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

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.

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First report of Fusarium brachygibbosum causing root rot on soybean in Northeastern China

Plant Disease ◽

10.1094/pdis-05-20-0941-pdn ◽

2021 ◽

Author(s):

Shuang Wang ◽

Xinmin Li ◽

Chunlai Liu ◽

Liang Liu ◽

Fan Yang ◽

...

Keyword(s):

Root Rot ◽

Fungal Pathogens ◽

Control Strategies ◽

Lateral Roots ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Culture Collection ◽

First Report ◽

Consensus Sequences ◽

Soybean Root

In August 2017, soybean root rot plants exhibiting root rot were observed in Baiquan County (47°60′N, 126°10′E), Heilongjiang province, China. The disease occurred on approximately 65% of soybean (cv. Heihe43) plantsroots in five fields (>10 ha). The disease resulted in yellowing or wilting and smaller sized leaves, absence of lateral roots and black lesions on tap roots. Infected root tissues from 10 individual plants (2 plants/each field) were surface disinfested with 0.5% NaOCl for 2 min, rinsed three times in sterile distilled water, placed on potato dextrose agar PDA, and incubated at 26℃ for 3 days. Eight fungal isolates were obtained by transferring hyphal tips.isolated and subcultured by transferring hyphal tips. Colonies on PDA were initially white to rose, then yellow in color with abundant aerial mycelium. The fungal colonies grew to a size of 7.4 cm in diameter four days after inoculation. Macroconidia were scarce and scattered, measuring 19.7 μm× 3.5 μm (n = 50) on carnation leaf agar. Typical macroconidium had 3-5 septa, slightly sharp apices with a distinct basal foot cell. Microconidia had 0-2 septa, and were slightly curved, measuring 10.7 μm × 3.2 μm (n = 50). Spherical chlamydospores had a mean diameter of 13.7μm (n = 50), were terminal and intercalary on PDA. According to these morphological characteristics, the fungus was identified as F. brachygibbosum (Padwick1945). Genomic DNA of a representative isolate P13-1was extracted. The Ef-1α, RPB1 and RPB2 regions were amplified using primers ef1/ef2, Fa/G2R and 5f2/7cr (O’Donnell et al. 2010).The consensus sequences (accession nos. MH748277, MH748278 and MH748279) showed 98.65%, 98.91% and 99.54% identity to the sequences of F. brachygibbosum strain NRRL 34033(accession no.GQ505418.1, HM347172.1 and GQ505482.1). Isolate P13-1was preserved in Agricultural Culture Collection of China, Stock ID number is ACCC 39715.To confirm pathogenicity of P13-1, soybean (cv. Heihe43) seeds were grown in 15-cm pots containing a commercial potting mix (5seeds per pot,3 pots/ treatment). Sorghum seeds (10 g) fully colonized by F. brachygibbosum (Li et al., 2018)were uniformly distributed in each pot and then covered with a 0.5-cm layer of sterile potting soil. , Sterilized sterilized sorghum seeds(10 g) were added to control pots. , incubated in a growth chamber at 25°C (12h day) / 20°C (12h night). 10 Ten days after inoculation , all inoculated plants showed symptoms consistent with those observed in the fields. The experiment was repeated two times. F. brachygibbosum was reisolated from diseased plants and identified as F. brachygibbosum based on morphological and gene sequences analysismolecular characteristics. No fungal pathogens were isolated from nontreated controls. To our knowledge, this is the first report of F. brachygibbosum on soybean in China. The soybean is the prime oil seed crop and the source of protein cultivated in Northeast China and this disease seriously affects the seedling growth. So, our findings are very important for the establishment of control strategies and breeding for resistance to soybean root rot.

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

Plant Disease ◽

10.1094/pd-90-0523a ◽

2006 ◽

Vol 90 (4) ◽

pp. 523-523 ◽

Cited By ~ 2

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.

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First Report of Pythium Root Rot of Rau Ram (Polygonum odoratum)

Plant Disease ◽

10.1094/pd-89-0340a ◽

2005 ◽

Vol 89 (3) ◽

pp. 340-340

Author(s):

E. N. Rosskopf ◽

C. B. Yandoc ◽

B. Stange ◽

E. M. Lamb ◽

D. J. Mitchell

Keyword(s):

Root Rot ◽

Vascular System ◽

Pond Water ◽

Centraalbureau Voor ◽

First Report ◽

Pathogenicity Tests ◽

Symptomatic Tissue ◽

Pythium Helicoides ◽

Production House ◽

Test Plants

Polygonum odoratum (= Persicaria odorata), known as rau ram or sang hum, is native to southeastern Asia and is a common herb in Vietnamese cuisine (1). It has been studied most extensively for its aromatic compound content (2). In Florida, rau ram commonly is grown hydroponically in greenhouses using large, cement beds with recirculated water. The plants form dense mats from which new growth is trimmed for market. During January of 2002, a severe dieback was observed in one production house in Saint Lucie County, FL. Plants with less severe symptoms were yellowed and stunted. Roots of symptomatic plants were largely decayed with root symptoms beginning as a tip necrosis. The cortex of severely affected roots slipped off easily, leaving a stringy vascular system. Plating of symptomatic tissue from 20 randomly selected plant samples was performed with multiple general and selective media including potato dextrose agar, corn meal agar with pimaricin, ampicillin, rifampicin, and pentachloronitrobenzene (PARP) (3). All colonies produced were identified as Pythium helicoides Drechsler on the basis of sporangial, oogonial, and antheridial characteristics (4). Isolates had proliferous, obovoid, papillate sporangia, and were homothallic with smooth-walled oogonia and thick-walled, aplerotic oospores. Multiple antheridial attachments per oogonium were common with the antheridium attached along its entire length. Pathogenicity tests were conducted using P. odoratum plants grown from commercial transplants. Two tests were performed. Each test was conducted using eight inoculated and eight control plants. In the first test, plants were maintained in 10-cm pots immersed in sterilized pond water for the duration of the test. Plants were inoculated with five 7- × 70-mm sections of freshly growing mycelial culture per plant using 10-day-old cultures of Pythium helicoides grown on water agar. Chlorosis was observed at approximately 2 months after inoculation. Root necrosis was observed in inoculated plants approximately 5 months after inoculation. This test was performed in the greenhouse with temperatures ranging from 20 to 30°C. The second test was performed in growth chambers at 35 to 40°C. Plants were maintained in 10-cm pots immersed in Hoagland's solution and were inoculated with four 6-mm plugs per plant. Symptoms were observed on inoculated plants at this temperature within 1 week of inoculation. No chlorosis or root decay was observed in noninoculated, immersed plants. The pathogen was reisolated from inoculated, symptomatic tissue. To our knowledge, this is the first report of root rot of P. odoratum caused by Pythium helicoides. References: (1) R. E. Bond. Herbarist 55:34, 1989. (2) N. X. Dung et al. J. Essent. Oil Res. 7:339, 1995. (3) M. E. Kannwischer and D. J. Mitchell. Phytopathology 68:1760, 1978. (4) A. J. van der Plaats-Niterink. Monograph of the Genus Pythium. Vol. 21, Studies in Mycology. Centraalbureau voor Schimmelcutltures, Baarn, The Netherlands, 1981.

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First Report of Leaf Spot and Root Rot Caused by Phoma betae on Beta vulgaris subsp. vulgaris (Garden Beet Group) in Italy

Plant Disease ◽

10.1094/pdis-91-11-1515c ◽

2007 ◽

Vol 91 (11) ◽

pp. 1515-1515 ◽

Cited By ~ 7

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Beta Vulgaris ◽

Morphological Characteristics ◽

Its Region ◽

Pathogenicity Test ◽

Vegetable Crops ◽

Plastic Bags ◽

Blastn Analysis ◽

Commercial Farms ◽

Pathogenicity Tests ◽

Phoma Betae

In the winter of 2007 in Piedmont (northern Italy), symptoms of a previously unknown disease were observed on beet (Beta vulgaris L. subsp. vulgaris) (garden beet group) grown under a tunnel on several commercial farms near Cuneo. First symptoms appeared on 1-month-old plants, occurring as brown, round-to-oval spots as much as 2 cm in diameter with dark concentric rings near the perimeter. Small, dark pycnidia were present throughout the spots in concentric rings. Generally, older, lower leaves were affected more than the younger ones. Ten to fifteen percent of the plants were affected. Symptoms on the roots began near the crown as small, dark, sunken spots that became soft and water soaked. Eventually, spots on the roots turned dark brown to black and black lines separated diseased and healthy tissues. Older infected tissues were black, dry, shrunken, and spongy. Pycnidia were not observed on affected roots. From infected leaves and roots, a fungus was consistently isolated on potato dextrose agar (PDA) amended with 25 mg/l of streptomycin. The fungus was grown on PDA and maintained at 22°C (12 h of light, 12 h of dark). After 10 days, black pycnidia (130 to 328 [204] μm in diameter) developed, releasing abundant hyaline, elliptical, nonseptate conidia measuring 3.9 to 6.7 (5.1) × 2.4 to 5.9 (3.6) μm. On the basis of its morphological characteristics, the fungus was identified as a Phoma sp. (1). The internal transcribed spacer (ITS) region was amplified using primers ITS4/ITS6 (2) and sequenced. BLASTn analysis of the 557 bp obtained showed an E-value of 0.0 with Phoma betae. The nucleotide sequence has been assigned GenBank Accession No. EU003450. Pathogenicity tests were performed by spraying leaves of healthy 20-day-old potted B. vulgaris plants with a spore and mycelial suspension (1 × 106 spores or mycelial fragments per ml). Noninoculated plants sprayed only with water served as controls. Fifteen plants (three per pot) were used for each treatment. Plants were covered with plastic bags for 5 days after inoculation and kept in a growth chamber at 20°C. Symptoms previously described developed on leaves of all inoculated plants 5 days after inoculation, while control plants remained healthy. Later, pycnidia and conidia, with the same dimensions and characteristics previously described, were observed on the infected leaves. The fungus was consistently reisolated from the lesions of the inoculated plants. The pathogenicity test was carried out twice. P. betae on B. vulgaris var. cycla has been reported in Canada (3) as well as in other countries. The same pathogen was reported in Italy on sugar beet (2). References: (1) G. H. Boerema and G. J. Bollen. Persoonia 8:111, 1975. (2) A. Canova. Inf. Fitopatol. 16:207, 1966. (3) D. E L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) J. R. Howard et al. Diseases of Vegetable Crops in Canada. Canadian Phytopathological Society, 1994.

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Phytophthora nicotianae. [Descriptions of Fungi and Bacteria].

IMI Descriptions of Fungi and Bacteria ◽

10.1079/dfb/20056401200 ◽

1994 ◽

Author(s):

G. Hall

Keyword(s):

Surface Water ◽

Nicotiana Tabacum ◽

Geographical Distribution ◽

Root Rot ◽

World Wide ◽

Phytophthora Nicotianae ◽

Fruit Rot ◽

Tomato Root ◽

Ornamental Crops ◽

The Tropics

Abstract A description is provided for Phytophthora nicotianae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Principally Lycopersicon esculentum, Nicotiana tabacum, Capsicum annuum and Citrus sp. A very large number of other agricultural and ornamental crops, both temperate and tropical, are also affected, including avocado, strawberry, pineapple, papaya, guava, eggplant and durian. DISEASE: Blackshank of tobacco, buckeye of tomato, root and fruit rot of capsicum, root rot of citrus. GEOGRAPHICAL DISTRIBUTION: World-wide, but particularly common in the tropics and sub-tropics. TRANSMISSION: By zoospores in surface water and rainsplash. Chlamydospores (and oospores, when formed) act as perennating structures.

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The occurrence of root-infecting fungi and parasitic nematodes in annual Medicago spp. in Western Australian pastures

Australian Journal of Agricultural Research ◽

10.1071/ar99049 ◽

2000 ◽

Vol 51 (4) ◽

pp. 435 ◽

Cited By ~ 10

Author(s):

M. P. You ◽

K. Sivasithamparam ◽

I. T. Riley ◽

M. J. Barbetti

Keyword(s):

Western Australia ◽

Root Rot ◽

Pathogenic Fungi ◽

Parasitic Nematodes ◽

Fungal Isolates ◽

As Species ◽

Significant Damage ◽

Pathogenicity Tests ◽

Annual Medicago

Asurvey of 30 medic pastures for root-rots was undertaken in Western Australia and pathogenicity tests of representative fungal isolates from roots sampled were conducted to determine the main factors contributing to medic decline and the association between those factors. In particular, the contribution of pathogenic fungi and nematodes to medic root-rot in Western Australia was studied. From a total of 30 000 pieces of root plated, 3836 fungal isolates were obtained and identified at least to genus level. Four hundred and seventy-two representative isolates were tested for in vitro pathogenicity in Medicago sphaerocarpos cv. Orion. Of these, 32 were further tested in the glasshouse. The pathogenicity tests indicated that 56% of isolates were capable of causing significant damage to the root system and it is likely that pathogenic fungi are largely responsible for medic root-rot in the field. In contrast, the number of Pratylenchus spp. in the roots was not found to relate to disease symptoms. It is concluded that soil-borne pathogenic fungi such as species of Pythium, Fusarium, and Phoma contribute significantly to medic pasture decline in Western Australia.

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Pathogenicity of Nectriaceous Fungi on Avocado in Australia

Phytopathology ◽

10.1094/phyto-03-17-0084-r ◽

2017 ◽

Vol 107 (12) ◽

pp. 1479-1485 ◽

Cited By ~ 9

Author(s):

Louisamarie E. Parkinson ◽

Roger G. Shivas ◽

Elizabeth K. Dann

Keyword(s):

Host Range ◽

Root Rot ◽

Severe Disease ◽

Persea Americana ◽

Broad Host Range ◽

Black Root Rot ◽

Calonectria Ilicicola ◽

Leaf Drop ◽

Custard Apple ◽

Pathogenicity Tests

Black root rot is a severe disease of young avocado trees in Australia causing black necrotic roots, tree stunting, and leaf drop prior to tree death. Nectriaceous fungi (Nectriaceae, Hypocreales), are commonly isolated from symptomatic roots. This research tested the pathogenicity of 19 isolates from Calonectria, Cylindrocladiella, Dactylonectria, Gliocladiopsis, and Ilyonectria, spp. collected from young avocado trees and other hosts. Glasshouse pathogenicity tests with ‘Reed’ avocado (Persea americana) seedlings confirmed that Calonectria ilicicola is a severe pathogen of avocado, causing stunting, wilting, and seedling death within 5 weeks of inoculation. Isolates of C. ilicicola from peanut, papaya, and custard apple were also shown to be aggressive pathogens of avocado, demonstrating a broad host range. An isolate of a Calonectria sp. from blueberry and avocado isolates of Dactylonectria macrodidyma, D. novozelandica, D. pauciseptata, and D. anthuriicola caused significant root rot but not stunting within 5 to 9 weeks of inoculation. An isolate of an Ilyonectria sp. from grapevine closely related to Ilyonectria liriodendri, and avocado isolates of Cylindrocladiella pseudoinfestans, Gliocladiopsis peggii, and an Ilyonectria sp. were not pathogenic to avocado.

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CHYTRIDS AND ALGAE: I. HOST–SUBSTRATE RANGE, AND MORPHOLOGICAL VARIATION OF SPECIES OF RHIZOPHYDIUM

Canadian Journal of Botany ◽

10.1139/b67-042 ◽

1967 ◽

Vol 45 (4) ◽

pp. 423-430 ◽

Cited By ~ 19

Author(s):

D. J. S. Barr ◽

C. J. Hickman

Keyword(s):

New Taxa ◽

Morphological Variation ◽

The Past ◽

Wide Range ◽

Pine Pollen ◽

Pure Cultures ◽

Pathogenicity Tests

Studies of pathogenicity and of morphological variation were made with pure cultures of Rhizophydium sphaerocarpum isolated from Spirogyra and of R. karlingii isolated from Ulothrix. R. sphaerocarpum was parasitic, virtually confined to species of Spirogyra amongst which there was a wide range of susceptibility. R. karlingii grew only on non-living algae and on pine pollen. The rhizoidal system of R. sphaerocarpum was quite variable in the extent of its branching. Variations in sporangium size and of the forms of the endobiotic portion of the thallus in R. karlingii grown on different substrates were observed. Such variations have been used in the past as the basis for creation of new taxa. Pathogenicity tests with Paterson's strain of R. sphaerocarpum confirmed that it is saprophytic on many algae and on pine pollen in contrast with the strain isolated from Spirogyra.

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Molecular identification of the rumen flukes Paramphistomum leydeni and Paramphistomum cervi in a concurrent infection of the red deer Cervus elaphus

Journal of Helminthology ◽

10.1017/s0022149x16000699 ◽

2016 ◽

Vol 91 (5) ◽

pp. 637-641 ◽

Cited By ~ 4

Author(s):

M. Sindičić ◽

F. Martinković ◽

T. Strišković ◽

M. Špehar ◽

I. Štimac ◽

...

Keyword(s):

Cervus Elaphus ◽

Red Deer ◽

Incident Light ◽

Morphological Identification ◽

Concurrent Infection ◽

Internal Transcribed Spacer Region ◽

Worldwide Distribution ◽

The Tropics ◽

Paramphistomum Leydeni ◽

Paramphistomum Cervi

AbstractParamphistomosis, caused by paramphistomid flukes, is a gastrointestinal parasitic disease of domestic and wild ruminants. Originally thought to be limited to the tropics and subtropics, the disease has recently been reported in temperate regions. Here we describe the concurrent infection of a red deer doe (Cervus elaphus) with Paramphistomum leydeni and Paramphistomum cervi. This is the first report of P. leydeni in Croatia. Flukes were identified on the basis of morphological keys (tegumental papillae) and sequencing of the internal transcribed spacer region 2 in ribosomal DNA. Our results confirm that the absence of tegumental papillae allows P. cervi to be differentiated morphologically from other paramphistomid species in Europe based on incident light stereomicroscopy. Nevertheless the limitations of morphological identification and taxonomic issues suggest that previous findings on paramphistomid infection should be interpreted carefully. The possible worldwide distribution of these pathogens means that paramphistomosis may be more common and its economic impact greater than previously thought.

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Pythium spp. Associated with Bell Pepper Production in Florida

Plant Disease ◽

10.1094/pdis.2000.84.12.1271 ◽

2000 ◽

Vol 84 (12) ◽

pp. 1271-1274 ◽

Cited By ~ 29

Author(s):

D. O. Chellemi ◽

D. J. Mitchell ◽

M. E. Kannwischer-Mitchell ◽

P. A. Rayside ◽

E. N. Rosskopf

Keyword(s):

Root Rot ◽

Production Systems ◽

Bell Pepper ◽

Root Tip ◽

Root Weight ◽

Plant Mortality ◽

Fresh Market ◽

Plant Weight ◽

Pathogenicity Tests ◽

Pepper Plants

Ten species of Pythium and a group of isolates that produced filamentous sporangia but did not form sexual structures (Pythium ‘group F’) were recovered from the root systems of fresh market bell pepper plants grown on polyethylene-mulched production systems in Florida. Pathogenicity tests using pasteurized field soil inoculated with infested wheat seed demonstrated that P. aphanidermatum, P. myriotylum, P. helicoides, and P. splendens can cause significant root rot and reductions in root growth of pepper. P. aphanidermatum and P. myriotylum caused the most severe root rot, the greatest reductions in plant weight, and 42 and 62% plant mortality, respectively. In pathogenicity tests with tomato plants, these four species produced similar plant weight losses and disease ratings to those observed in pepper, but little or no plant mortality. Low incidences of root tip necrosis in pepper plants were observed with P. arrhenomanes, P. catenulatum, P. graminicola, and P. irregulare, but none of these species caused losses in root weight and only P. irregulare reduced shoot weight. P. periplocum, P. spinosum, and Pythium sp. F colonized root tissue of pepper but caused no significant root rot and did not adversely affect growth. Similar trends were observed with tomato, except that P. arrhenomanes caused limited root tip necrosis without affecting plant growth and P. catenulatum, P. graminicola, P. irregulare, P. spinosum, and Pythium sp. F colonized at least some of the plants but did not cause root disease. A significant interaction between temperature and P. aphanidermatum or P. myriotylum was observed on pepper transplants. The greatest reductions in growth occurred at 28°C, whereas plant mortality only occurred at 34°C.

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