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

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 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 Macrophomina phaseolina Causing Pre-harvest Cassava Root Rot in Benin and Nigeria

Plant Disease ◽

10.1094/pdis.1998.82.12.1402c ◽

1998 ◽

Vol 82 (12) ◽

pp. 1402-1402 ◽

Cited By ~ 7

Author(s):

W. Msikita ◽

B. James ◽

H. T. Wilkinson ◽

J. H. Juba

Keyword(s):

Plant Height ◽

Root Rot ◽

Macrophomina Phaseolina ◽

Hot Water ◽

Stem Rot ◽

Rice Seed ◽

First Report ◽

Cassava Root ◽

Number Of Leaves ◽

Lower Stem

In diagnostic surveys conducted in parts of Benin and Nigeria to determine the incidence of pre-harvest cassava root and stem rot during the dry season, Macrophomina phaseolina (Tassi) Goidanich constituted 14.2 and 18.7% of the total fungi (n = 201) associated with cassava root and stem rot from Benin and Nigeria (1). Pathogenicity of M. phaseolina on cassava was tested with cv. Agric. Inocula for pathogenicity tests were prepared by incubating 5-mm-diameter mycelial plugs for each of five isolates (Mp 1 to Mp 5, all collected from Benin) with 500 ml of autoclaved, sterilized, dehusked rice seed for 14 days at 30°C. Five 30-cm-long stem portions per isolate were cut from healthy cassava, surface disinfested in hot water (52°C, 5 min), and planted into 1-liter pots containing autoclaved, sterilized sand mixed with 10 ml of air-dried inoculum. Five plants per isolate similarly treated but not inoculated served as controls. Plants were watered once a week, and maintained in a greenhouse under natural light at 28 to 30°C. Lower leaves of inoculated plants gradually wilted, usually preceded by chlorosis, and brown to black lesions formed on the lower stem portions of some roots. Control plants remained asymptomatic. Plant height and percentage of leaf wilt (determined by counting the number of leaves wilted per plant and dividing by the total number of leaves per plant) were measured on a weekly basis for 8 weeks for each of the control and inoculated plants. At the end of 8 weeks, lesion length on the lower stem was measured. There were significant differences (P < 0.05) in length of the lesions and percentage of leaf wilt induced by the different isolates of M. phaseolina. Isolate Mp 1 induced the longest lesion (7.2 cm), followed by Mp 4 (4.1 cm), Mp 3 and Mp 5 (3.8 cm each), and Mp 2 (1.2 cm). Mp 4 induced the highest percentage of wilted leaves (53%), followed by Mp 1, Mp 3, and Mp 5 (30%), and Mp 2 (10%). All five M. phaseolina isolates (except Mp 3) reduced plant height, compared with control treatments. M. phaseolina was isolated from all infected plants, and the identification was independently confirmed by the International Mycological Institute, Surrey, UK. This is the first report of M. phaseolina causing pre-harvest cassava root rot in Benin and Nigeria. Reference: (1) W. Msikita et. al. Plant Dis. 81:1332, 1997.

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First Report of Cylindrocarpon macrodidymum on Acer palmatum in Virginia

Plant Disease ◽

10.1094/pdis-06-11-0474 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1592-1592 ◽

Cited By ~ 2

Author(s):

N. L. Dart ◽

S. M. Weeda

Keyword(s):

Root Rot ◽

Root Systems ◽

Specific Primers ◽

First Report ◽

Root Stock ◽

Species Specific ◽

Stem Cankers ◽

Lower Stem ◽

Tree View ◽

Unknown Isolate

In October 2010, containerized Acer palmatum Thunb. trees (‘Red Select’, ‘Viridis’, and ‘Hubb's Red Willow’) with crown cankers and root rot were observed at a central Virginia nursery. Sections of lower stem cankers and rootlets were sampled from 14 trees by surface-sterilizing tissue and plating on V8 juice agar. A species of Cylindrocarpon was isolated from 72% of sampled trees and recovered from 57% of 50 cankers and 74% of 50 sections of symptomatic rootlets. On potato dextrose agar (PDA), macroconidia were cylindrical, straight, and rounded at both ends. Chlamydospores were common and intercalary or terminal in the mycelium. To identify to species, the internal transcribed spacer of ribosomal DNA and partial sequences of the beta tubulin gene were sequenced and compared with published sequences (GenBank Accession Nos. AM419110.1 and AM419109.1), which exactly matched sequences of Cylindrocarpon macrodidymum, a recently described species (1,2). Neighbor-joining analyses using Blast Tree View placed C. macrodidymum and the unknown isolate in a closely related but distinct clade from C. pauciseptatum and C. liriodendri. Species-specific primers also confirmed the isolates to be C. macrodidymum (2). A. palmatum seedlings (generic root stock) were inoculated by placing a colonized PDA plug over 1-cm scalpel incision wounds (n = 12) and wrapping treated sections of stem with Parafilm to prevent desiccation. Twelve root systems were inoculated by mixing a colonized PDA plate with 1 liter of water and drenching the soil of each plant. Twelve wounds and root systems were inoculated with uncolonized PDA for controls. After 4 weeks, inoculated wounded seedlings developed brown lesions extending 1 to 3 cm from incision wounds. Inoculated roots developed root rot. Controls produced no visible symptoms. A Cylindrocarpon sp. was recovered from 85% of surface-sterilized sections of inoculated wounded stem and 100% inoculated symptomatic roots. No Cylindrocarpon sp. was isolated from stem or root controls. To our knowledge, this is the first report of this pathogen on A. palmatum. Other reported hosts include grapevines (Vitis spp.) and apple (Malus spp.) (3). This finding demonstrates the ability of C. macrodidymum to impact an ornamental host and the potential for this pathogen to impact the ornamental nursery industry. References: (1) S. Alaniz et al. Plant Dis. 93:821, 2009. (2) J. Auger et al. Plant Dis. 91:470, 2007. (3) Y. T. Tewoldemedhin et al. Eur. J. Plant Pathol. 129:637, 2011.

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

Revista Brasileira de Fruticultura ◽

10.1590/0100-29452016048 ◽

2016 ◽

Vol 38 (3) ◽

Author(s):

JAQUELINE FIGUEREDO DE OLIVEIRA COSTA ◽

IRAÍLDES PEREIRA ASSUNÇÃO ◽

GAUS SILVESTRE DE ANDRADE LIMA ◽

MARIA DE FÁTIMA SILVA MUNIZ ◽

EDNA DORA MARTINS NEWMAN LUZ

Keyword(s):

Phylogenetic Tree ◽

Ribosomal Dna ◽

Root Rot ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Physiological Characteristics ◽

Northeastern Brazil ◽

High Identity ◽

First Report

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 Grape Root Rot Caused by Roesleria subterranea in Michigan

Plant Disease ◽

10.1094/pdis-93-7-0765c ◽

2009 ◽

Vol 93 (7) ◽

pp. 765-765 ◽

Cited By ~ 1

Author(s):

T. D. Miles ◽

A. M. C. Schilder

Keyword(s):

Root Rot ◽

Aqueous Suspension ◽

Root Weight ◽

Its Sequencing ◽

American Phytopathological Society ◽

Potato Dextrose Broth ◽

First Report ◽

Root Decay ◽

Image Library ◽

Vine Decline

In September of 2008, declining grapevines were observed in two vineyards (Vitis interspecific hybrids ‘Canada Muscat’ and ‘Chardonel’) in Fennville, MI. Affected vines were stunted with shortened internodes and yellow leaves; others had dead cordons or were entirely dead. The grower reported that vines were losing vigor and collapsing during a period of 2 years. Renewal trunks would collapse during the second season of growth. Several symptomatic vines showed signs of root decay. On one vine, distinctive fruiting bodies (mazaedia) were apparent on the roots below the soil line and resembled those of Roesleria subterranea (Weinm.) Redhead (2,3,4). The mazaedia were 4 to 5 mm tall and 1 mm in diameter with white-to-tan stipes and powdery, gray-to-greenish hemispherical heads. Ascospores were hyaline to light grayish green, disk shaped, and 4 to 6 μm in diameter. This fungus, also known as R. hypogaea Thüm & Pass., has been previously reported to cause grape root rot, vine decline, and replant problems in North America and Europe (2,3,4). The fungus was cultured from ascospores on potato dextrose agar (PDA). Colonies grew slowly (approximately 2 mm per day at 22 to 24°C) and were green in the center. No spores were produced. DNA was extracted, and internal transcribed spacer (ITS) sequences obtained by PCR were compared with known sequences using BLASTn (1). Our isolate had 100% ITS sequence homology to an isolate from Germany, Roesleria subterranea strain IB (Accession No. EF060304.1). To test for pathogenicity, the fungus was grown in potato dextrose broth for 14 days at 22 to 24°C. An aqueous suspension (0.1 g of fungus per ml) was prepared by blending mycelia with sterile deionized water (SDW) in a food processor. Five two-node, rooted ‘Chardonnay’ cuttings (45 days old) were placed in the suspension. Five other cuttings were placed in SDW (control). After 3 h, plants were removed and repotted in fresh BACTO soil (Michigan Peat Company, Houston, TX) and kept in a growth chamber at 23°C with a 16/8-h light/dark cycle. After 25 days, inoculated plants were, on average, 63% smaller with 77% lower fresh-root weight and fewer fine roots than the control plants. The pathogen was recovered from surface-disinfested roots of all five inoculated plants but not from the control plants. Cultures appeared similar to the original isolate and their identity was confirmed by ITS sequencing. To our knowledge, this is the first report of R. subterranea on grapes in Michigan and the Midwest. This fungus needs to be recognized as a potential cause of vine decline and replant problems in Midwestern vineyards. References: (1) S. F. Altschul et al. J. Mol. Biol. 215:403, 1990. (2) W. Gärtel. Page 40 in: Compendium of Grape Diseases. R. C. Pearson and A. C. Goheen, eds. The American Phytopathological Society, St. Paul, MN, 1988. (3) M. Kirchmair et al. Mycol. Res. 112:1210, 2009. (4) J. R. Liberato et al. Pest and Diseases Image Library. Online publication, 2009.

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First Report of Fusarium oxysporum Causing Root Rot in Ophiopogon bodinieri in China

Plant Disease ◽

10.1094/pdis-07-19-1542-pdn ◽

2020 ◽

Vol 104 (4) ◽

pp. 1254

Author(s):

B. H. Lu ◽

Z. Wang ◽

G. J. Yi ◽

G. W. Tan ◽

F. Zeng ◽

...

Keyword(s):

Fusarium Oxysporum ◽

Root Rot ◽

First Report

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Phytophthora mediterranea sp. nov., a New Species Closely Related to Phytophthora cinnamomi from Nursery Plants of Myrtus communis in Italy

Forests ◽

10.3390/f12060682 ◽

2021 ◽

Vol 12 (6) ◽

pp. 682

Author(s):

Carlo Bregant ◽

Antonio A. Mulas ◽

Giovanni Rossetto ◽

Antonio Deidda ◽

Lucia Maddau ◽

...

Keyword(s):

New Species ◽

Root Rot ◽

Phytophthora Cinnamomi ◽

Colony Growth ◽

Phytophthora Species ◽

Maximum Temperature ◽

Pathogenicity Test ◽

Forest Nurseries ◽

Collar And Root Rot ◽

A New Species

Monitoring surveys of Phytophthora related diseases in four forest nurseries in Italy revealed the occurrence of fourteen Phytophthora species to be associated with collar and root rot on fourteen plants typical of Mediterranean and alpine regions. In addition, a multilocus phylogeny analysis based on nuclear ITS and ß-tubulin and mitochondrial cox1 sequences, as well as micromorphological features, supported the description of a new species belonging to the phylogenetic clade 7c, Phytophthora mediterranea sp. nov. Phytophthora mediterranea was shown to be associated with collar and root rot symptoms on myrtle seedlings. Phylogenetically, P. mediterranea is closely related to P. cinnamomi but the two species differ in 87 nucleotides in the three studied DNA regions. Morphologically P. mediterranea can be easily distinguished from P. cinnamomi on the basis of its smaller sporangia, colony growth pattern and higher optimum and maximum temperature values. Data from the pathogenicity test showed that P. mediterranea has the potential to threaten the native Mediterranean maquis vegetation. Finally, the discovery of P. cinnamomi in alpine nurseries, confirms the progressive expansion of this species towards cold environments, probably driven by climate change.

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