Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Root rot”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Studies on control of root rot on Panax notoginseng].

Chemical Control tests of pot, plot and field for Panax notoginseng root rot were conducted during 1995-1996. The results indicated that the chemical control is a effect measure to control rapidly occurring and spreading of Panax notoginseng root rot. It was the best treatment to coordinate use of bactericide and fungicide, obviously better than alone or mixed use of fungicide and also better than alone use of bactericide. In the pot and plot tests, the best coordinate treatment was the treatment of 10% phenazine plus 70% dexon plus 50% bavistin and plus water (1:1:500), the control effect was 70%; in the field test, the control effect of over 70% was also get with the treatment of 10% phenazine plus 70% dexon and plus small soil (1 Kg:1 Kg:150 Kg) per mu.

Benzenesulfonates↗
PubMed2000

Control of Pythium root rot on hydroponically grown cucumbers with silver-coated cloth.

Silver-coated cloth (SCC) effectively controlled root rot that was caused by Pythium aphanidermatum in hydroponically grown cucumber plants. The presence of SCC in the hydroponic solution reduced the root rot from 100% to 10% 20 days after inoculation with zoospores of P. aphanidermatum. It was suggested that the inhibition of SCC was caused not only by the silver ion dissolved from SCC, but also by the metallic silver and silver compounds formed on the surface of the root.

Cucumis sativus↗
PubMed2006

Development of a 9600-clone procedure for oligonucleotide fingerprinting of rRNA genes: utilization to identify soil bacterial rRNA genes that correlate in abundance with the development of avocado root rot.

Oligonucleotide fingerprinting of rRNA genes (OFRG) is an array-based method that generates microbial community profiles through analysis of rRNA gene clone libraries. The original OFRG method allowed 1536 clones to be analyzed per experiment. This report describes a procedure for analyzing 9600 clones per experiment, including a new probe set for bacterial analysis, and improved data processing and statistical analysis tools. The software tools are available at the OFRG website (). Use of the 9600-clone procedure was demonstrated by examining the bacterial rRNA gene compositions of soils subjected to various temperature treatments. These treatments produced a series of soils with a range of abilities to suppress avocado root rot, enabling the identification of bacterial rRNA genes that correlate in abundance with root rot suppressiveness. OFRG analysis of these soils produced 8876 bacterial rRNA gene fingerprints grouped into 5123 clusters, or operational taxonomic units (OTUs). Eleven OTUs exhibited a positive correlation between the number of clones and the percentage of healthy roots. An in silico analysis was performed to examine the relationship between the number of rRNA genes analyzed and the number of correlates (rRNA gene-avocado root rot symptoms) identified. As the number of clones decreased, fewer correlates were identified. To further increase the throughput of the OFRG method, use of a glass slide-fluorescent probe microarray format was also explored.

DNA Fingerprinting↗
PubMed2006

Biocontrol of avocado dematophora root rot by antagonistic Pseudomonas fluorescens PCL1606 correlates with the production of 2-hexyl 5-propyl resorcinol.

A collection of 905 bacterial isolates from the rhizospheres of healthy avocado trees was obtained and screened for antagonistic activity against Dematophora necatrix, the cause of avocado Dematophora root rot (also called white root rot). A set of eight strains was selected on the basis of growth inhibitory activity against D. necatrix and several other important soilborne phytopathogenic fungi. After typing of these strains, they were classified as belonging to Pseudomonas chlororaphis, Pseudomonas fluorescens, and Pseudomonas putida. The eight antagonistic Pseudomonas spp. were analyzed for their secretion of hydrogen cyanide, hydrolytic enzymes, and antifungal metabolites. P. chlororaphis strains produced the antibiotic phenazine-1-carboxylic acid and phenazine-1-carboxamide. Upon testing the biocontrol ability of these strains in a newly developed avocado-D. necatrix test system and in a tomato-F oxysporum test system, it became apparent that P. fluorescens PCL1606 exhibited the highest biocontrol ability. The major antifungal activity produced by strain P. fluorescens PCL1606 did not correspond to any of the major classes of antifungal antibiotics produced by Pseudomonas biocontrol strains. This compound was purified and subsequently identified as 2-hexyl 5-propyl resorcinol (HPR). To study the role of HPR in biocontrol activity, two Tn5 mutants of P. fluorescens PCL1606 impaired in antagonistic activity were selected. These mutants were shown to impair HRP production and showed a decrease in biocontrol activity. As far as we know, this is the first report of a Pseudomonas biocontrol strain that produces HPR in which the production of this compound correlates with its biocontrol activity.

Ascomycota↗
PubMed2004

The occurrence of root rot and crown rot of rice in Gilan and Zanjan provinces, Iran.

Root rot and crown rot of rice is one of the important fungal diseases of rice in Gilan and Zanjan provinces, Iran. During 1999--2002, samples of plant and soil around the roots of infected rice plants were collected and used to identify the causal agent. Root and crown parts were surface sterilized with sodium hypochlorite and then cultured on PDA (potato dextrose agar), PPA (pepton pentacholoritobenzene agar) and CLA (carnation leaf agar) media. Soil samples prepared in water agar were used to isolate the pathogen. The causal agent was identified as Fusarium moniliforme. Colonies were initially white but turned violet to grey late. Microconidia were arranged in chain and macroconidia were cylindrical and long with 3-5 septa. The disease was severe in Zanjan province particularly along Ghezel Ozan river where the infection ranged from 70-80%. Root and crown rot was more prevalent in areas where Champa and Gerdeh were being cultivated continuously. On the other hand, Sadri cultivars had relatively less infection. Persistent cultivation of rice and seed sowing method intensified disease development and caused significant economic losses.

Fusarium↗
PubMed1996

Identification of RAPD markers for common root rot and spot blotch (Cochliobolus sativus) resistance in barley.

The identification of RAPD markers associated with genes for resistance to Cochliobolus sativus in barley would increase the efficiency of gene manipulation by reducing the number of lines that must be evaluated from a resistant by susceptible cross and by allowing selection during the off season. Two barley crosses consisting of resistant and susceptible parent genotypes ('Virden' x 'Ellice' and Fr926-77 x 'Deuce', both 2 row x 6 row crosses) and more than 140 homozygous progeny lines were rated for their reactions in field nurseries to common root rot and in a controlled environment for spot blotch. Putative RAPD markers were identified using bulked segregant analysis followed by individual progeny line analyses. Polymorphisms associated with disease reaction were detected between bulked segregant samples as differences in the band intensity of DNA fragments. The bulked segregant samples were screened against 186 RAPD primers (decamers) using the polymerase chain reaction. For the cross Fr926-77 x 'Deuce', one RAPD marker was obtained that did not segregate as expected but was associated with both diseases. For the cross 'Virden' x 'Ellice', a single RAPD marker was obtained that did not have the expected segregation ratio but was associated with spot blotch reaction. One RAPD marker linked to 2-rowed and 6-rowed spike locus was obtained in each cross, and both the marker and row type were associated with common root rot and spot blotch reactions. For the cross 'Virden' x 'Ellice', a linkage group consisting of three RAPD markers was associated with common root rot and spot blotch reaction. The genes associated with these markers condition significant levels of resistance to C. sativus and may be used to increase the speed and precision of resistance gene manipulation in barley germplasm.

Ascomycota↗
PubMed2002

[Allelopathic effect of root exudates on pathogenic fungi of root rot in continuous cropping soybean].

Allelopathic effect of root exudates on pathogenic fungi of root rot in continuous cropping soybean was studied by sand culture, water culture, and indoor culture experiments. The results showed that allelopathic promotion of root exudates on the growth of Fusarium semitectum, Gliocladium roseum and Fusarium oxysporum, especially Fusarium semitectum reached significant level or especially significant level in continuous cropping soybean compared with the control. Allelopathic promotion of root exudates on the growth of Fusarium semitectum and Gliocladium roseum in continuous cropping soybean was distinctly larger than that in rotation soybean, and the difference reached significant level under their low concentration. Allelopathic promotion of high concentration of root exudates on the growth of Fusarium semitectum was smaller than that of low concentration of root exudates, and the difference reached significant level in continuous cropping soybean. Allelopathic inhibition of high concentration of phthalic acid and propanedioic acid (L5 and B5) on the growth of Fusarium semitectum. Gliocladium roseum and Fusarium oxysporum, especially Fusarium semitectum reached significant level or especially significant level compared with the control. However, allelopathic promotion of low concentration of phthalic acid and propanedioic acid on the growth of Fusarium semitectum, Gliocladium roseum and Fusarium oxysporum partly reached significant level.

Fusarium↗
PubMed2005

Reaction of selected soybean cultivars to Rhizoctonia root rot and other damping-off disease agents.

Eight soybean cultivars; Giza 21. Giza 22, Giza 35, Giza 82, Giza 83, Crawford, Holladay and Toamo were evaluated to Rhizoctonia root rot using agar plate and potted plant techniques. Data cleared that, in agar plate assay all soybean cultivars were moderately susceptible (MS), although the differences between them were significant (P=0.05). Generally, in potted assay, the reactions were resistant (R) or moderately resistant (MR) to root rots. Also, the differences between cultivars were significant (P=0.05). These cultivars were inoculated under greenhouse conditions with Fusarium solani, Macrophomina phaseolina, Rhizoctonia solani and Sclerotium rolfsii Generally, G21 had the least pre-emergence damping-off followed by Giza 35, Crawford and Giza 83 with averages of 19.0, 20.0, 20.5 and 21.5%, respectively. In case of post-emergence, Giza 35 had the least values, followed by Giza 21, Crawford and Giza 82 with averages 3.95, 4.10, 4.10 and 4.25%, respectively. Under naturally infested soil in the field conditions the reactions of the same cultivars to damping-off were evaluated in two successive seasons. In 2002 season, G35 had the least pre-emergence damping-off % followed by Giza 21 and Giza 22 with averages of 22.61, 24.33 and 29.33%, respectively. Also, G35 had the least post-emergence damping-off % followed by Toamo and Giza 21 with averages of 9.40, 10.33 and 10.41%, respectively. In 2003 season, the same trend was appeared with light grade where Giza 35 had the least pre-emergence damping of % followed by Giza 22 and Giza 21 with averages of 30.67, 31.00 and 36.67%, respectively and Giza 35 was the most resistant cultivar against post-emergence damping-off, followed by Giza 21 and Giza 22 with averages of 10.91, 11.32 and 11.80%, respectively. Generally, Giza 21 significantly surpassed the other cultivars in plant height, number of pods per plant and 100-seed weight. Moreover, also it had second grade with the other traits.

Colony Count, Microbial↗
PubMed2003

An ultrastructural investigation of the 'microsclerotia' formed in single cells of root cortical cells associated with corky root rot of tomato.

White and Scott (1973) described two forms of microsclerotia associated with corky root rot of tomato, one being formed in single cells of the outer root cortical cells and the other produced in culture from isolation of diseased roots and in degenerated root debris. By assuming that both forms were of fungal origin, they conducted an ultrastructural study using the microsclerotia produced in culture but not those formed in single cells. They demonstrated that the microsclerotia from culture consisted of hardened, interwoven hyphae of the fungus, Pyrenochaeta lycopersici. Since there have been doubts about the nature of the microsclerotia formed in single cells, an ultrastructural study was conducted. The results demonstrated clearly that the 'microsclerotia' formed in single cells of the root cortical cells were not composed of fungal mycelia, indeed these blackened cells or 'microsclerotia' were filled with numerous crystallines. There was no evidence of the presence of fungal hyphae in or around these cells. Both diseased and healthy, and young and old root cortex cells of many cultivars of tomato contained cells filled with crystallines. Therefore, it is clear that the 'microsclerotia' formed in single cells of the outer cortex described by White and Scott are not microsclerotia of the fungus, P. lycopersici.

Fungi↗
PubMed2003

Responses of the root rot fungus Collybia fusipes to soil waterlogging and oxygen availability.

Collybia fusipes is a common root rot fungus in mature pedunculate oak forest, that causes drastic destruction of the tree root systems, especially in dry or mildly waterlogged soils. We wanted to check, under controlled conditions or in forest ecosystems, whether reduced O2 during saturation of the soil by water could interact with disease evolution. Susceptibility of waterlogged oak seedlings to C. fusipes was tested in a greenhouse and the survival of the pathogen in woody substrates was assessed in hydromorphic soils in a forest. A direct and detrimental effect of soil waterlogging on C. fusipes survival was evidenced both under controlled conditions and in forest stands. Growth of C. fusipes mycelium on agar media was monitored under low O2 mole fraction and compared to that of Armillaria mellea and Heterobasidion annosum. A drastic reduction in mycelial growth was evidenced in C. fusipes and H. annosum but not in A. mellea.

Agaricales↗
PubMed2005

Visualization of interactions between a pathogenic and a beneficial Fusarium strain during biocontrol of tomato foot and root rot.

The soilborne fungus Fusarium oxysporum f. sp. radicis-lycopersici causes tomato foot and root rot (TFRR), which can be controlled by the addition of the nonpathogenic fungus F. oxysporum Fo47 to the soil. To improve our understanding of the interactions between the two Fusarium strains on tomato roots during biocontrol, the fungi were labeled using different autofluorescent proteins as markers and subsequently visualized using confocal laser scanning microscopy. The results were as follows. i) An at least 50-fold excess of Fo47over F. oxysporum f. sp. radicis-lycopersici was required to obtain control of TFRR. ii) When seedlings were planted in sand infested with spores of a single fungus, Fo47 hyphae attached to the root earlier than those of F. oxysporum f. sp. radicis-lycopersici. iii) Subsequent root colonization by F. oxysporum f. sp. radicis-lycopersici was faster and to a larger extent than that by Fo47. iv) Under disease-controlling conditions, colonization of tomato roots by the pathogenic fungus was significantly reduced. v) When the inoculum concentration of Fo47 was increased, root colonization by the pathogen was arrested at the stage of initial attachment to the root. vi) The percentage of spores of Fo47 that germinates in tomato root exudate in vitro is higher than that of the pathogen F. oxysporum f. sp. radicis-lycopersici. Based on these results, the mechanisms by which Fo47 controls TFRR are discussed in terms of i) rate of spore germination and competition for nutrients before the two fungi reach the rhizoplane; ii) competition for initial sites of attachment, intercellular junctions, and nutrients on the tomato root surface; and iii) inducing systemic resistance.

Bacterial Proteins↗
PubMed1998

Identification of Pythium carolinianum causing 'root rot' of cotton in Egypt and its possible biological control by Pseudomonas fluorescens.

A severe root rot disease of cotton caused by Pythium carolinianum was diagnosed in a cotton field in Beni-Musa village, 20 km southwest of El-Minia city, Egypt, during the summer of 1996. This was the first reported isolation of this fungus in Egypt. In the light of the importance of the cotton industry in Egypt, research was initiated to develop a biocontrol agent against Pythium carolinianum. In vitro agar plate technique identified a Pseudomonas fluorescens strain that was highly antagonist to Pythium carolinianum. Subsequent plant growth experiments establish that substantial disease control could be obtained by applying Pseudomonas fluorescens to the soil. Optimal control was obtained by mixing the bacteria with the soil rather than by dipping the cotton roots in the bacterial suspension immediately before planting. Disease was more severe in autoclaved soil than in nonsterile soil.

Journal Article↗
PubMed2002

Primary structure of the histone 2B gene in the white root rot fungus, Rosellinia necatrix.

The nucleotide sequence of the histone 2B (H2B) gene in the white root rot fungus, Rosellinia necatrix, was determined. The gene has two introns in the coding region at positions conserved in the Neurospora crassa and Aspergillus nidulans H2B genes, but the third intron present in the H2B gene from N. crassa and A. nidulans is absent in the R. necatrix H2B gene. The amino acid sequence of the coding region of the R. necatrix gene resembled that of N. crassa and A. nidulans. Therefore, the third intron in the H2B gene of N. crassa and A. nidulans may have been inserted into the present position after species diversification.

Amino Acid Sequence↗
PubMed2001

Molecular cloning of three genes encoding G protein alpha subunits in the white root rot fungus, Rosellinia necatrix.

Three genes encoding G protein alpha subunits were cloned from the white root rot fungus, Rosellinia necatrix, and characterized. Only one copy of each gene was present in the genome. The protein sequences of Rga1, Rga2, and Rga3 are very similar to those of MagA, MagB and MagC of Magnaporthe grisea, respectively. Moreover, Rga1 is similar to Mod-D which is closely related to vegetative incompatibility in Podospora anserina, which suggests that Rga1 is important in the vegetative incompatibility reaction in R. necatrix. Reverse transcription PCR (RT-PCR) analysis of Rga1, Rga2, and Rga3 mRNA expression showed that the three genes were all transcribed in R. necatrix cells.

Amino Acid Sequence↗
PubMed2003

Primary structure of cytochrome c gene from the white root rot fungus Rosellinia necatrix.

The nucleotide sequence of the cytochrome c (CytC) gene of the white root rot fungus Rosellinia necatrix was analyzed. The structure of this gene, which had three introns in the coding region, was similar to that of Aspergillus nidulans. The second intron of the R. necatrix CytC gene was not present in Neurospora crassa or Fusarium oxysporum. However, the amino acid sequence of R. necatrix was most similar to that of Neurospora crassa. Thus, it seemed that the second intron of the R. necatrix CytC gene was inserted into its present position after R. necatrix and its closest relatives diverged evolutionarily.

Amino Acid Sequence↗
PubMedDate not supplied

Mapping genes conferring resistance to Phytophthora root rot of soybean, Rps1a and Rps7.

A linkage map was constructed for two Phytophthora sojae Kauf. +Gerd. root rot resistance genes, Rps1a and Rps7, in soybean (Glycine max (L.) Merr.) using microsatellite or simple sequence repeat (SSR) markers. An F2 population consisting of 81 individuals derived from a cross between OX281, which carries Rps7, and Mukden, which carries Rps1a, was used as the mapping population. A linkage map consisting of 10 SSR markers was first constructed using the computer software MapMaker/EXP 3.0. Rps1a and Rps7 were then placed at two different loci in the same linkage group with LOD scores of 2.88 and 9.16, respectively. Rps1a and Rps7 were linked at a distance of 13.8 cM. Rps1a was flanked by Satt159 (0.7 cM) and Satt009 (3.2 cM). Rps7 was flanked by Satt009 (10.6 cM) and Satt125 (29.1 cM).

Chromosome Mapping↗
PubMed2002

Detection of a double-stranded RNA virus from a strain of the violet root rot fungus Helicobasidium mompa Tanaka.

Three double-stranded (ds) RNA species (ca. 1.30, 1.27 and 1.23 x 106) were isolated by CF-11 cellulose chromatography from a strain of the violet root rot fungus Helicobasidium mompa recovered from apple roots. Purified virion preparations contained isometric particles about 25 nm in diameter, and also the same three species of dsRNA isolated from total extracts by CF-11 cellulose chromatography. The molecular mass of the coat protein was about 67 K when estimated by SDS-PAGE. The largest dsRNA (referred to as dsRNA1) contains a single, long open reading frame of 1794 nucleotides that encodes a putative polypeptide containing 598 amino acid residues with a molecular mass of 69.9 K. This polypeptide contains amino acid sequence motifs conserved in putative RNA-dependent RNA polymerases of RNA viruses. Phylogenetic analysis revealed similarities to RNA-dependent RNA polymerases from Atkinsonella hypoxylon 2H virus, a member of the family Partitiviridae.

Amino Acid Sequence↗