scholarly journals Lavender Cotton Root Rot: A New Host of Phytophthora tentaculata Found in Spain

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 523-523 ◽  
Author(s):  
L. A. Álvarez ◽  
A. Pérez-Sierra ◽  
M. León ◽  
J. Armengol ◽  
J. García-Jiménez
Keyword(s):  
Root Rot ◽  
Soil Extract ◽  
Selective Medium ◽  
Distilled Water ◽  
Internal Transcribed Spacer Region ◽  
New Host ◽  
Stalk Rot ◽  
Pure Cultures ◽  
Pathogenicity Tests ◽  
Short Pedicel

Lavender cotton, Santolina chamaecyparissus, is an evergreen shrub growing primarily in dry, calcareous habitats and is grown in rock gardens and mixed borders mainly for its ornamental and aromatic foliage. During 2004, several commercial nurseries in Valencia Province (eastern Spain) reported high mortality of lavender cotton. The foliage of the diseased plants turned brown, wilted, and died. A Phytophthora sp. was isolated consistently from the soil and roots of infected plants using apple baits and the selective medium PARBH (1), respectively. Four pure cultures (PS-31, PS-32, PS-33, and PS-34) were established from hyphal tips and characterized. Colony morphology on potato dextrose agar (PDA) at 24°C was stoloniferous (short stubby branches) with a growth rate of 2.2 mm per day. Sporangia, chlamydospores, and oospores were produced on V8 agar. The sporangia were ovoid to obpyriform, 27.5 to 64.8 (48.3) × 25 to 52.5 (37.5) μm, length/breadth ratio of 1.3:1, and papillate, from which 20% were caducous with a short pedicel (<5 μm). Hyphal swellings and chlamydospores (22 to 38 μm in diameter) were present. Isolates were homothallic, oogonia were globose, mostly terminal 27.5 to 40 (36.2) μm in diameter, 88% of the antheridia were paragynous, monoclinous, or diclinous, and occasionally with two paragynous antheridia per oogonium. Amphigynous antheridia (12%) were also observed. Oospores were aplerotic, 25 to 35 (32.3) μm in diameter, and thin walled. These characteristics and measurements conformed to the description of P. tentaculata described by Kröber and Marwitz (2). Sequencing the internal transcribed spacer region of Santolina isolates PS-32 and PS-34 and comparison of these sequences with other sequences available in GenBank revealed that they were identical to P. tentaculata (AF266775). Pathogenicity tests used 10 4-to-5-month-old potted lavender cotton and two methods. In the first method, inoculum was prepared on a media of 200 g of oats and 120 ml of V8 juice to 1 liter of distilled water. The medium was inoculated with P. tentaculata grown on PDA and incubated in the dark at 20°C for 4 weeks. Inoculum was buried into the compost mixture around the roots at a rate of 3% (w/v). The second method applied a zoospore drench of 50 ml per plant (1 × 104 zoospores per ml) obtained by inducing zoospores in sterile soil extract from cultures of V8 juice agar. The control plants were inoculated with sterile media and sterile distilled water. The following day, the pots were flooded for 2 days, plants were maintained in a glasshouse at 24 ± 5°C, and watered twice a week. All plants inoculated with the first method had wilted foliage and died within 2 months after inoculation, while plants inoculated with zoospores died after 3 months. P. tentaculata was reisolated and the test was repeated twice. The control plants did not show any symptoms of the disease. P. tentaculata was first reported causing root and stalk rot on Chrysanthemum frutescens hybrids, C. leucanthemum, Delphinium ajacis, and Verbena hybrids in Germany (2). It has also been reported on Verbena hybrids in Spain (3). To our knowledge, this is the first report of P. tentaculata causing root rot on lavender cotton. References: (1) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986. (2) H. Kröber and R. Marwitz. Z. Pflanzenkr. Pflanzenschutz 100:250, 1993. (3) E. Moralejo et al. Plant Pathol. 53:806, 2004.

scholarly journals Root Rot of Hydroponically Grown Lettuce Caused by Phytophthora drechsleri in Mexico

Plant Disease ◽  
2009 ◽  
Vol 93 (10) ◽  
pp. 1077-1077
Author(s):  
G. Rodríguez-Alvarado ◽  
M. I. Pérez-Cáliz ◽  
K. B. Caudillo-Ruiz ◽  
E. Garay-Serrano ◽  
R. Rodríguez-Fernández ◽  
...  
Keyword(s):  
Root Rot ◽  
Morphological Characteristics ◽  
The United States ◽  
Soil Extract ◽  
Internal Transcribed Spacers ◽  
Distilled Water ◽  
Lettuce Seedling ◽  
Phytophthora Drechsleri ◽  
Pathogenicity Tests ◽  
Hydroponically Grown

During March of 2008, bibb lettuce (Lactuca sativa L.) plants with severe wilting and root rot were observed in a commercial liquid-hydroponic greenhouse in Guanajuato, Mexico. By July of that year, the disease affected most plants in the facility. A Phytophthora sp. was consistently isolated from diseased roots on potato carrot agar. Several Phytophthora isolates were morphologically characterized. Sporulation was achieved by placing colonized disks of clarified V8 juice agar (V8A) into nonautoclaved soil extract (10 g avocado soil/1,000 ml distilled water, stirred for 3 h, and filtered). Sporangia were persistent, nonpapillate, and 40 to 58 μm long × 30 to 40 μm wide. External and internal proliferation was observed. Hyphal swellings were predominantly rounded. Oospores were not observed. The isolates grew on V8A at 35°C. Pathogenicity tests were conducted twice by utilizing a representative isolate (AC1) on bibb lettuce seedlings (10 replicates per experiment). Seeds were placed on sterile, water-soaked paper in petri dishes. After 10 days, each lettuce seedling was placed into a tube containing approximately 2 ml of sterile distilled water and 2,000 zoospores. Control plants were placed in tubes with water only. Plants were incubated for 7 days in a moist chamber at 25°C. Symptoms of wilting and root necrosis were observed 2 to 3 days after inoculation. All plants were dead 5 to 7 days after inoculation. A Phytophthora sp. was always isolated from the roots of inoculated plants. Control plants remained healthy. The pathogen was identified as Phytophthora drechsleri Tucker according to morphological characteristics. To confirm the identity of the pathogen, sequences of the internal transcribed spacers (ITS) were obtained from three representative isolates. The ITS sequences that were obtained shared 100% homology to several strains of P. dreschleri, including isolates from cucurbits (GenBank Accession No. AF228097). The ITS sequence was deposited in NCBI as Accession No. FJ790770. P. cryptogea and P. dreschleri have been reported as causing root rot on lettuce grown hydroponically in the United States and Korea (1,2). To our knowledge, this is the first report of P. drechsleri causing root rot on lettuce in Mexico. References: (1) H. J. Jee et al. Plant Pathol. J. 17:311, 2001. (2) A. R. Linde et al. Plant Dis. 74:1037, 1990.

scholarly journals First Report of Stalk Rot Caused by Phytophthora tentaculata on Aucklandia lappa in China

Plant Disease ◽  
2008 ◽  
Vol 92 (9) ◽  
pp. 1365-1365 ◽  
Author(s):  
J. Meng ◽  
Y. C. Wang
Keyword(s):  
Its Region ◽  
Lima Bean ◽  
Selective Medium ◽  
Maximum Temperature ◽  
Mycelium Growth ◽  
First Report ◽  
Stalk Rot ◽  
Pure Cultures ◽  
Short Pedicel ◽  
Colony Surface

Phytophthora tentaculata causes root and stalk rot of Chrysanthemum spp., Delphinium ajacis, and Verbena spp. in nurseries in the Netherlands and Germany (2). In later years, P. tentaculata was isolated from Verbena hybrids (3) and lavender cotton (Santolina chamaecyparissus) in Spain (1). In August 2007, stalk rot symptoms were observed on Aucklandia lappa (Asteraceae), an economically important Chinese medicinal plant, in some fields in Yunnan Province of China. Small groups of infected plants were randomly distributed throughout the fields. Plants showing stalk rot and wilting died rapidly. Diseased tissues were cut into 10-mm pieces and plated onto Phytophthora selective medium, P5ARP (2), to obtain the pure cultures. Seven isolates were obtained, and five isolates were grown on solidified LBA (60 g of lima bean powder and 15 g of agar per 10,000 ml of distilled water) and 10% V8 juice liquid medium for examination of morphological and physiological characteristics (4). The colony surface texture was uniform and formed sparse, loosely branched mycelium on LBA medium. Radial growth rate was 2 to 3 mm per day at 24°C on LBA. In water, relatively small swellings were formed at hyphal branches. Sporangia were spherical or ovoid to obpyriform and some were distorted and papillate with a narrow exit pore. Approximately 10% of the sporangia were caducous with a short pedicel. Sporangial dimensions were 28 to 47 (35) × 21 to 36 (29) μm, length/breadth ratio 1.2. Chlamydospores formed on LBA after 1 week and were terminal, spherical, thin walled, and 21 to 31 (27) μm in diameter. The isolates were homothallic. Oogonia abundantly formed on LBA and were 25 to 36 (31) μm in diameter. One or two paragynous antheridia (15 × 10 μm) were attached to the oogonia. Oospores were spherical, hyaline, aplerotic, and 20 to 32 (25) μm in diameter. The minimum temperature for mycelium growth was 8°C and maximum temperature was 34°C. The internal transcribed spacer (ITS) region was amplified and sequenced and agreed 100% with sequences of four P. tentaculata isolates deposited in GenBank (Accession Nos. AJ854302, AY881001, DQ335634, and AF266775). Pathogenicity was assessed by flooding three potted A. lappa plants with a 104 ml–1 zoospore suspension and incubating at 20 to 22°C. As controls, two potted A. lappa plants were flooded with deionized water. All three inoculated A. lappa plants exhibited stalk rot after 15 days, from which the pathogen was reisolated using selective medium, P5ARP. Controls remained healthy 15 days after inoculation, To our knowledge, this is the first report of P. tetaculata H. Kroeber & R. Marwitz infection of A. lappa in China. We speculate that the pathogen might have been introduced from other countries on seeds. References: (1) L. A. Álvarez et al. Plant Dis. 90:523, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) E. Moralejo et al. Plant Pathol. 53:806. 2004. (4) X. B. Zheng. Methods in Phytophthora. Chinese Agriculture Press, Beijing, China, 1995.

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

Agriculture ◽  
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.

scholarly journals Collar and Root Rot of Olive Trees Caused by Phytophthora megasperma in Sicily

Plant Disease ◽  
2001 ◽  
Vol 85 (1) ◽  
pp. 96-96 ◽  
Author(s):  
S. O. Cacciola ◽  
G. E. Agosteo ◽  
G. Magnano di San Lio
Keyword(s):  
Root Rot ◽  
Radial Growth ◽  
Selective Medium ◽  
Phytophthora Megasperma ◽  
Electrophoretic Patterns ◽  
Pure Cultures ◽  
Olive Trees ◽  
Maximum Temperatures ◽  
Single Hypha ◽  
Collar And Root Rot

Olive (Olea europea L.) is grown on about 154,000 ha in Sicily (southern Italy). In the summer of 1999, a few 3-year-old olive trees with decline symptoms were observed in a recently planted commercial orchard in the Enna province (Sicily). The trees were propagated on wild olive (O. europea L. var. sylvestris Brot.) rootstock. Aerial symptoms, consisting of leaf chlorosis, wilting, defoliation, and twig dieback followed in most cases by plant death, were associated with root rot and basal stem cankers. A Phytophthora sp. was consistently isolated from rotted rootlets and trunk cankers using the BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Pure cultures were obtained by single-hypha transfers. The species isolated from symptomatic olive trees was identified as P. megasperma Drechsler on the basis of morphological and cultural characteristics. All isolates were homothallic, with paragynous antheridia. The diameter of oospores varied from 28 to 42 μm (mean ± SE = 36.3 ± 0.4) when they were produced on potato-dextrose agar (PDA) and from 30 to 43 μm (mean ± SE = 37.8 ± 0.4) when they were produced in saline solution. Sporangia were non-papillate. Optimum and maximum temperatures for radial growth of the colonies on PDA were 25 and 30°C, respectively. At 25°C, radial growth rate was about 6 mm per day. The identification was confirmed by the electrophoresis of mycelial proteins on a polyacrylamide slab gel. The electrophoretic banding patterns of total soluble proteins and three isozymes (esterase, fumarase, and malate dehydrogenase) of the isolate from olive were identical to those of two isolates of P. megasperma obtained from cherry and from carrot in Italy and characterized previously (1). Conversely, they were clearly distinct from the electrophoretic patterns of four isolates of P. megasperma var. sojae Hildebr. from soybean (= P. sojae Kauf. & Ger.), from those of three isolates from asparagus tentatively identified as P. megasperma sensu lato (1) and from those of reference isolates of various species producing non-papillate sporangia, including P. cambivora (Petri) Buisman, P. cinnamomi Rands, P. cryptogea Pethybr. & Laff., P. drechsleri Tucker, and P. erythroseptica Pethybr. Pathogenicity of the isolate from olive was tested in the greenhouse at 18 to 25°C using 18-month-old rooted cuttings of olive cv. Biancolilla. Cuttings were inoculated on the lower stem by inserting a 3-mm plug taken from actively growing colonies on PDA into an incision made with a sterile scalpel. The wound was sealed with waterproof tape. Agar plugs with no mycelium were placed into the stem of cuttings used as a control. The bark was stripped and lesion areas were traced and measured 60 days after inoculation. The isolate from olive produced a brown necrotic lesion (mean size = 500 mm2) around the inoculation wound and was reisolated from the lesion. Conversely, the wound healed up on control plants. P. megasperma has previously been recognized as a pathogen of olive in Greece and Spain (3). However, this is the first report of P. megasperma causing root and collar rot of olive in Italy. References: (1) S. O. Cacciola et al. Inf. Fitopatol. 46:33, 1996. (2) D. C. Erwin and O. K. Ribeiro, 1996. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN. (3) M. E. Sánchez-Hernádez et al. Plant Dis. 81:1216, 1997.

scholarly journals An Emerging Strawberry Fungal Disease Associated with Root Rot, Crown Rot and Leaf Spot Caused by Neopestalotiopsis rosae in Mexico

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2054-2059 ◽  
Author(s):  
Angel Rebollar-Alviter ◽  
Hilda Victoria Silva-Rojas ◽  
Dionicio Fuentes-Aragón ◽  
Uriel Acosta-González ◽  
Merari Martínez-Ruiz ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Root Rot ◽  
Phylogenetic Reconstruction ◽  
Elongation Factor ◽  
Fungal Disease ◽  
Crown Rot ◽  
Internal Transcribed Spacer Region ◽  
Pathogenicity Tests ◽  
Vitro Effect

In the 2017 strawberry season, several transplant losses reaching 50% were observed in Zamora, Michoacán Valley, Mexico, due to a new fungal disease associated with root rot, crown rot, and leaf spot. In this year the disease appeared consistently and increased in the following seasons, becoming a concern among strawberry growers. Thus, the aim of this research was to determine the etiology of the disease and to determine the in vitro effect of fungicides on mycelial growth of the pathogen. Fungal isolates were obtained from symptomatic strawberry plants of the cultivars ‘Albion’ and ‘Festival’ and were processed to obtain monoconidial isolates. Detailed morphological analysis was conducted. Concatenated phylogenetic reconstruction was conducted by amplifying and sequencing the translation elongation factor 1 α, β-tubulin partial gene, and the internal transcribed spacer region of rDNA. Pathogenicity tests involving inoculation of leaves and crowns reproduced the same symptoms as those observed in the field, fulfilling Koch’s postulates. Morphology and phylogenetic reconstruction indicated that the causal agent of the described symptoms was Neopestalotiopsis rosae, marking the first report anywhere in the world of this species infecting strawberry. N. rosae was sensitive to cyprodinil + fludioxonil, captan, iprodione, difenoconazole, and prochloraz.

scholarly journals First report of Dematophora bunodes causing root rot of taro (Colocasia esculenta ) and leatherleaf fern (Rumohra adiantiformis) in Brazil

Plant Disease ◽  
2021 ◽  
Author(s):  
Adans Colmán ◽  
Helcio Costa ◽  
Inorbert Melo Lima ◽  
R.W. Barreto
Keyword(s):  
Root Rot ◽  
Culture Collection ◽  
Colocasia Esculenta ◽  
Consensus Sequences ◽  
Worldwide Distribution ◽  
Pure Cultures ◽  
Blastn Analysis ◽  
Pathogenicity Tests ◽  
Rumohra Adiantiformis ◽  
The Tropics

Colocasia esculenta, taro (T), is a major staple food crop in the tropics, including Brazil. Rumohra adiantiformis, leatherhead fern (LF), is broadly cultivated for its ornamental fronds that are used as a component of flower arrangements. Soft root rot of T and LF, and accompanying rapid plant wilt and death, was observed in plantations in Espírito Santo (Brazil), at Venda Nova do Imigrante, in April 2014 (LF) and July 2015 (T). Great losses were observed. Firstly, a few individual scattered plants showed symptoms of disease in the plantations, then aggregates of plants and, after a few seasons, the majority of the plants in the field died before harvest, leading to the abandonment of the activity by farmers. A white mycelial matt was observed on the crown and roots ofying T and LF plants. Infected corms become necrotic and dark brown mycelial strands were observed internally in tissues. Diseased organs were carefully washed and surface sterilized in 10% sodium hypochlorite. Samples of tissue were removed from the boundary of necrotic tissues and placed on potato dextrose-agar (PDA) plates and incubated at 23±2 C in the dark. Homogeneous mycelial colonies were isolated from both T and LF and, upon observation of microscope mounts under an Olympus BX 53 light microscope, pear-shaped hyphal swellings at the septae (Castro et al. 2013) were observed. . A representative isolate from each host was deposited in the local culture collection as COAD 2911 (LF isolate) and COAD 2912 (T isolate). Additionally, DNA was extracted from each culture using the Wizard Genomic DNA Purification Kit (Promega) and the internal transcriptional spacer region was PCR amplified using the primers ITS5 and ITS1 (White et al. 1990). The amplicons were sequenced by MACROGEN (http://www.macrogen.com). Consensus sequences were deposited in GenBank: MW561595 (LF), MW561596 (T). Consensus regions were compared against other sequences available in Genbank. A BLASTn analysis resulted in LF and T sequences respectively 99% (526/531bp) and 98% (412/420 bp) identity with that of Dematophora bunodes (MN984619). Additionally, a phylogenetic analysis of a selected sequence alignment was performed on the CIPRES webportal (Miller et al., 2010) using MrBayes v.3.1.1 (Ronquist & Huelsenbeck, 2003). A phylogenetic tree was generated showing that the placement of LF and T isolates is in D. bunodes (Wittstein et al. 2020). Pathogenicity tests were performed for LF and T isolates against their original hosts. For inoculum, bags of twice-autoclaved parboiled rice were seeded separately with each isolate, which were allowed to colonize the rice for two weeks. Four healthy young LF and T plants were utilized. Two extra healthy plants grown in the same conditions, but not inoculated, served as controls. Thirty g of Dematophora-colonized rice was placed in direct contact with stems or roots of each LF or T plant. Plants were maintained in a dew chamber for 48 h after inoculation and then transferred to a greenhouse bench. All inoculated plants developed wilt and root rot and died after 15-20 days. Controls remained healthy. White mycelial colonies were formed over tissues of diseased LF and T and upon observation under the microscope, typical pear-shaped swellings were observed in slides prepared from newly obtained pure cultures from LF and T. Dematophora bunodes (formerly Rosellinia bunnodes) has a worldwide distribution and is well known as a polyphagous plant pathogen (Farr and Rossman, 2020) but has never been reported as a pathogen either of LF or T before in Brazil and worldwide. Its report on LF and T further expands an already large host-range and resolves the etiology of the disease on LF and T.

scholarly journals First Report of Phaeoacremonium parasiticum Causing Petri Disease of Grapevine in Peru

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 200-200 ◽  
Author(s):  
L. C. Romero-Rivas ◽  
L. A. Álvarez ◽  
D. Gramaje ◽  
J. Armengol ◽  
C. Cadenas-Giraldo
Keyword(s):  
Restriction Enzymes ◽  
Sodium Hypochlorite Solution ◽  
Malt Extract ◽  
Distilled Water ◽  
Internal Transcribed Spacer Region ◽  
Poor Growth ◽  
First Report ◽  
Grapevine Decline ◽  
Pathogenicity Tests ◽  
Weak Growth

Since 2005, symptoms of grapevine decline have been observed on 4- to 8-month-old grapevines (cvs. Red globe and Crimson) grafted onto 1103 P rootstock in Ica and Pisco valleys in southern Peru. Affected plants exhibited weak growth, interveinal chlorosis, necrosis and wilting of leaves, and death. Dark brown-to-black streaking of the xylem was seen when transverse or longitudinal cuts were made in the trunk and shoots. Symptomatic plants were collected and sections (5 cm long) were cut from the zone between the rootstock and the scion, surface sterilized for 1 min in a 1.5% sodium hypochlorite solution, and washed twice with sterile distilled water. The sections were split longitudinally, and small pieces of discolored tissues were placed onto potato dextrose agar (PDA) supplemented with oxytetracycline (500 mg liter–1). Plates were incubated at 25°C in the dark for 15 days. A Phaeoacremonium sp. was consistently isolated from necrotic tissues. Single conidial isolates were obtained and grown on PDA and malt extract agar (MEA) in the dark at 25°C for 3 weeks until colonies produced spores (3). Colonies were brown on PDA and olive brown on MEA. Conidiophores were branched, 27.5 to 67.5 (42.5) μm long, and often consisting of a single phialide. Conidia were hyaline, oblong ellipsoidal, 2.5 to 4.5 (3.6) μm long, and 1.2 to 1.9 (1.6) μm wide. On the basis of these characteristics, the isolates were identified as Phaeoacremonium parasiticum (Ajello, Georg & C.J.K Wang) W. Gams, Crous & M.J. Wingf. (teleomorph Togninia parasitica L. Mostert, W. Gams & Crous) (2,3). Identity of isolate Ppa-1 was confirmed by PCR-restriction fragment length polymorphism of the internal transcribed spacer region (Phaeoacremonium-specific primers Pm1-Pm2) with the restriction enzymes BssKI, EcoO109I, and HhaI (1). Additionally, the beta-tubulin gene fragment (primers T1 and Bt2b) of this isolate was sequenced (GenBank Accession No. FJ151015). The sequence was identical to the sequence of P. parasiticum (GenBank Accession No. AY328379). Pathogenicity tests were conducted using the isolate Ppa-1. Approximately 20 μl of a suspension containing 103 conidia ml–1 was injected into the pith of four nodes on each of 10 dormant, unrooted, 15 cm long cuttings of cv. Red Globe. Four nodes on each of 10 cuttings were used as controls and injected with an equal volume of sterile distilled water. Inoculation points were covered with Parafilm. The cuttings were planted in plastic pots and maintained at 24 ± 3°C in diffuse light, watering as needed. Within 2 months of inoculation, all P. parasicitum-inoculated cuttings exhibited shoots with very poor growth with small leaves and short internodes. In the xylem vessels, black streaks identical to symptoms observed in declining vines in the vineyard were observed. Control plants did not show any of these symptoms. The fungus was reisolated from internal tissues of symptomatic shoots of all inoculated cuttings but not from the control shoots. To our knowledge, this is the first report of P. parasiticum causing young grapevine decline in Peru. References: (1) A. Aroca and R. Raposo. Appl. Environ. Microbiol. 73:2911, 2007. (2) P. W. Crous et al. Mycology 88:786, 2006. (3) L. Mostert et al. Stud. Mycol. 54:1, 2006.

scholarly journals First Report of Phytophthora spp. as Pathogens of Pandorea jasminoides in Italy

Plant Disease ◽  
2008 ◽  
Vol 92 (2) ◽  
pp. 313-313 ◽  
Author(s):  
A. Pane ◽  
S. O. Cacciola ◽  
A. Chimento ◽  
C. Allatta ◽  
S. Scibetta ◽  
...  
Keyword(s):  
Growth Temperature ◽  
Root Rot ◽  
Selective Medium ◽  
Phytophthora Nicotianae ◽  
Optimum Growth ◽  
Internal Transcribed Spacer Region ◽  
Phytophthora Root Rot ◽  
First Report ◽  
Optimum Growth Temperature ◽  
Phytophthora Spp

In the summer of 2005, approximately 5% of a nursery stock of 12-month-old potted plants of bower vine (Pandorea jasminoides (Lindl.) K. Schum.) in Sicily (Italy) showed wilt, leaf chlorosis, defoliation, root rot, and collapse of the entire plant. Three Phytophthora spp. (20, 50, and 30% of the isolations of the first, second, and third species, respectively) were isolated from rotted roots on BNPRAH selective medium (2). Single-hypha isolates of the first species formed petaloid colonies on potato dextrose agar (PDA) and had an optimum growth temperature of 25°C (9.3 mm/day); on V8 juice agar, they produced uni- and bipapillate, ovoid to limoniform sporangia with mean dimensions of 45 × 30 μm and a mean length/width (l/w) ratio of 1.4:1. They did not produce gametangia when paired with A1 and A2 isolates of Phytophthora nicotianae. The second species formed arachnoides colonies on PDA, had an optimum growth temperature of 30°C (6.9 mm/day) and produced sporangia that were uni- and bipapillate, ellipsoid, ovoid, or pyriform to spherical (dimensions 44 × 34 μm; l/w ratio 1.3:1). All isolates were A2 mating type and produced amphyginous antheridia and spherical oogonia with smooth walls. The third species formed rosaceous colonies on PDA, had an optimum growth temperature of 28 to 30°C (11.9 mm/day), and produced uni- and bipapillate, ellipsoid or limoniform, caducous sporangia (dimensions 52 × 26 μm; l/w ratio 2.1:1) with a tapered base and a long pedicel (as much as 150 μm). All isolates were A1 type and produced amphigynous antheridia and spherical oogonia with smooth walls. The three species were identified as P. citrophthora, P. nicotianae, and P. tropicalis, respectively. The electrophoretic analysis of the mycelial proteins and four isozymes (1) confirmed the identification. Blast analysis of the sequence of the internal transcribed spacer region of the rDNA of a P. tropicalis isolate from bower vine (GenBank Accession No. EU076731) showed 99% similarity with the sequence of a P. tropicalis isolate from Cuphea ignea (GenBank Accession No. DQ118649). The pathogenicity of three isolates from bower vine, IMI 395552 (P. citrophthora), IMI 395553 (P. nicotianae), and IMI 395346 (P. tropicalis), was tested on 3-month-old potted bower vine plants (10 plants for each isolate) by applying 10 ml of a suspension (2 × 104 zoospores/ml) to the root crown. The plants were maintained at 24°C and 95 to 100% relative humidity. All inoculated plants wilted after 4 weeks. Noninoculated control plants remained healthy. The three Phytophthora spp. were reisolated from symptomatic plants. To our knowledge, this is the first report of Phytophthora root rot of bower vine in Italy. References: (1) S. O. Cacciola et al. Plant Dis. 90:680, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996.

scholarly journals First Record of Crown and Root Rot Caused by Cylindrocladium pauciramosum on Brush Cherry in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (5) ◽  
pp. 547-547 ◽  
Author(s):  
G. Polizzi ◽  
A. Vitale ◽  
D. Aiello ◽  
I. Castello ◽  
V. Guarnaccia ◽  
...  
Keyword(s):  
Root Rot ◽  
Uv Light ◽  
Ornamental Plants ◽  
First Record ◽  
Common Species ◽  
Selective Medium ◽  
Centraalbureau Voor ◽  
Potted Plants ◽  
Pathogenicity Tests ◽  
Crown And Root Rot

Brush cherry (Eugenia myrtifolia Sims; synonym Syzygium paniculatum Gaertn.) is a woody evergreen ornamental plant belonging to the Myrtaceae family. This plant is a very common species in Sicilian landscapes. In June of 2008, a new blight disease was detected in a commercial nursery located in Sicily (Italy) in a stock of 10,000 2-year-old E. myrtifolia cv. Newport potted plants obtained from cuttings. The disease was randomly distributed, affecting approximately 2% of the plants. Twig dieback, followed in some cases by plant death, was associated with crown and root rot. Roots were necrotic and crown tissue was brown. A Cylindrocladium sp. was consistently isolated from symptomatic roots, crowns, and lower stems of affected plants on potato dextrose agar petri dishes. Phytophthora isolates were not found associated with symptomatic tissues with BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Five Cylindrocladium isolates were selected and subsequently identified as single-conidial colonies on carnation leaf agar. Isolates were incubated at 25°C under near-UV light with a 12-h_light/dark regimen and examined after 7 days (1). Isolates were characterized by having conidiophores terminating in obpyriform to broadly ellipsoidal vesicles and conidia hyaline, one septate, and straight with rounded ends, (50-) 54 to 55 (-59) × (3.5-) 4 to 6 μm. These characteristics, as well as their ability to produce perithecia when mated with Italian tester strains of Cylindrocladium pauciramosum, allowed their identification as C. pauciramosum C.L. Schoch & Crous (1,4). One mating type (MAT1-1) was found to be present on this host and a representative fungal isolate (DISTEF-Em3) was deposited at the Centraalbureau voor Schimmelcultures (CBS) open fungi collection (Fungal Biodiversity Centre, Utrecht, NL) with Accession No. 123917. Pathogenicity of the isolate DISTEF-Em3 was confirmed by applying 10 ml of a spore suspension (105 conidia per ml) to the crowns of 20 potted 4-month-old E. myrtifolia cv. Newport cuttings that were subsequently maintained in a greenhouse (23 to 25°C and 80 to 90% relative humidity). The same number of untreated plants was used as control. After 4 weeks, only four treated plants developed symptoms identical to those observed in the nursery. Control plants remained symptomless. C. pauciramosum was always reisolated from the infected plants and the identification of the isolate was made as previously described. Pathogenicity tests were repeated twice. In Italy, C. pauciramosum is a widespread pathogen in nurseries that causes extensive losses on young ornamental plants belonging to several genera (2,3). On the basis of the limited spread of the disease in the nursery and the pathogenicity tests, we consider Cylindrocladium crown and root rot of brush berry as a minor disease. However, this work demonstrated the susceptibility of brush cherry to C. pauciramosum that could lead to more extensive losses in association with other biotic or abiotic stresses. To our knowledge, this is the first record of crown and root rot caused by C. pauciramosum on brush cherry. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) G. Polizzi et al. Plant Dis. 85:803, 2001. (3) G. Polizzi et al. Plant Dis. 90:1459, 2006. (4) C. L. Schoch et al. Plant Dis. 85:941, 2001.

scholarly journals First Report of Crown and Root Rot Caused by Binucleate Rhizoctonia AG-A on Thryptomene saxicola in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 275-275 ◽  
Author(s):  
G. Polizzi ◽  
D. Aiello ◽  
I. Castello ◽  
A. Vitale ◽  
M. Kato ◽  
...  
Keyword(s):  
Root Rot ◽  
Selective Medium ◽  
Fluorescent Light ◽  
First Report ◽  
Binucleate Rhizoctonia ◽  
Potted Plants ◽  
Rdna Its ◽  
Pathogenicity Tests ◽  
Crown And Root Rot ◽  
Safranin O

Thryptomene saxicola (Hook.) Schauer is an evergreen shrub native to Western Australia and a member of the Myrtaceae. In Italy, this species was recently introduced as an ornamental plant from abroad. From July of 2008 to September 2009, a new crown and root rot of T. saxicola was observed on several stocks of approximately 20,000 1- to 3-year-old potted plants. Diseased plants were obtained from a commercial nursery in eastern Sicily, Italy. They were propagated from cuttings and grown under drip irrigation. More than 30% of the plants showed disease symptoms. Infected plants were characterized by a lack of vigor. Roots and crowns were partially or completely destroyed, and as a consequence, infected plants were chlorotic and often wilted. Early in the disease development, roots and crowns showed brown lesions. Successively, mature crown lesions turned dark brown. Longitudinal sections of crown tissues revealed a discoloration of the basal stem. Diseased tissues were surface disinfested for 1 min in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate, and then incubated at 25°C. A binucleate Rhizoctonia (BNR) species was consistently isolated from affected tissues of plants. Phytophthora isolates were not recovered from symptomatic tissues plated on BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Fungal colonies were white with floccose, aerial hyphae. Hyphal cells were determined to be binucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with five different tester isolates of BNR AG-A on 2% water agar in petri plates (3). Anastomosis was observed with all tester isolates. The rDNA-ITS of one isolate of BNR (DISTEF-TS1) was sequenced (GenBank Accession No. AB514570) (2). The sequence from this isolate exhibited 99% homology with BNR AG-A (GenBank Accession No. AY738628). Pathogenicity tests were conducted on potted, healthy, 1-year-old plants of T. saxicola. Forty plants were inoculated by placing 1/cm2 plugs of PDA from 5-day-old mycelial cultures near the base of the stem. The same number of plants was treated with 1/cm2 PDA plugs as controls. Plants were kept at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Root and crown rots, identical to those observed in the nursery, appeared 45 days after inoculation, and 80% of the inoculated plants died within 4 months. Control plants remained healthy. Binucleate Rhizoctonia was reisolated from symptomatic tissues, completing Koch's postulates. To our knowledge, this is the first report in the world of BNR causing disease on T. saxicola. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) M. Hyakumachi et al. Phytopathology 95:784, 2005. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

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