First Report of Phytophthora tentaculata Causing Stem and Root Rot on Celery in China

Celery (Apium graveolens) is an important vegetable in China. In August 2012, about 20 to 70% declining plants with root and basal stem rot were observed in Bengbu, Anhui Province, China. Typical symptoms included large dark brown to black water-soaked lesions near the soil line of stems. As the disease progressed, lesions girdled the stem, and plants became brown, wilted, and eventually died. A Phytophthora-like organism was consistently isolated from symptomatic tissues on a selective medium, P5ARP. Resultant isolates were identified as Phytophthora tentaculata based on their morphological features and rDNA sequence. Sporangia, chlamydospores, hyphal swellings, and oospores were produced on V8 agar. Sporangia were ovoid to pyriform, 28.5 to 52.5 × 21.5 to 40.6 μm, average 35.3 × 29.8 μm, with one or occasionally two papillae. Chlamydospores were spherical, 21.3 to 30.2 μm in diameter, average 25.7 μm. The isolates were homothallic, and one or occasionally two paragynous antheridia were attached to the global oogonia (24 to 39 μm in diameter, average 29.5 μm). The internal transcribed spacer region of rDNA was amplified with primer pair ITS1/ITS4 for one isolate (1), and the sequence (GenBank Accession No. KF501392) showed >99% similarity with those P. tentaculata isolates deposited in GenBank (AJ854302.1). Pathogenicity was confirmed by inoculating Shijihuangqin, a local cultivar of celery, with isolate PT12081. The isolate was cultivated on V8 agar at 25°C for 5 to 7 days to produce sporangia. Five 2-month-old, disease-free celery were drench-inoculated with 10 ml of a suspension of 2 × 104 zoospores/ml, and five control plants per pot were treated with sterile water. There were four pots for each of the inoculated and non-inoculated treatments, and the experiment was repeated twice. All plants were maintained at 25°C for 10 days. Symptoms similar to those observed in the field developed 7 days after inoculation. Ten days later, five plants wilted and two or three died in each pot inoculated with PT12081, but the control plants remained symptomless. P. tentaculata was consistently re-isolated from the symptomatic plants. P. tentaculata has been reported to infect Chrysanthemum spp., Delphinium ajacis, Verbena spp., and Origanum vulgare (2,3). To our knowledge, this is the first report of Phytophthora blight caused by P. tentaculata on celery in China. References: (1) H. Guo et al. Plant Dis. 96:1072, 2012. (2) P. Martini et al. Plant Dis. 93:843, 2009. (3) J. Meng and Y. C. Wang. Plant Dis. 92:1365, 2008.

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First Report of Cercospora apii, Causal Agent of Cercospora Early Blight of Celery, in Serbia

Plant Disease ◽

10.1094/pdis-02-14-0135-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1157-1157 ◽

Cited By ~ 1

Author(s):

A. Milosavljević ◽

E. Pfaf-Dolovac ◽

M. Mitrović ◽

J. Jović ◽

I. Toševski ◽

...

Keyword(s):

Early Blight ◽

Molecular Data ◽

Causal Agent ◽

Apium Graveolens ◽

Universal Primers ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Molecular Features ◽

Sterile Needle ◽

Histone H3 Gene

Celery (Apium graveolens var. dulce) is a very important vegetable crop intensively cultivated in eastern and southern Serbia. During a field survey in August and September 2012, we observed symptoms similar to those of Cercospora early blight in eastern Serbia, with some of the affected fields showing up to 80% disease severity. The lesions on leaves were amphigenous, subcircular to angular and more or less confluent. Lesions enlarged and merged with age, followed by the development of necrotic area causing a continuous deterioration of the plant. Conidiophores arising from the stromata formed dense fascicles, sometimes appearing solitary, brown at the base, paler toward the apex, simple, straight to slightly curved, and rarely geniculate (dimensions 40 to 90 × 5 to 8 μm). Conidia were solitary, hyaline, at first cylindro-obclavate then acicular to acicular-obclavate, straight to slightly curved, subacute to obtuse at the apex, while truncated and thickened at the base (dimensions 45 to 160 × 4 to 5 μm), 5 to 13 septate. Based on the morphological features, we identified the pathogen as Cercospora apii Fresen. (2). In order to obtain monosporic isolates of the fungus, single conidia were cultivated on potato dextrose agar (PDA). To confirm the pathogenicity of the isolates, 5 mm-diameter mycelial plugs from the PDA plates were placed upside down on the adaxial leaf surface of 2-week-old celery seedlings of cv. Yuta. Control plants were inoculated with a sterile PDA plug. Three leaves per plant were disinfected with 70% ethanol, epidermis was scratched with a sterile needle to promote the infection, and inoculated. A total of 12 plants were inoculated with the mycelial plugs and 12 were used as control plants. Inoculated and control plants were kept in a moist chamber for 48 h and then transferred to a greenhouse at 25 ± 2°C. After 2 weeks, the first necrotic spots appeared on inoculated leaves, similar to the symptoms manifested in the field, while control plants remained symptomless. The pathogen was re-isolated and its identity was verified based on morphological and molecular features. To confirm the pathogen's identity, three isolates (CAC4-1, CAC24, and CAC30) were subjected to molecular identification based on the internal transcribed spacer region (ITS) using the ITS1/ITS4 universal primers (5), a partial calmodulin gene (CAL) using CAL-228F/CAL2Rd primers (1,4), and partial histone H3 gene (H3) using CYLH3F/CYLH3R primers (3). Sequences of the amplified regions were deposited in GenBank under accessions KJ210596 to KJ210604. The BLAST analyses of the ITS sequences revealed 100% identity with several Cercospora species (e.g., C. apii [JX143532], C. beticola [JX143556], and C. zebrina [KC172066]), while sequences of CAL and H3 showed 100% identity solely with sequences of C. apii (JX142794 and JX142548). Based on combined morphological and molecular data, the pathogen infecting celery was identified as C. apii, which to our knowledge represents the first report of the presence of the causal agent of Cercospora early blight disease in Serbia. References: (1) I. Carbone and L.M. Kohn. Mycologia 91:553, 1999. (2) P. W. Crous and U. Braun. CBS Biodivers. Ser. 1:1, 2003. (3) P. W. Crous et al. Stud. Mycol. 50:415, 2004. (4) J. Z. Groenewald. Stud. Mycol. 75:115, 2013. (5) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, Inc., San Diego, CA, 1990.

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First Report of Alternaria tenuissimain Causing Leaf Spot of Celery (Apium graveolens) in China

Plant Disease ◽

10.1094/pdis-09-20-2083-pdn ◽

2020 ◽

Author(s):

Jianqiang Zhang ◽

Kangli Wu ◽

Xiaomeng Zhang ◽

Jiajia Li ◽

Abdramane salah zene ◽

...

Keyword(s):

Dna Sequences ◽

Leaf Spot ◽

Leaf Age ◽

Apium Graveolens ◽

Control Group ◽

Sterile Water ◽

Internal Transcribed Spacer Region ◽

Data Set ◽

First Report ◽

Initial Symptoms

Celery (Apium graveolens) is one of the most widely grown vegetables in the world. A survey in Anding District of Gansu Province in 2019 showed that the incidence of celery leaf spot was 25%-45%. The disease mainly occurs in late June and July. The leaf spot is conducive to the onset at high temperature and humidity environment. The initial symptoms were many small light brown, irregular-shaped on the leaves. The lesions gradually enlarged in the later stage of the disease, and multiple lesions coalesced to form large irregular brown spots, eventually the whole leaves died. A 3~4mm leaf tissue was cut from the junction of the diseased leaf and the healthy area, the leaf tisse was surface-sterilized in 1.5% NaClO for 1 min and washed with sterile water. Then, it was incubated on potato dextrose agar (PDA) and obtained the pure culture (Q1). After 5 days of cultivation at 25°C, the fungal colonies were olivaceous to dark olive with white margins and abundant aerial mycelia. The conidia were obclavate or ellipsoid, pale brown, with 3~4 longitudinal septa and 2~7 transverse septa, and measured 20.0 to 50.0 × 3.5 to 14.0μm (n=50). Conidiophores were septate, arising singly, and measured 3.5 to 40.0 × 2.5 to 4.5 μm (n=50). Based on morphological characteristics, the fungus was preliminarily identified as A.tenuissima (Simmons 2007). To further confirm the identification, the internal transcribed spacer region (ITS), translation elongation factor 1-α gene (TEF), RNA polymerase II second largest subunit (RPB2), major allergen Alt a 1 gene (Alt a 1), endopolygalacturonase gene (endoPG), anonymous gene region (OPA10-2) and glyceraldehyde 3-phos-phatedehydrogenase (GAPDH) were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004), EF1-728F/EF1-986R (Carbone et al. 1999), RPB2-5F2/RPB2-5R (Sung et al. 2007), Alt-for/Alt-rev (Hong et al. 2005), EPG-specific/EPG-3b (Peever et al. 2004), OPA10-2R/OPA10-2L (Peever et al. 2004) and Gpd1/Gpd2 (Berbee et al. 1999) (GenBank accession no.MN046364, MW016001, MW016002, MW016003, MW016004, MW016005, MW016006). DNA sequences of TEF, RPB2, endoPG, OPA10-2 and GAPDH were 100% identical to those of A. tenuissima (MN256108, MK605866, KP789503, JQ859829 and MK683802), but ITS and Alt a 1 were 100% similarity with A. tenuissima (MN615420, JQ282277) and A. alternate (MT626589, KP123847). The ITS and Alt a 1 sequence did not distinguish A. tenuissima from the A. alternate complex. Maximum likelihood phylogenetic analyses were performed for the combined data set with TEF, RPB2, and endoPG using MEGA6 under the Tamura-Nei model (Kumar et al. 2016). The isolate Q1 clustered with type strain A. tenuissima CBS 918.96. The 20 celery plants of 4-7 leaf age were used test the pathogenicity of Q1, the ten plants were sprayed with 20ml of spore suspension (1×105 spores/ml), the control was sprayed with 20mL sterile water, which were placed in a growth chamber (25℃, a 14h light and 10h dark period, RH > 80%). Eight days after inoculation, 40% of the leaves formed lesions, which were consistent with the field observation，the control group was asymptomatic. The pathogen was reisolated from infected leaves to fulfill Koch’s postulates. To our knowledge, this is the first report of A. tenuissima causing leaf spot on celery in China.

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First Report of Phytophthora pseudosyringae Associated with Ink Disease of Castanea sativa in Italy

Plant Disease ◽

10.1094/pdis-94-8-1068b ◽

2010 ◽

Vol 94 (8) ◽

pp. 1068-1068 ◽

Cited By ~ 8

Author(s):

B. Scanu ◽

B. T. Linaldeddu ◽

A. Franceschini

Keyword(s):

Plant Protection ◽

Castanea Sativa ◽

Pond Water ◽

Culture Collection ◽

Selective Medium ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Representative Sequence ◽

Agar Plug ◽

Ink Disease

Since December 2008, a severe outbreak of ink disease has been observed in a chestnut grove in the Sardinia Region in Italy (40°01′N, 9°13′E, 1,200 m above sea level). Trees have shown symptoms such as microphylly and yellowish foliage as well as necrosis on the main roots and collar. Isolations were made from infected roots and soil using green apples as baits. Small pulp pieces were cut from the lesions that developed in the apples and plated on Phytophthora selective medium (1). In addition to Phytophthora cambivora, another Phytophthora sp. was detected from 60% of 25 symptomatic trees sampled. Colonies subcultured onto carrot agar (CA) were generally appressed and stellate. Growth occurred from 2 to 26°C with an optimum at 20°C (mean radial growth rate of 4.5 mm/day). Sporangia were produced abundantly in unsterile pond water; they were semipapillate, rarely bipapillate, limoniform or ovoid, occasionally caducous with short pedicels (<5 μm), and 35.2 to 58.1 (46.3) × 22.1 to 35.3 (31.9) μm, with a length/breadth ratio of 1.5:1. Catenulate hyphal swellings were frequently present, whereas no chlamydospores were observed. Isolates produced numerous homothallic oogonia with diameters from 23.7 to 31.7 (27.3) μm. Antheridia were predominantly paragynous. Cultural and morphological features were in close agreement with those described for P. pseudosyringae (2). Identity was confirmed by analysis of the internal transcribed spacer region (ITS1-5.8S-ITS2) of rDNA. BLAST searches at GenBank showed 100% identity with reference sequences of P. pseudosyringae (Accession Nos. AY230190 and EU074793). The representative sequence of one P. pseudosyringae strain (CST2A), stored in the culture collection of the Department of Plant Protection-University of Sassari, was submitted to GenBank (Accession No. GU460375). Koch's postulates were fulfilled by inoculating 10 5-month-old chestnut seedlings grown in pots. One shallow cut was made into the bark on the main stem and an agar plug colonized by P. pseudosyringae was inserted beneath the flap. Seedlings were kept at the laboratory at temperatures varying from 16 to 22°C and watered as necessary. After 20 days, extensive, sunken, necrotic lesions measuring 27.2 ± 1.9 mm (mean + standard error) developed around the inoculation sites. Control plants inoculated with sterile CA plugs did not show any disease symptoms. The pathogen was consistently reisolated from infected tissues. P. pseudosyringae has recently been reported as the causal agent of stem necroses on chestnut seedlings in a nursery in Spain (3). To our knowledge, this is the first report of P. pseudosyringae on Castanea sativa in Italy. References: (1) C. M. Brasier and S. A. Kirk. Plant Pathol. 50:218, 2001. (2) T. Jung et al. Mycol. Res. 107:772, 2003. (3) C. Pintos Varela et al. Plant Dis. 91:1517, 2007.

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First Report of Phytophthora tentaculata Causing Root and Stem Rot of Oregano in Italy

Plant Disease ◽

10.1094/pdis-93-8-0843b ◽

2009 ◽

Vol 93 (8) ◽

pp. 843-843 ◽

Cited By ~ 2

Author(s):

P. Martini ◽

A. Pane ◽

F. Raudino ◽

A. Chimento ◽

S. Scibetta ◽

...

Keyword(s):

Dna Amplification ◽

Its Region ◽

Selective Medium ◽

Stem Rot ◽

Universal Primers ◽

Basal Stem Rot ◽

First Report ◽

Soilborne Disease ◽

Potted Plants ◽

Morphological Criteria

Oregano (Origanum vulgare L.; Lamiaceae) is cultivated for culinary and medicinal purposes and as an ornamental. In October of 2007, 1- to 2-year-old potted plants of oregano showed symptoms of decline associated with root and basal stem rot in a nursery in Liguria (northern Italy) that produces 1 million to 1.5 million potted aromatic plants per year. Aboveground symptoms included leaf russeting and chlorosis, wilt, defoliation and dieback of twigs, browning of the basal stem, and subsequent collapse of the entire plant. Approximately 80% of the plants died within 30 days after the appearance of the first symptoms on the canopy. Approximately 20% of a stock of 30,000 oregano plants was affected. Stocks of other aromatic species, such as mint, lavender, rosemary, and sage, appeared healthy. A Phytophthora species was consistently isolated from symptomatic stems and roots of oregano plants on BNPRAH selective medium (2). Ten pure cultures were obtained by single-hypha transfers, and the species was identified as Phytophthora tentaculata Kröber & Marwitz by morphological criteria and sequencing of the internal transcribed spacer (ITS) region of rDNA using the ITS 4 and ITS 6 universal primers for DNA amplification. Isolates from oregano formed stoloniferous colonies with arachnoid mycelium on potato dextrose agar and had a growth rate of 2 to 3 mm per day at 24°C with optimum, minimum, and maximum temperatures of 24, 8, and 34°C, respectively. Sporangia formed in soil extract solution and were papillate and spherical or ovoid to obpyriform with a length/breadth ratio of 1.3:1. Few sporangia were caducous and all had a short pedicel (<5 μm). Hyphal swellings and chlamydospores were produced in sterile distilled water and corn meal agar, respectively. All isolates were homothallic and produced globose terminal oogonia (mean diameter of 34 μm) with one or occasionally two paragynous, monoclinous, or diclinous antheridia. Amphigynous antheridia were also observed. The sequence of the ITS region of the rDNA (GenBank No. FJ872545) of an isolate from oregano (IMI 395782) showed 99% similarity with sequences of two reference isolates of P. tentaculata (Accession Nos. AF266775 and AY881001). To test for pathogenicity, the exposed root crowns of 10 6-month-old potted plants of oregano were drench inoculated with 10 ml of a suspension of 2 × 104 zoospores/ml of isolate IMI 395782. Sterile water was pipetted onto the roots of 10 control plants. All plants were maintained in 100% humidity at 22 to 24°C in a greenhouse under natural light and watered once a week. Within 3 weeks after inoculation, all inoculated plants developed symptoms identical to those observed in the nursery and died within 30 to 40 days after the appearance of the first symptoms. Control plants remained healthy. P. tentaculata was reisolated solely from symptomatic plants. P. tentaculata has been reported previously on several herbaceous ornamental plants (1,3). However, to our knowledge, this is the first report of this species on O. vulgare. Root and basal stem rot caused by P. tentaculata is the most serious soilborne disease of oregano reported in Italy so far. References: (1) G. Cristinzio et al. Inf. Fitopatol. 2:28, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) H. Kröber and R. Marwitz. Z. Pflanzenkr. Pflanzenschutz 100:250, 1993.

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First report of Erysiphe cruciferarum causing powdery mildew of Alliaria petiolata in Maryland

Plant Disease ◽

10.1094/pdis-09-21-2060-pdn ◽

2021 ◽

Author(s):

Michael Robert Fulcher ◽

Paul C Owen-Smith

Keyword(s):

Powdery Mildew ◽

Invasive Plant ◽

Local Population ◽

Alliaria Petiolata ◽

Specific Information ◽

Garlic Mustard ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Erysiphe Cruciferarum ◽

Disease Free

Alliaria petiolata (Bieb.) Cavara & Grande (garlic mustard) is a biennial crucifer native to Europe and invasive in North America, where it outcompetes native plants in deciduous forests. In July 2021, powdery mildew was observed on A. petiolata in Frederick County, Maryland. Signs of the disease included white, tomentose mycelium producing abundant conidia (Fig S1). A majority of plants were affected, and severity ranged from the presence of small, discrete infections to complete colonization of leaves, stems, and ripening seed pods. Conidia from field collected leaves were transferred to disease-free A. petiolata for maintenance in a growth chamber at 20°C and 80% RH with a 12 hr photoperiod. Fungal morphology was recorded 30 days after this transfer. Appressoria were irregularly lobed, and conidiophores were straight and composed of 2-3 cells. Cylindrical to oblong conidia were produced singly in pseudochains of 2-6 (x̄ = 3), measured 39-64 by 18-29 (x̄ = 52 by 24) μm, had a length to width ratio greater than two, and germinated at the ends. Fibrosin bodies were absent from conidia, and chasmothecia were not observed in the field or on inoculated plant material. Based on anamorphic characteristics, the pathogen was placed in the genus Erysiphe (Boesewinkel 1980). Species level identity was determined using DNA sequences. Conidia and mycelia were scraped from leaves and used for genomic DNA extraction with the Quick-DNA Fungal/Bacterial Miniprep Kit (Zymo Research, Irvine, CA). A portion of the internal transcribed spacer region of rDNA was amplified using the primers ITS5/ITS4 (White et al. 1990). Purified amplicons (PCR & DNA Cleanup Kit, New England BioLabs Inc., Ipswich, MA) were sequenced at Eurofins Genomics (Louisville, KY). The resulting sequence was compared to those in NCBI GenBank using the blastn algorithm (Altschul et al. 1990). The newly generated sequence (GenBank: OK157430) was identical (599/599 bp) to samples of E. cruciferarum from the United Kingdom (GenBank: KY660931.1, KY660879.1, KY660752.1). Because E. cruciferarum sensu lato is heterogeneous (Pastirčáková et al. 2016), additional sequence comparisons were made to the E. cruciferarum sensu stricto holotype (589/599 bp, GenBank: KU672364) and a vouchered E. cruciferarum s. lat. (596/599 bp, GenBank: LC009943). This supports identification of the pathogen as E. cruciferarum s. lat. and suggests the taxonomy of isolates from A. petiolata should be reassessed following any revision to E. cruciferarum. A modified Koch’s postulates procedure was followed to confirm pathogenicity. Leaves colonized by E. cruciferarum were briefly pressed against the leaves of three disease-free plants grown from seed in a greenhouse. After 14 days, inoculated plants showed signs of powdery mildew similar to those observed in the field, and a control treatment using pathogen-free leaves resulted in no disease. This inoculation experiment was performed twice, and the identity of the pathogen was reconfirmed based on morphology. This is the first report of powdery mildew on A. petiolata in Maryland. Erysiphe cruciferarum s. lat. is widely distributed on other hosts and has been found on A. petiolata throughout Europe and in Ohio and Indiana (Farr and Rossman 2021; Blossey et al. 2001; Enright and Cipollini 2007; Ciola and Cipollini 2011). This pathogen has been proposed as a biological control agent (Cipollini and Enright 2009; Cipollini et al. 2020), and the presence of disease in Maryland suggests the local population of A. petiolata is susceptible to E. cruciferarum and the environment there is favorable to disease development. References: Altschul, S. F., et al. 1990. J. Mol. Biol. 215:403. Blossey, B., et al. 2001. Nat. Areas J. 21:357. Boesewinkel, H. J. 1980. Bot. Rev. 46:167. Ciola, V., and Cipollini, D. 2011. Am. Midl. Nat. 166:40-52. Cipollini, D., and Enright, S. M. 2009. Invasive Plant Sci. Manag. 2:253. Cipollini, D., et al. 2020. Biol. Invasions. 22:1657-1668. Enright, S. M., and Cipollini, D. 2007. Am. J. Bot. 94:1813. Farr, D. F., and Rossman, A. Y. 2021. Fungal Databases, Syst. Mycol. Microbial. Lab., ARS, USDA. https://nt.ars-grin.gov/fungaldatabases/ Pastirčáková, K., et al. 2016. Mycol. Prog. 15:36 White, T. J., et al. 1990. Page 315 in: PCR Protocols. A Guide to Methods and Applications, Academic Press, San Diego. Keywords: Alliaria petiolata, Erysiphe cruciferarum, garlic mustard, powdery mildew, invasive plant, biocontrol Funding and Disclaimer: The author(s) declare no conflict of interest. This work was supported by USDA-ARS Appropriated Project Number 8044-22000-047-000-D. Mention of trade names or commercial products in this report is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity lender, provider, and employer.

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First Report of Wilt and Dieback on Pokeweed (Phytolacca decandra) Caused by Phytophthora nicotianae

Plant Disease ◽

10.1094/pdis.2003.87.1.101c ◽

2003 ◽

Vol 87 (1) ◽

pp. 101-101

Author(s):

A. Belisario ◽

M. Maccaroni ◽

L. Corazza

Keyword(s):

Tap Water ◽

Selective Medium ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Malt Extract ◽

Internal Transcribed Spacer Region ◽

Invasive Weed ◽

Disease Symptoms ◽

First Report ◽

Perennial Plant

Pokeweed (Phytolacca decandra, synonym Phytolacca americana) is a root perennial plant that produces a succulent annual stem. In late June 2001, a severe dieback occurred on a group of pokeweed plants being grown as ornamentals in a garden in Rome. Disease symptoms consisted of leaf wilting followed by collapse of the plant. Stem collars and roots had dark brown-to-black water-soaked lesions. A wet rot was observed on plants with advanced disease symptoms. Isolations, from sections of roots and stems previously washed in running tap water, were made on PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, and 20 g of agar in 1,000 ml of H2O) (2), followed by incubation at 20°C. A species of Phytophthora identified based on morphological and cultural characteristics (1) was isolated consistently from rotted roots and collars of diseased plants. All isolates produced papillate, spherical, ovoid to obturbinate, noncaducous sporangia and terminal and intercalary chlamydospores. Hyphal swellings with hyphal outgrowths were present. Observed characteristics were similar to those described for P. nicotianae. Isolates were mating type A2 with amphigynous antheridia in paired cultures with the A1 tester isolate of P. nicotianae. Identification was confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of ribosomal DNA with those obtained from previously identified Phytophthora species. Pathogenicity tests were conducted on 10 2-month-old potted pokeweed plants. Inoculum was prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and growing for 4 weeks. The inoculum was added to potting soil at 3% (wt/vol), and sporulation was induced by flooding the soil for 48 h. Five uninoculated plants were used as controls. Plants were maintained outdoors and assessed for symptoms within 2 months after inoculation. Wilting, root rot, and dark brown lesions on the collar developed on inoculated plants. The pathogen was reisolated from the inoculated plants and morphologically identical to the original isolates, which confirmed P. nicotianae as the causal agent of the disease. Few diseases have been reported on Phytolacca decandra. This species is not only an invasive weed, but is also cultivated as an ornamental and medicinal plant. In addition, antiviral (PAP) and antifungal (Pa-AFP) proteins that are used as a remedy for several human and plant infections have been extracted from the plant. To our knowledge, this is the first report of P. nicotianae on pokeweed. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) A. M.Vettraino et al. Plant Pathol. 50:90, 2001.

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First Report of Phytophthora cryptogea in Walnut Stands in Italy

Plant Disease ◽

10.1094/pdis.2002.86.3.328c ◽

2002 ◽

Vol 86 (3) ◽

pp. 328-328 ◽

Cited By ~ 4

Author(s):

A. M. Vettraino ◽

A. Belisario ◽

M. Maccaroni ◽

N. Anselmi ◽

A. Vannini

Keyword(s):

Lateral Root ◽

Root Zone ◽

Lateral Roots ◽

Juglans Regia ◽

Central Italy ◽

The United States ◽

Selective Medium ◽

Northern Italy ◽

Internal Transcribed Spacer Region ◽

First Report

English (Persian) walnut (Juglans regia L.) is among the most widely cultivated species in pure and mixed plantations of broadleaved trees in Italy. A decline of walnut of increasing occurrence has been reported recently in new plantations in central and northern Italy. Symptoms of the decline were typically characterized by yellowing of the foliage, defoliation, and plant death. Dark, flame-shaped necroses were often present at the collar. Phytophthora cactorum, P. cambivora, and P. cinnamomi were among the species associated with necrotic tissues of the collar and main roots (1). Furthermore, a Phytophthora sp. was isolated from soil removed from the lateral root zone of 6 of 15 declining trees in 3 walnut plantations, 2 in northern Italy and 1 in central Italy. Isolations were made by baiting with Rhododendron leaves and plating on PARBhy selective medium (3). The species isolated was identified as P. cryptogea on the basis of morphological and cultural characteristics (2). All isolates produced oval to obpyriform, nonpapillate sporangia and were mating type A2. Identification of the isolates was confirmed by comparing the restriction fragment length polymorphism patterns of the internal transcribed spacer region of ribosomal DNA with those obtained from previously identified Phytophthora species. Pathogenicity tests on potted 2-year-old walnut seedlings were conducted using two isolates of P. cryptogea. Inoculum was prepared by growing isolates on sterilized millet seeds added to soil at 2.5% (wt/vol). Sporulation was induced by 24-h flooding of the soil. Symptoms were assessed 1 month after inoculation. Ten uninoculated seedlings were used as controls. Inoculated seedlings showed no symptoms on the tap root, but there were extensive necroses of lateral roots ranging from 14 to 75% (average 38.6 ± 6.7 SE) of total lateral root (dry weight) compared with values of 0 to 11% (average 3 ± 1.5 SE) for uninoculated seedlings. P. cryptogea was easily reisolated from infected lateral roots and from the soil of inoculated pots. The inoculation trials confirmed P. cryptogea as a feeder-root pathogen of walnut in Italy. To our knowledge, this is the first report of P. cryptogea on English walnut in Italy. This species often has been associated with walnut decline in the United States (2) and on other woody plants in Italy (3). References: (1) A. Belisario et al. Petria 11:127, 2001. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Association, St. Paul, MN, 1996. (3) A. M. Vettraino et al. Plant Pathol. 50:90, 2001.

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First Report of Phytophthora spp. as Pathogens of Pandorea jasminoides in Italy

Plant Disease ◽

10.1094/pdis-92-2-0313b ◽

2008 ◽

Vol 92 (2) ◽

pp. 313-313 ◽

Cited By ~ 3

Author(s):

A. Pane ◽

S. O. Cacciola ◽

A. Chimento ◽

C. Allatta ◽

S. Scibetta ◽

...

Keyword(s):

Growth Temperature ◽

Root Rot ◽

Selective Medium ◽

Phytophthora Nicotianae ◽

Optimum Growth ◽

Internal Transcribed Spacer Region ◽

Phytophthora Root Rot ◽

First Report ◽

Optimum Growth Temperature ◽

Phytophthora Spp

In the summer of 2005, approximately 5% of a nursery stock of 12-month-old potted plants of bower vine (Pandorea jasminoides (Lindl.) K. Schum.) in Sicily (Italy) showed wilt, leaf chlorosis, defoliation, root rot, and collapse of the entire plant. Three Phytophthora spp. (20, 50, and 30% of the isolations of the first, second, and third species, respectively) were isolated from rotted roots on BNPRAH selective medium (2). Single-hypha isolates of the first species formed petaloid colonies on potato dextrose agar (PDA) and had an optimum growth temperature of 25°C (9.3 mm/day); on V8 juice agar, they produced uni- and bipapillate, ovoid to limoniform sporangia with mean dimensions of 45 × 30 μm and a mean length/width (l/w) ratio of 1.4:1. They did not produce gametangia when paired with A1 and A2 isolates of Phytophthora nicotianae. The second species formed arachnoides colonies on PDA, had an optimum growth temperature of 30°C (6.9 mm/day) and produced sporangia that were uni- and bipapillate, ellipsoid, ovoid, or pyriform to spherical (dimensions 44 × 34 μm; l/w ratio 1.3:1). All isolates were A2 mating type and produced amphyginous antheridia and spherical oogonia with smooth walls. The third species formed rosaceous colonies on PDA, had an optimum growth temperature of 28 to 30°C (11.9 mm/day), and produced uni- and bipapillate, ellipsoid or limoniform, caducous sporangia (dimensions 52 × 26 μm; l/w ratio 2.1:1) with a tapered base and a long pedicel (as much as 150 μm). All isolates were A1 type and produced amphigynous antheridia and spherical oogonia with smooth walls. The three species were identified as P. citrophthora, P. nicotianae, and P. tropicalis, respectively. The electrophoretic analysis of the mycelial proteins and four isozymes (1) confirmed the identification. Blast analysis of the sequence of the internal transcribed spacer region of the rDNA of a P. tropicalis isolate from bower vine (GenBank Accession No. EU076731) showed 99% similarity with the sequence of a P. tropicalis isolate from Cuphea ignea (GenBank Accession No. DQ118649). The pathogenicity of three isolates from bower vine, IMI 395552 (P. citrophthora), IMI 395553 (P. nicotianae), and IMI 395346 (P. tropicalis), was tested on 3-month-old potted bower vine plants (10 plants for each isolate) by applying 10 ml of a suspension (2 × 104 zoospores/ml) to the root crown. The plants were maintained at 24°C and 95 to 100% relative humidity. All inoculated plants wilted after 4 weeks. Noninoculated control plants remained healthy. The three Phytophthora spp. were reisolated from symptomatic plants. To our knowledge, this is the first report of Phytophthora root rot of bower vine in Italy. References: (1) S. O. Cacciola et al. Plant Dis. 90:680, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996.

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First Report of Phytophthora Blight of Lily Caused by Phytophthora nicotianae in China

Plant Disease ◽

10.1094/pdis-94-6-0782a ◽

2010 ◽

Vol 94 (6) ◽

pp. 782-782 ◽

Cited By ~ 2

Author(s):

X. M. Yang ◽

J. H. Wang ◽

S. P. Qu ◽

L. H. Wang ◽

L. C. Peng

Keyword(s):

Soil Surface ◽

Soft Rot ◽

Selective Medium ◽

Phytophthora Nicotianae ◽

Cut Flower ◽

Phytophthora Blight ◽

First Report ◽

Research Technology ◽

Initial Symptoms ◽

Plant Pathol

Lily (Lilium spp.) is an economically important cut flower in China. In August 2009, 30 to 40% of plants of lily cv. Siberia in a greenhouse for cut flower production in Yunnan, China were severely diseased. Infected plants developed water-soaked lesions and soft rot on the base of stems and leaves near the soil surface. As the disease progressed, stems bent and plants collapsed. Soft rot symptoms were observed on some bulbs and roots of severely diseased plants. Small, diseased tissue fragments (approximately 3 mm) were surface disinfected with 0.5% NaOCl and then plated to Phytophthora selective medium (10% V8 juice agar) (4). Inoculated dishes were incubated at 25°C in the dark. After 5 days, white colonies with abundant aerial mycelia developed from all plated tissue samples. The fungus had aseptate hyphae. Sporangia were papillate, both caducous and noncaducous, and the shape ranged from ovoid to spherical. The dimensions of sporangia were 30 to 62 × 21 to 46 μm. On the basis of morphological features, isolates were identified as Phytophthora nicotianae Breda de Haan. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS1/ITS4 and sequenced. BLAST analysis of the 835-bp fragment showed a 99% homology with the sequence of P. nicotianae AY833527. The nucleotide sequence has been assigned GenBank No. GU299778. PCR amplification of genomic DNAs using the P. nicotianae-specific primer pair ITS3-PNIC1 generated a 455-bp sequence (3). The result further confirmed the identity of P. nicotianae. Pathogenicity tests were conducted in the greenhouse on lily cv. Siberia grown in pots. Ten 3-month-old plantlets were inoculated by watering the wounded stem bases and soil surface with 30 ml of zoospore suspensions (105 spores per ml). Five uninoculated plantlets were used as controls. All plantlets were covered with plastic bags and incubated at room temperature (22 to 26°C) for 48 h. Inoculated plants developed initial symptoms of slight chlorosis and wilting of lower leaves. Within a 3-week period, all plants died due to soft rot of stem bases and leaves. The pathogen was reisolated from inoculated plants but not from control plants that were symptomless. P. nicotianae has been reported as the causal agent of Phytophthora blight on lily in Korea, Japan, and Hungary (1,2). To our knowledge, this is the first report of Phytophthora blight of lily in China. References: (1) J. Bakonyi et al. Plant Pathol. 50:795, 2001. (2) H. J. Jee and W. G. Kim. Plant Pathol. J. 14:452, 1998. (3) P. W. Tooley et al. Appl. Environ. Microbiol. 63:1467, 1997. (4) X. B. Zheng. Phytophthora and Its Research Technology. Beijing. China Agriculture Press, Beijing, 1997.

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First Report of Phytophthora taxon niederhauserii Causing Root and Stem Rot of Mimosa in Italy

Plant Disease ◽

10.1094/pdis-09-12-0889-pdn ◽

2013 ◽

Vol 97 (5) ◽

pp. 688-688 ◽

Cited By ~ 3

Author(s):

R. Faedda ◽

S. O. Cacciola ◽

A. Pane ◽

P. Martini ◽

M. Odasso ◽

...

Keyword(s):

Mating Type ◽

Consensus Sequence ◽

Aerial Mycelium ◽

Selective Medium ◽

Phytophthora Species ◽

Stem Rot ◽

Basal Stem Rot ◽

First Report ◽

Acacia Dealbata ◽

Potted Plants

Mimosa [Acacia dealbata Link, syn. Acacia decurrens (Wendl. F.) Wild. var. dealbata (Link) F. Muell., Fabaceae] is an evergreen shrub native to southeastern Australia that is cultivated as an ornamental plant in warm temperate regions of the world. In spring 2010, in a commercial nursery in Liguria (northern Italy), 6- to 10-month-old potted plants of A. dealbata showed symptoms of sudden collapse, defoliation, and wilt associated with root and basal stem rot. An abundant gum exudate oozed from the basal stem. A Phytophthora species was consistently isolated from roots and stem on BNPRAH selective medium (4). On V8 agar (V8A), axenic cultures obtained by single hyphal transfers formed stellate to radiate colonies with aerial mycelium whereas on potato dextrose agar (PDA) the colonies grew more slowly than on V8A and showed stoloniform mycelium and irregular margins. Minimum and maximum growth temperatures on PDA were 10 and 35°C, with the optimum at 30°C. In water, all isolates produced catenulate or single fusiform hyphal swellings and ellipsoid, nonpapillate, persistent sporangia. Dimensions of sporangia were 46.1 to 65.4 × 23.1 to 30.8 μm (mean l/b ratio 2.1). All isolates were A1 mating type and produced spherical oogonia with amphyginous antheridia when paired with A2 mating type of P. drechsleri Tucker on V8A plus β-sytosterol (4). Internal transcribed spacer (ITS) regions of rDNA of the representative Phytophthora isolate IMI 500394 from A. dealbata were amplified and sequenced in both directions with primers ITS6/ITS4. The consensus sequence (GenBank Accession No. JF900371) was 99% similar to sequences of several isolates identified as Phytophthora taxon niederhauserii Z.G. Abad and J.A. Abad (e.g., GQ848201 and EU244850). Pathogenicity tests were performed on 1-year-old potted plants of A. dealbata with isolate IMI 500394. Twenty plants were transplanted into pots (12-cm-diameter) filled with soil infested (4% v/v) with the inoculum of IMI500394 produced on kernel seeds. Plants were kept in a greenhouse with natural light at 25 ± 2°C and watered to field capacity weekly. All inoculated plants showed symptoms of wilt, leaf chlorosis, and basal stem rot within 3 to 4 weeks. Twenty control plants transplanted in autoclaved soil mix remained healthy. P. taxon niederhauserii was reisolated solely from inoculated plants, thus fulfilling Koch's postulates. Since 2003, this pathogen has been found on bottlebrush and rock rose grown in a nursery in Sicily (southern Italy), as well as on Banksia in a nursery in Liguria (2,3). To our knowledge, this is the first report of P. taxon niederhauserii on A. dealbata. P. taxon niederhauserii, recently described as P. niederhauserii sp. nov. (1), is a polyphagous pathogen that was originally reported on arborvitae and ivy in North Carolina in 2001. References: (1) Z. G. Abad et al. Mycologia (in press), 2013. (2) S. O. Cacciola et al. Plant Dis. 93:1075, 2009. (3) S. O. Cacciola et al. Plant Dis. 93:1216, 2009. (4) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996.

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