FIRST REPORT OF Phytophthora nicotianae CAUSING ROOT ROT OF SOURSOP IN NORTHEASTERN BRAZIL

ABSTRACT In 2013, soursop trees showing symptoms of root rot were observed in a field in Maceió, state of Alagoas, Brazil. It was isolated Phytophthora sp. which pathogenicity was confirmed in the host seedlings. Morphological and physiological characteristics in carrot-agar modified medium were consistent with Phytophthora nicotianae description. The PCR sequences products obtained with ITS1/ITS4 primers were compared to sequences of ribosomal DNA of Phytophthora species from the GenBank database observing high identity with other P. nicotianae isolates. A phylogenetic tree was performed to compare the isolate with other sequences of P. nicotianae, which clustering has been verified with 99% of bootstrap, confirming the morphophysiological studies. This is the first report of this pathogen on annonaceous plants in the Northeastern Brazil.

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First Report of Collar and Root Rot Caused by Phytophthora nicotianae on Oriental Paperbush (Edgeworthia papyrifera) in Italy

Plant Disease ◽

10.1094/pdis-94-7-0917a ◽

2010 ◽

Vol 94 (7) ◽

pp. 917-917

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Root Rot ◽

Infected Plant ◽

Its Region ◽

Soil Extract ◽

Phytophthora Nicotianae ◽

Control Treatment ◽

Experimental Unit ◽

Peat Moss ◽

Late Winter ◽

First Report

Edgeworthia papyrifera, Oriental paperbush, is a deciduous flowering shrub becoming increasingly popular because of its clove-like perfumed flowers appearing in late winter-early spring. During August of 2009 in a commercial nursery close to Maggiore Lake (Verbano-Cusio-Ossola Province) in northwest Italy, 2-year-old plants of E. papyrifera showed extensive chlorosis and root rot. Twigs wilted and died, dropping leaves in some cases. Most frequently, wilted leaves persisted on stems. At the soil level, dark brown-to-black water-soaked lesions formed and coalesced, girdling the stem. All of the crown and root system was affected. Infected plants died within 14 days of the appearance of symptoms. Disease was widespread and severe, affecting 90 of the 100 plants present. After disinfestation for 1 min in a solution containing 1% NaOCl, rotting root and collar pieces of E. papyrifera consistently produced a Phytophthora-like organism when plated on a medium selective for oomycetes (3). The pathogen was identified morphologically as Phytophthora nicotianae (= P. parasitica) (2). On V8 agar, coenocytic hyphae, 4 to 8 μm in diameter, formed fluffy, aerial colonies and spherical, intercalary chlamydospores, 21.0 to 36.5 (average 26.7) μm in diameter. Colonies grew well at 35°C and stopped growing at 40°C. Sporangia were produced by growing a pure hyphal-tip culture in a diluted, sterilized soil-extract. Sporangia were borne singly, laterally attached to the sporangiophore, were noncaducous, spherical to ovoid, papillate, and measured 28.6 to 55.2 × 22.4 to 45.1 (average 42.4 × 34.6) μm, length/breadth ratio (1.1:1)-1.2:1-(1.3:1). Papillae measured 3.1 to 7.6 (average 4.6) μm. The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified with primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 839-bp segment showed 99% homology with the sequence of P. nicotianae (No. AJ854296). The sequence has been assigned the GenBank No. GU353341. Pathogenicity of isolates Edg.1 and Edg.2 obtained, respectively, from the root and collar of an infected plant was confirmed by inoculating 1-year-old plants of E. papyrifera. Both strains were grown for 15 days on a mixture of 70:30 wheat/hemp kernels, and 4 g/liter of the inoculum was mixed into a substrate containing sphagnum peat moss/pumice/pine bark/clay (50:20:20:10 vol/vol). One plant per 3-liter pot was transplanted into the substrate and constituted the experimental unit. Five plants were used for each test strain and noninoculated control treatment; the trial was repeated once. All plants were kept in a greenhouse at 25 to 28°C. Plants inoculated with Edg.1 and Edg.2 developed chlorosis and root rot 18 and 14 days after the inoculation, respectively, and wilt rapidly followed. Control plants remained symptomless. P. nicotianae was consistently reisolated from inoculated plants. To our knowledge, this is the first report of P. nicotianae on E. papyrifera in Italy as well as worldwide. The current economic importance of the disease is minor due to the limited number of farms that grow this crop in Italy, although spread could increase as the popularity of plantings expand. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phtytopathological Society, St Paul, MN, 1996. (3) H. Masago et al. Phytopathology 67:425, 1977.

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First Report of Phytophthora nicotianae Causing Asparagus Spear and Root Rot in China

Plant Disease ◽

10.1094/pdis-05-17-0635-pdn ◽

2018 ◽

Vol 102 (5) ◽

pp. 1042

Author(s):

D. L. Li ◽

J. F. Cao ◽

C. Huo ◽

N. A. Rajput ◽

Z. J. Zhao

Keyword(s):

Root Rot ◽

Phytophthora Nicotianae ◽

First Report

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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 Phytophthora nicotianae on Skimmia japonica in Italy

Plant Disease ◽

10.1094/pdis.2004.88.8.905c ◽

2004 ◽

Vol 88 (8) ◽

pp. 905-905

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Root Rot ◽

Northern Italy ◽

Ornamental Plant ◽

Phytophthora Nicotianae ◽

Plant Production ◽

Control Treatment ◽

American Phytopathological Society ◽

First Report ◽

Average Temperature ◽

Lower Stem

Skimmia japonica, an evergreen flowering shrub, is becoming increasingly popular as a potted ornamental plant in northern Italy and represents 5% of acidophilous plant production; cv. Rubella accounts for 99% of production. During the spring of 2003, in many commercial nurseries located in northwestern Italy, plants of S. japonica cv. Rubella showed extensive chlorosis and root rot, and diseased plants eventually wilted and died without dropping leaves. The disease was widespread and severe, and in some nurseries, 40% of plants were affected. A Phytophthora-like organism was isolated consistently from infected lower stem and root pieces of S. japonica that had been disinfested for 1 min in 1% NaOCl and plated on a medium selective for oomycetes (2). The pathogen was identified based on morphological and physiological features as Phytophthora nicotianae (= P. parasitica [1]). The sporangia produced on V8 medium were ± spherical to obpyriform, obturbinate, papillate, and measured 33 to 94 × 25 to 48 μm (average 56.4 × 36.8 μm). Papillae measured 3.5 to 19 μm (average 7.8 μm). Chlamydospores were spherical with a diameter ranging from 26 to 32 μm (average 29.2 μm). Pathogenicity of four isolates obtained from infected plants was confirmed by inoculating 9-month-old plants of S. japonica cv. Rubella grown in 1-liter pots containing a substrate based on sphagnum peatmoss, pine bark, and clay (70-20-10% vol/vol/vol). Inocula, which consisted of 90-mm-diameter V8 agar disks per pot containing mycelium of each isolate, were introduced and mixed into the substrate in all pots before transplanting. One plant was transplanted into each pot and served as a replicate, and noninoculated plants served as controls. Eight replicates were used for each isolate and the control treatment, and the trial was repeated. All plants were kept outside at temperatures ranging from 16 to 38°C (average temperature 27°C). Inoculated plants developed symptoms of chlorosis, root rot, and wilt within 20 days, while control plants remained symptomless. P. nicotianae consistently was isolated from inoculated plants. Previously, P. nicotianae has been reported on S. japonica in Poland (3). To our knowledge, this is the first report of P. nicotianae on S. japonica in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (2) H. Masago et al. Phytopathology, 67:425, 1977 (3) G. Szkuta and L. B. Orlikowski. Prog. Plant Prot. 42:808, 2002.

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First Report of Collar and Root Rot Caused by Phytophthora nicotianae on Daphne odora in Italy

Plant Disease ◽

10.1094/pdis-93-8-0848a ◽

2009 ◽

Vol 93 (8) ◽

pp. 848-848

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Root Rot ◽

The United States ◽

Phytophthora Nicotianae ◽

Control Treatment ◽

Peat Moss ◽

Late Winter ◽

American Phytopathological Society ◽

First Report ◽

Daphne Odora

Daphne odora is becoming popular in gardens because of its variegated foliage and fragrant flowers in late winter and early spring. During October of 2008 in a commercial nursery near Maggiore Lake (Verbano-Cusio-Ossola Province) in northwestern Italy, plants of D. odora showed extensive chlorosis and root rot. Diseased plants eventually wilted and died, dropping leaves in some cases. Most frequently, wilted leaves persisted on stems. At the soil level, dark brown-to-black water-soaked lesions that coalesced often girdled the stem. All of the crown and root system was affected. Disease was widespread and severe with 70% of 2,500 potted plants being affected. A Phytophthora-like organism was isolated consistently on a medium selective for oomycetes (4) after disinfestation of lower stem and root pieces of D. odora for 1 min in a solution containing 1% NaOCl. Tissue fragments of 1 mm2 were excised from the margins of the lesions and plated. The pathogen was identified based on morphological and physiological features as Phytophthora nicotianae (= P. parasitica) (2). Sporangia were produced for identification by growing a pure culture in sterilized soil extract solution at neutral pH (obtained by shaking and then centrifuging 300 g of soil in 1 liter of distilled water). They were spherical to ovoid, papillate, and measured 39.2 to 54.5 × 31.7 to 41.7 μm (average 44.8 × 34.5 μm). Papillae measured 2.4 to 4.9 μm (average 3.7 μm). Chlamydospores were spherical with a diameter ranging from 15.8 to 36.1 μm (average 25.4 μm). The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 804-bp segment showed a 100% homology with the sequence of P. nicotianae EF140988. The nucleotide sequence has been assigned GenBank No. FJ843100. Pathogenicity of two isolates obtained from infected plants was confirmed by inoculating 12-month-old plants of D. odora. Both isolates were grown for 15 days on a mixture of 70:30 wheat/hemp kernels and then 80 g/liter of the inoculum was mixed into a substrate containing sphagnum peat moss/pumice/pine bark/clay (50:20:20:10 vol/vol). One plant per 3-liter pot was transplanted into the substrate and constituted the experimental unit. Three replicates were used for each isolate and noninoculated control treatment; the trial was repeated once. All plants were kept in a greenhouse at temperatures from 20 to 25°C. Plants inoculated with isolate no. 1 developed symptoms of chlorosis and root rot within 14 days and then a wilt rapidly followed. Isolate no. 2 was less aggressive causing the same symptoms within 20 days. Control plants remained symptomless. P. nicotianae consistently was reisolated from inoculated plants. Previously, P. nicotianae (= P. parasitica) has been reported in several states of the United States on D. odora (3). To our knowledge, this is the first report of P. nicotianae on D. odora in Italy. The economic importance of the disease is low because of the limited number of farms that grow this crop in Italy, although spread could increase as the popularity of plantings expand. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (3) D. F. Farr et al. Fungi on Plants and Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (4) H. Masago et al. Phytopathology, 67:425, 1977.

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First report of Fusarium proliferatum causing stem and root rot on lucky bamboo (Dracaena braunii) in Iraq

Hellenic Plant Protection Journal ◽

10.2478/hppj-2019-0001 ◽

2019 ◽

Vol 12 (1) ◽

pp. 1-5

Author(s):

A.A. Lahuf

Keyword(s):

Ribosomal Dna ◽

Root Rot ◽

Internal Transcribed Spacer ◽

Morphological Characteristics ◽

Its Region ◽

Fusarium Proliferatum ◽

Ornamental Plant ◽

Sequence Analyses ◽

First Report

Summary Lucky bamboo (Dracaena braunii) is a popular ornamental plant in Iraq. Individuals of this plant showing stem and root rot symptoms were observed during a survey conducted from November 2015 to February 2016 in several nurseries in Kerbala province, Iraq. Based on morphological characteristics and sequence analyses of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA), the pathogen was identified as Fusarium proliferatum. This is the first report of stem and root rot caused by F. proliferatum on lucky bamboo (D. braunii) in Iraq.

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First Report of Phytophthora × pelgrandis Causing Root Rot and Lower Stem Necrosis of Common Box, Lavender and Port-Orford-Cedar in Hungary

Plant Disease ◽

10.1094/pdis-07-12-0662-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 152-152 ◽

Cited By ~ 3

Author(s):

A. Szigethy ◽

Z. Á. Nagy ◽

A. M. Vettraino ◽

A. Józsa ◽

S. O. Cacciola ◽

...

Keyword(s):

Root Rot ◽

Ornamental Plants ◽

Maximum Growth ◽

Phytophthora Species ◽

Root Weight ◽

Isoenzyme Analysis ◽

First Report ◽

Buxus Sempervirens ◽

Port Orford Cedar ◽

Lower Stem

In 2008 and 2009, necrotic bark lesions at the root collar and lower stem associated with root rot, reduced growth, and wilting were observed on container-grown common box (Buxus sempervirens L.), lavender (Lavandula angustifolia Mill. ‘Hidcote’), and Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl. ‘Columnaris’) in three ornamental nurseries in western Hungary. Number of affected plants ranged from approximately 100 (Port-Orford-cedar) to 250 (lavender). Isolations from necrotic root collars of each host plant species yielded four Phytophthora isolates developing uniform colonies on carrot agar with a maximum growth temperature of 35 to 36°C. The isolates were homothallic with smooth-walled oogonia (32.2 ± 2.3 to 35.9 ± 3.5 μm), aplerotic oospores (27.5 ± 1.8 to 32.1 ± 3.1 μm) and both amphigynous and paragynous antheridia, and produced chlamydospores (25.8 ± 3.9 to 29.1 ± 5.2 μm) and papillate sporangia (35.2 ± 2.5 to 43.5 ± 5.6 μm long and 27.6 ± 2.2 to 32.0 ± 3.8 μm wide), mostly obpyriform to nearly spherical or rarely distorted with two or three apices. In spring water, sporangia were both caducous with short pedicel and non-caducous. Multiplex ITS-PCR assay of DNA from all isolates, using primers specific for P. nicotianae (NICF1 and NICR2.1) and P. cactorum (CACTF1 and CACTR1) (1), amplified DNA fragments of the expected size for each Phytophthora species. In addition, isoenzyme analysis revealed a characteristic banding pattern of one heterodimer and two homodimer bands at both loci of the dimeric enzyme malate dehydrogenase. These bands comigrated with those of P. × pelgrandis (Gerlach et al.) (CBS 123385) and isolate PD 93/1339 (courtesy of W. A. Man in ‘t Veld), two natural hybrid strains of P. nicotianae and P. cactorum (2,3), proving that our four isolates can be referred to as this interspecific hybrid. Pathogenicity was tested on 1- or 3-year-old plants of the original host species and cultivars (for common box, cv. Faulkner was used). Cultures were grown for 4 to 6 weeks at 20°C on autoclaved millet grains moistened with V8 broth. Infested and uninfested grains were mixed with autoclaved soil in a ratio of 6% (w/v), and the mixes were used as potting media for transplanting five treated and five control plants per isolate, respectively. Plants were kept in a growth chamber (20°C, 70% RH, 12-h photoperiod). Pots were flooded for 24 h on the 1st and 21st day after transplanting. All plants in infested potting mix showed symptoms of wilt associated with basal stem and root necrosis, similar to those observed on the plants from the field, within 2 and 3 months on lavender and both common box or Port-Orford-cedar, respectively. Additionally, a reduction of root weight ranging from 35 to 68% compared to the control was recorded. Growth reduction was significant at P ≤ 0.019 according to Mann Whitney test. Control plants remained healthy. The same Phytophthora hybrid was reisolated solely from inoculated plants. In Europe, hybrid isolates of P. nicotianae × P. cactorum have been reported on several ornamental plants, including lavender, in the Netherlands and Germany (2,3). However, to our knowledge, this is the first report of this hybrid in Hungary and as a pathogen of common box and Port-Orford-cedar in the world. References: (1) P. J. M. Bonants et al. Phytopathology 90:867, 2000. (2) W. A. Man in ‘t Veld et al. Phytopathology 88:922, 1998. (3) H. I. Nirenberg et al. Mycologia 101:220, 2009.

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First Report of Cherry Stem Rot and Leaf Necrosis Disease Caused by Phytophthora nicotianae in Yantai, China

Plant Disease ◽

10.1094/pdis-05-14-0489-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 284-284

Author(s):

X. L. Yu ◽

X. Q. Liu ◽

P. S. Wang ◽

Y. Z. Wang

Keyword(s):

Average Length ◽

Morphological Characteristics ◽

Its Region ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Control Measures ◽

Stem Rot ◽

Economic Losses ◽

First Report ◽

Leaf Necrosis

Cherry (Cerasus avium (Linn.) Moench) is the third most economically important fruit in Yantai, Shandong Province, China. In August 2012, brown spots or necrosis on cherry seedling leaves, with an incidence of 8.2 to 34.3%, were observed in some fields of cherry seedlings in Yantai. Our survey indicated that the economic losses could reach up to 15.3% if disease conditions, such as a cool rainy summer season, were favorable. Conspicuous watery lesions on the stems turned to brown streaks; the leaves all wilted; and finally the plants collapsed. Diseased stem and leaf samples were surface-disinfected in 1% sodium hypochlorite for 1 min, rinsed three times in sterile water, which was absorbed with filter paper, and then transferred to 10% V8 juice agar medium containing 50 μg/ml ampicillin and 5 μg/ml carbendazim (1). The plates were incubated at 22°C in the dark for 5 days. The colonies consisted of white, loose, fluffy aerial mycelia. Eight isolates were obtained, and all were identified as Phytophthora nicotianae based on morphological characteristics and the sequence of the internal transcribed spacer (ITS) region of rDNA. The sporangia were ovoid/spherical, obturbinate with rounded bases and prominent papillae that were 37.5 to 62.5 × 30 to 50 μm (average 46.4 × 37.8 μm, n = 100) in size, with an average length-to-breadth ratio of 1.2. Chlamydospores were terminal, intercalary, and measured 19 to 42 μm (average 30.4 μm), which is typical of P. nicotianae (2). The genomic DNA of the eight isolates was extracted from mycelia. The ITS region of all eight isolates was amplified using primers ITS1 and ITS4, producing specific products that were directly sequenced. The sequence of a representative isolate P1401 (895 bp) was submitted to GenBank (Accession No. KJ754387). It was 100% similar to P. nicotianae strains NV-20T and TARI 22073 (KC768775 and GU111667). To confirm the pathogenicity, at least 10 cherry leaves and new stems were inoculated with mycelial plugs (5 × 5 mm) from each isolate. Necrosis of leaves and stems was observed 4 and 7 days after inoculation, respectively. No symptoms were observed on the control leaves and stems that were inoculated with blank agar plugs. P. nicotianae was re-isolated from the infected leaves, and the ITS sequence was analyzed to confirm its identity. Phytophthora species, such as P. cambivora, P. megasperma, and P. drechsleri, had been previously isolated from cherry (3), but to the best of our knowledge this is the first report of stem rot and leaf necrosis disease caused by P. nicotianae on cherry. Since the economic loss caused by this disease could reach 15% if an outbreak occurred in a rainy summer, control measures should be implemented. References: (1) Y. Balci et al. Mycol. Res. 112:906, 2008. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (2) S. M. Mircetich and M. E. Matheron. Phytopathology 66:549, 1976.

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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 nicotianae on Limonium in Europe

Plant Disease ◽

10.1094/pdis.2001.85.4.445b ◽

2001 ◽

Vol 85 (4) ◽

pp. 445-445

Author(s):

E. Ilieva ◽

W. A. Man in 't Veld ◽

B. F. Wessels-Berk ◽

R. P. Baayen

Keyword(s):

The Netherlands ◽

Mating Type ◽

Root Rot ◽

The United States ◽

Phytophthora Nicotianae ◽

Isozyme Analysis ◽

American Phytopathological Society ◽

Disease Symptoms ◽

Liquid Cultures ◽

First Report

Limonium (statice or sea-lavendar, family Plumbaginaceae) is grown in the Netherlands as a perennial (Limonium sinense) or annual (Limonium sinuatum) crop. Plants have tufted leaves and numerous clustered flowers of different colors and are used for flower arrangements. In August 2000, we received diseased plants of L. sinense cv. Diamond and L. sinuatum. Disease symptoms consisted of leaf wilting followed by plant collapse. The base of the leaves showed progressive necrotic areas that later turned dark brown to black. The cortex of the stem and roots was water-soaked and dark brown to black. Longitudinal sections of stems and roots of diseased plants displayed discoloration of tissues. Rotted root tissue was brown with a characteristic black margin. Rotted vascular tissues and other stem parts were also dark brown. Pith parenchyma turned gray-brown and had a firm, wet rot. In plants with advanced disease symptoms, a cavity in the stem parenchyma was observed. Isolations were made from sections of symptomatic leaves, stems and roots of both Limonium species on cherry and water agar (WA), followed by incubation at 20°C. Phytophthora sp. was isolated consistently from the base of leaves, stems, and roots of diseased plants and identification of isolates was based on morphological characteristics and by isozyme analysis (3). Observations of colony morphology and growth at 35°C were made on V8 agar. Mating type was determined in dual cultures with mating type A2 (P. nicotianae, P 1923 [4]) and A1 (P. nicotianae, PD98/8/10402). Sporangial features were observed from liquid cultures of the isolates (autoclaved soil-extract or sterile distilled water). All isolates formed colonies consisting of loose, fluffy aerial mycelia. Sporangia and chlamydospores were present in all fungal isolates and all isolates were able to grow at 35°C. Few sporangia were produced on solid media (WA and V8 juice agar), but were abundant in liquid cultures. Sporangia were borne singly or in simple sympodial sporangiophores (3 to 4 sporangia), and were ovoid/spherical, obturbinate with rounded base and had prominent papillae (some had two papillae). Sporangia measured 40 to 64 × 24 to 56 μm, (average 50.4 × 38.4 μm) and had an average length:breath ratio of 1.3:1. Chlamydospores were terminal and intercalary and measured 18 to 44 μm (average 31.6 μm). Hyphal swellings with hyphal outgrowths were present. Isolates of the fungus were heterothallic and produced oogonia and oospores rapidly and abundantly on V8 agar at 22°C only with the A1 mating type of P. nicotianae. We concluded that all isolates from Limonium had the A2 compatibility type. Antheridia were amphigynous. Oogonia were spherical and ranged from 20 to 30 μm, (average 27.5 μm). Oospores ranged from 18 to 27 μm, (average 23.1 μm). The observed characteristics are similar to those described for P. nicotianae. Isozyme analysis, using the dimeric enzymes malic enzyme (EC 1.1.1.40) and malate dehydrogenase (EC 1.1.1.37), revealed the presence of the Mdhp100 allele and the Mdh-2100 allele. Both alleles are characteristic for P. nicotianae (3). Based on morphological features and isozyme genotyping, isolates of Phytophthora from diseased Limonium plants could be assigned to P. nicotianae van Breda de haan (1). A report from Florida associated Phytophthora sp. with root rot of Limonium plants (2) but did not identify the species. According to the multi-decade records at the Netherlands Plant Protection Service (unpublished data) Phytophthora has never been observed on Limonium before. This is the first report of P. nicotianae associated with root rot and basal rot of Limonium plants in Europe. References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul, MN. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (3) W. A. Man in 't Veld et al. Phytopathology 88:922–929, 1998. (4) P. Oudemans and M. D. Coffey. Mycol. Res. 95:1025–1046, 1991.

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