Parasitism of oospores of Pythium spp. by strains of Actinoplanes spp.

1993 ◽  
Vol 39 (10) ◽  
pp. 964-972 ◽  
Author(s):  
N. I. Khan ◽  
A. B. Filonow ◽  
L. L. Singleton ◽  
M. E. Payton
Keyword(s):  
Biological Control ◽  
Host Specificity ◽  
Pythium Ultimum ◽  
Pythium Myriotylum ◽  
Pythium Irregulare ◽  
Pythium Arrhenomanes ◽  
Parasite Specificity ◽  
Host Parasite ◽  
First Time

Strains of Actinoplanes spp. were evaluated for their in vitro parasitism of oospores of Pythium aphanidermatum, Pythium arrhenomanes, Pythium irregulare, Pythium myriotylum, and Pythium ultimum. Oospores of Pythium arrhenomanes, Pythium irregulare, and Pythium myriotylum were identified for the first time as hosts of Actinoplanes spp. Newly recorded parasites of oospores of Pythium spp. were Actinoplanes azureus, Actinoplanes brasiliensis, Actinoplanes caeruleus, Actinoplanes ferrugineus, Actinoplanes ianthinogenes, Actinoplanes italicus, Actinoplanes minutisporangius, Actinoplanes rectilineatus, Actinoplanes teichomyceticus, Actinoplanes utahensis, Actinoplanes violaceous, Actinoplanes yunnahenis, plus 15 strains of Actinoplanes yet to be speciated. Parasitized oospores had disorganized cytoplasms and hyphae of Actinoplanes sp. emerging from them. Infection of oospores in vitro varied from 0 to > 90%. Strains also were very active parasites of oospores in sterile soils. When added to nonsterile soils, several strains increased (p = 0.05) the level of oospore parasitism compared with nonsupplemented soils. Strains of Actinoplanes spp. exhibited a host specificity for species of Pythium in vitro and in soil. Sporulation of Actinoplanes sp. from infected oospores incubated on soil was frequent and more abundant than that observed in vitro.Key words: Pythium spp., Actinoplanes spp., actinomycetes, biological control, host–parasite specificity.

Secondary Metabolite- and Endochitinase-Dependent Antagonism toward Plant-Pathogenic Microfungi of Pseudomonas fluorescens Isolates from Sugar Beet Rhizosphere

1998 ◽  
Vol 64 (10) ◽  
pp. 3563-3569 ◽  
Author(s):  
Mette Neiendam Nielsen ◽  
Jan Sørensen ◽  
Johannes Fels ◽  
Hans Christian Pedersen
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Secondary Metabolite ◽  
Pythium Ultimum ◽  
Medium Composition ◽  
Fungal Antagonism ◽  
Lipopeptide Antibiotic

ABSTRACT Forty-seven isolates representing all biovars of Pseudomonas fluorescens (biovars I to VI) were collected from the rhizosphere of field-grown sugar beet plants to select candidate strains for biological control of preemergence damping-off disease. The isolates were tested for in vitro antagonism toward the plant-pathogenic microfungi Pythium ultimum and Rhizoctonia solani in three different plate test media. Mechanisms of fungal inhibition were elucidated by tracing secondary-metabolite production and cell wall-degrading enzyme activity in the same media. Most biovars expressed a specific mechanism of antagonism, as represented by a unique antibiotic or enzyme production in the media. A lipopeptide antibiotic, viscosinamide, was produced independently of medium composition by P. fluorescens bv. I, whereas the antibiotic 2,4-diacetylphloroglucinol was observed only in glucose-rich medium and only in P. fluorescens bv. II/IV. Both pathogens were inhibited by the two antibiotics. Finally, in low-glucose medium, a cell wall-degrading endochitinase activity in P. fluorescens bv. I, III, and VI was the apparent mechanism of antagonism toward R. solani. The viscosinamide-producing DR54 isolate (bv. I) was shown to be an effective candidate for biological control, as tested in a pot experiment with sugar beet seedlings infested with Pythium ultimum. The assignment of different patterns of fungal antagonism to the biovars of P. fluorescens is discussed in relation to an improved selection protocol for candidate strains to be used in biological control.

Biological control of damping-off of sugar-beet and cotton with Chaetomium globosum or a fluorescent Pseudomonas sp.

1988 ◽  
Vol 34 (5) ◽  
pp. 631-637 ◽  
Author(s):  
D. Walther ◽  
D. Gindrat
Keyword(s):  
Biological Control ◽  
Sugar Beet ◽  
Seed Treatment ◽  
Pythium Ultimum ◽  
Chaetomium Globosum ◽  
Pseudomonas Sp ◽  
Damping Off ◽  
Antifungal Metabolites ◽  
Fluorescent Pseudomonas

Seed treatment with ascospores of Chaetomium globosum reduced damping-off of sugar-beet caused by seed-borne Phoma betae and soil-borne Pythium ultimum or Rhizoctonia solani in growth chamber experiments. Seed treatment with a fluorescent Pseudomonas sp. controlled Ph. betae and P. ultimum but not R. solani. Coating cotton seeds with ascospores controlled P. ultimum and R. solani damping-off. In some experiments, biological seed treatments were equally or more effective than seed treatment with captan. However, greater variability in disease control occurred with the antagonists than with captan. Fifty percent of freshly harvested ascospores of C. globosum germinated in 8 h on water agar. When ascospores were stored under air-dried conditions for 3 days to 2.5 years, germination increased to > 90%. Under same storage conditions, survival of Pseudomonas sp. was detected after 4 months. Antagonistic activities observed in vitro were hyphal coiling of C. globosum on R. solani, and mycostasis was induced by C. globosum or Pseudomonas sp. on agar and soil. The presumed cause of mycostasis is the diffusible antifungal metabolites which may also be involved in the biological control of damping-off.

A Consideration of the Relation of Host-specificity of Helminths and other Metazoan Parasites to the Phenomena of Age Resistance and Acquired Immunity

Parasitology ◽  
1929 ◽  
Vol 21 (3) ◽  
pp. 227-255 ◽  
Author(s):  
J. H. Sandground
Keyword(s):  
Host Specificity ◽  
Acquired Immunity ◽  
Metazoan Parasites ◽  
Ancylostoma Caninum ◽  
Specific Host ◽  
Parasite Specificity ◽  
Ancylostoma Duodenale ◽  
Host Parasite ◽  
Syngamus Trachea

1.The relation of host-parasite specificity to age resistance.Conclusive demonstration of a substantial resistance developing concomitantly with the ageing of the host has been made with reference to four helminths, namely: Ancylostoma duodenale andA. caninumin the dog andAscaridia lineataandSyngamus tracheain the chicken.A. duodenalein the dog andS. tracheain the chicken are manifestly in abnormal hosts. In contrast with this, it is to be noted that the normal hosts of these parasites, respectively man and the turkey, exhibit no appreciable age resistance. With regard to the remaining two cases, those ofAncylostoma caninumandAscaridia lineata, the association of age resistance and a specific host-parasite mal-adjustment is not nearly so clear. In nature, both parasites enjoy a polyxenous distribution, neither having acquired the need for strictly specific host conditions for development. As a result of recent researches withA. caninumit has been brought out that the species is comprised of strains better adapted to one species of host than to another, and it has been demonstrated that a higher degree of age resistance is exhibited in the host parasitised with a foreign strain. Although no information on the matter is available, it is quite possible that age resistance will be found to be less markedly expressed in other species or races of suitable hosts, when the bionomics of bothAncylostoma caninumandAscaridia lineataare further investigated.

scholarly journals FUNGICIDAL PROPERTIES OF GARLIC EXTRACT IN Sphagnum PEAT- AND SAND-BASED SUBSTRATES

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 880a-880
Author(s):  
Ramsey Sealy ◽  
Michael R. Evans ◽  
Craig Rothrock
Keyword(s):  
Rhizoctonia Solani ◽  
Fusarium Oxysporum ◽  
Nutrient Solution ◽  
Nutrient Medium ◽  
Pythium Ultimum ◽  
Garlic Extract ◽  
Single Application ◽  
Pythium Irregulare ◽  
Cornmeal Agar

Growth of Pythium aphanidermatum, Pythium ultimum, Pythium irregulare, Phytophthora nicoctianae, Phytophthora cinnomomi, Fusarium oxysporum, Rhizoctonia solani and Thielaviopsis basicoli was inhibited in vitro when grown in a clarified V-8 nutrient solution containing 10% garlic extract. After exposure to 10% garlic extract for 3 days, all fungi and fungal-like organisms failed to grow after being washed and transferred to fresh cornmeal agar nutrient medium without garlic extract. When Sphagnum peat was inoculated with P. aphanidermatum and drenched with solutions containing varying concentrations of garlic extract, a single drench of 35% garlic extract or two drenches of 15% garlic extract were required to rid the substrate of viable P. aphanidermatum. In sand, a single application of 25% garlic extract or two applications of 10% garlic extract were required to rid the sand of viable P. aphanidermatum Thus, Sphagnum peat appeared to partially inactivate the components in garlic and did so to a greater extent than sand. Therefore, efficacy of garlic extract as a soil drench fungicide will be affected by the type of substrate or soil to which the garlic extract is applied.

scholarly journals Antifungal properties of Norway spruce (Picea abies (L.) Karst.) seedling homogenates

2014 ◽  
Vol 68 (3) ◽  
pp. 191-195 ◽  
Author(s):  
Grzegorz Kozłowski ◽  
Jean P. Métraux
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Early Stage ◽  
Antimicrobial Effect ◽  
Pythium Ultimum ◽  
Forest Tree ◽  
In Vitro Assays ◽  
Pythium Irregulare ◽  
Seed Coats

The presence of antimicrobials in root, hypocotyl and cotyledon homogenates of Norway spruce was studied using in vitro assays with soil-borne pathogens. For the studies presented here Norway spruce (<em>Picea abies</em> (L.) Karst.) as a typical host and forest tree and <em>Pythium</em> as a typical soil-bome pathogen were used. The highly virulent species <em>Pythium ultimum</em> and the less virulent species <em>Pythium irregulare</em> were chosen for all experiments. They are both the causal agents of damping-off disease, which can affect plants at a very early stage. The strongest antimicrobial effect was observed using medium prepared from older seedlings and containing extracts from cotyledons. The influence of various treatments on antimicrobials accumulation in spruce extracts was also tested. Seed coat shedding was observed to affect mortality of <em>Picea abies</em> seedlings infected by <em>Pythium</em>. Seedlings which had shed their seed coats were more resistant to <em>Pythium</em> attack. This phenomenon could be correlated with antimicrobial production in well developed cotyledons.

scholarly journals Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

2021 ◽  
Vol 3 ◽  
Author(s):  
Cora S. McGehee ◽  
Rosa E. Raudales
Keyword(s):  
Root Rot ◽  
Cannabis Sativa ◽  
Disease Incidence ◽  
Elongation Factor ◽  
Pythium Myriotylum ◽  
Internal Transcribed Spacer Region ◽  
Pythium Irregulare ◽  
Coconut Coir

Oomycetes and fungi were recovered from coconut coir and rockwool substrates where marijuana (Cannabis sativa L. cv. Silver and Citron) plants with root rot and wilt symptoms were grown in a commercial growing facility in Connecticut. The objectives of this study were to identify the isolates collected from these substrates, determine the pathogenicity of the isolates on hemp seedlings in vitro and in vivo, and evaluate the pathogens' sensitivity to mefenoxam. Pythium and Globisporangium isolates were identified by sequencing the mitochondrially-encoded cytochrome oxidase genes (COI and COII) and Fusarium sp. with the translation elongation factor (EF-1α) region and internal transcribed spacer region (ITS4 and ITS5) genes. Three isolates were identified as Globisporangium irregulare (formerly Pythium irregulare), 21 isolates were Pythium myriotylum, and one was Fusarium oxysporum. All the isolates tested were pathogenic to hemp plants in vitro and in vivo, with disease incidence between 6.7 and 100%. Inoculated plants were smaller by 32% or more compared with the non-inoculated control. On average, hemp plants infected with Pythium myriotylum produced the lowest biomass and relative greenness values. None of the Pythium and Globisporangium isolates were resistant to mefenoxam—all were sensitive to ≥5 μg·mL−1 mefenoxam. This is the first report of G. irregulare causing root rot on marijuana and hemp plants. The results of this study provide information about the characteristics of pathogens that can be found potentially in soilless substrates in controlled environment agriculture.

The taxonomy, ecology and host-specificity of some Phyllobothriidae (Cestoda: Tetraphyllidea), a critical revision of Phyllobothrium Beneden, 1849 and comments on some allied genera

1968 ◽  
Vol 253 (786) ◽  
pp. 231-307 ◽  
Keyword(s):  
Host Specificity ◽  
Marine Mammals ◽  
Original Description ◽  
Gut Mucosa ◽  
Self Fertilization ◽  
Critical Revision ◽  
Host Parasite ◽  
First Time ◽  
Time Information

Two new and twelve little known species of Phyllobothrium or of allied genera, mainly from elasmobranchs and teleosts caught off the British Isles, have been investigated. As some of these could not be identified to species and the others presented difficulties, material from various other sources was obtained and examined for comparison. In addition, the literature on about 100 species allocated to Phyllobothrium was consulted and brought together. A critical appraisal of this literature is given and the genus is revised for the first time. Information on most of the species was found to be inadequate to provide a key and, therefore, a host-parasite list was compiled. As only about fifty species of Phyllobothrium sensu lato have been found in about 100 of the 3000 species of elasmobranchs known to exist, it is estimated that a very large number of Phyllobothrium spp. remains to be discovered and described. The possible significance of this fact is discussed. Brief descriptions of the most well-known species of Phyllobothrium are given and reasons against listing synonyms for these are emphasized. Of the 100 species already allocated to the genus only twenty-two are accepted at present; further studies may show that only three of these, viz. P. lactuca , P. dagnallium and P. serratum , show the typical features of the genus, as originally described. Fourteen of the twenty-two may, eventually, be placed in Anthocephalum Linton, 1890, if this genus is revived; the erection of a new genus or genera may be necessary for the remainder. P. britannicum sp.nov., from Raja montagui , is provisionally placed near P. lactuca but the bothridia are only slightly bifid, their margins are not so folded and the species is euapolytic. P. minutum sp.nov. from R. fullonica closely resembles P. auricularia, P. foliatum and P. loculatum and may, eventually, fall as a synonym of one of these; at present they are all little-known forms. Reasons are given for provisionally retaining Crossobothrium and Monorygma , with about ten species in each. It is suggested that three species originally placed in Phyllobothrium may be allied to Sphaerobothrium lubeti Euzet, 1959. An examination of the type material of P. ketae Ganavan, 1928, previously regarded as unique or as a neotenic form, has shown that the original description was partly based on a pseudophyllidean and possibly on the larvae of P. caudatum . A number of larvae of Phyllobothrium in invertebrates, teleosts and marine mammals, fourteen little-known species of the genus and invalid members are discussed. A detailed discussion is given of the ecology, host specificity and attachment of Phyllobothrium and allied genera to the gut mucosa of elasmobranchs. In a general discussion brief comments are made on life-history, the identification and classification of Phyllobothrium , self-fertilization and on ‘segmentation’. Almost 200 references are cited.

scholarly journals Zoosporic fungi in the ice of some water reservoirs

2014 ◽  
Vol 68 (2) ◽  
pp. 143-147
Author(s):  
Bazyli Czeczuga ◽  
Elżbieta Muszyńska ◽  
Anna Pankiewicz
Keyword(s):  
Water Reservoirs ◽  
Pythium Myriotylum ◽  
Pythium Irregulare ◽  
Fungus Species ◽  
Zoosporic Fungus ◽  
Eutrophic Water ◽  
Zoosporic Fungi ◽  
First Time ◽  
Chemical Loading

The presence of 65 zoosporic fungi species was noted in the water obtained from melting ice from five water (3 ponds and 2 rivers). In the water of the all basins the number of zoosporic fungus species decreases along with the increasing chemical loading (more eutrophic water). Out of these 65 species, 18 are known as necrotrophs of fish. The following fungi were recorded for the first time from Poland: <em>Achlya conspicua</em>, <em>Apodachlyella completa</em>, <em>Pythiomorpha undulata</em>, <em>Pythium butleri</em>, <em>Pythium carolinianum</em>, <em>Pythium gracile</em>, <em>Pythium imperfectum</em>, <em>Pythium indicum</em>, <em>Pythium irregulare</em>, <em>Pythium myriotylum</em>, <em>Pythium papillatum</em>, <em>Pythium pyrilobum</em> and <em>Pythium rostratum</em>.

Phytophthora drechsleri Tucker and Pythium spp. as pathogens of safflower in New South Wales

1973 ◽  
Vol 13 (63) ◽  
pp. 455 ◽  
Author(s):  
G Stovold
Keyword(s):  
Root Rot ◽  
New South ◽  
New South Wales ◽  
Field Capacity ◽  
Pythium Ultimum ◽  
Carthamus Tinctorius ◽  
Pythium Myriotylum ◽  
Pythium Irregulare ◽  
South Wales ◽  
Phytophthora Drechsleri

Pythiaceous fungi associated with a widespread root rot disease of safflower (Carthamus tinctorius) in New South Wales include Phytophthora drechsleri, Pythium myriotylum, Pythium ultimum Pythium irregulare, Pythium acanthicum, and a number of sterile Pythium spp. Pathogenicity of these fungi was tested against safflower seedlings and older plants growing either in soil with moisture content at field capacity or in flooded soil. Phytophthora drechsleri, Pythium myriotylum, Pythium ultimum and Pythiumirregulare caused severe pre-emergence damping off. When safflower plants, three and eight weeks old, were inoculated with each of the fungi, only Phytophthora drechsleriand Pythium myriotylum killed a high proportion of plants. The pathogenicity of Phytophthora drechsleri, Pythium myriotylum, Pythium ultimum, and Pythium irregulare was increased by flooding the soil for ninety hours after inoculation. Phytophthora drechsleri was isolated from naturally infected saffron thistle (Carthamus lanatus). Cross inoculation tests with Phytophthora drechsleri isolates from safflower and saffron thistle showed that both isolates could infect each host. Saffron thistle could be an important alternative host of Phytophthora drechsleri in the field. It is concluded that Phytophthora drechsleri is the major cause of root rot of safflower in New South Wales.

Somatic Embryogenesis and In vitro Plant Regeneration in Vigna trilobata (L.) Verd. - A Potential Pasture Legume

1970 ◽  
Vol 19 (1) ◽  
pp. 89-99
Author(s):  
K. Choudhary ◽  
M. Singh ◽  
M. S. Rathore ◽  
N. S. Shekhawat
Keyword(s):  
Somatic Embryogenesis ◽  
Growth Regulators ◽  
Somatic Embryos ◽  
Basal Medium ◽  
Long Term Study ◽  
Continuous Application ◽  
First Time ◽  
Pasture Legume

This long term study demonstrates for the first time that it is possible to propagate embryogenic Vigna trilobata and to subsequently initiate the differentiation of embryos into complete plantlets. Initiation of callus was possible on 2,4-D. Somatic embryos differentiated on modified MS basal nutrient medium with 1.0 mg/l  of 2,4-D and 0.5 mg/l  of Kn. Sustained cell division resulted in globular and heart shape stages of somatic embryos. Transfer of embryos on to a fresh modified MS basal medium with 0.5 mg/l of Kn and 0.5 mg/l of GA3 helped them to attain maturation and germination. However, the propagation of cells, as well as the differentiation of embryos, were inhibited by a continuous application of these growth regulators. For this reason, a long period on medium lacking these growth regulators was necessary before the differentiation of embryos occurred again. The consequences for improving the propagation of embryogenic cultures in Vigna species are discussed. Key words: Pasture  legume, Vigna trilobata, Globular, Heart shape, somatic embryogenesis D.O.I. 10.3329/ptcb.v19i1.4990 Plant Tissue Cult. & Biotech. 19(1): 89-99, 2009 (June)

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