First Report of Armillaria mellea on a Fern from Italy

Several perennial species of rhizomatous herbaceous ferns are cultivated as ornamental foliage plants. During late summer 1999, in a garden at the foot of Mount Etna, eastern Sicily (Italy), we noted a fern hedge showing patches of withered or stunted plants. The fern was identified as Cyrtomium falcatum (L.f.) C. Presl. (=Polystichum falcatum (L.f.) Diels), a house holly fern or Japanese holly fern, which is an ornamental fern native to East and South Asia. Other woody plants in the immediate vicinity had died over the last few years, including apricot and cedar trees whose stumps had not been removed. A close examination of uprooted ferns revealed the presence of creamy white fan-shaped mycelial mats with an odor typical of Armillaria species that were intermixed with the felt-like tangle formed by the rhizomes and roots of the ferns. In autumn, clumps of honey mushrooms with an annulus grew around patches of the withered fern hedge and in other parts of the same garden. The spore print of the basidiocarp was light cream. Basidiospores (8 to 9 × 5 to 6.5 µm) examined under a microscope were hyaline and apiculate. The fungus was isolated in pure culture from infected rhizomes with the selective medium of Kulman and Hendrix (3). In pure culture on 2% malt agar, the fungus formed ribbon-shaped, contorted, fast-growing rhizomorphs that branched profusely. Mycelial proteins of the isolate were analyzed by both polyacrylamide slab gel and starch gel electrophoreses, as described by Bragaloni et al. (1). The electrophoretic patterns of five isozymes (esterase, glutamic oxalacetic transaminase, phospho-glucomutase, alcohol dehydrogenase, and polygalacturonase) of the isolate from fern were identical to those of the reference isolate of A. mellea (Vahl:Fr.) Kumm. from grapevine. Conversely, the patterns were clearly distinct from those of reference isolates from other species, including A. ostoyae (Romagnesi) Herink, A. bulbosa (Barla) Kile et Watling, and A. cepistipes Velenovsky. Thus, on the basis of cultural, morphological, and biochemical characteristics, the species infecting the fern was identified as A. mellea. This pathogen, very common and widespread on wooded or previously wooded sites, has an extremely wide host range, encompassing both woody and herbaceous plants (2,4). However, this is the first report of A. mellea on a fern in Italy. References: (1) M. Bragaloni and N. Anselmi. Eur. J. For. Pathol. 27:147, 1997. (2) D. F. Farr et al. 1989. Fungi on Plants and Plants Products in the United States. The American Phytopathological Society, St. Paul, MN. (3) E. G. Kulman and F. F. Hendrix. Phytopathology 52:1310, 1962. (4) C. G. Shaw and G. A. Kile. 1991 Armillaria root disease. Agric. Handb. No 691. U.S. Department of Agriculture Forest Service, Washington, DC.

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

Plant Disease ◽

10.1094/pdis-10-13-1030-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 849-849 ◽

Cited By ~ 1

Author(s):

A. Colmán ◽

R. A. da Silva ◽

R. Alves ◽

M. Silva ◽

R. W. Barreto

Keyword(s):

Pure Culture ◽

Leaf Surface ◽

The United States ◽

Culture Collection ◽

Commonwealth Mycological Institute ◽

First Report ◽

Leaf Spots ◽

Nucleotide Homology ◽

Query Coverage ◽

Representative Samples

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

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First Report of Phytophthora hydropathica Causing Wilting and Shoot Dieback on Viburnum in Italy

Plant Disease ◽

10.1094/pdis-03-14-0308-pdn ◽

2014 ◽

Vol 98 (11) ◽

pp. 1582-1582 ◽

Cited By ~ 5

Author(s):

S. Vitale ◽

L. Luongo ◽

M. Galli ◽

A. Belisario

Keyword(s):

Natural Infection ◽

Morphological Characteristics ◽

Leaf Tissue ◽

The United States ◽

Selective Medium ◽

Phytophthora Species ◽

Phytophthora Ramorum ◽

Width Ratio ◽

Morphological Identification ◽

First Report

The genus Viburnum comprises over 150 species of shrubs and small trees such as Laurustinus (Viburnum tinus L.), which is one of the most widely used ornamental plants in private and public gardens. Furthermore, it commonly forms stands of natural woodland in the Mediterranean area. In autumn 2012, a survey was conducted to determine the presence of Phytophthora ramorum on Viburnum in commercial nurseries in the Latium region where wilting, dieback, and death of twigs were observed on 30% of the Laurustinus plants. A Phytophthora species was consistently recovered from soil rich in feeder roots from potted Laurustinus plants showing symptoms. Soil samples were baited with rhododendron leaves. Small pieces of leaf tissue cut from the margin of lesions were plated on P5ARPH selective medium (4). Pure cultures, obtained by single-hypha transfers on potato dextrose agar (PDA), were petaloid. Sporangia formation was induced on pepper seeds (3). Sporangia were almost spherical, ovoid or obpyriform, non-papillate and non-caducous, measuring 36.6 to 71.4 × 33.4 to 48.3 μm (average 53.3 × 37.4 μm) with a length/width ratio of 1.4. Chlamydospores were terminal and 25.2 to 37.9 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in culture or on the host. All isolates examined had 30 to 35°C as optimum temperatures. Based on these morphological characteristics, the isolates were identified as Phytophthora hydropathica (2). Morphological identification was confirmed by internal transcribed spacer (ITS), and mitochondrial partial cytochrome oxidase subunit 2 (CoxII) with BLAST analysis in the NCBI database revealing 99% identity with ITS and 100% identity with CoxII. The sequences of the three isolates AB234, AB235, and AB236 were deposited in European Nucleotide Archive (ENA) with the accession nos. HG934148, HG934149, and HG934150 for ITS and HG934151, HG934152, and HG934153 for CoxII, respectively. Pathogenicity tests were conducted in the greenhouse on a total of six 1-year-old shoots cut from V. tinus plants with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis into the phloem. Controls were treated as described above except that sterile PDA plugs replaced the inoculum. Shoots were incubated in test tubes with sterile water in the dark at 24 ± 2°C. After 2 weeks, lesions were evident at the inoculation points and symptoms were similar to those caused by natural infection. P. hydropathica was consistently re-isolated from the margin of lesions, while controls remained symptomless. In the United States in 2008, P. hydropathica was described as spreading from irrigation water to Rhododendron catawbiense and Kalmia latifolia (2). This pathogen can also attack several other horticultural crops (1), but to our knowledge, this is the first report of P. hydropathica causing wilting and shoot dieback on V. tinus. References: (1) C. X. Hong et al. Plant Dis. 92:1201, 2008. (2) C. X. Hong et al. Plant Pathol. 59:913, 2010. (3) E. Ilieva et al. Eur. J. Plant Path. 101:623, 1995. (4) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986.

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Shoot Blight of Forsythia × intermedia in Virginia Nurseries Caused by Phytophthora nicotianae

Plant Disease ◽

10.1094/pd-89-0430c ◽

2005 ◽

Vol 89 (4) ◽

pp. 430-430 ◽

Cited By ~ 2

Author(s):

C. X. Hong ◽

P. A. Richardson ◽

P. Kong

Keyword(s):

Single Strand Conformation Polymorphism ◽

The United States ◽

Morphological Characters ◽

Selective Medium ◽

Shoot Tips ◽

Phytophthora Nicotianae ◽

First Report ◽

Plastic Bags ◽

Shoot Blight ◽

Polymorphism Pattern

A severe blighting of shoots on Forsythia × intermedia cv. Lynwood Gold plants was observed at several commercial nurseries in Virginia from 2001 to 2004. Crop losses ranged from 10 to 35%. Symptoms first occurred at the tips of shoots, including those that were trimmed and not trimmed, and then progressed downward. Diseased shoots wilted quickly and usually turned black, and foliage on these shoots withered and became necrotic. With PARP-V8 selective medium (2), a species of Phytophthora was isolated consistently from symptomatic shoots (including tissues from shoot tips, leaves, and stems) as well as from apparently healthy roots. These isolates produced arachnoid mycelia and numerous noncaducous, papillate sporangia but did not produce sexual structures on isolation plates; these morphological characters are consistent with those of Phytophthora nicotianae. All isolates produced a single-strand conformation polymorphism pattern typical of P. nicotianae (3). To test pathogenicity, 1-year-old, healthy-appearing cv. Lynwood Gold forsythia plants (canopy size = 100 cm × 60 cm) in four 12-liter containers were sheared. Two plants were inoculated by spraying each plant with 200 ml of a zoospore suspension (1.6 × 104 spores per ml, prepared from one isolate), and the other two plants were not treated and served as controls. Plants were covered with plastic bags overnight to encourage infection and then were grown in a field (temperature range = 20 to 33°C). Severe blight developed on trimmed shoots and new shoot tips of inoculated plants within 1 week after inoculation. The same pathogen was isolated from all blighted leaf and stem pieces assayed. Blight symptoms were not observed on control plants during a 1-month observation period. Phytophthora nicotianae has been reported to attack F. viridissima in Italy (1) causing root and collar rot but not shoot blight. To our knowledge, this is the first report of shoot blight on Forsythia spp. caused by P. nicotianae and the first report of P. nicotianae on Forsythia spp. in the United States. References: (1) S. O. Cacciola et al. Plant Dis. 78:525, 1994. (2) A. J. Ferguson and S. N. Jeffers. Plant Dis. 83:1129, 1999. (3) P. Kong et al. Fun. Gen. Biol. 39:238, 2003.

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First Report of Grapevine leafroll-associated virus 2 in a Hybrid Grape ‘Vidal Blanc’ in Missouri

Plant Disease ◽

10.1094/pdis-10-11-0834 ◽

2012 ◽

Vol 96 (3) ◽

pp. 462-462 ◽

Cited By ~ 3

Author(s):

S. Lunden ◽

W. Qiu

Keyword(s):

New York ◽

Leaf Roll ◽

Late Summer ◽

The United States ◽

Coding Region ◽

Rt Pcr ◽

Protein Coding ◽

First Report ◽

Stem Lesions ◽

Grape Cultivars

Grapevine leaf roll disease (GLRD) is one of the most prevalent viral diseases in vineyards worldwide. At least 10 Grapevine leafroll-associated viruses (GLRaV-1 to -7, and -9, -10, and -11) are associated with GLRD. GLRaV-2 has a number of distinct isolates that are associated not only with GLRD, but also with graft incompatibility, young vine decline, and rootstock stem lesions. In the United States, GLRaV-2 isolates have been reported in the states of California (4), New York (1), Oregon, and Washington (3). A survey of grapevine viruses was conducted on seven grape cultivars, Norton, Chambourcin, Chardonel, Vignoles, Vidal Blanc, Traminette, and Cayuga White, in a vineyard located at Mountain Grove, MO during the falls of 2009 and 2010 and late summer of 2011. Vines from each cultivar were assigned into three blocks. From each block, six individual vines were randomly selected. Phloem scrapings were collected for detecting viruses by ELISA and reverse-transcription (RT)-PCR. To test for GLRaV-2, a set of primers, GLRaV-2-Forward (5′-GGTGATAACCGACGCCTCTA, nt 6745 to 6764) and GLRaV-2-Reverse (5′-CCTAGCTGACGCAGATTGCT, nt 7268 to 7287), were designed from the coat protein coding region as reported previously (2). GRLaV-2 was detected only in the samples of ‘Vidal Blanc’. The detection of GLRaV-2 was further verified by ELISA using GRLaV-2-specific antisera (Bioreba AG, Reinach, Switzerland). The GLRaV-2-infected ‘Vidal Blanc’ vines did not exhibit visible symptoms. The RT-PCR amplified 543-bp cDNA fragments were isolated from agarose gel and cloned into the pCR2.1 vector (Invitrogen, Carlsbad, CA). Plasmid DNA was purified from three individual clones and sequenced from both directions. Comparison of the 543-bp sequences showed that the sequences shared 99% nt identity with the corresponding regions of 21 GLRaV-2 isolates, including PMC-083 isolate from Croatia (GenBank Accession No. HM185277), LN isolate from China (GenBank No. FJ786017), SE isolate from Brazil (GenBank No. EU204909), and four isolates from Washington (GenBank Nos. EU760836, 760838, 760843, and 760848). ‘Vidal Blanc’ is a white interspecific hybrid grape. Absence of visible symptoms on this cultivar emphasizes the importance of planting certified grapevines that have been indexed for viruses. Discovery of GLRaV-2 in asymptomatic white grape cultivars will warn growers on the potential damages and epidemics of GLRD in Midwest vineyards and promote planting clean grapevines. To our knowledge, this is the first report of GLRaV-2 in grapevines in Missouri. References: (1) M. Fuchs et al. Plant Dis. 93:395, 2009. (2) G. Gambino and I. Gribaudo. Phytopathology 96:1223, 2006. (3) R. R. Martin et al. Plant Dis. 89:763, 2005. (4) A. Rowhani et al. Phytopathology (Abstr.) 92:(suppl.):S71, 2002.

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First Report of Fusarium oxysporum on Lettuce in Europe

Plant Disease ◽

10.1094/pdis.2002.86.9.1052b ◽

2002 ◽

Vol 86 (9) ◽

pp. 1052-1052 ◽

Cited By ~ 42

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

M. L. Gullino

Keyword(s):

Fusarium Oxysporum ◽

Vascular System ◽

The United States ◽

Selective Medium ◽

Northern Italy ◽

Infested Soil ◽

Pathogenicity Test ◽

First Report ◽

Vascular Tissues ◽

Brown Discoloration

In spring 2001, plants of the lettuce cv. Salad Bowl showing symptoms of a wilt disease were observed in several commercial plastic greenhouses near Bergamo, in northern Italy. Wilted plants were first observed during the spring and summer of 2001 when temperatures were between 26 and 35°C. Symptoms were observed in the same area and the same farms in March 2002, in concomitance with a period of high temperatures. Although the distribution of the disease was generally uniform, symptoms were more severe in the central part of the greenhouses where temperatures were warmest. Symptoms were first observed at thinning, when seedlings (30 days old) appeared wilted. Vascular tissues of affected seedlings appeared red or brown. Affected plants were stunted and developed yellow leaves and brown or black streaks in the vascular system. The vascular streaks in the yellow leaves extended from the crown and were continuous with a red-brown discoloration in the vascular system of the crown and upper taproot. Symptoms were typically not visible on the outside of the crowns or roots. Fusarium oxysporum was consistently and readily isolated from symptomatic vascular tissues on a Fusarium-selective medium (2). Seeds of cv. Salad Bowl were planted in steam-sterilized soil artificially infested with 1 × 104 CFU/g soil of each of two isolates of F. oxysporum obtained from infected plants. Plants grown in noninfested soil served as noninoculated control treatments. Plants (25 per treatment) were grown at 25 to 28°C in growth chambers. Wilt symptoms and vascular discoloration of the roots, crown, and veins developed 20 days after seeding for all plants grown in the infested soil, and F. oxysporum was consistently reisolated from infected plants. The pathogenicity test was conducted twice. To our knowledge, this is the first report of F. oxysporum on lettuce in Europe. A wilt of lettuce attributed to F. oxysporum f. sp. lactucae was reported in Japan in 1967 (3) and in the United States in 1993 (1), in the latter case the incitant organism was described as F. oxysporum f. sp. lactucum. References: (1) J. C. Hubbard and J. S. Gerik. Plant Dis. 77:750, 1993. (2) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (3) T. Matuo and S. Motohashi. Trans. Mycol. Soc. Jpn. 8:13, 1967.

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First Report of Armillaria Butt Rot Caused by Armillaria mellea on Phoenix canariensis in Italy

Plant Disease ◽

10.1094/pdis-91-11-1517b ◽

2007 ◽

Vol 91 (11) ◽

pp. 1517-1517 ◽

Cited By ~ 1

Author(s):

F. M. Grasso ◽

A. Pane ◽

S. O. Cacciola

Keyword(s):

Morphological Characteristics ◽

Phytopathogenic Fungi ◽

Mount Etna ◽

Malt Extract ◽

Wood Fibers ◽

First Report ◽

Butt Rot ◽

Armillaria Mellea ◽

Phoenix Canariensis ◽

Electrophoretic Patterns

During 2006, in a garden in the Mount Etna Piedmont, eastern Sicily (Italy), a 40-year-old specimen of Canary Island date palm (Phoenix canariensis hort. ex Chabaud) with a trunk circumference at breast height of 220 cm showed a rotted lesion with a viscous, brown ooze at the stem base and root initials. The lesion extended to approximately one-third of the trunk circumference. Trunk excavation exposed a wet rot of internal tissues, a cream-colored mycelial mat, and a mushroom-like smell. Although the rot spread inward (approximately 25 cm deep) with decay of nonlignified ground tissues and blackening of wood fibers, the palm did not show symptoms on the canopy. Conversely, ferns, apricot, and cedar trees growing at the same site had died from Armillaria rot over the last 10 years (2). In late autumn, clumps of honey mushroom-like sphorophores with a prominent annulus encircling the stalk formed at the base of the trunk. The spore print of the basidiocarp was light cream. The morphology of 100 basidiospores was determined microscopically. The basidiospores were smooth, elliptical, hyaline, and measured 7 to 9.5 × 5 to 7 μm. The fungus was isolated from diseased tissues on selective benomyl-dichloran medium (3) and was transferred to 2% malt extract agar where it formed ribbon-shaped, fast-growing, and profusely branching rhizomorphs. Armillaria mellea (Vahl.) P. Kumm. was identified on the basis of cultural and morphological characteristics. Identification was confirmed by electrophoresis of mycelial proteins and isozymes in polyacrylamide and starch slab gels (1,2). The electrophoretic patterns of the isolate from P. canariensis were identical to those of reference isolates of A. mellea from grapevine and fern isolated previously at the same site (2). The pathogenicity of the A. mellea isolate from palm (A-palm5) was tested on 20 3-year-old potted seedlings of P. canariensis grown in a greenhouse at 24 ± 4°C. Seedlings were inoculated with wood pieces of holly oak (Quercus ilex L.) colonized by the fungus (two pieces for each seedling) (4). Ten noninoculated plants served as controls. After 12 months, mycelial fans colonizing the root initials, the base of the stem, and the leaf stalks were observed on 14 inoculated seedlings. Although only four infected seedlings showed decline symptoms, the fungus was reisolated from all inoculated plants. No infections were observed in control plants. To our knowledge, this is the first report of Armillaria butt rot on a palm in Europe. References: (1) M. Bragaloni et al. Eur. J. For. Pathol. 27:147, 1997. (2) S. Grasso et al. Plant Dis. 84:592, 2000. (3) T. C. Harrington et al. Armillaria. Page 81 in: Methods for Research on Soilborne Phytopathogenic Fungi. The American Phytopathological Society, St. Paul, MN, 1992. (4) R. Metaliaj et al. Phytopathol. Mediterr. 45:3, 2006.

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First Report of Bud Rot of Canary Island Date Palm Caused by Phytophthora palmivora in Italy

Plant Disease ◽

10.1094/pdis-91-8-1059a ◽

2007 ◽

Vol 91 (8) ◽

pp. 1059-1059

Author(s):

A. Pane ◽

C. Allatta ◽

G. Sammarco ◽

S. O. Cacciola

Keyword(s):

Canary Island ◽

Date Palm ◽

Brown Rot ◽

Selective Medium ◽

Phytophthora Species ◽

Phytophthora Palmivora ◽

American Phytopathological Society ◽

First Report ◽

Phoenix Canariensis ◽

Electrophoretic Patterns

Canary Island date palm (Phoenix canariensis hort. ex Chabaud) is planted as an ornamental in Mediterranean climatic regions of the world. From 2004 to 2006, withering of the spear leaf was observed on screenhouse-grown potted plants of this palm in Sicily (Italy). The first symptom was a dark brown rot that extended from the petiole base of the spear to the adjacent youngest leaves and killed the bud. Dissection of plants revealed a foul-smelling internal rot. After the bud died, external older leaves remained green for months. As much as 10% of plants in a single nursery were affected. A Phytophthora species was consistently isolated from symptomatic plants on BNPRAH selective medium (4). Single zoospore isolates were obtained from the colonies. The species isolated was identified as Phytophthora palmivora (E. J. Butler) E. J. Butler on the basis of morphological and cultural characteristics (3). On V8 juice agar, the isolates produced elliptical to ovoid, papillate sporangia (33 to 77 × 22 to 38 μm) with a mean length/breadth ratio of 1.8. Sporangia were caducous with a short pedicel (mean pedicel length = 5 μm) and had a conspicuous basal plug. All isolates were heterothallic and produced amphigynous antheridia, oogonia, and oospores when paired with reference isolates of P. nicotianae and P. palmivora of the A2 mating type. The oogonium wall was smooth. Identification was confirmed by electrophoresis of mycelial proteins in polyacrylamide slab gels (1). The electrophoretic patterns of total mycelial proteins and four isozymes (alkaline phosphatase, esterase, glucose-6-phosphate dehydrogenase, and malate dehydrogenase of the isolates) from Phoenix canariensis were identical to those of P. palmivora reference isolates, including four Italian ones, two from pittosporum and olive, respectively, and two (IMI 390579 and 390580) from Grevillea spp. Phoenix canariensis isolates were clearly distinct from those of other heterothallic papillate species including P. capsici, P. citrophthora, P. katsurae, P. nicotianae, and P. tropicalis. Pathogenicity of one isolate from Phoenix canariensis (IMI 395345) was tested on 10 2-year-old potted Canary Island date palm plants. An aqueous 105 zoospores per ml suspension (200 μl) was pipetted onto unwounded petiole bases of the three youngest central leaves of each plant. Sterile water was pipetted onto 10 control plants. All plants were incubated in 100% humidity at 24°C for 48 h and maintained in a greenhouse at 20 to 28°C. Within 3 weeks after inoculation, inoculated plants developed symptoms identical to those observed on plants with natural infections. Control plants remained healthy. P. palmivora was reisolated from symptomatic plants. Phytophthora bud rot is a common palm disease worldwide and Phoenix canariensis is reported as a host (2). To our knowledge, this is the first report of Phytophthora bud rot on Phoenix canariensis in Italy. References: (1) S. O. Cacciola et al. EPPO Bull. 20:47, 1990. (2) M. L. Elliot et al., eds. Compendium of Ornamental Palm Diseases and Disorders. The American Phytopathological Society, St. Paul, MN, 2004. (3) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (4) H. Masago et al. Phytopathology, 67:425, 1977.

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First Report of Phytophthora palmivora on Grevillea spp. in Italy

Plant Disease ◽

10.1094/pdis.2003.87.8.1006a ◽

2003 ◽

Vol 87 (8) ◽

pp. 1006-1006

Author(s):

S. O. Cacciola ◽

A. M. Pennisi ◽

G. E. Agosteo ◽

G. Magnano di San Lio

Keyword(s):

Mating Type ◽

Glucose Dehydrogenase ◽

Field Capacity ◽

Selective Medium ◽

Phytophthora Palmivora ◽

Width Ratio ◽

Submerged Cultures ◽

Reference Isolate ◽

Electrophoretic Patterns ◽

Pure Cultures

The genus Grevillea (family Proteaceae) comprises over 300 species and is a popular and widely cultivated group of Australian plants. In the last 3 years, numerous potted grevilleas with symptoms of decline associated with a rot of feeder roots were found in ornamental nurseries in Sicily. Aboveground symptoms were reduced growth, yellowing of foliage, wilt, dieback, and death of the entire plant. The disease was observed on many commercial cultivars and was especially severe on G. alpina (mountain grevillea), G. juniperina (juniper-leaf grevillea), G. lavandulacea (lavender grevillea), and G. rosmarinifolia (rosemary grevillea) as well as the hybrid cultivars Clearview David (G. lavandulacea × rosmarinifolia) and Poorinda Rondeau (G. baueri × lavandulacea), while G. lanigera (woolly grevillea) cv. Mount Tamboritha and G. thelemanniana subsp. obtusifolia appeared resistant. A species of Phytophthora was consistently isolated from rotted roots of symptomatic plants using a selective medium (4), and pure cultures were obtained by single-hypha transfers. The species was identified as P. palmivora (E.I. Butler) E.I. Butler on the basis of morphological and cultural characters. On solid media, all isolates produced elliptical to ovoid, papillate sporangia with a mean length/width ratio of 1.8. Sporangia were caducous with a short pedicel (5 μm) and a conspicuous basal plug. All isolates were heterothallic (mating type A1) and produced oogonia and oospores only when paired with A2 mating type reference isolates of P. nicotianae and P. palmivora. Antheridia were amphyginous. Identification was confirmed by electrophoresis of mycelial proteins in polyacrylamide slab gels (1). The electrophoretic patterns of total soluble proteins and six isozymes (alkaline phosphatase, esterase, fumarase, NAD-glucose dehydrogenase, malate dehydrogenase, and superoxide dismutase) of isolates from grevillea were identical to those of a reference isolate of P. palmivora from Coronilla valentina subsp. glauca (2) but distinct from those of reference strains of eight other papillate species of Phytophthora included in Waterhouse's taxonomic group VI. Koch's postulates were fulfilled using 6-month-old rosemary grevillea plants that were transplanted into pots filled with soil that was artificially infested with chlamydospores (50 per gram of soil) produced in submerged cultures (3) by grevillea isolate IMI 390579. Plants were maintained in a glasshouse at 20 to 28°C and watered to field capacity once a week. One month after transplanting, infected plants showed decline symptoms similar to those of naturally infected plants. Control plants grown in pots containing noninfested soil remained healthy. P. palmivora was reisolated from roots of symptomatic plants. It appears that P. palmivora has become a widespread root pathogen in commercial ornamental nurseries in Italy (2). References: (1) S. O. Cacciola et al. EPPO Bull. 20:47, 1990.D. (2) S. O. Cacciola et al. Plant Dis. 86:327, 2002. (3) J. Y. Kadooka and W. H. Ko. Phytopathology 63:559, 1973. (4) H. Masago et al. Phytopathology 67:425, 1977.

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First Report of Phytophthora tropicalis on Rhododendron in Italy

Plant Disease ◽

10.1094/pdis-04-13-0445-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1385-1385 ◽

Cited By ~ 2

Author(s):

L. Luongo ◽

M. Galli ◽

S. Vitale ◽

A. Haegi ◽

A. Belisario

Keyword(s):

Late Summer ◽

Selective Medium ◽

Phytophthora Species ◽

Width Ratio ◽

Broad Host Range ◽

In Planta ◽

First Report ◽

European Nucleotide Archive ◽

Pure Cultures

The genus Rhododendron comprises over 1,000 species, which represent many important ornamental shrubs. Microbial isolations were made from Rhododendron catawbiense plants showing symptoms of wilt, dieback, and death of shoots obtained from two nurseries in the Latium region in the late summer of 2012. A Phytophthora species was consistently recovered by plating small pieces of stem and collar tissues, cut from the margin of lesions, on P5ARPH selective medium. Pure cultures were obtained by single-hyphal transfers and they grew in a rosaceous pattern on potato dextrose agar (PDA) at an optimum temperature of 28 to 30°C. Sporangia formation was induced on pepper seeds (3). Sporangia were ellipsoid, fusiform or obpyriform, papillate, occasionally bipapillate, caducous, with a long pedicel (up to 100 μm), and mean dimensions of 45 × 25 μm with a mean length/width ratio of 1.8. Chlamydospores ranged from 25 to 32 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, the isolates were identified as Phytophthora tropicalis Aragaki & Uchida. Identity was confirmed by sequence comparison in GenBank with 99% homology both for internal transcribed spacer (ITS) and mitochondrial partial COI for cytochrome oxidase subunit 1. The sequences of two isolates AB211 and AB212 were deposited in the European Nucleotide Archive (ENA) with accession nos. HF937577 and HF937578 for ITS, and HF937579 and HF937580 for COI, respectively. Pathogenicity tests were conducted in the greenhouse on a total of six 1-year-old shoots cut from R. catawbiense plants with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis to the phloem. Controls were treated as described above except for inoculation with sterile PDA plugs. Inoculated shoots were incubated in test tubes with sterile water for 1 week in the dark at 26 ± 2°C. Lesions were evident at the inoculation points. P. tropicalis was consistently reisolated from the margin of symptomatic tissues. Control shoots remained symptomless. In Italy, P. tropicalis has been reported on several ornamental species (1) and on apricot trees (4) indicating a broad host range. On the same host it has been reported in Virginia, United States (2). To the best of our knowledge, this is the first report of Phytophthora damage on Rhododendron caused by P. tropicalis in Italy. References: (1) S. O. Cacciola et al. Plant Dis. 90: 680, 2006. (2) C. X. Hong et al. Plant Dis. 90: 525, 2006. (3) E. Ilieva et al. Eur. J. Plant Path. 101: 623, 1995. (4) A. Pane et al. Plant Dis. 93: 844, 2009.

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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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