scholarly journals First report of Mycoleptodiscus terrestris causing root rot of soybean in Indiana

Plant Disease ◽  
2020 ◽  
Author(s):  
Christopher Detranaltes ◽  
Guohong Cai
Keyword(s):  
Root Rot ◽  
Biological Control Agent ◽  
Lateral Roots ◽  
Its Region ◽  
Selective Medium ◽  
Internal Transcribed Spacers ◽  
Root Tissue ◽  
Pathogenicity Test ◽  
First Report ◽  
Soybean Seedlings

During the summers in 2019 and 2020, 137 soybean (Glycine max (L.) Merr) seedlings (V1-V3 stage) showing stunting, delayed emergence, and/or crown lesions were collected at Purdue’s Agronomy Center for Research and Education in West Lafayette, Indiana. Four seedlings were stunted with reddish-brown girdled lesions along the hypocotyl and crown, rotted tap and lateral roots, and brown discoloration of the cortex and vascular tissues. Four fungal isolates (AC4, AC58, AC96, and AC127) were recovered by plating surface-sterilized symptomatic root tissue onto water agar plates and incubating on the benchtop until mycelia emerged. The growing hyphal tips were transferred to the semi-selective medium DCPA (Andrews and Pitt 1986). On potato dextrose agar, the fungal colonies developed olivaceous green mycelia which melanized into a mat of black microsclerotia with time and no conidia were observed. On 1.5% water agar plates amended with twice autoclaved soybean leaf and root tissue collected from flowering soybean plants, conidia were formed in sporodochia in darkness at 28 οC within one week. Conidia were 1-2 septate, cylindrical with two setae on either end, and measured 20.8 to 26.4 x 4 to 5.6 μm (average 23.9 x 4.7 μm, n=20). The morphological characters matched with the description of Mycoleptodiscus terrestris (Gerd.) Ostaz (Gerdemann 1953). Species identification was further confirmed by sequencing the internal transcribed spacers (ITS) region of rDNA amplified by ITS1 and ITS4 primers (White et al. 1990) and the translation elongation factor 1 alpha (TEF1-α) gene using 983F and 1567R primers with annealing temperature at 53 ○C (Rehner and Buckley 2005). The sequences were deposited in GenBank under the following accession numbers: ITS: MW002684, MT998441, MW010258, and MW010260; and TEF1-α: MW015941-MW015944. The GenBank BLAST searches revealed 100% identity in the ITS region (accession NR_145373.1) and 99.75% identity in the TEF1-α region (MK495977.1) to M. terrestris. Pathogenicity test was conducted on soybean seedlings (cv. Williams) at V1 growth stage using a root dip assay. Isolate AC58 was grown in a modified cotton seed meal broth (CSMB) to produce microsclerotia as inoculum (Gray 1978; Shearer and Jackson 2006). Microsclerotia concentration was measured using a hemocytometer and adjusted to 1.5 x 104 per ml. Five soybean seedlings each were dipped into inoculum or sterile CSMB for 30 minutes then planted individually in vermiculite-filled Styrofoam cups placed on flooded trays in 16-hr photoperiod light racks at room temperature. Seven days after inoculation, all inoculated plants were visibly stunted with root and crown symptoms identical to field symptoms while all controls were healthy. M. terrestris was successfully re-isolated from inoculated plants, but not from the controls, and identified by morphology and sequencing as above. M. terrestris has been previously reported causing root rot of soybean in Illinois (Gray 1978) and Wisconsin (Smith et al. 1998). To our knowledge, this is the first report of M. terrestris infecting soybean in Indiana. Increased geographic distribution of this pathogen warrants more attention for its control. M. terrestris has been proposed as a biological control agent against multiple aquatic weeds (Verma and Charudattan 1993; Shearer and Jackson 2006). Introduction of this fungus into soybean production regions should be avoided.

scholarly journals First Report of Citrus Root Rot Caused by Phytophthora palmivora in Egypt

Plant Disease ◽  
2014 ◽  
Vol 98 (1) ◽  
pp. 155-155 ◽  
Author(s):  
Y. Ahmed ◽  
A. M. D'Onghia ◽  
A. Ippolito ◽  
T. Yaseen
Keyword(s):  
Mating Type ◽  
Root Rot ◽  
Its Region ◽  
Selective Medium ◽  
Phytophthora Palmivora ◽  
Universal Primers ◽  
Potential Threat ◽  
First Report ◽  
Citrus Root ◽  
International Mycological Institute

During spring-summer 2009, a survey was conducted to determine the species of Phytophthora present in citrus nurseries in Egypt. A total of 300 samples of soil and fibrous roots were collected from the rhizosphere of symptomatic Volkameriana lemon (Citrus volkameriana Tan. & Pasq.) plants growing in Delta (Benha-Qalyubia) and a desert (Cairo/Alexandria desert road) citrus nurseries. Plants showed various symptoms. Canopies of affected plants showed few and yellowish leaves, a general stunted growth, no new vegetation, and sometimes sudden desiccation; the root system showed few dark brown feeder roots, no new yellow-white apexes, and a fibrous appearance of the rootlets due to disintegration of the cortical bark but not of the xylem. Collected rootlets and soil were plated in Petri dishes containing a selective medium for the oomycete Phytophthora (2) and incubated for 3 to 6 days at 19 ± 1°C as described by Ippolito et al. (1). Pure cultures were obtained by single-hypha transfers and the isolates were identified as Phytophthora palmivora (Butler) Butler on the basis of morphological and cultural characteristics (3). Isolates formed stoloniferous colonies on potato dextrose agar (PDA) and grew between 10 and 30°C, with the optimum at 25°C. On V8 juice agar, they showed a highly fluffy pattern and produced terminal and intercalary globose chlamydospores. Sporangia were papillate, elliptical (45 to 51 × 29 to 35 μm; length/breadth ratio of 1.3:1.8), and were caducous with short pedicel. All isolates were A2 mating type, forming spherical oogonia and amphigynous antheridia in dual cultures with reference P. palmivora isolate of A1 mating type. Identification of the isolates was further confirmed by amplification and sequencing of the internal transcribed spacer (ITS) region using the universal primers ITS4 and ITS6. BLASTn analysis of ITS sequences (GenBank Accession No. HE583183) showed 99% homology with P. palmivora isolates available in GenBank. Pathogenicity tests for P. palmivora were conducted by inoculating three groups of ten 6-month-old Volkameriana lemon plants, transplanted into 1.4 liter pots with growing medium artificially inoculated at the rate of 1% (v/v) of P. palmivora inoculum produced according to Yaseen (4). Ten uninoculated plants served as a control. Two months after the inoculation, plants were analyzed for canopy symptoms and the presence of pathogen in feeder roots. More than 50% of inoculated plants showed foliage symptoms and extensive decay of feeder roots. Colonies of Phytophthora were recovered from necrotic rootlets and identified as P. palmivora, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of P. palmivora as a pathogen to citrus plants in the Egyptian nurseries. P. palmivora should be considered a potential threat to the Egyptian citrus industry since it may negatively influence the nurseries and orchards production in the future. References: (1) A. Ippolito, V. De Cicco, and M. Salerno. Rivista di Patologia Vegetale 2:57, 1992. (2) H. Masago, M. Yoshikawa, M. Fukada, and N. Nakanishi. Phytopathology 67:425, 1977. (3) D. J. Stamps. Revised tabular key to the species of Phytophthora. CAB International Mycological Institute, Kew, Surrey, 1990. (4) T. Yaseen. Molecular diagnosis and biological control of Phytophthora-citrus root rot. PhD thesis. University of Bari, Italy, 2004.

scholarly journals First Report of Mulberry Root Rot Caused by Lasiodiplodia theobromae in China

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1581-1581 ◽  
Author(s):  
H.-H. Xie ◽  
J.-G. Wei ◽  
F. Liu ◽  
X.-H. Pan ◽  
X.-B. Yang
Keyword(s):  
Root Rot ◽  
Management Strategies ◽  
Its Region ◽  
Pathogenic Fungi ◽  
Fruit Trees ◽  
Morphological Characters ◽  
Pathogenicity Test ◽  
Total Production ◽  
Lasiodiplodia Theobromae ◽  
First Report

Mulberry (Morus alba L.) is an important cash crop and medicinal plant that has been cultivated for more than 5,000 years in China. The area of mulberry production in Guangxi Province is 45% of total production in China, with 1.3 million ha planted. In recent years, a mulberry root rot occurred in Heng County covering all the mulberry planting farms. Observations of 200 diseased plants were made. The xylem of infected roots first turned brown, and then became black followed by cortex rot. The xylem and cortex of infected roots were easily separated. The xylem of the stem of symptomatic plants was also brown and the bark was slightly darker than normal. Leaves of diseased plants turned yellow and wilted, but the wilted leaves remained on the affected branches for about 3 weeks. All affected branches and stem dried after a month. The affected area was 12,000 ha with incidences varying from 13 to 52%. About 8% of young mulberry trees died in severely infested orchards. The disease caused more than $3 million in losses within a year in Heng County alone. The causal fungus was isolated from xylem tissues of symptomatic roots of 62 mulberry plants with an isolation rate of 90%. Pathogenicity test was made by inoculating 5-month-old healthy mulberry plants with PDA plugs (5 × 5 mm) grown 5 days with viable mycelia of the fungus. Nine healthy plants were wounded on the roots with a sterile knife, and mycelial plugs of three Lasiodiplodia theobromae (Pat.) Griffon & Maubl isolates were placed on the wounds, covered with sterile moist cotton, and wrapped with Parafilm. Nine control plants were treated with PDA plugs. The test was repeated three times. All treated plants were kept in a greenhouse at ~28°C and 40% RH. After 3 days, the root xylem of inoculated plants turned brown and gradually became dark, similar to symptoms observed in the field. After 8 days, inoculated seedlings gradually wilted, and all the treated plants died after 11 days with leaves undetached. The fungus was re-isolated from all nine diseased plants and no symptoms were observed on the roots of control plants. The causal agent, of which conidia were dark brown, one-septate, thick walled, and ellipsoid with 4 or 6 vertical lines of dashes, 12.50 to 13.75 × 13.75 to 25.63 μm (n = 100), was identified as L. theobromae based on morphological characters described by Punithalingam (3) and sequences of the ITS region of rDNA using primers ITS1 and ITS4 and EF1-α using primers EF728F and EF986R. The ITS sequence (HG917932) was similar to the ITS sequences of AY640255 (CBS164.96) and AY236952 (CMW9074) in GenBank with identities of 98.8 and 99.8%, respectively. The EF1-α sequence HG917934 was similar to that of AY640258 (CBS164.96) and AY236901 (CMW9074) with identities of 99.7 and 99.7%, respectively. L. theobromae is a cosmopolitan fungus causing both field and storage diseases on more than 280 plant species including crops, fruits, and cash fruit trees (1,2,5). Mulberry root rot caused by L. theobromae has been reported in India (4) and ours is the first report in China. This finding clarifies the pathogen of mulberry root rot previously thought as Fusarium sp. in China, which is critical to develop management strategies to control this disease. References: (1) N. M. Celiker and T. J. Michailides. New Dis. Rep. 25:12, 2012. (2) I. H. Fischer et al. Australia Plant Dis. Notes 3:116, 2008. (3) E. Punithalingam. Botryodiplodia theobromae. CMI Descriptions of Pathogenic Fungi and Bacteria No. 519. CAB International, Wallingford, UK, 1976. (4) N. V. Radhakrishnan et al. Indian Phytopathol. 48:490, 1995. (5) B. C. Sutton. The Coelomycetes. Commonwealth Mycology Institute, Kew, Surrey, England, 1980.

scholarly journals First report of Fusarium fujikuroi causing root rot and seedling elongation of soybean in Indiana

Plant Disease ◽  
2021 ◽  
Author(s):  
Christopher Detranaltes ◽  
Christopher Robert Jones ◽  
Guohong Cai
Keyword(s):  
Root Rot ◽  
Lateral Roots ◽  
Small Subunit ◽  
The State ◽  
Gibberella Fujikuroi ◽  
Fusarium Fujikuroi ◽  
Pathogenicity Test ◽  
Single Spore ◽  
New Host ◽  
First Report

In summer 2020, 127 soybean (Glycine max (L.) Merr) seedlings (V1-V3 stage) showing reduced vigor or crown lesions were collected at Purdue’s Agronomy Center for Research and Education in West Lafayette, Indiana. Root tissues from two seedlings with necrotic cotyledons and root rot were surface-sterilized and plated on dichloran-chloramphenicol-peptone agar (Andrews and Pitt 1986). Emerging hyphal tips were transferred to potato dextrose agar (PDA). Single-spore cultures were obtained and grown on PDA. Both isolates developed floccose white aerial mycelia with reddish-pink coloration in the media in 2 weeks on the benchtop. On carnation leaf agar, macroconidia formed on orange sporodochia within 2 weeks in darkness at 25C. Macroconidia were 3-5 septate, measuring 26 – 41 × 2.5 – 3.7 μm (avg. 34.8 × 3.2 μm, n=40). Microconidia were abundant in chains and false heads forming on both mono- and polyphialides, and measured 2.5 – 8.75 x 2.5 μm (avg. 5.9 × 2.5 μm, n=40). These characteristics were consistent with species descriptions of F. fujikuroi [Sawada] Wollenw. (teleomorph Gibberella fujikuroi) (Leslie and Summerell 2006). DNA was extracted from mycelium and the following genes were amplified and sequenced: the internal transcriber spacer (ITS) region using ITS1/ITS4 primers (White et al. 1990) (GenBank accessions MW463362/MW463363), the mitochondrial small subunit (mtSSU) rDNA using MS1/MS2 primers (White et al. 1990) (MW465310/MW465307), and the partial translation elongation factor 1-alpha (TEF1α) gene using 983F/1567R primers (Rehner and Buckley 205) (MW475297/MW475298). In GenBank BLAST searches, these sequences showed 100% identity to both F. proliferatum and F. fujikuroi. Species-specific forward primers Fuji1F and Proli1F were then used in combination with reverse primer TEF1R to amplify another region in the TEF1α gene (Amatulli et al. 2012). Proli1F/TEF1R primers failed under a variety of annealing temperatures while Fuji1F/TEF1R primers succeeded, and the products were sequenced (MW475299/MW475300). GenBank BLAST searches revealed 100% identity of both isolates to F. fujikuroi (MT448248.1). A pathogenicity test was conducted with isolate AC13 in the greenhouse following the protocol of (Ellis et al. 2013). Ten seeds (cv. Williams) each were used for inoculation and control, respectively, with one seed per cup. Root rot symptoms similar to those observed in the field were observed 14 days after planting on all inoculated plants but not on controls (VC stage). Infected plants showed symptoms of pre-emergence damping off, reddish-brown lesions on the tap and lateral roots, and root necrosis. Three plants also exhibited hyper-elongation of the stem (12.5, 11.1, and 18 cm, vs controls: avg. 6.8 cm, max. 8.5 cm, stdev 0.78 cm). F. fujikuroi was successfully reisolated from inoculated plants but not from controls and identified as described above. F. fujikuroi has been reported causing soybean root rot in China (Zhao et al. 2020), Korea (Choi et al. 2019), and the state of Kansas (Pedrozo et al. 2015). To our knowledge this is the first report of F. fujikuroi infecting soybeans in the state of Indiana. F. fujikuroi is known to cause elongated seedlings in rice (Leslie and Summerell 2006). Pedrozo et al. (2015) reported that F. fujikuroi isolated from soybean caused seedling elongation in rice but not in soybean. The increased distribution and new host symptomology observed here warrants heightened attention for the control of this pathogen.

scholarly journals First Report of a Pythiogeton sp. Causing Root and Basal Stalk Rot of Wild Rice in California

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 851-851 ◽  
Author(s):  
H. K. Doan ◽  
R. M. Davis ◽  
F. F. Sartori ◽  
D. B. Marcum
Keyword(s):  
Dna Sequences ◽  
Wild Rice ◽  
Block Design ◽  
Its Region ◽  
Internal Transcribed Spacers ◽  
Pathogenicity Test ◽  
First Report ◽  
Stalk Rot ◽  
Pure Cultures ◽  
Root Tissues

In the summer of 2012, an outbreak of a newly discovered root and basal stalk rot of wild rice (Zizania palustris L.) cv. Franklin was observed in a 16-ha field in Big Valley, Lassen County, California (GPS coordinates 41°08′41.93″ N 121°10′07.49″ W). Infected plants exhibiting rot and dieback of roots and stalks were in various stages of decline, including death. Symptomatic stem and root tissues from affected plants were surface disinfected in 1% NaOCl for 90 s and placed on PARP agar plates, which were then incubated at 25°C in the dark for 1 week. Hyphal tips were used to start and maintain the organism in pure cultures. Isolates were transferred into petri plates with water and sterilized blades of turfgrass for the production of hyphae and reproductive structures. Isolates had coenocytic hyphae and produced zoospores 20 to 30 μm in diameter outside of sporangia (75 to 160 × 46 to 110 μm) from a naked mass of protoplasm, unlike from a vesicle, which is characteristic of Pythium spp. (2). Based on these morphological features, the isolate was tentatively identified as a Pythiogeton sp. Total genomic DNA was extracted from mycelia using the DNeasy Plant Mini Kit (Qiagen Inc., Valencia, CA). The internal transcribed spacers (ITS) 1 and 2 flanking the 5.8S rRNA regions were amplified by PCR and sequenced using universal ITS5 and ITS4 primers. A BLAST search of the 855-bp sequences revealed 98% similarity with a sequence of P. ramosum isolate Pg-164 (GenBank Accession No. JQ610190.1). The 21 nucleotide differences suggest that the isolate from wild rice may be an unreported species. The sequences were submitted to GenBank (KF719169). To fulfill Koch's postulates and confirm pathogenicity, 100 wild rice seeds were surface disinfected in 1% NaOCl for 90 s and placed in a 500 ml sterile pot with 250 g of autoclaved sand. Three 5 mm-diameter disks from the margin of a 7-day-old culture growing on PARP were placed in each of five pots. As a control, three 5 mm-diameter disks from a non-inoculated PARP plate were placed in five different pots, and five pots with autoclaved sand were not inoculated. All pots were kept in a randomized complete block design at 25°C for 14 days under a 14-h photoperiod. The pathogenicity test was repeated three times. After 14 days, the inoculated plants in all tests developed root and basal stalk rot, consistent with the symptoms observed on diseased wild rice in the field. The Pythiogeton sp. was consistently re-isolated on PARP from symptomatic plants but not from control plants. The non-inoculated wild rice plants remained asymptomatic. DNA sequences of the ITS region of the re-isolated Pythiogeton sp. revealed 100% identity with the isolate from the field. There have been reports of P. zeae on corn in Korea and P. zizaniae on water bamboo in Taiwan (1,2,3). This is the first report of a Pythiogeton sp. on wild rice. References: (1) P. J. Ann et al. Mycologia 98:116, 2006. (2) J. Huang et al. Mycoscience 54:130, 2013. (3) H. J. Jee et al. Mycologia 92:522, 2000.

scholarly journals First Report of Phytophthora ramorum on Viburnum bodnantense in Belgium

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 203-203 ◽  
Author(s):  
D. De Merlier ◽  
A. Chandelier ◽  
M. Cavelier
Keyword(s):  
The Netherlands ◽  
Plant Protection ◽  
Morphological Characteristics ◽  
Pcr Primers ◽  
Selective Medium ◽  
Phytophthora Species ◽  
Phytophthora Ramorum ◽  
Pathogenicity Test ◽  
First Report ◽  
Root Necrosis

In the past decade, a new Phytophthora species inducing shoot canker on Rhododendron and dieback of Viburnum has been observed in Europe, mainly in Germany and the Netherlands, and California. This new pathogen has been named Phytophthora ramorum (3). In May 2002, a diseased Viburnum plant (Viburnum bodnantense) from the Plant Protection Service (Ministry of Agriculture, Belgium) was submitted to our laboratory for diagnosis. Symptoms included wilting, leaves turning from green to brown, discolored vascular tissues, and root necrosis. The plant came from a Belgian ornamental nursery that obtained supplies of stock plants from the Netherlands. Pieces of necrotic root tissue were excised, surface-disinfected, and transferred aseptically to a Phytophthora selective medium. P. ramorum was identified based on morphological characteristics, including the production of numerous, thin-walled chlamydospores (25 to 70 µm in diameter, average 43 µm) and deciduous, semi-papillate sporangia arranged in clusters. Radial growth after 6 days at 20°C on V8 juice agar was 2.8 mm per day. Random amplified microsatellite markers (RAMS) (2) from the total genomic DNA of the Belgian strain (CBS 110901) were similar to those of P. ramorum reference strains (CBS 101330, CBS 101332, and CBS 101554). Using PCR primers specific for P. ramorum, the identification was confirmed by W. A. Man in't Veld (Plantenziektenkundige Dienst, Wageningen, the Netherlands) (1). A pathogenicity test was carried out on three sterile cuttings of Rhododendron catawbiense (3). Brown lesions were observed on the inoculated cuttings after 6 to 7 days. None of the three uninoculated cuttings showed symptoms of infection. P. ramorum was reisolated from lesion margins on the inoculated cuttings. To our knowledge, this is the first report of the fungus from Belgium. Since our initial observation, we have found P. ramorum in other Belgian nurseries on R. yakusimanum. References: (1) M. Garbelotto et al. US For. Ser. Gen. Tech. Rep. PSW-GRT. 184:765, 2002. (2) J. Hantula et al. Mycol. Res. 101:565, 1997. (3) S. Werres et al. Mycol. Res. 105:1155, 2001.

scholarly journals First Report of Mucor spp. Causing Root Rot of Radix pseudstellariae in Guizhou Province of China

Plant Disease ◽  
2020 ◽  
Author(s):  
Hongmiao Wu ◽  
Jiachun Wu ◽  
Feng Li ◽  
Ling Zheng ◽  
Jingkai Fan ◽  
...  
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Acid Soils ◽  
Its Region ◽  
Significant Loss ◽  
Day Length ◽  
Guizhou Province ◽  
First Report ◽  
Chinese Medicinal Plants ◽  
Branched Chains

Radix pseudostellariae L. is one of the most common and highly-prized Chinese medicinal plants with various pharmacological effects, and mainly produced in acid soils in the Guizhou and Fujian provinces of southwestern and southeastern China, respectively (Wu et al. 2020). However, consecutive monoculture of R. pseudostellariae results in severe root rot and decline in biomass and quality of underground tubers. Root tubers of R. pseudostellariae are typically planted in December and harvested in next June. Root rot commonly starts developing in May. The disease incidence of root rot was ranging from 37 to 46% in root portions and basal stem of R. pseudostellariae under the consecutive monoculture fields in Shibing County, Guizhou Province, China (108°12ʹE, 27°03ʹN) (Li et al. 2017). Severe root rot was observed in Shibing County in May 2018. Infected plants displayed curly, withered, and yellow leaves, blight, retarded growth, root rot, and yield losses. Abundant whitish mycelia were observed on roots and surrounding soil. Two fungal isolates, designated GZ20190123 and GZ20190124, were obtained from symptomatic roots cultured on potato dextrose agar (PDA). The optimum temperature range for growth of the two isolates was 25 to 30°C. The optimum pH range for the growth of GZ20190123 was 5 to 5.5, whereas GZ20190124 grew better between pH 5 to 8.5. The mean mycelial growth rates of GZ20190123 and GZ20190124 at 30°C were 2.1 and 1.5 cm/day, respectively. Conidia of the two isolates were ovoid or obclavate and were produced in single or branched chains. The internal transcribed spacer (ITS) region was amplified with primers ITS1 and ITS4 (White et al. 1990). The sequences were deposited in GenBank as accession No. MN726736 for GZ20190123 and MN726738 for GZ20190124. Sequence comparison revealed 99% (GZ20190123) and 97% (GZ20190124) identity with previously reported isolate xsd08071 of Mucor racemosus Bull. (accession No. FJ582639.1) and isolate BM3 of Mucor fragilis Bainier (accession No. MK910058.1), respectively, which was confirmed by phylogenetic analysis. The two isolates were tested for pathogenicity on R. pseudostellariae. Six roots of R. pseudostellariae were surface-sterilized with 75% ethanol and stab inoculated with mycelia using a sterile toothpick for each isolate. Sterile distilled water was stab inoculated to twelve roots to serve as the control. Treated roots were incubated in a greenhouse with 16 h day length [light intensity 146.5 μmol/(m2·s)] and day/night temperature 26°C/18°C. The inoculated roots showed the expected symptoms on roots and sprouts 7 days after inoculation, whereas the control roots with sprouts did not show any symptom. The fungi were re-isolated from the diseased roots and confirmed as expected M. racemosus or M. fragilis based on the ITS sequences, which satisfied Koch’s postulates. Thus, isolate GZ20190123 was identified as M. racemosus and GZ20190124 as M. fragilis. Previously, M. racemosus and M. fragilis have been reported as a pathogen on tomato (Kwon and Hong 2005) and grape (Ghuffar et al. 2018), respectively. To our knowledge, this is the first report of M. racemosus and M. fragilis causing root rot of R. pseudostellariae in southwestern China, where the disease could cause a significant loss to production of this important medicinal plant.

scholarly journals First Report of Phytophthora citrophthora on Penstemon barbatus in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1260-1260 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
D. Minerdi ◽  
M. L. Gullino
Keyword(s):  
Its Region ◽  
The United States ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
Phytophthora Citrophthora ◽  
First Report ◽  
Blastn Analysis ◽  
Root And Crown Rot ◽  
Pathogenicity Tests

Penstemon barbatus (Cav.) Roth (synonym Chelone barbata), used in parks and gardens and sometimes grown in pots, is a plant belonging to the Scrophulariaceae family. During the summers of 2004 and 2005, symptoms of a root rot were observed in some private gardens located in Biella Province (northern Italy). The first symptoms resulted in stunting, leaf discoloration followed by wilt, root and crown rot, and eventually, plant death. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on a semiselective medium for Oomycetes (4). The microorganism consistently isolated from infected tissues, grown on V8 agar at 22°C, produced hyphae with a diameter ranging from 4.7 to 5.2 μm. Sporangia were papillate, hyaline, measuring 43.3 to 54.4 × 26.7 to 27.7 μm (average 47.8 × 27.4 μm). The papilla measured from 8.8 to 10.9 μm. These characteristics were indicative of a Phytophthora species. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 800 bp obtained showed a 100% homology with Phytophthora citrophthora (R. & E. Sm.) Leonian. The nucleotide sequence has been assigned GenBank Accession No. DQ384611. For pathogenicity tests, the inoculum of P. citrophthora was prepared by growing the pathogen on autoclaved wheat and hemp kernels (2:1) at 25°C for 20 days. Healthy plants of P. barbatus cv. Nano Rondo, 6 months old, were grown in 3-liter pots (one plant per pot) using a steam disinfested substrate (peat/pomix/pine bark/clay 5:2:2:1) in which 200 g of kernels per liter of substrate were mixed. Noninoculated plants served as control treatments. Three replicates were used. Plants were maintained at 15 to 20°C in a glasshouse. The first symptoms, similar to those observed in the gardens, developed 21 days after inoculation, and P. citrophthora was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice with similar results. A nonspecified root and crown rot of Penstemon spp. has been reported in the United States. (2). To our knowledge, this is the first report of P. citrophthora on P. barbatus in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) F. E. Brooks and D. M. Ferrin. Plant Dis. 79:212, 1995. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) H. Masago et al. Phytopathology 67:425, 1977.

scholarly journals First Report of Postharvest Fruit Rot in Persimmon Caused by Phacidiopycnis washingtonensis in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 788-788 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. T. Amatulli ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Its Region ◽  
The United States ◽  
Fruit Rot ◽  
Diospyros Kaki ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
First Report ◽  
Pathogenicity Tests ◽  
Phacidiopycnis Washingtonensis

Persimmon (Diospyros kaki L.) is widely grown in Italy, the leading producer in Europe. In the fall of 2009, a previously unknown rot was observed on 3% of fruit stored at temperatures between 5 and 15°C in Torino Province (northern Italy). The decayed area was elliptical, firm, and appeared light brown to dark olive-green. It was surrounded by a soft margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. On the decayed tissue, black pycnidia that were partially immersed and up to 0.5 mm in diameter were observed. Light gray conidia produced in the pycnidia were unicellular, ovoid or lacriform, and measured 3.9 to 6.7 × 2.3 to 3.5 (average 5.0 × 2.9) μm. 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 23 and 26°C under alternating light and darkness. Colonies of the fungus initially appeared ash colored and then turned to dark greenish gray. After 14 days of growth, pycnidia and conidia similar to those described on fruit were produced. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 502-bp segment showed a 100% similarity with the sequence of Phacidiopycnis washingtonensis Xiao & J.D. Rogers (GenBank Accession No. AY608648). The nucleotide sequence has been assigned the GenBank Accession No. GU949537. Pathogenicity tests were performed by inoculating three persimmon fruits after surface disinfesting in 1% sodium hypochlorite and wounding. Mycelial disks (10 mm in diameter), obtained from PDA cultures of one strain were placed on wounds. Three control fruits were inoculated with plain PDA. Fruits were incubated at 10 ± 1°C. The first symptoms developed 6 days after the artificial inoculation. After 15 days, the rot was very evident and P. washingtonensis was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice. Since P. washingtonensis was first identified in the United States on decayed apples (2), ‘Fuji’, ‘Gala’, ‘Golden Delicious’, ‘Granny Smith’, ‘Red Chief’, and ‘Stark Delicious’, apple fruits also were artificially inoculated with a conidial suspension (1 × 106 CFU/ml) of the pathogen obtained from PDA cultures. For each cultivar, three surface-disinfested fruit were wounded and inoculated, while three others served as mock-inoculated (sterile water) controls. Fruits were stored at temperatures ranging from 10 to 15°C. First symptoms appeared after 7 days on all the inoculated apples. After 14 days, rot was evident on all fruit inoculated with the fungus, and P. washingtonensis was consistently reisolated. Controls remained symptomless. To our knowledge, this is the first report of the presence of P. washingtonensis on persimmon in Italy, as well as worldwide. The occurrence of postharvest fruit rot on apple caused by P. washingtonensis was recently described in the United States (3). In Italy, the economic importance of the disease on persimmon fruit is currently limited, although the pathogen could represent a risk for apple. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) Y. K. Kim and C. L. Xiao. Plant Dis. 90:1376, 2006. (3) C. L. Xiao et al. Mycologia 97:473, 2005.

scholarly journals First Report of Root Rot of Soybeans Caused by Corynespora cassiicola in Wisconsin

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 696-696 ◽  
Author(s):  
S. J. Raffel ◽  
E. R. Kazmar ◽  
R. Winberg ◽  
E. S. Oplinger ◽  
J. Handelsman ◽  
...  
Keyword(s):  
Root Rot ◽  
Growth Stage ◽  
Lateral Roots ◽  
Seedling Emergence ◽  
Fluorescent Light ◽  
Corynespora Cassiicola ◽  
First Report ◽  
Seedling Roots ◽  
Symptomatic Tissue ◽  
Soybean Plants

Corynespora cassiicola (Berk. & M. A. Curtis) C. T. Wei was isolated from diseased soybean plants (Glycine max) collected in two fields near Racine and Arlington, WI. Plants sampled at seedling emergence (VC), late vegetative (V5), and mid-reproductive (R5) stages exhibited reddish to dark brown longitudinal lesions on the exterior of the tap root extending vertically on the hypocotyl to the soil line, and extensive necrosis of lateral roots. Sample size at each growth stage was 144 plants per site. Roots were surface sterilized in 0.5% sodium hypochlorite for 2 min and sections of symptomatic tissue placed on water agar (12 g/liter) containing 100 μg of streptomycin per ml. Sporulation occurred on lesions and on mycelium that had grown out from the plant tissue onto the water agar following a 2-week incubation at 24°C under fluorescent light (280 μmol s-1 m-2). Incidence of isolation of C. cassiicola at both sites was 40% of plants sampled at growth stage VC, 67% at V5, and 78% at R5. Conidia characteristic of C. cassiicola were particularly abundant on the surface of necrotic lateral root tissue. Elongated conidia produced on water agar were 151 ± 5 μm × 15 ± 0.5 μm with an average of 13 ± 0.4 cells separated by hyaline pseudosepta (1). To confirm pathogenicity, a 1-cm lateral slice into each of four 5-day-old soybean seedling roots was made and a plug of agar taken from the margin of a colony of C. cassiicola grown on potato dextrose agar was placed in each wound and incubated for 14 days at 24°C in a growth chamber. Symptoms similar to those of diseased field plants were observed and C. cassiicola was reisolated from all plants inoculated with C. cassiicola; all controls treated with agar alone had no symptoms and C. cassiicola was recovered from none of the noninoculated controls. This is the first report of root rot caused by C. cassiicola on soybean in Wisconsin. Reference: (1) W. L. Seaman and R. A. Shoemaker. Can. J. Bot. 43:1461, 1965.

scholarly journals First Report of Web Blight on Oregano (Origanum vulgare L.) Caused by Rhizoctonia solani AG-1-IB in Italy

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1119-1119 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
P. Pensa ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
Rhizoctonia Solani ◽  
Its Region ◽  
Morphological Characters ◽  
Anastomosis Group ◽  
Morphological Identification ◽  
Pathogenicity Test ◽  
Origanum Vulgare ◽  
First Report ◽  
Plastic Bags ◽  
Hyphal Diameter

Origanum vulgare L., common name oregano, family Labiatae, is grown for its aromatic and medicinal properties and as ornamental. In the fall of 2012, a blight was observed in a farm located near Albenga (northern Italy) on 6% of 30,000 50-day-old plants, grown in trays in a peat/perlite mix. Semicircular, water soaked lesions appeared on leaves and stems, starting from the basal ones. As the disease progressed, blighted leaves turned brown, withered, clung to the shoots, and matted on the surrounding foliage. Eventually, infected plants died. Leaf and stem fragments taken from the margin of the diseased tissues belonging to 10 plants were disinfected for 10 s in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA). A fungus with the morphological characters of Rhizoctonia solani was consistently recovered. Three isolates of R. solani obtained from affected plants were successfully anastomosed with R. solani isolate AG 1 (ATCC 58946). Three pairings were made for each tester strain. The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (2). Isolates from oregano were paired with R. solani isolates AG 2, 3, 4, 6, 7, or 11 and examined microscopically. Anastomosis was not observed in any of the pairings. Tests were conducted twice. Mycelium of 10-day-old isolates from oregano appeared reddish brown, coarse, and radiate. Numerous dark brown sclerotia, 0.3 to 1.0 mm diameter (average 0.7) developed within 10 days after transfer of mycelia to PDA in 90 mm diameter petri dishes at 21 to 24°C. The descriptions of mycelium and sclerotia were typical for subgroup IB Type 1 (4). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and sequenced. BLASTn analysis (1) of the 538 bp showed a 99% homology with the sequence of R. solani FJ746937, confirming the morphological identification of the species. The nucleotide sequence has been assigned the GenBank Accession KC493638. For pathogenicity tests, one of the isolates assigned to the anastomosis group AG-1-IB was tested by placing 9 mm diameter mycelial disks removed from PDA 10-day-old cultures of the fungus on leaves of 90-day-old oregano plants (n = 35). Thirty-five plants inoculated with non-inoculated PDA disks served as controls. Plants were covered with plastic bags and maintained in a growth chamber at 25 ± 1°C with 12 h light/dark. The first symptoms, similar to those observed in the farm, developed 3 days after inoculation. Nine days after the artificial inoculation, 50% of plants were dead. About 10 colonies of R. solani were reisolated from infected leaves of inoculated plants. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. Symptoms caused by R. solani have been recently observed on O. vulgare in Greece (3). This is, to our knowledge, the first report of blight of O. vulgare caused by R. solani in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res., 25:3389, 1997. (2) D. E. Carling. Grouping in Rhizoctonia solani by hyphal anastomosis reactions. In: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease control. Kluwer Academic Publishers, The Netherlands, pp. 37-47, 1996. (3) C. D. Holevas et al. Benaki Phytopathol. Inst., Kiphissia, Athens, 19:1-96, 2000. (4) R. T. Sherwood. Phytopathology 59:1924, 1969.

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