First Report of Phytophthora nicotianae on Skimmia japonica in Italy

A. Garibaldi; D. Bertetti; M. L. Gullino

doi:10.1094/pdis.2004.88.8.905c

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 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 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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First Report of Powdery Mildew Caused by Erysiphe aquilegiae var. aquilegiae on Aquilegia flabellata in Italy

Plant Disease ◽

10.1094/pdis.2004.88.6.681a ◽

2004 ◽

Vol 88 (6) ◽

pp. 681-681

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Powdery Mildew ◽

The United States ◽

Northern Italy ◽

American Phytopathological Society ◽

First Report ◽

Powdery Mildews ◽

The Family ◽

White Mycelium ◽

The University

Aquilegia flabellata Sieb. and Zucc. (columbine) is a perennial garden species belonging to the family Ranunculaceae. During the summer of 2003, a severe outbreak of a previously unknown powdery mildew was observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia were hyaline, ellipsoid, and measured 31.2 to 47.5 × 14.4 to 33 μm (average 38.6 × 21.6 μm). Fibrosin bodies were not present. Cleistothecia were globose, brown, had simple appendages, ranged from 82 to 127 (average 105) μm in diameter, and contained one to two asci. Ascocarp appendages measured five to eight times the ascocarp diameter. Asci were cylindrical (ovoidal) and measured 45.3 to 58.2 × 30.4 to 40.2 μm. Ascospores (three to four per ascus) were ellipsoid or cylindrical and measured 28.3 to 31.0 × 14.0 to 15.0 μ;m. On the basis of its morphology, the pathogen was identified as Erysiphe aquilegiae var. aquilegiae (1). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five, healthy A. flabellata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a garden where temperatures ranged between 20 and 30°C. After 10 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on Aquilegia flabellata in Italy. E. communis (Wallr.) Link and E. polygoni DC. were reported on several species of Aquilegia in the United States (2), while E. aquilegiae var. aquilegiae was previously observed on A. flabellata in Japan and the former Union of Soviet Socialist Republics (3). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) U. Braun. Nova Hedwigia, 89:700, 1987. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) K. Hirata. Host Range and Geographical Distribution of the Powdery Mildews. Faculty of Agriculture, Niigata University, 1966.

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First Report of Brown Root Rot of Alfalfa Caused by Phoma sclerotioides in Maine, Ontario, and Pennsylvania

Plant Disease ◽

10.1094/pdis-93-3-0317c ◽

2009 ◽

Vol 93 (3) ◽

pp. 317-317 ◽

Cited By ~ 1

Author(s):

M. J. Wunsch ◽

R. Kersbergen ◽

A. U. Tenuta ◽

M. H. Hall ◽

G. C. Bergstrom

Keyword(s):

Root Rot ◽

Control Treatment ◽

Cortical Lesions ◽

Eastern Canada ◽

Diagnostic Pcr ◽

First Report ◽

South Central ◽

Phoma Sclerotioides ◽

Single Amplicon ◽

Brown Root Rot

Brown root rot (BRR), caused by the fungal pathogen Phoma sclerotioides G. Preuss ex Sacc. (synonym Plenodomus meliloti Dearn. & G.B. Sanford), is associated with yield loss of alfalfa (Medicago sativa L.) in regions with severe winters (1). In the spring of 2007, 9 to 69 alfalfa plants were collected from each of five production fields in Maine, 10 fields in Ontario, and nine fields in Pennsylvania. All alfalfa stands existed at least two winters. P. sclerotioides was isolated from alfalfa root and crown lesions from five fields in Maine (Penobscot, Somerset and Waldo counties), seven fields from southwestern (Woodstock and Niagara), south-central (Lindsay and Belleville), and southeastern Ontario (near Ottawa), and four fields in Pennsylvania (Columbia, Crawford, and Jefferson counties; 41.1 to 41.6°N). BRR incidence was 9 to 29% in Maine, 5 to 29% in Ontario, and 8 to 22% in Pennsylvania. In Ontario, some lesions girdled the crown; in three fields in Maine, large pycnidia characteristic of P. sclerotioides were present on alfalfa crowns and overwintered stems. On potato dextrose agar, conidia (5 to 8 × 2 to 3 μm, unicellular, hyaline, and ovoid) and pycnidia (0.33 to 1.15 mm in diameter with multiple beaks) of single-conidium isolates were characteristic of P. sclerotioides (2). Diagnostic PCR (3) of isolates resulted in a single amplicon of expected size (500 bp). The internal transcribed spacer (ITS) 1, 5.8S, and ITS2 of the rDNA were sequenced for 12 representative isolates, and sequences (GenBank Accession Nos. FJ179151 to FJ179162) were 95.5 to 100% identical to P. sclerotioides ATCC isolate 56515 over a 488-bp alignment. Eight months after seeding, potted ‘Vernal’ alfalfa was inoculated (4), kept at 4°C for 8 weeks, 0 to –2°C for 12 weeks, 4°C for 8 weeks, and 10 to 15°C for 7 weeks. Of 108 plants inoculated with the Maine isolates, 35 developed severe cortical lesions and 16 died. Of 18 plants inoculated with the Ontario isolates, 16 developed severe cortical lesions and eight died. Of 18 plants inoculated with a Pennsylvania isolate, 11 developed severe cortical lesions and five died. Lesions were typical of BRR: light to very dark brown, sometimes with a darker border, and often containing abundant pycnidia. Plant mortality was associated with lesions that girdled the root and crown. Of 18 plants in the control treatment, three developed severe cortical lesions and none died. BRR is common in Alberta, Saskatchewan, and Manitoba, but in eastern Canada it has been reported only in Nova Scotia. To our knowledge, this is the first report of BRR in Maine, Ontario, and Pennsylvania and the southernmost report of BRR in eastern North America. References: (1) B. Berkenkamp et al. Can. J. Plant Sci. 71:211, 1991. (2) G. H. Boerema et al. Persoonia 15:431, 1994. (3) R. C. Larsen et al. Plant Dis. 86:928, 2002. (4) M. J. Wunsch et al. Plant Dis. 91:1293, 2007.

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First Report of Root Rot Caused by Sclerotium rolfsii on Daucus carota var. sativa in Southern Korea

Plant Disease ◽

10.1094/pdis-03-11-0233 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1585-1585

Author(s):

J.-H. Kwon ◽

Y. H. Lee ◽

H.-S. Shim ◽

J. Kim

Keyword(s):

Daucus Carota ◽

Root Rot ◽

Pathogenic Fungus ◽

Sclerotium Rolfsii ◽

Agricultural Science ◽

Control Treatment ◽

Pathogenicity Test ◽

Optimum Temperature ◽

First Report ◽

Causal Fungus

Carrot (Daucus carota var. sativa DC.), an important root vegetable, is cultivated widely because of its dietary fiber and beta carotene. In June 2009 and June 2010, a disease suspected as root rot of carrot caused by Sclerotium rolfsii occurred in a 5-ha field in Jinju, Korea. Early symptoms consisted of water-soaked lesions on root and lower stem tissue near the soil line. Infected plants gradually withered and white mycelial mats appeared on the surface of roots. Numerous sclerotia were often produced on stem and root surfaces in contact with the soil. The heavily infected carrots became rotted and blighted and the whole plant eventually died. The freshly isolated pathogenic fungus was grown on potato dextrose agar (PDA) and examined microscopically. Optimum temperature for mycelia growth or sclerotia formation was 25 to 30°C. Numerous globoid sclerotia formed on the PDA after 18 days of mycelial growth. The sclerotia (1 to 3 mm in diameter) were white at first and then gradually turned dark brown. Aerial mycelia usually formed, consisting of many narrow hyphal strands 3 to 9 μm wide. The white mycelium formed a typical clamp connection after 5 days of growth at optimum temperature. To fulfill Koch's postulates, 10 carrot seedlings were inoculated with colonized agar discs (6 mm in diameter) of the causal fungus directly on the root and incubated in a humid chamber at 25°C for 24 h. Ten carrot seedlings were inoculated similarly with agar discs as the control treatment. After this period, the inoculated and noninoculated plants were maintained in a greenhouse. Eight days after inoculation, the disease symptoms seen in the field were reproduced and the fungus was reisolated from the artificially inoculated plants. To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA region of the causal fungus was amplified using the primers ITS1 and ITS4 (2) and sequenced. The resulting sequence of 684 bp was deposited in GenBank (Accession No. JF342557). The sequence was 99% similar to sequences of Athelia rolfsii (Sclerotium rolfsii) in GenBank. Cultures of S. rolfsii have been deposited with the Korean Agricultural Culture Collection (KACC 45154), National Academy of Agricultural Science, Korea. On the basis of symptoms, fungal colonies, the ITS sequence, and the pathogenicity test on the host plant, this fungus was identified as S. rolfsii Saccardo (1). To our knowledge, this is the first report of root rot of carrot caused by S. rolfsii in Korea. This disease is highly dependent upon environmental conditions, including warm weather and high humidity. Recent occurrence of the disease suggests that S. rolfsii could spread widely. References: (1) J. E. M. Mordue. CMI Descriptions of Pathogenic Fungi and Bacteria. No. 410, 1974. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, Inc., New York, 1990.

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First Report of Phytophthora Root Rot of Sugar Beet, Caused by Phytophthora cryptogea, in Greece

Plant Disease ◽

10.1094/pdis.2000.84.5.593b ◽

2000 ◽

Vol 84 (5) ◽

pp. 593-593 ◽

Cited By ~ 3

Author(s):

G. S. Karaoglanidis ◽

D. A. Karadimos ◽

K. Klonari

Keyword(s):

Sugar Beet ◽

Root Rot ◽

Soil Extract ◽

American Phytopathological Society ◽

Phytophthora Root Rot ◽

Phytophthora Cryptogea ◽

First Report ◽

Solid Media ◽

Necrotic Spots ◽

Extract Medium

A severe rot of sugar beet roots was observed in the Amyndeon area of Greece during summer 1998. Infected plants initially showed a temporary wilt, which became permanent, and finally died. Slightly diseased roots showed necrotic spots toward the base, whereas more heavily diseased roots showed a more extensive wet rot that extended upward. Feeder roots also were infected and reduced in number because of decay. Rotted tissue was brown with a distinguishing black margin. In most of the isolations, carried out on potato dextrose agar (PDA), the pathogen obtained was identified as Phytophthora cryptogea Pethybr. & Lafferty Mycelium consisted of fairly uniform, fine hyphae that showed a slightly floral growth pattern. In autoclaved soil-extract medium, chains or clusters of hyphal swellings (average 12 µm diameter) formed. Sporangia were not produced on solid media but were abundant in soil-extract medium. Sporangia were oval to obpyriform in shape, nonpapillate with rounded bases, and varied in size (39 to 80 × 24 to 40 µm). Oospores were plerotic, thick-walled, and averaged 25 µm in diameter. The isolated pathogen, cultured on PDA, could not grow at all at 36°C. The closely related species P. drechsleri Tucker has been reported to cause similar root rot symptoms on sugar beet (3). However, P. drechsleri grows well at 36°C, while P. cryptogea cannot grow at this temperature; this is the major distinguishing feature that separates the two species (1). To test the pathogenicity of the organism, surface-sterilized sugar beet roots (cv. Rizor) were inoculated with 5-mm-diameter PDA plugs containing actively growing mycelium. Sterile PDA plugs were used to inoculate control sugar beet roots. Inoculated roots were kept at 27°C in the dark for 10 days. Extensive decay of inoculated roots developed, similar to decay observed in the field, whereas control roots showed no decay. P. cryptogea was reisolated from rotted tissues. This pathogen has been recognized previously as a cause of root rot of sugar beet in Japan (1) and Wyoming (2). This is the first report of Phytophthora root rot of sugar beet in Greece. References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN. (2) P. C. Vincelli et. al. Plant Dis. 74:614, 1990. (3) E. D. Whitnew and J. E. Duffus, eds. 1986. Compendium of Beet Diseases and Insects. The American Phytopathological Society, St. Paul, MN.

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First Report of Fusarium Root Rot of Stored Carrot Caused by Fusarium avenaceum in Serbia

Plant Disease ◽

10.1094/pdis-07-14-0724-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 286-286

Author(s):

I. Stanković ◽

K. Milojević ◽

A. Vučurović ◽

D. Nikolić ◽

B. Krstić ◽

...

Keyword(s):

Root Rot ◽

Apical Cell ◽

Morphological Characteristics ◽

Fusarium Avenaceum ◽

Control Treatment ◽

Fluorescent Light ◽

Fungal Mycelium ◽

Vegetable Crops ◽

Orange Pigment ◽

First Report

Carrot (Daucus carota L. subsp. sativus (Hoffm.) Thell., Apiaceae), a widely consumed antioxidant-rich plant, is among the major vegetable crops grown in Serbia, with average annual production of 65,400 tons on approximately 7,000 ha (4). In May 2013, a severe root rot was observed on approximately 20% of cold-stored carrot roots originating from Gospođinci, South Bačka District, Serbia. Symptoms included dry rot of the collar and crown as well as large, brown to dark brown, circular, sunken lesions on the stored roots. Frequently, abundant whitish mycelium was observed covering the surface of the colonized roots. To determine the causal agent, small pieces of infected tissue were surface-disinfested with 2% NaOCl without rinsing, air-dried, and placed on potato dextrose agar. Five single-spore isolates obtained from collar and crown tissue sections, as well as nine isolates from root sections, all formed abundant, cottony white to pale salmon fungal colonies with reddish orange pigment on the reverse surface of the agar medium when grown at 25°C under 12 h of fluorescent light per day. All recovered isolates formed numerous, three- to six-septate, hyaline, needle-like, straight to slightly curved, fusoid macroconidia (30 to 80 × 4 to 5.5 μm, average 58.3 × 4.9 μm, n = 100 spores) each with a tapering apical cell. Microconidia of all isolates were generally scarce, two- to four-septate, spindle-shaped, and 15 to 35 × 3 to 5 μm (average 21.3 × 4.2 μm). Chlamydospores were not observed. Based on these morphological characteristics, the pathogen was identified as Fusarium avenaceum (Fries) Saccardo (1). The pathogenicity on carrot was tested for isolate 19-14 by inoculating each of five carrot roots surface-disinfected with 2% NaOCl, by placing a mycelial plug into the surface of a wound created with a cork borer. Carrot roots inoculated with sterilized PDA plugs served as a negative control treatment. After 5 days of incubating the roots at 25°C, root rot symptoms identical to those observed on the source carrot plants developed on all inoculated roots, and the pathogen was re-isolated from each of these roots using the same procedure descibed above. There were no symptoms on the control roots. Morphological species identification was confirmed by sequencing the translation elongation factor (EF-1α) gene (2). Total DNA was extracted directly from fungal mycelium of isolate 19-14 with a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany), and PCR amplification was performed with primer pair EF-1/EF-2 (2). Sequence analysis of the EF-1α gene revealed 100% nucleotide identity of isolate 19-14 (GenBank Accession No. KM102536) with the EF-1α sequences of two F. avenaceum isolates from Canada (KC999504 from rye and JX397864 from Triticum durum). To our knowledge, this is the first report of F. avenaceum causing collar, crown, and root rots of stored carrot in Serbia. Since F. avenaceum can produce several mycotoxins, including moniliformin, acuminatopyrone, and chrysogine (3), the presence of this pathogen on stored carrots could represent a significant constraint for carrot production in Serbia, for both direct yield losses and potential mycotoxin contamination. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual, Blackwell Publishing, London, UK, 2006. (2) K. O'Donnell et al. Proc. Natl. Acad. Sci. U.S.A. 95:2044, 1998. (3) J. L. Sorenson. J. Agric. Food Chem. 57:1632, 2009. (4) Statistical Office, Republic of Serbia. Retrieved from http://webrzs.stat.gov.rs in May 2014.

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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 Rhizoctonia solani Causing a Disease of Sunflower in India

Plant Disease ◽

10.1094/pdis-94-4-0488c ◽

2010 ◽

Vol 94 (4) ◽

pp. 488-488 ◽

Cited By ~ 5

Author(s):

K. Srinivasan ◽

S. Visalakchi

Keyword(s):

Rhizoctonia Solani ◽

Root Rot ◽

Crown Rot ◽

Pathogenicity Test ◽

American Phytopathological Society ◽

First Report ◽

Leaf Yellowing ◽

Crown Tissue ◽

Symptomatic Tissue ◽

White Mycelium

During the spring of 2009, symptoms including leaf yellowing and wilting, root rot, and death of plants were noted in sunflower (Helianthus annuus L.) crops in Dharmapuri District, Tamilnadu, India. In some fields, approximately 30% of the plants were affected. The disease began when plants were approximately 10 weeks old and occurred on scattered or adjacent plants. The presence of white mycelium was observed on necrotic crowns. Symptomatic tissue was surface disinfested in 70% alcohol for 30 s and 0.5% sodium hypochlorite for 1 min and plated onto potato dextrose agar (PDA) (1). One isolate (coded SV001) had near right-angle branching with basal constriction and adjacent septa and sclerotia typical of Rhizoctonia spp. (2). Cream-colored colonies produced irregular, light brown sclerotia that were 3.0 to 7.3 mm (average 3.8 mm) in diameter. Hyphae were 6.8 to 7.0 μm (average 6.9 μm) wide and multinucleate (8 to 15 nuclei per cell). On the basis of hyphal anastomosis with several known AG testers, the fungus was characterized as Rhizoctonia solani Kühn AG-IV (3). One culture was deposited at the Madras University Botany Laboratory, Center for Advanced Studies in Botany, University of Madras, Chennai, India. In a pathogenicity test, R. solani SV001 was grown on PDA for 5 days at 24°C in the dark. Five-millimeter-diameter disks were placed at the base of sunflower plants (cv. Mordan). Four sunflower plants in each of three pots were inoculated; noninoculated plants served as controls. Plants were placed in a glasshouse maintained at 25 to 27°C. Inoculated plants developed yellow foliage and crown rot and root rot symptoms after 7 to 12 days and died in 17 to 20 days. No symptoms were observed on noninoculated plants. The pathogen was reisolated from fragments of necrotic crown tissue of inoculated plants. To our knowledge, this is the first report of R. solani AG-IV causing a disease of sunflower plants in India. References: (1). R. C. Fenille et al. Plant Pathol. 54:325, 2005. (2). J. R. Parmeter et al. Phytopathology 59:1270, 1969. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St Paul, MN, 1991.

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