Bud and Root Rot of Windmill Palm (Trachycarpus fortunei) Caused by Simultaneous Infections of Phytophthora palmivora and P. nicotianae in Sicily

In June 2009 in a commercial nursery in eastern Sicily (Italy), 3-year-old potted windmill palms (Trachycarpus fortunei (Hooker) H. Wendl.) showed a decline in growth, wilt, droop, and basal rot of the youngest leaves. The rot progressed inward and killed the bud. Initially, older leaves remained green but eventually the entire plant collapsed. Root rot was consistently associated with aboveground symptoms. Two Phytophthora species were consistently isolated from the petiole base, heart, roots, and rhizosphere soil of symptomatic plants on a selective medium (2) and occasionally recovered from roots and rhizosphere soil of asymptomatic plants. Pure cultures were obtained by single-hypha transfers and the two species were identified on the basis of morphological and molecular characters as Phytophthora palmivora and P. nicotianae. Both species were recovered from all symptomatic plants. From multiple tissue samples per plant, we recovered either or both species. On potato dextrose agar (PDA), P. palmivora isolates grew between 10 and 35°C, with the optimum at 27°C. On V8 juice agar, they produced elliptical to ovoid, papillate, caducous sporangia (32 to 78 × 23 to 39 μm) with a mean length/breadth (l/b) ratio of 1.8:1 and a short pedicel (mean pedicel length = 5 μm). Isolates of P. nicotianae produced arachnoid colonies on PDA, grew at 37°C but did not grow at 40°C. Sporangia (29 to 55 × 23 to 45 μm) were spherical to ovoid (l/b ratio 1.3:1), papillate and often bipapillate, and noncaducous. Isolates of both species produced amphigynous antheridia and oogonia only when paired with reference isolates of P. nicotianae of the A2 mating type. The internal transcribed spacer (ITS) region of rDNA of two isolates of P. palmivora (IMI 398987 and IMI 398988) and an isolate of P. nicotianae (IMI 398989) from T. fortunei was amplified with primers ITS6/ITS4 and sequenced (1). Blast analysis of the sequences of isolates IMI 398987 and IMI 398988 (GenBank Accession Nos. HQ596556 and HQ596558) showed 99% homology with the sequence of two reference isolates of P. palmivora (GQ398157.1 and GU258862), while the sequence of isolate IMI 398989 (HQ596557) showed 99% homology with a reference isolate of P. nicotianae (EU331089.1). Pathogenicity of isolates IMI 398987 and IMI 398989 was proved by inoculating separately each isolate on 1-year-old potted plants of T. fortunei (10 plants per isolate). A zoospores suspension (2 × 104 zoospores/ml) was pipetted onto the petiole base of the three central leaves (200 μl per leaf) of each plant. Sterile water was used for control plants. All plants were incubated at 25 ± 2°C with 100% humidity for 48 h and then maintained in a greenhouse at 24 to 28°C. Within 3 weeks, all inoculated plants showed symptoms of bud rot. Control plants remained healthy. P. palmivora and P. nicotianae were reisolated only from inoculated plants. Bud rot of palms caused by P. palmivora was reported previously in Italy (3). However, to our knowledge, this is the first report of simultaneous infections of P. palmivora and P. nicotianae as causal agents of this disease. Outbreak of bud rot may have been favored by overhead sprinkler irrigation. The recovery of P. palmivora and P. nicotianae from rhizosphere soil and roots of asymptomatic plants suggests infested soil was the primary inoculum source. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) H. Masago et al. Phytopathology 67:425, 1977. (3) A. Pane et al. Plant Dis. 91:1059, 2007.

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Phytophthora palmivora a New Pathogen of Lavender in Italy

Plant Disease ◽

10.1094/pdis.2002.86.5.561c ◽

2002 ◽

Vol 86 (5) ◽

pp. 561-561 ◽

Cited By ~ 3

Author(s):

S. Davino ◽

S. O. Cacciola ◽

A. M. Pennisi ◽

M. G. Li Destri Nicosia

Keyword(s):

Root Rot ◽

Irrigation System ◽

Phytophthora Nicotianae ◽

Phytophthora Palmivora ◽

Infested Soil ◽

Trickle Irrigation ◽

Mycelium Growth ◽

Reference Isolate ◽

Commercial Cultivation ◽

Oat Seeds

Root rot caused by Phytophthora nicotianae is considered the most serious disease of lavender in commercial cultivations in Italy. In summer 2001, in the Gela area (Sicily), ≈60% of 34,000 2-year-old landscape shrubs of English lavender (L. angustifolia) grown in a clay loam soil showed symptoms of dieback associated with root rot. Plants had been transplanted from pots in May and watered using a trickle irrigation system. A species of Phytophthora was isolated consistently from roots of symptomatic plants using potato dextrose agar (PDA) containing benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol. The species was identified as P. palmivora on the basis of morphological and cultural characters. Ten representative single-zoospore isolates were characterized. On agar media, the isolates produced elliptical to ovoid, papillate sporangia, with a mean length/breadth ratio of 1.8. Sporangia, produced on sporangiophores forming simple sympodia (as many as 20 sporangia per sympodium), were caducous with a short pedicel (mean pedicel length = 5 μm) and a conspicuous basal plug. In addition to typical sporangia, all isolates produced sporocysts, i.e., subglobose, nonpapillate sporangia (2). The minimum temperature for mycelium growth on PDA was 10°C, the optimum was 27°C, and the maximum was 35°C. All isolates were A1 mating type. Antheridia were amphyginous. The identification was confirmed by electrophoresis of mycelial proteins on a polyacrylamide slab gel. Electrophoretic banding patterns of total soluble proteins and eight isozymes of the isolates from lavender were identical to those of a reference isolate of P. palmivora from olive (1). Conversely, the electrophoretic phenotype of the isolates from lavender was distinct from those of reference isolates of other species, including P. cactorum, P. capsici, P. citrophthora, P. nicotianae, and P. tropicalis. The pathogenicity of a representative isolate of P. palmivora from lavender was tested in the greenhouse using 6-month-old plants of English lavender, Rosea, a commercial cultivar very susceptible to root rot caused by P. nicotianae (3). Inoculum was produced on a mixture of vermiculite and autoclaved oat seeds (4) and mixed with soil (sand/lime/peat 1:1:1) at a concentration of 4% (vol/vol). Plants were transplanted to pots filled with infested soil. Control plants were grown in pots containing noninfested soil. After transplanting, all pots were flooded for 24 h by plugging the drain hole. Three months after transplanting all plants grown in pots containing infested soil showed extensive root necrosis and dieback symptoms. Control plants remained healthy. P. palmivora was recovered from roots of symptomatic plants. To our knowledge, this is the first report from Italy of P. palmivora on lavender. Root rot caused by P. palmivora may be a potential problem for commercial cultivation of lavender. References: (1) S. O. Cacciola et al. Plant Dis. 84:1153, 2000. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (3) G. Minuto et al. Inf. Fitopatol. 51:69, 2001. (4) E. Sánchez-Hernández et al. Plant Dis. 85:411, 2001.

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

Plant Disease ◽

10.1094/pdis-02-13-0206-pdn ◽

2014 ◽

Vol 98 (1) ◽

pp. 155-155 ◽

Cited By ~ 1

Author(s):

Y. Ahmed ◽

A. M. D'Onghia ◽

A. Ippolito ◽

T. Yaseen

Keyword(s):

Mating Type ◽

Root Rot ◽

Its Region ◽

Selective Medium ◽

Phytophthora Palmivora ◽

Universal Primers ◽

Potential Threat ◽

First Report ◽

Citrus Root ◽

International Mycological Institute

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

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Diversity and Distribution of Phytophthora Species in Protected Natural Areas in Sicily

Forests ◽

10.3390/f10030259 ◽

2019 ◽

Vol 10 (3) ◽

pp. 259 ◽

Cited By ~ 9

Author(s):

Thomas Jung ◽

Federico La Spada ◽

Antonella Pane ◽

Francesco Aloi ◽

Maria Evoli ◽

...

Keyword(s):

Host Plants ◽

Rhizosphere Soil ◽

Stream Water ◽

Its Region ◽

Morphological Characters ◽

Phytophthora Species ◽

Riparian Ecosystems ◽

Forest Stands ◽

Natural Areas ◽

Protected Natural Areas

: The aim of this study was to investigate the occurrence, diversity, and distribution of Phytophthora species in Protected Natural Areas (PNAs), including forest stands, rivers, and riparian ecosystems, in Sicily (Italy), and assessing correlations with natural vegetation and host plants. Fifteen forest stands and 14 rivers in 10 Sicilian PNAs were studied. Phytophthora isolations from soil and stream water were performed using leaf baitings. Isolates were identified using both morphological characters and sequence analysis of the internal transcribed spacer (ITS) region. A rich community of 20 Phytophthora species from eight phylogenetic clades, including three new Phytophthora taxa, was recovered (17 species in rhizosphere soil from forest stands and 12 species in rivers). New knowledge about the distribution, host associations, and ecology of several Phytophthora species was provided.

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Phylogeny and Pathogenicity of Phytophthora Species Associated with Artichoke Crown and Root Rot and Description of Phytophthora marrasii sp. nov.

Agriculture ◽

10.3390/agriculture11090873 ◽

2021 ◽

Vol 11 (9) ◽

pp. 873

Author(s):

Carlo Bregant ◽

Giovanni Rossetto ◽

Antonio Deidda ◽

Lucia Maddau ◽

Antonio Franceschini ◽

...

Keyword(s):

Root Rot ◽

Sequence Data ◽

Its Region ◽

Phytophthora Species ◽

Globe Artichoke ◽

New Host ◽

Field Surveys ◽

Brown Discoloration ◽

Pathogenicity Tests ◽

Crown And Root Rot

Field surveys conducted on nine farms over a 2-year period showed the widespread presence of Phytophthora-related diseases on globe artichoke plants in the main growing area in Sardinia (Italy). Characteristic symptoms included wilting and necrosis of the outermost leaves and dark brown discoloration of stem tissues, as well as root rot. A total of 18 Phytophthora colonies belonging to three species were isolated and characterized. Based on morphological features and ITS sequence data, Phytophthora isolates were identified as P. crassamura (eight isolates) and P. cactorum (four isolates). Six isolates could not be assigned to any formally described species of Phytophthora and are therefore described here as Phytophthora marrasii sp. nov. The ITS phylogeny places P. marrasii in a terminal clade basal to the sister taxa (P. foliorum, P. hibernalis, P. lateralis, and P. ramorum) of the clade 8c. In particular, P. marrasii is phylogenetically related to P. foliorum, a species from which it differs in 62 nucleotides in the ITS region. At the same time, it can easily be distinguished morphologically from P. foliorum mainly because of the low minimum temperature for growth, the bigger and persistent non-papillate sporangia, and smaller oogonia. Pathogenicity tests confirmed that all three Phytophthora species are pathogenic on globe artichokes, which represent a new host for these pathogens.

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First Report of Phytophthora palmivora as a Pathogen of Olive in Italy

Plant Disease ◽

10.1094/pdis.2000.84.10.1153a ◽

2000 ◽

Vol 84 (10) ◽

pp. 1153-1153 ◽

Cited By ~ 6

Author(s):

S. O. Cacciola ◽

G. E. Agosteo ◽

A. Pane

Keyword(s):

Southern Italy ◽

Glucose Dehydrogenase ◽

Selective Medium ◽

Phytophthora Palmivora ◽

Infested Soil ◽

Banding Patterns ◽

First Report ◽

Breadth Ratio ◽

Pathogenicity Tests ◽

Olive Trees

Olive (Olea europea L.) is an economically important crop in Italy and is planted on about 1 million ha. The Apulia, Calabria, and Sicily regions of Southern Italy account for about 70% of the production. Many new plantations have been established during the last 10 years. In summer 1999, 1- to 2-year-old olive trees (cv. Carolea) with decline symptoms were observed in new plantations in Catanzaro Province (Calabria). The symptoms associated with the root rot were leaf chlorosis, defoliation, wilting, twig dieback, and eventual plant collapse. In some cases, more than 40% of the trees were affected. A Phytophthora sp. was isolated consistently from rotted rootlets of diseased trees using a selective medium (2). Single-zoospore isolates were obtained from the colonies. The species isolated from olive roots was identified as P. palmivora (E. Butler) E. Butler on the basis of morphological and cultural characters according to Erwin and Ribeiro (1). All isolates produced papillate sporangia, which were elliptical to ovoid, caducous (mean pedicel length = 5 µm), with a length-breadth ratio of 1.8. In addition, some isolates produced subglobose, non-papillate sporangia with a length-breadth ratio ranging from 1.2 to 1.5. Electrophoresis of mycelial proteins on polyacrylamide gels confirmed that all isolates were pure cultures and that they all belonged to the same species. The electrophoretic banding patterns of total soluble mycelial proteins and eight isozymes (alkaline phosphatase, esterase, fumarase, NAD-glucose dehydrogenase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, and superoxide dismutase) of all olive isolates were identical to those of two strains of P. palmivora from parlor palm and from pittosporum. Conversely, they were clearly distinct from the electrophoretic banding patterns of reference isolates of P. cactorum (Lebert & Cohn) Schroter, P. capsici Leonian, P. citrophthora (R. E. Sm. & E. H. Sm.) Leonian, and P. nicotianae van Breda de Haan. All isolates of P. palmivora from olive were of the A1 mating type. The pathogenicity of four P. palmivora isolates from olive, two producing only typical and two producing both types of sporangia, was tested in the greenhouse at 18 to 25°C, using 20 1-year-old rooted cuttings of olive cv. Carolea for each isolate. Twenty noninoculated cuttings were used as a control. The inoculum for pathogenicity tests was produced on autoclaved rice grains moistened with V-8 juice. Cuttings were transplanted to pots filled with soil infested with inoculum at 2% (wt/vol). Control plants were grown in pots containing a mixture of soil and 2% autoclaved rice. After transplanting, all pots were flooded once a week for 24 h by plugging the drain hole of the pot. One month after planting, all the plants in infested soil had died and no difference in virulence was observed among the isolates. Control plants remained healthy. P. palmivora was reisolated from the roots of symptomatic plants. Pathogenicity tests were repeated twice with similar results. In a survey of nurseries in Southern Italy, P. palmivora was recorded frequently from roots of young olive trees suggesting that infections originated from nurseries. This is the first report from Italy of P. palmivora on olive. This species has been described recently as a pathogen of olive in Spain (3). References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. American Phytopathological Society. St. Paul, MN. (2) H. Masago et al. Phytopathology 67:25, 1977. (3) M. E. Sanchez Hernandez et al. Eur. J. Plant Pathol. 104:347, 1998.

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First Report of Root Rot and Twigs Wilting of Olive Trees in Argentina Caused by Phytophthora nicotianae

Plant Disease ◽

10.1094/pdis-93-7-0765b ◽

2009 ◽

Vol 93 (7) ◽

pp. 765-765 ◽

Cited By ~ 7

Author(s):

A. M. Vettraino ◽

G. Lucero ◽

P. Pizzuolo ◽

S. Franceschini ◽

A. Vannini

Keyword(s):

Root Rot ◽

Disease Incidence ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Phytophthora Palmivora ◽

System Control ◽

Olive Trees ◽

Olive Varieties ◽

Lateral Branches ◽

Old Trees

In Argentina, olives (Olea europaea) are planted on approximately 90,000 ha located primarily in the northwest continental regions. During a 2005 survey, root rot was recorded at several olive plantations in Catamarca, La Rioja, and San Juan provinces (3). Aboveground symptoms associated with root rot were twigs wilting with or without chlorosis, defoliation, and death. Symptoms were initiated on lateral branches and sometimes affected the entire crown. Even if young (5-year-old) trees displayed root rot, aerial symptoms may or may not be seen until years later. Disease incidence varied from 3 to 30%. Rotted rootlets were associated mainly with the infection of Phytophthora palmivora Butler and less frequently with another Phytophthora species. Isolates of this species were heterothallic, had a fluffy growth on carrot agar, and arachnoid growth on potato dextrose agar. Chlamydospores approximately 36 μm in diameter were also produced. The species developed prominent, papillate, noncaducous sporangia of different shapes ranging from ellipsoid to spherical when submerged in saline solution. Sporangia were 35 to 57 × 25 to 45 μm (average 44 × 33 μm), L:B ratio from 1.1 to 1.7. Isolates formed oogonia and amphyginous antheridia following mating type assays. On the basis of morphological features, these isolates were identified as P. nicotianae Breda de Haan. Identity was confirmed by sequencing the rDNA internal transcribed spacer (GenBank Accession No. FJ746693) (1). One-year-old O. europea seedlings were challenged with P. nicotianae (A1 isolates 306G and 339) through soil infestation assay in a growth chamber at 25°C. Infested and uninfested autoclaved millet grains moistened with V8 juice were used to inoculate 15 olive seedlings per isolate and controls, respectively. Fifty days after inoculation, seedlings showed foliar symptoms similar to those observed in the field and had an average of 50% reduction in the root system. Control plants remained healthy. P. nicotianae was always reisolated from symptomatic roots. P. nicotianae was reported on Citrus aurantium in Argentina in 1947 and is currently associated with several hosts (2). In 2002, the same species was reported associated with olive root rot in southern Italy (4). It is possible that P. nicotianae was recently introduced into Argentina through importation of Mediterranean olive varieties. The demonstrated pathogenicity of P. nicotianae on olive together with the recently reported detection of P. palmivora (3) presents a serious threat to olive cultivation in Argentina. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) M. J. Frezzi. Rev. Investig. Agric. 4:47, 1950. (3) G. Lucero et al. Plant Pathol. 56:728, 2007. (4) F. Nigro and A. Ippolito. Acta Hortic. 586:777, 2002.

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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 cinnamomi on Quercus laurifolia

Plant Disease ◽

10.1094/pdis.2002.86.4.441d ◽

2002 ◽

Vol 86 (4) ◽

pp. 441-441 ◽

Cited By ~ 7

Author(s):

A. K. Wood ◽

F. H. Tainter

Keyword(s):

Phytophthora Cinnamomi ◽

Soil Extract ◽

Selective Medium ◽

Phytophthora Species ◽

Soil Samples ◽

Tissue Samples ◽

First Report ◽

Central Florida ◽

Oak Trees ◽

Length Width

In May 2001, bleeding cankers were observed on several laurel oak (Quercus laurifolia) trees in central Florida. Affected trees had chlorotic leaves, sparse canopies, and little new growth. Multiple cankers were present on the trunk and extended from the soil line up to approximately 5 m. Each canker had a reddish to dark brown or black exudate. From two of the infected trees, tissue samples were taken from beneath the bark around the edge of an actively growing lesion and transferred directly to Phytophthora-selective medium (1), and three soil cores (2 cm in diameter, 20 cm deep) were collected from the base of each tree. A baiting bioassay (with camellia leaf disks and shore juniper and eastern hemlock needles as baits) was used to assay fresh composite soil samples for Phytophthora species (1). P. cinnamomi was recovered from both tissue and soil samples (2). Mycelia were coralloid with abundant hyphal swellings. Sporangia were produced in 1.5% nonsterilized soil extract solution. Sporangia were ovoid to ellipsoid in shape and nonpapillate. Average sporangium size was 72 × 45 μm (length × width). To our knowledge, this is the first report of P. cinnamomi on laurel oak trees. References: (1) A. J. Ferguson and S. N. Jeffers. Plant Dis. 83:1129, 1999. (2) G. M. Waterhouse. Key to the species of Phytophthora de Bary. Mycol. Pap. 92. CMI. Kew, UK, 1963.

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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 a Decline and Wilt of Young Olive Trees Caused by Simultaneous Infections of Verticillium dahliae and Phytophthora palmivora in Sicily

Plant Disease ◽

10.1094/pdis-07-10-0480 ◽

2010 ◽

Vol 94 (11) ◽

pp. 1372-1372 ◽

Cited By ~ 3

Author(s):

V. Lo Giudice ◽

F. Raudino ◽

R. Magnano di San Lio ◽

S. O. Cacciola ◽

R. Faedda ◽

...

Keyword(s):

Verticillium Dahliae ◽

Dry Weight ◽

Selective Medium ◽

Phytophthora Palmivora ◽

Conidial Suspension ◽

Reference Isolate ◽

Leaf Chlorosis ◽

Pure Cultures ◽

Olive Trees ◽

Single Hypha

In summer 2008, leaf chlorosis, defoliation, exceptional fruit set, twig dieback, and wilt were observed on 4-year-old olive (Olea europea L.) trees cv. Tonda Iblea in a drip-irrigated orchard in eastern Sicily. Rot of fine roots was associated with these symptoms and on ~15% of symptomatic trees rot extended to the crown and basal stem. Trees declined slowly or collapsed suddenly with withered leaves still attached. Incidence of affected trees was ~10%. A fungus identified as Verticillium dahliae Kleb. was isolated from the xylem of main roots and basal stem. An oomycete identified as Phytophthora palmivora (Butler) Butler was isolated from roots and basal trunk bark. Both pathogens were recovered from symptomatic trees with mean frequency of positive isolations per tree of 80 and 30% for V. dahliae and P. palmivora, respectively. To isolate V. dahliae, wood chips were surface disinfested in 0.5% NaOCl for 1 min and plated onto potato dextrose agar (PDA). The fungus was identified on the basis of microsclerotia, verticillate arrangement of phialides on conidiophores, and hyaline single-celled conidia. Ten monoconidial isolates were characterized by PCR using primer pairs INTND2f/INTND2r and DB19/espdef01 (3). Only 824-bp amplicons, diagnostic of the virulent, nondefoliating V. dahliae pathotype, were obtained. P. palmivora was isolated on selective medium (2) and pure cultures were obtained by single-hypha transfers. Colonies grew on PDA between 10 and 35°C (optimum at 27°C). Chlamydospores and elliptical to ovoid, papillate, caducous (mean pedicel length = 5 μm) sporangia (length/breadth ratio of 1.8) were produced on V8 juice agar. All isolates were paired with reference isolates of P. nicotianae and produced gametangia only with isolates of the A2 mating type. PCR amplicons of a representative isolate generated using primers ITS 6 and ITS 4 (1) were sequenced and found to be identical to those of a reference isolate of P. palmivora (GenBank No. AY208126). Pathogenicity of V. dahliae (IMI 397476) and P. palmivora (IMI 397475) was tested on 6-month-old rooted cuttings of olive cv. Tonda Iblea. Ten cuttings were transplanted into pots with steam-sterilized soil and inoculum of P. palmivora (4% vol/vol) produced on wheat kernels. Ten olive cuttings were inoculated with V. dahliae by injecting the stem with 150 μl of a conidial suspension (107 conidia ml–1) and 10 cuttings were stem inoculated with V. dahliae and transplanted into soil infested with P. palmivora. Controls were 10 noninoculated cuttings transplanted into steam-sterilized soil. Pots were kept in a greenhouse (25 ± 3°C) for 4 months. No aerial symptoms were observed on cuttings transplanted into soil infested with P. palmivora. However, root dry weight was reduced by 40% in comparison with the controls. Cuttings inoculated solely with V. dahliae had a 15% reduction in height compared with the controls but only four cuttings wilted. All cuttings inoculated with P. palmivora and V. dahliae wilted, indicating a synergism between the two pathogens. Controls remained healthy. Each pathogen was reisolated solely from inoculated cuttings and both pathogens were reisolated from cuttings with double inoculations. A similar syndrome ‘seca’ (drying) was reported in Spain (4). References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) H. Masago et al. Phytopathology 67:425, 1977. (3) J. Mercado-Blanco et al. Plant Dis. 87:1487, 2003. (4) M. E. Sánchez-Hernández et al. Eur. J. Plant Pathol. 104:34, 1998.

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