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A–C: Pythium catenulatum . A: chains of hyphal swellings, B: inflated sporangia, C: oogonia and antheridia, D–G: Pythium diclinum , D: appressoria, E: oogonia and antheridia, F: oogonium with oospore, G: oogonium with oospore. (A: bar = 80 μ m, other photographs: bar = 20 μ m).
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Pythium catenulatum, P. diclinum and P. paroecandrum, as well as asexual forms with filamentous sporangia were isolated from irrigation water in the Poniente region of Almería (south-eastern Spain). The taxonomic and morphological details of these fungal isolates are described. P. catenulatum and P. diclinum are new reports to Spain.
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Citations
... The distribution of Pythium and Phytopythium spp. has been investigated in agricultural soils, irrigation water and reservoirs (Abdelzaher et al. 1994a(Abdelzaher et al. , b, 1995Jacobs 1982;Hong and Moorman 2005;Nechwatal et al. 2008;Sánchez and Gallego 2000;Watanabe 1981Watanabe , 1984, but few studies have been conducted in non-agricultural areas such as forests and rivers (Abdelzaher and Kageyama 2020). Pythium, Phytophthora, and Phytopythium spp. ...
In recent years, plant pathogenic oomycetes have become a cause of destruction of nature due to their contribution to new forest diseases and damages to agricultural production, and have attracted attention as important pathogens. It is essential to understand the ecology of pathogenic fungi to elucidate the causes of disease outbreaks. However, there has been little focus on how pathogenic fungi behave in the environment. In this study, we investigated several parameters of two representative genera of plant pathogenic oomycetes, Pythium and Phytopythium species, in terms of (a) their distribution in Japan, (b) seasonal variation from upstream to downstream of rivers with different anthropogenic impacts, (c) morphological and molecular phylogenetic characteristics of river water isolates and (d) pathogenicity. The results suggest that phytopathogenic oomycetes are naturally found in rivers and can act as pathogens when they invade agricultural production sites, indicating the need to pay attention to river water and irrigation water as one of the pathogen transmission routes.Keywords
Pythium
Phytopythium
IrrigationWater supplyCrop productionHorticulture
... The other ARD species identified in the current study have previously been reported to occur in surface water and include P. litorale (Shokes and McCarter 1979;Parkunan and Ji 2013;Shrestha et al. 2013;Zappia et al. 2014), Pythium spp. complex B2A (Shokes and McCarter 1979;Sánchez and Gallego 2001;Zappia et al. 2014) andP. ultimum (Ali-Shtayeh et al. 1991;Rankovic 2005;Zappia et al. 2014). ...
Apple replant disease (ARD) is a biological phenomenon caused by soilborne agents that include selected species of fungi (Rhizoctonia and ‘Cylindrocarpon’-like), oomycetes (Pythium, Phytopythium and Phytophthora) and nematodes (Pratylenchus). Old orchard soils previously planted to apple or related species are a primary inoculum source of ARD pathogens. In the current study, nursery trees and irrigation water were investigated as potential external ARD inoculum sources in South Africa. Investigations conducted at five nurseries over two years revealed that roots of nursery trees were infested by several ARD agents. In the 2013 sampling year, Pythium irregulare and Pythium ultimum were obtained from trees in five and two of the nurseries, respectively, using isolation studies. Based on isolation studies conducted on individual trees in 2013, 47% and 4% of all surveyed trees contained P. irregulare and P. ultimum, respectively. In the 2014 season, real-time quantitative PCR (qPCR) analyses of root tissue from individual trees demonstrated that all of the nurseries and 95% of trees contained P. irregulare, whereas three nurseries and 41% of trees contained P. utlimum. The only other oomycete pathogens that were detected in nursery tree roots were Pythium spp. complex B2A and Pythium sylvaticum and each only occurred in one nursery in one of the sampling years. For all nurseries in both years, trees were consistently infected with ‘Cylindrocarpon’-like spp. Pratylenchus spp., which were only analysed in 2013, was present in all five nurseries and in 29% of the trees. Infestation levels were high, with 22% of trees having Pratylenchus root densities that exceeded 100 per 5 g of roots. Pythium irregulare was the dominant oomycete pathogen detected in irrigation water samples (31% to 76% of the samples) obtained from 13 orchards over two years on a monthly basis. The ARD pathogens P. ultimum, Phytopythium litorale and Pythium spp. complex B2A were rarely identified in irrigation water, along with five other non-pathogenic Pythium and Phytopythium species. The association of ARD causative agents with nursery trees and irrigation water suggests that these could function as potential ARD inoculum sources that might limit post-plant tree growth.
... Therefore, no correlation could be made between the Phytophthora species and the incidence of disease in citrus crops. Several other works have also inferred pathogenicity without providing conclusive evidence (eg Bush et al., 2003; Davison et al., 2003; Gill, 1970; Harvey, 1952; Hong et al., 2001; Klotz et al., 1959a; Klotz et al., 1959b; Lauderdale & Jones, 1997; MacDonald et al., 1994; Oudemans, 1999; Sanchez & Gallego, 2000; Themann et al., 2002; Thomson & Allen, 1974; Tjosvold et al., 2008; Von Broembsen & Charlton, 2000; Whiteside & Oswalt, 1973; Wills, 1964). It is worth mentioning here that with current DNA technology it is now possible to link an isolate from water with an isolate from a plant (Hong & Moorman, 2005). ...
... All rights reserved. & McCarter, 1979) P. chamaihyphon natural waterway USA (Shrestha et al., 2013) P. citrinum natural waterway USA (Shrestha et al., 2013) P. coloratum water retention pond USA (MacDonald et al., 1994) P. debaryanum natural waterway USA (Harvey, 1952) P. diclinum irrigation channel; natural waterway Spain (Sanchez & Gallego, 2000; Shrestha et al., 2013) P. dissoticum irrigation pond (water and sediment); reservoir UK; USA (Pittis & Colhoun, 1984; Shokes & McCarter, 1979) P. helicoides natural waterway USA (Shrestha et al., 2013) P. inflatum irrigation pond (water and sediment) USA (Shokes & McCarter, 1979) P. irregulare irrigation pond (water and sediment) USA (Shokes & McCarter, 1979) P. litorale natural waterway USA (Hulvey et al., 2010; Shrestha et al., 2013) P. mamillatum irrigation reservoir; natural waterway Australia; UK (Palzer, 1980; Pittis & Colhoun, 1984) P. middletonii water retention pond; UK; USA (MacDonald et al., 1994; Pittis & ...
... All rights reserved.MacDonald et al., 1994; Pittis & Colhoun, 1984; Shokes & McCarter, 1979 USA (Shokes & McCarter, 1979) P. undulatum natural waterway USA (Shrestha et al., 2013) P. ultimum natural waterway; water retention pond USA (Harvey, 1952; MacDonald et al., 1994) P. vexans irrigation pond (water and sediment) USA (Shokes & McCarter, 1979; Shrestha et al., 2013) ?Unspecified Pythium spp. irrigation channel; pond (water and sediment); reservoir; natural waterway; water retention pond Spain; UK; USA (Bush et al., 2003; Gill, 1970; Harvey, 1952; Lauderdale & Jones, 1997; MacDonald et al., 1994; Pittis & Colhoun, 1984; Sanchez & Gallego, 2000; Shokes & McCarter, 1979; Waterhouse, 1942) ...
Water used for the irrigation of plants has the potential to harbour and spread plant pathogens yet little research is conducted within this field. This review was undertaken to critically review our understanding of water-borne fungal and oomycete plant pathogens in open irrigation systems, particularly in the context of plant biosecurity. It was determined that very limited data exists on these plant pathogens, with the majority of previous studies only recording pathogen presence. There are significant gaps in our knowledge of pathogen survival and spread, and very limited information on their ability to cause disease when contaminated irrigation water is applied to crops. This review has highlighted the need for new research on the epidemiology and pathogenicity of putative plant pathogens isolated from water, in order to determine their risk to crops. The importance of regular monitoring of irrigation systems for the early detection of plant pathogens is also discussed.This article is protected by copyright. All rights reserved.
... Many of the Pythium spp. isolated during this survey, including Pythium helicoides, Pythium catenulatum, Pythium marisipium, Pythium myriotylum, Pythium irregulare, Pythium vexans, and Pythium adhaerens, have previously been reported from surface water sources (34)(35)(36)(37). Four Pythium spp. ...
Fruit and vegetable growers continually battle plant diseases and food safety concerns. Surface water is commonly used in
the production of fruits and vegetables and can harbor both human- and plant-pathogenic microorganisms that can contaminate
crops when used for irrigation or other agricultural purposes. Treatment methods for surface water are currently limited,
and there is a need for suitable treatment options. A liquid-processing unit that uses UV light for the decontamination of
turbid juices was analyzed for its efficacy in the treatment of surface waters contaminated with bacterial or oomycete pathogens,
i.e., Escherichia coli, Salmonella enterica, Listeria monocytogenes, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, and Phytophthora capsici. Five-strain cocktails of each pathogen, containing approximately 108 or 109 CFU/liter for bacteria or 104 or 105 zoospores/liter for Ph. capsici, were inoculated into aliquots of two turbid surface water irrigation sources and processed with the UV unit. Pathogens were
enumerated before and after treatment. In general, as the turbidity of the water source increased, the effectiveness of the
UV treatment decreased, but in all cases, 99.9% or higher inactivation was achieved. Log reductions ranged from 10.0 to 6.1
and from 5.0 to 4.2 for bacterial pathogens and Ph. capsici, respectively.
... Disease outbreaks have been attributed to water contaminated with plant pathogens (McIntosh, 1966;Whiteside & Oswalt, 1973). Several plant pathogenic microorganisms including bacteria (Schuster, 1959;Thompson, 1965), fungi and oomycetes (McIntosh, 1966;Easton et al., 1969;Gill, 1970;Thompson & Allen, 1974;Shokes & McCarter, 1979;Ali-Shtayeh et al., 1991;Lutz & Menge, 1991;Neher & Duniway, 1992;Sanogo & Moorman, 1993;MacDonald et al., 1994;Dukes et al., 1997;Wakeham et al., 1997;Pettitt et al., 1998;Ristaino & Johnston, 1999;Sánchez & Gallego, 2000;Bush et al., 2003) and nematodes (Schuster, 1959;Faulkner & Bolander, 1970) were isolated from surface irrigation water. Phytophthora and Pythium spp. ...
... Baiting (McIntosh, 1966;Gill, 1970;Grimm & Alexander, 1973;Whiteside & Oswalt, 1973;Thompson & Allen, 1974;Erwin & Ribeiro, 1996;Oudemans, 1999;Sánchez & Gallego, 2000;Bush et al., 2003) and fi ltering (Thompson & Allen, 1974;Shokes & McCarter, 1979;MacDonald et al., 1994;Pottorff & Panter, 1997;Wakeham et al., 1997;Bush et al., 2003) techniques are used to recover species of Phytophthora and Pythium from water and soil. Lemon (Citrus limon (L.) Burm. ...
SummaryA current trend in Florida agriculture to conserve water is to irrigate with surface runoff water (tailwater) recovered in retention ponds and canals. Water filtration and lemon leaf baiting recovered Phytophthora capsici and other plant pathogenic Oomycetes in runoff water from ponds and canals. A total of 196 isolates of Phytophthora spp. and 471 isolates of Pythium spp. were recovered. Phytophthora spp. included P. capsici, P. cinnamomi, P. lateralis, P. nicotianae, P. citricola, P. cryptogea and P. erythroseptica. Species of Pythium were P. aphanidermatum, P. catenulatum, P. helicoides, P. irregulare, P. myriotylum, and Pythium‘group F’. Isolates of P. aphanidermatum, P. irregulare, P. myriotylum, and Pythium‘group F’ were pathogenic on pepper and tomato. Recovery of P. capsici propagules was related to soil moisture-holding capacity and time interval but not temperature. Recovery of P. capsici propagules at 100% soil moisture-holding capacity and 30° C was 57 days. In tailwater, recovery of propagules of P. capsici was 63 days at 24°C to 25°C. The potential exists to reintroduce and disseminate species of Phytophthora and Pythium when using tailwater for irrigation or other practices.
... Centrifugation combined with direct observation via electron microscopy, indicator plant inoculation, ELISA, or other techniques have been used to detect viruses in water (Tošic and Tošic, 1984; Pares et al., 1992; Berkelmann et al., 1995; Kramberger et al., 2004). Another frequently used method for detection is baiting with plant parts or whole trap plants and plating the colonized tissue onto media (Tucker, 1931; Klotz et al., 1959; Easton et al., 1969; Gill, 1970; Dukes et al., 1977; Kegler et al., 1982; Datnoff et al., 1984; Pares et al., 1992; Themann and Werres, 1998; Sanchez et al., 2000; Bush et al., 2003; Hong et al., 2003a). The trap plant or bait detection efficacy and pathogen species selectivity must be examined. ...
Plant pathogens in irrigation water were recognized early in the last century as a significant crop health issue. This issue has increased greatly in scope and degree of impact since that time and it will continue to be a problem as agriculture increasingly depends on the use of recycled water. Plant pathogens detected from water resources include 17 species of Phytophthora, 26 of Pythium, 27 genera of fungi, 8 species of bacteria, 10 viruses, and 13 species of plant parasitic nematodes. There is substantial evidence demonstrating that contaminated irrigation water is a primary, if not the sole, source of inoculum for Phytophthora diseases of numerous nursery, fruit, and vegetable crops. These findings pose great challenges and opportunities to the plant pathology community. A variety of water treatment methods are available but few have been assessed for agricultural purposes under commercial conditions. Investigations into their technical feasibility and economics are urgently needed. Aquatic ecology of plant pathogens is an emerging field of research that holds great promise for developing ecologically based water decontamination and other strategies of pathogen mitigation. Pathogen detection and monitoring as well as biological and economic thresholds are much-needed IPM tools and should be priorities of future research. Teaming with hydrologists, agricultural engineers, ecologists, geneticists, economists, statisticians, and farmers is essential to effectively attack such a complex issue of growing global importance. Research should proceed in conjunction with nutrient and pesticide management studies in a coordinated and comprehensive approach as they are interrelated components of water resource conservation and protection.
... En embalses para riego del mismo Poniente almeriense se detectó la presencia de Olpidium [13] y también la presencia de Pythium y asimismo, se realizó el contaje del número de cebos vegetales colonizados [14]. Por último, también se ha descrito la presencia en las albercas del Poniente almeriense de P. catenulatum y aislados con esporangios filamentosos [15]. ...
La densidad de población (nº propágulos/l) de Pythium en el agua de riego se ha estudiado en las albercas del Poniente almeriense (Almería, España). Estas albercas son utilizadas de forma habitual en el riego de las hortalizas de inverna-dero de la comarca. Desde octubre de 1994 a agosto de 1997 se efectuaron 17 campañas de muestreo; se visitaron 23 albercas y tres de ellas se muestrearon durante tres años. Para ello, se recogieron 300 ml de la superficie del agua y se analizaron en el laboratorio mediante filtrado con papel Whatman nº 1, situado sobre medio selectivo de Ponchet e incubado a 20 ºC. Se tomaron datos de las características físico-químicas del agua (temperatura, pH, CE, aniones y catio-nes). Se efectuaron análisis de la distribución (geográfica, temporal) de la pobla-ción y de las correlaciones con las características analizadas. Las densidades de población más frecuentes fueron entre 0-100 propágulos/l. Se observó una estacionalidad de la población, con máximo en invierno y mínimo en verano. A una mayor cantidad de Cl¯ en el agua apareció una menor cantidad de propágulos/l. Seasonal variation of Pythium Pringsh (Pythiaceae, Oomycetes) in the irrigation reservoirs of the Poniente Almeriense (Almería, Spain) Population density (number of propagules/l) of Pythium in the irrigation water has been studied in the reservoirs of the Poniente Almeriense (Almería, Spain). These reservoirs are habitually used in the watering of the greenhouse crops of the district. From October 1994 to August 1997, 17 sampling campaigns were carried out, 23 reservoirs were visited and three of them were sampled during three years. 300 ml of superficial water were sampled and analyzed in the labo-ratory by means of filtration with paper Whatman nº 1, placed on Ponchet selecti-ve medium and incubated at 20ºC. Data of the physical-chemical characteristics of the water (temperature, pH, CE, anions and cations) were taken. The geo-graphical and seasonal distributions of the population were correlated with the analyzed characteristics. The more frequent densities were among 0-100 propa-gules/l. A population's seasonality was observed, with a maximum in winter and a minimum in summer. When Cl¯ concentration was higher, the number of propa-gules/l was smaller.
Pythium diseases are common in hydroponic crop production and often threaten the greenhouse production of cucumber, tomato, lettuce, and other crops. In tobacco transplant production, where float-bed hydroponic greenhouses are commonly used, Pythium diseases can cause up to 70% seedling loss. However, there have been few comprehensive studies on the composition and diversity of Pythium communities in tobacco greenhouses. In a 2017 survey, 360 Pythium isolates were collected from 41 tobacco greenhouses across four states (VA, MD, GA, and PA). Samples were collected from one to seven sites within each greenhouse. Twelve described Pythium species were identified (P. adhaerens, P. aristosporum, P. attrantheridium, P. catenulatum, P. coloratum, P. dissotocum, P. inflatum, P. irregulare, P. myriotylum, P. pectinolyticum, P. porphyrae, and P. torulosum) among the isolates obtained. Approximately 80% of the surveyed greenhouses harbored Pythium in at least one of four sites (bay water, tobacco seedlings, weeds, and center walkways) within the greenhouse. The structure of Pythium communities was diverse among the surveyed greenhouses: multiple Pythium species coexisted in the same sample, and multiple species were present within the same greenhouse, at different sites. This diversity appeared to be influenced by the sampling sites within the surveyed tobacco greenhouses, sample type, and sampling time. Intraspecific variation may also exist among the P. dissotocum populations found in this study. These results uncovered the complexity and diversity of the Pythium communities within float tobacco transplant greenhouses, which could play a role in the variation in Pythium diseases observed in these production systems.
In this study, we identified and characterize a plant pathogenic isolate, collected from naturally infested bean (Phaseolus vulgaris var. Anupama) seedlings presenting root rot symptoms from an agricultural land of the Prayagraj district, Uttar Pradesh, India. Based on morphological features, growth characteristics and the ITS sequencing-based molecular data, the isolate was assumed very closed to the species of the Pythium genera. However, ITS sequencing data and the BLAST results for gene annotation clustered the identified isolate more closely to the Pythium catenulatum (p-value e-value), and therefore, confirmed as P. catenulatum. The pathogenicity assay confirmed the role of the isolate as a root rot causing pathogen. Furthermore, the isolate was tested for its growth under in-vitro conditions against several environmental parameters including temperature, pH, salt, drought and metals. The Biolog FF MicroPlate method assessed the carbon utilization profile and reported the ability of the isolate in utilizing both carbohydrates and amino acids as a primary energy source. Moreover, in-vitro colony growth inhibition assay performed with different agrochemicals (fungicides and insecticides) and the dyes determined their efficacy in suppressing the growth and development of the isolated pathogen. The dual culture assay of the isolate along with several fungal and bacterial strains confirmed the antagonistic potential of some tested microbes in delimiting the growth of the pathogen. Overall, the study provides a new sustainable, effective and eco-friendly solution for controlling the root rot pathogen.
