB sequences showed that the isolates in this study were clustered in a strongly supported group 98% maximum likelihood with type strain N. osmanthi (Kumar et al. 2016). The pathogenicity of all isolates was confirmed by inoculation on ten healthy leaves of five potted 4-week-old O. stamineus plants using a conidial suspension (1 x 106 spores/ml) produced on 7-days-old PDA cultures. An equal number of plants were sprayed with sterile distilled water only to serve as a control and the treated plants were kept in a growth chamber for 2 weeks at 28 ± 1°C and 95% relative humidity. The experiment was repeated twice. The inoculated leaves developed brown lesions which enlarged into blight symptoms similar to those observed on naturally infected leaves after 5 days of inoculation, while control plants remained healthy. Nigrospora osmanthi was successfully re-isolated from the infected leaves, but not from leaves of non-inoculated control plants, thus satisfying Koch’s postulates. . N. osmanthi has been recently reported to cause leaf blight on Ficus pandurata (Liu et al. 2019) and Stenotaphrum secundatum in China (Mei et al. 2019). This disease can cause a significant threat to the cultivation of O. stamineus which has been extensively grown for the production of herbal Java tea. Accurate identification of this pathogen could assist in developing an effective disease management strategy to control this disease.

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First Report of Alternaria alternata Causing Fruit Rot on Fig (Ficus carica) in Montenegro

Plant Disease ◽

10.1094/pdis-07-13-0770-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 424-424 ◽

Cited By ~ 2

Author(s):

N. Latinović ◽

S. Radišek ◽

J. Latinović

Keyword(s):

Alternaria Alternata ◽

Direct Sequencing ◽

Disease Incidence ◽

Morphological Characteristics ◽

Fruit Rot ◽

Conidial Suspension ◽

Culture Collections ◽

First Report ◽

Control Fruit ◽

Rot Disease

In July 2012, a fruit rot disease was observed in several commercial fig tree orchards located in the Podgorica region in Montenegro. Symptoms on fruits initially appeared as small circular to oval, light brown, necrotic, sunken spots located mostly on the areas surrounding the ostiolar canal with an average diameter of 5 to 10 mm, which gradually enlarged in size leading to total fruit rot. Disease incidence on fruit across the fields ranged from 15 to 20% but the disease did not increase further due to hot and dry conditions thereafter. No foliar symptoms were observed. Small pieces (5 mm2) of symptomatic fruits were excised from the junction of diseased and healthy tissue, surface sterilized in 70% ethanol solution for 1 min, washed in three changes of sterile distilled water, air dried, and transferred to potato dextrose agar (PDA). After 2 to 3 days of incubation at 25°C, a fungus was consistently isolated. The isolates had radial growth and produced sooty black colonies. Microscopic observations of the colonies revealed brown septate hyphae and simple or branched conidiophores 30 to 65 μm long and 3 to 4.5 μm wide. Dark brown conidia were in chains (3 to 7), sized 10 to 35 × 5 to 9 μm, ellipsoid to ovoid, with 2 to 5 transverse and a few (1 to 3) to no longitudinal septa. Based on morphological characteristics, the fungus was identified as Alternaria alternata (3). For molecular identification, DNA was extracted from mycelia and conidia of two representative single spore isolates designated as ALT1-fCG and ALT2-fCG. PCR was carried out using internal transcribed spacer (ITS) region primers ITS4/ITS5 and A. alternata species-specific primers AAF2/AAR3 (1). Both primer pairs gave PCR products that were subjected to direct sequencing. BLAST analysis of the 546-bp ITS4/ITS5 (KF438091) and 294-bp AAF2/AAR3 (KF438092) sequences revealed 100% identity with several A. alternata isolates. Pathogenicity tests were conducted on 30 detached almost ripe and healthy fig fruit (cv. Primorka) by spraying them with a conidial suspension of the isolated fungus (106 conidia/ml) with a handheld sprayer. Thirty fruit inoculated with sterile water served as the non-inoculated control. Inoculated and control fruit were kept in a moist chamber at 25°C. Symptoms appeared on inoculated fruit 2 to 3 days after inoculation and all fruit were completely rotted 5 to 6 days after inoculation. Control fruit did not display any symptoms. A. alternata was consistently re-isolated from inoculated fruit, fulfilling Koch's postulates. The fig fruit rot caused by A. alternata has been reported before in California (2) and elsewhere mainly as postharvest pathogen. To our knowledge, this is the first report of fruit rot caused by A. alternata on fig in Montenegro. Considering Podgorica as the largest fig-producing area and the importance of fig as a traditionally grown crop, it could pose a threat to fig production in Montenegro. Voucher specimens are available at the culture collections of the University of Montenegro, Biotechnical Faculty. References: (1) P. Konstantinova et al. Mycol. Res. 106:23, 2002. (2) T. J. Michailides et al. Plant Dis. 78:44-50, 1994. (3) E. G. Simmons. Page 775 in: Alternaria and Identification Manual. CBS Fungal Biodiversity Centre, 2007.

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