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

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 Taxon Walnut in Lombardy, North Italy

Plant Disease ◽

10.1094/pdis-07-13-0766-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 424-424 ◽

Cited By ~ 2

Author(s):

B. Ginetti ◽

A. Ragazzi ◽

S. Moricca

Keyword(s):

Optimal Growth ◽

Pond Water ◽

Selective Medium ◽

Its Rdna ◽

Sequence Information ◽

Cox1 Gene ◽

Riparian Ecosystems ◽

First Report ◽

Agar Plug ◽

Crown Thinning

The park Boscoincittà, Milan, North Italy (136 m a.s.l., 45°29′06″ N, 9°5′32″ E), has an area of 110 ha and includes tree stands, wood clearings, trails, and watercourses. Recently, common walnut (Jugland regia) trees in the park have begun to suffer from a progressive dieback that has caused roughly 90% mortality. Aerial symptoms were stunted growth, loss of vigor, crown thinning, and bark cankers with tarry exudates on the lower stem. The xylem tissue of trees showed large necrosis and flame-shaped discoloration below the bark. Since the dieback seemed caused by Phytophthora, samples were taken from three symptomatic trees and, by baiting, from the nearby soil and watercourses. Isolations from apple baits were carried out after a week. Isolations taken from tissue at the edge of active lesions of the trees were transferred on the selective medium V8A-PARPNH (1) and incubated at 24°C. Cottony colonies appeared after 3 days and single hyphal tip derivatives were transferred to V8A for a further 4 to 7 days. Fragments (1 cm2) of mycelium of the subcultured colonies were then placed in filtered (Ø 0.22 μm nitrocellulose filters, Millipore) pond water. Three isolates were retrieved within 24 h, two from tree tissue and one from water. These produced ovoid, non-papillate sporangia, of which 30 per isolate were measured. Sporangia averaged 52.5 ± 9.6 × 32.9 ± 4.7 μm (range 30.8 to 67 × 22.5 to 42.8) with a l:b ratio of 1.59 ± 0.19 (range 1.27 to 2.05), and exit pores of 11.1 ± 1.7 μm (range 7.31 to 14.21). External proliferation from previously emptied sporangia and hyphal swellings were observed on V8A. On V8A, colonies had optimal growth at 32°C (5.7 ± 0.8 mm d–1) with a maximum at 37°C. Colonies had a chrysanthemum-shaped, scanty fluffy aspect on PDA. Isolates were identified as Phytophthora taxon walnut on the basis of macro- and micro-morphology and sequence information from the ITS-rDNA region, that was amplified with primers ITS6 and ITS4 (3) after DNA extraction with a commercial kit (Sigma Aldrich). A region of the cox1 gene of isolate B164 was also amplified with primers OomCoxILevup and Fm85mod (4) and sequenced (GenBank Accession No. KC291584), but this was irrelevant for identification purposes because that gene region has not been sequenced for other isolates of this taxon. A BLAST search in GenBank and the Phytophthora database revealed a 99% identity of the ITS-rDNA from our isolate B164 (KC291550) with the P. taxon walnut isolate P532 (AF541910) (2). Inoculation trials were conducted on 10 detached leaves. A little lesion was produced with a sterile scalpel on the lower leaf surfaces and a 0.5 cm Ø agar plug was placed over the wounds. Necrotic lesions averaged 3.7 ± 1.6 × 2.0 ± 0.5 cm after 1 week of incubation at 20°C in the dark. Control leaves showed no symptoms. Re-isolations on V8-PARPNH agar confirmed Phytophthora taxon walnut as the causal agent. Members of the Phytophthora genus grouping with the Phytophthora taxon walnut in clade 6 are mainly reported as saprophytes or pathogens from riparian ecosystems and forests (2). To our knowledge, this is the first report of Phytophthora taxon walnut from Italy. Since the oomycete proved in our growth trial to be distinctly thermophilic, we hypothesize that its spread is being favored by the rising temperatures observed during the last decades in the area. References: (1) Y. Balci et al. Plant Dis. 91:705, 2007. (2) C. M. Brasier et al. Mycol. Res. 107:277, 2003. (3) D. E. L. Cooke et al. Fungal Gen. Biol. 30:17, 2000. (4) G. P. Robideau et al. Bioinformatics 19:1572, 2011.

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First Report of Foliar Infection of Maianthemum racemosum by Phytophthora ramorum

Plant Disease ◽

10.1094/pd-89-0204c ◽

2005 ◽

Vol 89 (2) ◽

pp. 204-204 ◽

Cited By ~ 3

Author(s):

D. Hüberli ◽

K. L. Ivors ◽

A. Smith ◽

J. G. Tse ◽

M. Garbelotto

Keyword(s):

Mixed Forest ◽

Personal Communication ◽

Culture Collection ◽

Phytophthora Ramorum ◽

Internal Transcribed Spacer Region ◽

Coast Redwood ◽

First Report ◽

Plastic Bags ◽

Artificial Inoculations ◽

Water Plants

In May 2003, Phytophthora ramorum S. Werres & A.W.A.M. de Cock was isolated from the leaf tips of a single plant of false Solomon's seal (Maianthemum racemosum (L.) Link, formely known as Smilacina racemosa (L.) Desf.), a native, herbaceous perennial of the Liliaceae family, at the Jack London State Park in Sonoma County, California. Affected leaves had cream-to-brown lesions on the tips that were delimited by a yellow chlorotic zone. Lesions on the stems were not observed. The isolate (American Type Culture Collection [ATCC], Manassas, VA, MYA-3280; Centraal Bureau voor Schimmelcultures, Baarn, the Netherlands, CBS 114391) was typical of P. ramorum with large chlamydospores and caduceus, semipapillate sporangia, and the sequence (GenBank Accession No. AY526570) of the internal transcribed spacer region of the rDNA matched those published previously (4). The site, from which wood rose (Rosa gymnocarpa) was recently identified as a host, is a mixed forest containing confirmed P. ramorum-infected coast redwood (Sequoia sempervirens), California bay laurel (Umbellularia californica), and tanoak (Lithocarpus densiflora) trees (2,3). Two leaves per asymptomatic, pesticide free, potted plant of false Solomon's seal were inoculated with zoospores of the P. ramorum isolate obtained from infected false Solomon's seal (1). Five plants were inoculated in trial 1, and the following day, three plants were inoculated in trial 2. A control leaf of each plant was dipped in sterile deionized water. Plants were enclosed in plastic bags, misted regularly with sterile distilled water, and maintained at 16 to 21°C in the greenhouse. In both trials, plants did not have lesions on the leaves after 16 days and were reinoculated on separate days for each trial with higher concentrations of zoospores (1 × 105 [trial 1] and 2 × 105 [trial 2] zoospores/ml). Cream-colored lesions, similar to those observed in the field, were evident 1 week after the second inoculation and stopped progressing in both trials by 17 days. Lesions starting from the leaf tips averaged 13 mm (range 8 to 24 mm) long, and P. ramorum was reisolated on Phytophthora-selective agar medium modified with 25 mg of pentachloronitrobenzene from 44% (trial 1) and 83% (trial 2) of all lesions (4). Control leaves had no lesions, and P. ramorum was not reisolated. Sporangia were not observed on any leaves when examined with the dissecting microscope. The fact that lesions developed only after a second inoculation with higher concentrations of zoospores, and these lesions stopped progressing after 17 days, suggests that false Solomon's seal is much less susceptible than other hosts such as western starflower (Trientalis latifolia) (1) and wood rose (2). To our knowledge, this is the first report of a plant from the Liliaceae as a natural host for P. ramorum, although Smilax aspersa was identified as being susceptible in artificial inoculations of detached leaves (E. Moralejo and L. Hernández, personal communication). False Solomon's seal is popular in the horticultural industry. References: (1) D. Hüberli et al. Plant Dis. 87:599, 2003. (2) D. Hüberli et al. Plant Dis. 88:430, 2004. (3) P. E. Maloney et al. Plant Dis. 86:1274, 2002. (4) D. M. Rizzo et al. Plant Dis. 86:205, 2002.

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First Report of Phytophthora ramorum on Viburnum bodnantense in Belgium

Plant Disease ◽

10.1094/pdis.2003.87.2.203c ◽

2003 ◽

Vol 87 (2) ◽

pp. 203-203 ◽

Cited By ~ 11

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.

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First Report of Grapevine Cankers Caused by Lasiodiplodia crassispora and Neofusicoccum mediterraneum in California

Plant Disease ◽

10.1094/pdis-94-6-0785b ◽

2010 ◽

Vol 94 (6) ◽

pp. 785-785 ◽

Cited By ~ 10

Author(s):

J. R. Úrbez-Torres ◽

F. Peduto ◽

W. D. Gubler

Keyword(s):

Dna Sequences ◽

Vascular Tissue ◽

Elongation Factor ◽

Fungal Culture ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Consensus Sequences ◽

Fast Growing ◽

Agar Plug ◽

Vascular Discoloration

Several species in the Botryosphaeriaceae family cause perennial cankers in the vascular tissue of grapevines and are responsible for the disease known as bot canker in California (3). Tissue from grapevine vascular cankers from samples submitted to our laboratory in the summer of 2009 were plated onto potato dextrose agar (PDA) amended with 0.01% tetracycline hydrochloride. Lasiodiplodia crassispora (Burgess & Barber) and Neofusicoccum mediterraneum (Crous, M.J. Wingf. & A.J.L. Phillips) were identified based on morphological and cultural characters as well as analyses of nucleotide sequences. L. crassispora isolates were characterized by a fast-growing, white mycelium that turned dark olivaceous with age on PDA. Conidia from pycnidia formed in cultures were thick walled and pigmented with one septum and vertical striations when mature. Conidia measured (25.8–) 27.5 to 30.5 (–33.4) × (12.1) 14.3 to 16.8 (–18.2) μm (n = 60). Pycnidia contained septate paraphyses. N. mediterraneum was characterized as having moderately fast-growing, light green mycelia on PDA. Pycnidia formation was induced with pine needles placed on 2% water agar. Conidia from pycnidia were hyaline, ellipsoidal, thin walled, unicellular, and measured (18.2–) 20.5 to 27.8 (–29) × (5.1) 5.9 to 6.5 (–7.2) μm (n = 60). DNA sequences of the internal transcribed spacer region (ITS1-5.8S-ITS2), part of the β-tubulin gene (BT2), and part of the translation elongation factor 1-α gene (EF1-α) from L. crassispora (UCD23Co, UCD24Co, and UCD27Co) and N. mediterraneum (UCD695SJ, UCD719SJ, UCD720SJ, UCD749St, and UCD796St) grapevine isolates from California were amplified and sequenced. Consensus sequences from L. crassispora and N. mediterraneum from California showed 99 to 100% homology with L. crassispora and N. mediterraneum isolates previously identified and deposited in GenBank (1,2). Sequences from the examined DNA regions of all isolates were deposited at GenBank (GU799450 to GU799457 and GU799473 to GU799488). Pathogenicity tests using three isolates per species were conducted on detached dormant canes of cv. Red Globe. Ten canes per isolate were inoculated by placing a 7-day-old 5-mm-diameter agar plug from each fungal culture into a wound made with a drill on the internode (4). Twenty shoots were inoculated with noncolonized PDA plugs for negative controls. Six weeks after inoculations, necrosis was measured from the point of inoculation in both directions. One-way analysis of variance was performed to assess differences in the extent of vascular discoloration and means were compared using Tukey's test. L. crassispora isolates caused an average necrotic length of 21.1 mm, which was significantly lower (P < 0.05) than the average necrotic length of 35.6 mm caused by the N. mediterraneum isolates. Reisolation of L. crassispora and N. mediterraneum from necrotic tissue was 100% for each species. The extent of vascular discoloration in infected canes was significantly greater (P < 0.05) than in control inoculations (8 mm) from which no fungi were reisolated from the slightly discolored tissue. To our knowledge, this is the first report of L. crassispora and N. mediterraneum as pathogens of Vitis vinifera and as a cause of grapevine cankers in California. References: (1) T. I. Burgess et al. Mycologia 98:423, 2006. (2) P. W. Crous et al. Fungal Planet. No. 19, 2007. (3) J. R. Úrbez-Torres and W. D. Gubler. Plant Dis. 93:584, 2009. (4) J. R. Úrbez-Torres et al. Am. J. Enol. Vitic. 60:497, 2009.

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First Report of Valsa leucostoma Causing Valsa Canker of Pyrus communis (cv. Duchess de' Angouleme) in China

Plant Disease ◽

10.1094/pdis-07-13-0704-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 422-422 ◽

Cited By ~ 1

Author(s):

M. X. Zhang ◽

L. F. Zhai ◽

W. X. Xu ◽

N. Hong ◽

G. P. Wang

Keyword(s):

Pyrus Communis ◽

Liaoning Province ◽

Post Inoculation ◽

Internal Transcribed Spacer Region ◽

Canker Disease ◽

First Report ◽

Agar Plug ◽

Valsa Canker ◽

Pear Trees ◽

Β Tubulin

Pear is a popular fruit in the world market, and has been widely cultivated in China. Since 2008, a severe canker disease has consistently been observed on 20-year-old pear trees (Pyrus communis cv. Duchess de' Angouleme) grown in a nursery in Xingcheng, Liaoning Province, China. Observed symptoms include brown elongated ulcerative lesions (more than 20 cm in length in general), with red brown conidia produced on wet lesions. Reductions in tree vigor and yield were observed for infected trees. Tree mortality was observed for severe infections. To diagnose the pathogen, 15 canker samples were collected from five pear trees in April, 2012. Bark pieces (3 to 5 mm) taken from the border of healthy and diseased tissue were surface-disinfected with 0.1% mercury bichloride and 75% ethanol for 45 s, and placed on potato dextrose agar (PDA) medium at 25°C in darkness. Fungal colonies with a common colony morphology were consistently recovered from three samples. These fungal colonies were initially white, becoming olive green in 3 days. Conidia produced on colonies were hyaline, allantoid, and single-celled with average length × width of 6.04 (5.43 to 6.59) × 0.65 (0.51 to 0.73) μm, which were consistent with descriptions of Valsa leucostoma (1). Genomic DNA was extracted from a representative isolate F-LN-32b, and subjected to PCR amplification of the internal transcribed spacer region (ITS), β-tubulin gene, and EF1 gene using the primer pairs ITS1/ITS4, Bt2a/Bt2b and EF1-728F/EF1-986R (3), respectively. Sequence alignment of the amplified fragments with the deposited data in NCBI showed that sequences of EF1, ITS, and β-tubulin (GenBank Accession No. KF293296 to KF293298, respectively) of isolate F-LN-32b had the highest similarity of 99% to those of V. leucostoma strain 32-2w (JQ900340, JN584644, and JQ900374), and suggested that isolate F-LN-32b is a V. leucostoma strain. Pathogenicity tests was carried out by placing a 5-mm-diameter, 2-day-old mycelium agar plug of isolate F-LN-32b onto a punched bark hole of a detached 1-year-old pear shoot after it was surface disinfested with ethanol. Inoculated shoots were incubated at 25°C in plastic containers covered with plastic film. Pathogenicity assays were conducted on 18 pear varieties (cvs. Qiuyue, Jinshui 2, Hohsui, Huali 1, Cuiguan, Shinseiki, Xuehua, Dangshansu, Zaosu, Hongxiangsu, Yuluxiang, Nanguoli, Xizilv, Bartlett, Huanghua, Huashan, Duchess de' Angouleme, and Packham's) collected from a nursery in Wuhan, Hubei Province, China. Six shoots were inoculated for each variety and the assay was conducted three times. All inoculated shoots developed the typical canker symptoms after 6 days post inoculation (dpi) and sporulated at 25 dpi while the control shoots inoculated with non-colonized PDA plugs remained asymptomatic. Isolates recovered from inoculated samples were of the same morphology and ITS sequence as F-LN-32b. Based on these results, V. leucostoma was determined as the pathogen responsible for the Valsa canker disease on pear. Valsa mali var. pyri was identified as the only pathogen causing Valsa canker disease on pear in China (2). To our knowledge, this is the first report of V. leucostoma causing a canker disease on pear in China. References: (1) G. C. Adams et al. Australas. Plant Pathol. 35:521, 2006. (2) X. L. Wang et al. Mycologia 103:317, 2011. (3) T. J. White et al. Pages 315-322 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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First Report of Curvularia eragrostidis Causing Postharvest Rot on Pineapple in Brazil

Plant Disease ◽

10.1094/pdis-03-14-0288-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1277-1277 ◽

Cited By ~ 4

Author(s):

A. P. S. Ferreira ◽

D. B. Pinho ◽

A. R. Machado ◽

O. L. Pereira

Keyword(s):

Mechanical Damage ◽

Morphological Characteristics ◽

Its Region ◽

Longitudinal Section ◽

Culture Collection ◽

Ananas Comosus ◽

Single Spore ◽

First Report ◽

Agar Plug ◽

Postharvest Rot

Pineapple (Ananas comosus L. Merril.) is the main plant of the Bromeliaceae, cultivated economically for the fruits' appealing flavor and a refreshing sugar-acid balance. In 2013, fruits with no initially visible symptoms began to show a postharvest rot after 3 days in a market in the municipality of Viçosa, Minas Gerais, Brazil. The rot can rarely be detected from the outside of the fruit, but a longitudinal section allows observation of extension of the affected area toward the center of the fruit. The symptoms initially appear as a dark brown to black rot on surface of the fruits, which gradually enlarges in size, leading to increased rot and disposal of infected fruits. Until now, this disease occurred sporadically and caused small losses. A fungus was isolated from rot observed in fruits from cultivar Pérola and a single-spore culture was deposited in the culture collection of the Universidade Federal de Viçosa (Accession No. COAD 1588). After 7 days of incubation at 25°C, the strain displayed radial growth and gray-white to black colonies. Microscopic observations revealed brown to light brown conidiophores present singly or in groups. The septate, simple or rarely branched conidiophores are straight or curved, up to 245 μm long and 5 μm wide, and some have a geniculate growth pattern near the apex. The conidia are ellipsoidal or barrel-shaped and 22 to 25 μm long and 10 to 12.5 μm wide. The median septum appears as a black band and the cells at each end of the conidia are pale, whereas the intermediate cells are brown or dark brown. Based on morphological characteristics, the fungus was identified as Curvularia eragrostidis (4). To confirm this identification, DNA was extracted and sequences of the internal transcribed spacer (ITS), 28S and 18S rDNA regions were obtained and deposited in GenBank (Accession Nos. KJ541818 to KJ541820). The sequence of the ITS region exhibited 99% identity over 530 bp with other C. eragrostidis sequence in GenBank (JN943449) and Bayesian inference analysis placed our isolate in the same clade with others C. eragrostidis (study S15670 deposited in TreeBASE). Koch's postulates were conducted by inoculating six fruits of pineapple previously disinfected with 2% sodium hypochlorite and washed in sterile distilled water. For inoculation, the isolate was grown in potato dextrose agar (PDA) for 15 days at 25°C. Six millimeter diameter disks were removed from the surface of fruits with a sterile cork borer and replaced with PDA disks containing mycelia from the margins of the culture. An agar plug was deposited in three control fruits and all fruits were maintained at 25°C in plastic trays. Inoculated fruits showed symptoms 7 days after inoculation that were similar to those initially observed in the infected fruits, while control fruits showed no symptoms. C. eragrostidis is a cosmopolitan pathogen that infects hosts from several botanical families (2,4). In Brazil, this fungus causes leaf spot on A. comosus (3) and also infects Allium sativum, Dioscorea alata, D. cayenensis, Oryza sativa, Sorghum bicolor, Vigna unguiculata, and Zea mays (1). To our knowledge, this is the first report of C. eragrostidis causing postharvest rot disease in pineapple in Brazil. Because invasion of the fungus can occur through minute fractures, fruits should be carefully handled to avoid mechanical damage. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases , 18 February 2014. (2) D. S. Manamgoda et al. Fungal Divers. 51:3, 2011. (3) J. J. Ponte et al. Fitopatologia 10:21, 1975. (4) A. Sivanesan. Mycological Papers 158:113, 1987.

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First Report of Southern Blight of Silvery Messerschmidia Seedlings in Taiwan

Plant Disease ◽

10.1094/pdis-91-9-1198a ◽

2007 ◽

Vol 91 (9) ◽

pp. 1198-1198

Author(s):

C. Y. Chen ◽

C. H. Fu ◽

W. W. Hsiao ◽

E. J. Sun

Keyword(s):

Plant Protection ◽

Plant Diseases ◽

First Report ◽

Southern Blight ◽

Republic Of China ◽

Agar Plug ◽

Initial Symptoms ◽

Stem Necrosis ◽

The Republic Of China ◽

The Republic

Silvery messerschmidia, Messerschmidia argentea (L.) Johnston, of the Boraginaceae, is indigenous to Taiwan and grown as an ornamental, for windbreaks, or as a shade tree. During the summer of 2005, a sudden wilt of 1-year-old plants was observed in a nursery in central Taiwan. Initial symptoms included stem necrosis at the collar, leaf yellowing, and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted, defoliated, and died. Necrotic tissues were covered with whitish mycelium with clamp connections that formed reddish brown spherical (1 to 2.2 mm in diameter) sclerotia. A fungus was consistently recovered from the interface of diseased and healthy stem tissue, disinfested for 1 min in 0.5% NaOCl, and plated on Difco (Sparks, MD) potato dextrose agar (PDA) amended with 100 ppm of ampicillin. Pure cultures were prepared by transferring single hyphal tips to PDA, and Sclerotium rolfsii (Sacc.) was identified (1). Pathogenicity of two S. rolfsii isolates was confirmed by inoculating 3-month-old silvery messerschmidia seedlings grown in pots. Inoculum consisted of a single agar disk of a 7-day-old culture used per pot or a single sclerotium produced in 10 days on PDA and added per pot. Both the mycelium on the 0.5-cm-diameter agar plug and the sclerotium touched the base of the plant stem. Four plants were inoculated with mycelia, four with sclerotia, and four were noninoculated controls. All plants were kept in a growth chamber at 25 to 35°C with relative humidity of more than 95%. Initially, the basal stems were covered by whitish mycelia growth with a fanlike pattern from the inoculum, and brown, water-soaked necrotic lesions developed near the soil line. Inoculated plants developed symptoms within 4 days, wilted gradually in 7 days, and all were eventually killed in 11 days. Plants inoculated with sclerotia developed disease at a slower rate and control plants remained symptomless. Sclerotia developed on diseased tissues and S. rolfsii was reisolated. This disease has been observed on many species of plants (2), but to our knowledge, this is the first report of southern blight of silvery messerschmidia seedlings caused by S. rolfsii in Taiwan. References: (1) R. K. Jones and D. M. Benson, eds. Diseases of Woody Ornamentals and Trees in Nurseries. The American Phytopathological Society, St. Paul, MN, 2001. (2) Y. P. Tsai, ed. List of Plant Diseases in Taiwan. The Plant Protection Society of the Republic of China and The Phytopathological Society of the Republic of China, 1991.

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First Report of Phoma strasseri as a Pathogen of Stachys officinalis in Bulgaria

Plant Disease ◽

10.1094/pdis.2002.86.6.699b ◽

2002 ◽

Vol 86 (6) ◽

pp. 699-699

Author(s):

S. G. Bobev ◽

A. F. Margina ◽

J. de Gruyter

Keyword(s):

Plant Protection ◽

Aerial Mycelium ◽

Culture Collection ◽

Leaf Spot Disease ◽

Oatmeal Agar ◽

First Report ◽

Average Temperature ◽

Leaf Spots ◽

Monarda Didyma

For several years, a leaf spot disease has been observed on Betony, Stachys officinalis (synonym Betonica officinalis), in an experimental field in Kazanlak, Bulgaria. The round to somewhat angular spots (6 to 8 mm diameter) are dark brown with a pale center and have a chlorotic halo. A Phoma species isolated from the lesions formed regular to irregular, light brown colonies on potato dextrose agar (PDA). The isolate was studied as described by de Gruyter and Noordeloos (2). After 7 days, the growth rate was 43 mm on oatmeal agar and 33 mm on malt agar; the colonies were olivaceous gray-to-glauceous gray with a regular outline and with finely floccose, white-to-olivaceous gray aerial mycelium. Pycnidia, produced after 2 weeks, were ostiolate, globose to subglobose, 120 to 280 μm in diameter, citrine or honey, and later olivaceous to olivaceous black. The conidiogenous cells were globose to bottle shaped, 2 to 6 × 3 to 5 μm. The conidia were hyaline and unicellular, 5 to 7.5 × 2.5 to 4.2 μm, cylindrical to ellipsoidal with several small, scattered guttules. Chlamydospores were absent. According to these in vitro characters and after comparing the isolate with several Phoma isolates present in the culture collection of the Dutch Plant Protection Service, Wageningen, the Netherlands, the fungus has been identified as Phoma strasseri Moesz. The pathogenicity of the isolate was confirmed by artificial leaf inoculation of potted S. officinalis plants with a spore suspension (8 × 106 spores per ml) kept in a moist chamber for 48 h at a mean average temperature of 16°C. Leaf spots observed 4 to 5 days after inoculation were similar to those observed in the field. P. strasseri was subsequently reisolated from the spots. P. strasseri (synonym Phoma mentae Strasser) has been recorded as the cause of rhizome and stem rot on mint, Mentha spp., in Europe, Japan, and North America (3). In addition, this fungus has been found in New Zealand (strain identified at the Dutch Plant Protection Service, unpublished data). To our knowledge, this is the first report of P. strasseri on S. officinalis in Bulgaria. P. strasseri may produce septate conidia and, therefore, can be classified in Phoma section Phyllostictoides Zherbele ex Boerema (1). P. strasseri clearly differs from other Phoma species described on Lamiaceae: Phoma leonuri Letendre (Phoma section Plenodomus (Preuss) Boerema et al., pycnidia scleroplectenchymatous, conidia aseptate, 3.5 to 5.5 × 1.5 to 2.5 μm), Phoma dorenboschii Noordel. & de Gruyter (Phoma Sacc. section Phoma, conidia aseptate, 3 to 5.5 × 2 to 2.5 μm, producing dendritic crystals in vitro), and Phoma valerianae Henn. (Phoma Sacc. section Phoma, conidia aseptate, 2.5 to 4 × 1.5 to 2 μm). Occasionally P. strasseri has been isolated from other Lamiaceae, namely Monarda didyma (Dutch Plant Protection Service, unpublished data). There is also a report from Valeriana sp. (3). References: (1) G. H. Boerema. Mycotaxon 64:321, 1998. (2) J. de Gruyter and M. E. Noordeloos. Persoonia 15(1):71, 1992. (3) C. E. Horner. Plant Dis. Rep. 55:814, 1971.

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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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