Relevant bibliographies by topics / Disease suppression; Rhizoctonia solani

Academic literature on the topic 'Disease suppression; Rhizoctonia solani'

Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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Journal articles on the topic "Disease suppression; Rhizoctonia solani"

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Dignam, B. E. A., M. O'Callaghan, L. M. Condron, J. M. Raaijmakers, G. A. Kowalchuk, and S. A. Wakelin. "A bioassay to compare the disease suppressive capacity of pasture soils." New Zealand Plant Protection 68 (January 8, 2015): 151–59. http://dx.doi.org/10.30843/nzpp.2015.68.5834.

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Dynamic pathogen complexes can develop under pastures thereby substantially reducing potential productivity Suppression of such pathogen complexes is therefore of great importance and bioassays can quantify disease suppression in soils This study describes the development of a pasturerelevant system Rhizoctonia solani AG 21 induced dampingoff (wirestem) of kale (Brassica oleracea) As kale is not a component of traditional ryegrass clover pasture swards the assay allows assessment of general disease suppression considered more enduring in multiplehostmultiplepathogen systems A pathogenic Rhizoctonia solani isolate was obtained from New Zealand pastoral soil Inoculation of soils with this isolate resulted in a level of dampingoff disease comparable to that induced by reference Rhizoctonia solani isolate Rs0432 Significantly different levels of inoculuminduced disease incidence and progression were found in four distinct pastoral soils In combination with soil physicochemical data and environmental DNA approaches this bioassay can be used to further advance understanding of the influence of farm management practices on disease suppression in pasture soils
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Grosch, Rita, Franziska Faltin, Jana Lottmann, A. Kofoet, and Gabriele Berg. "Effectiveness of 3 antagonistic bacterial isolates to control Rhizoctonia solani Kühn on lettuce and potato." Canadian Journal of Microbiology 51, no. 4 (April 1, 2005): 345–53. http://dx.doi.org/10.1139/w05-002.

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Rhizoctonia solani causes yield losses in numerous economically important European crops. To develop a biocontrol strategy, 3 potato-associated ecto- and endophytically living bacterial strains Pseudomonas fluorescens B1, Pseudomonas fluorescens B2, and Serratia plymuthica B4 were evaluated against R. solani in potato and in lettuce. The disease-suppression effect of the 3 biocontrol agents (BCAs) was tested in a growth chamber and in the field. In growth chamber experiments, all 3 BCAs completely or significantly limited the dry mass (DM) losses on lettuce and the disease severity (DS) caused by R. solani on potato sprouts. Strain B1 showed the highest suppression effect (52% on average) on potato. Under field conditions, the DS on both crops, which were bacterized, decreased significantly, and the biomass losses on lettuce decreased significantly as well. The greatest disease-suppression effect on potato was achieved by strain B1 (37%), followed by B2 (33%) and then B4 (31%), whereas the marketable tuber yield increased up to 12% (B1), 6% (B2), and 17% (B4) compared with the pathogen control at higher disease pressure. Furthermore, in all experiments, B1 proved to be the most effective BCA against R. solani. Therefore, this BCA could be a candidate for developing a commercial product against Rhizoctonia diseases. To our knowledge, this is the first report on the high potential of endophytes to be used as a biological control agent against R. solani under field conditions.Key words: biocontrol, Rhizoctonia solani, field grown lettuce and potato, antagonistic bacteria, endophytes.
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Mazzola, Mark, and Yu-Huan Gu. "Wheat Genotype-Specific Induction of Soil Microbial Communities Suppressive to Disease Incited by Rhizoctonia solani Anastomosis Group (AG)-5 and AG-8." Phytopathology® 92, no. 12 (December 2002): 1300–1307. http://dx.doi.org/10.1094/phyto.2002.92.12.1300.

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The induction of disease-suppressive soils in response to specific cropping sequences has been demonstrated for numerous plant-pathogen systems. The role of host genotype in elicitation of the essential transformations in soil microbial community structure that lead to disease suppression has not been fully recognized. Apple orchard soils were planted with three successive 28-day cycles of specific wheat cultivars in the greenhouse prior to infestation with Rhizoctonia solani anastomosis group (AG)-5 or AG-8. Suppressiveness to Rhizoctonia root rot of apple caused by the introduced isolate of R. solani AG-5 was induced in a wheat cultivar-specific manner. Pasteurization of soils after wheat cultivation and prior to pathogen introduction eliminated the disease suppressive potential of the soil. Wheat cultivars that induced disease suppression enhanced populations of specific fluorescent pseudomonad genotypes with antagonistic activity toward R. solani AG-5 and AG-8, but cultivars that did not elicit a disease suppressive soil did not modify the antagonistic capacity of this bacterial community. When soils were infested prior to the initial wheat planting, all cultivars were uniformly susceptible to R. solani AG-8. However, when pathogen inoculum was added after three growth-cycles, wheat root infection during the fourth growth-cycle varied in a cultivar specific manner. The same wheat cultivar-specific response in terms of transformation of the fluorescent pseudomonad community and subsequent suppression of Rhizoctonia root rot of apple was observed in three different orchard soils. These results demonstrate the importance of host genotype in modification of indigenous saprophytic microbial communities and suggest an important role for host genotype in the success of biological control.
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Davey, Rowena S., Ann M. McNeill, Stephen J. Barnett, and Vadakattu V. S. R. Gupta. "Organic matter input influences incidence of root rot caused by Rhizoctonia solani AG8 and microorganisms associated with plant root disease suppression in three Australian agricultural soils." Soil Research 57, no. 4 (2019): 321. http://dx.doi.org/10.1071/sr18345.

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Soil-borne plant root disease caused by Rhizoctonia solani AG8 is prevalent in cereal farming systems worldwide, particularly in semiarid agricultural regions. A controlled environment study was undertaken using three Australian soils to test the hypothesis that OM input from crop roots and residues decreases infection by Rhizoctonia root rot via biologically mediated disease suppression. The specific aim was to determine the relative effect of two different OM inputs (wheat stubble or roots) on (a) abundance (DNA) of the pathogen R. solani AG8 and soil organisms putatively associated with disease suppression, and (b) incidence of Rhizoctonia root rot infection of wheat seedlings (% root infected). An increase in microbial biomass carbon (C) following OM amendment indicated a potential for enhanced general biological disease suppression in all soils. OM inputs also increased the population size (DNA) of certain bacteria and fungi putatively associated with specific suppression for Rhizoctonia root rot, suggesting a C resource-mediated change in microbial functions related to disease suppression. There were no significant changes to measured pathogens with stubble addition. However, OM inputs via root residues and rhizodeposits from living roots increased the populations of R. solani AG8 and Gaeumannomyces graminis var. tritici so that in subsequently planted wheat there was greater incidence of root disease infection and reduced plant shoot and root DM compared with that following OM input as stubble. Differences between soils in terms of plant and soil organism responses to each OM input suggest that abiotic factors modify the development of biological disease suppression and the expression of the disease.
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Wright, Peter J., Rebekah A. Frampton, Craig Anderson, and Duncan Hedderley. "Factors associated with soils suppressive to black scurf of potato caused by Rhizoctonia solani." New Zealand Plant Protection 75 (August 30, 2022): 31–49. http://dx.doi.org/10.30843/nzpp.2022.75.11761.

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Soils in which disease fails to develop despite pathogen presence are considered disease-suppressive. They offer sustainable, effective protection to plants against infection by soil-borne pathogens. Naturally disease-suppressive soils have been reported for diseases of a diverse range of agricultural crops worldwide yet the underlying mechanisms of disease suppression are still not completely understood. Two large greenhouse experiments, conducted during 2017/18 (Year 1) and 2018/19 (Year 2), determined that soils naturally suppressive to stem canker and black scurf of potato (caused by Rhizoctonia solani) are present in vegetable-arable cropping soils of the Auckland and Waikato regions of New Zealand. Soil was pre-treated with heat prior to inoculation with R. solani and compared with untreated and uninoculated controls to ascertain if stem canker and black scurf suppression was ‘general’, or ‘specific’ (i.e. transferable; possibly involving specific microorganisms). Rhizoctonia solani inoculation was also combined with transfer of one part test soil to nine parts of a known disease-conducive soil. Abiotic factors such as soil texture and organic matter content influenced black scurf incidence and severity. Soil microorganisms were also involved in disease suppression since black scurf incidence and severity markedly increased when they were eliminated or reduced by soil heat pre-treatment. Microbial profiling of the soils through sequencing revealed that taxa of geographically close soils of the same type had similar fungal and bacterial community structure and diversity even though they differed in their capacity to suppress black scurf. These results suggest that although the soil microbiome as a whole, was mainly responsible for soil disease suppressiveness, certain bacterial genera or species may play a role in black scurf suppression.
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Barnett, Stephen J., David K. Roget, and Maarten H. Ryder. "Suppression of Rhizoctonia solani AG-8 induced disease on wheat by the interaction between Pantoea, Exiguobacterium, and Microbacteria." Soil Research 44, no. 4 (2006): 331. http://dx.doi.org/10.1071/sr05113.

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Rhizoctonia solani AG-8 is a major wheat root pathogen; however, soils can become suppressive to the expression of disease under intensive cropping with retention of crop residues. This is in part due to the action of soil microorganisms. A step-wise approach was used to determine which microorganisms contributed to suppression of R. solani induced disease in a disease-suppressive soil. Using wheat-soil-pathogen bioassays it was determined that the interaction between 3 phylogenetically diverse groups of bacteria, Pantoea agglomerans, Exiguobacterium acetylicum, and Microbacteria (family Microbacteriaceae), was a major contributor to disease suppression. Inoculation of a sterilised soil with the combination of these groups resulted in greatly increased seedling shoot dry weight and reduced infection compared with diseased control plants with no bacterial inoculation, or inoculated with individual types of bacteria. These groups, however, did not reduce levels of pathogen DNA, although inoculation with suppressive soil (at 10% w/w) did reduce pathogen DNA. Root associated P. agglomerans and E. acetylicum promoted the growth of infected wheat plants and soil associated Microbacteria reduced root infection by R. solani.
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Rahman, M. A., R. Jannat, A. M. Akanda, M. A. R. Khan, and M. T. Rubayet. "Role of Chitosan in Disease Suppression, Growth and Yield of Carrot." European Journal of Agriculture and Food Sciences 3, no. 3 (May 10, 2021): 34–40. http://dx.doi.org/10.24018/ejfood.2021.3.3.266.

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An attempt was made for controlling of Rhizoctonia canker caused by Rhizoctonia solani and southern blight caused by Sclerotium rolfsii in pot and field experiments under inoculated condition and also to increase the growth promoting factors and yield of carrot through the application of chitosan. Before setting the experiments in the field, laboratory experiments were carried out to select virulent isolates of R. solani and S. rolfsii and effective dose of chitosan on mycelial growth inhibition of virulent isolates of test pathogens. In the pathogenicity test, R. solani isolate R-1 and S. rolfsii isolate S-1 were found to be the most virulent against carrot seedlings. In vitro application of 1.0% chitosan was found to inhibit 100% mycelial growth of both tested pathogens. The field experiment was laid out following randomized complete block design with four treatments, where no treatment was done in T1, pathogen was inoculated in T2 and seed treatment and soil amendment with 1.0% chitosan was done in T3 and T4, respectively, in pathogen inoculated condition. Application of 1.0% chitosan as seed treatment or soil amendment significantly reduced post-emergence seedling mortality, incidence of diseases and enhanced seedling growth and also yields of carrot. On the contrary, post-emergence seedling mortality, incidence of Rhizoctonia canker and southern blight of carrot were highest in treatment T2 where soil was inoculated with pathogens. Chitosan could be used as an alternative of fungicide to suppress Rhizoctonia canker and southern blight in sustainable agriculture and improvement the yield of carrot.
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Tewoldemedhin, Y. T., S. C. Lamprecht, and M. Mazzola. "Rhizoctonia Anastomosis Groups Associated with Diseased Rooibos Seedlings and the Potential of Compost as Soil Amendment for Disease Suppression." Plant Disease 99, no. 7 (July 2015): 1020–25. http://dx.doi.org/10.1094/pdis-11-14-1211-re.

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Rhizoctonia spp. associated with rooibos in the Western Cape province of South Africa were recovered during the 2008 season by planting seedlings in rhizosphere soils collected from 14 rooibos nurseries. In all, 75 Rhizoctonia isolates were obtained, of which 67 were multinucleate and 8 were binucleate Rhizoctonia spp. The identity of these isolates to anastomosis group (AG) was determined through sequence analysis of the ribosomal DNA internal transcribed spacer region. The collection of multinucleate isolates included representatives of AG-2-2 (67%), AG-4 HGI (14%), AG-11 (5%), and R. zeae (3%). Binucleate AGs included AG-Bo (4%) and AG-K (4%) and an unidentified binucleate Rhizoctonia (3%). Rhizoctonia solani AG-2-2 was the most widely distributed species of Rhizoctonia detected among the 11 nurseries sampled. All AGs recovered from rooibos have been previously reported on crop plants in South Africa, with the exception of R. zeae. However, this is the first study to classify the Rhizoctonia AGs recovered from rooibos. In glasshouse bioassays, the most virulent Rhizoctonia AGs on rooibos and lupin were AG-2-2, AG-4 HGI, and AG-11. Although plant damage was less than that observed for lupin and rooibos, oat was significantly affected by AG-2-2 and AG-4 HGI. Two composts sourced from independent suppliers were evaluated for disease suppression under glasshouse conditions. Compost amendment suppressed damping-off by most R. solani AGs, except for AG-4 HGI. Furthermore, within AG-2-2, suppression by compost was isolate specific.
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Davey, Rowena S., Ann M. McNeill, Stephen J. Barnett, and Vadakattu V. S. R. Gupta. "Potential for suppression of Rhizoctonia root rot is influenced by nutrient (N and P) and carbon inputs in a highly calcareous coarse-textured topsoil." Soil Research 59, no. 4 (2021): 329. http://dx.doi.org/10.1071/sr20247.

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Bioassays were undertaken in a controlled environment to assess whether the potential for suppression of Rhizoctonia root rot of wheat, in a highly calcareous topsoil, was positively influenced by nutrient (nitrogen (N) or phosphorus (P)) addition and whether any disease suppression response to augmented nutrition was affected by the addition of carbon (C), either as a readily available C source (sucrose) or as wheat stubble. The soil was P deficient, which limited plant growth, populations of putatively beneficial soil microorganisms, and microbial activity and diversity. This ultimately reduced potential for suppression of Rhizoctonia solani AG8. Addition of fertiliser P to the soil increased R. solani AG8 DNA and percent root infection but not the effectiveness of the pathogen. A positive effect of P fertiliser on plant growth partially compensated for the negative effect of increased root infection. Addition of P increased DNA for Microbacterium spp. where labile C had been added and in the presence of plant roots. Stubble addition alone, after 6 weeks of incubation, increased DNA for Pantoea agglomerans, Trichoderma A and Microbacterium spp. although differences in microbial activity and diversity between stubble treatments were only detected after the bioassay had commenced and P was added. Fertiliser P addition to stubble-amended soil resulted in less Rhizoctonia infection compared with that in soil without P or stubble addition. Effectiveness of R. solani AG8 was decreased by 50% with stubble amendment. The application of N alone did not have a marked effect on plant growth or potential for suppression of Rhizoctonia root disease. Agronomic management practices that affect quantity and lability of C input to soil, when combined with strategic P fertiliser decisions, are likely to improve the potential for development of suppression of Rhizoctonia root rot disease in cereal crops on alkaline and highly calcareous soils.
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Zinati, Gladis M. "Compost in the 20th Century: A Tool to Control Plant Diseases in Nursery and Vegetable Crops." HortTechnology 15, no. 1 (January 2005): 61–66. http://dx.doi.org/10.21273/horttech.15.1.0061.

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The discovery of disease suppression in certain bark composts increased the interest in using compost as growing substrate to control root rot diseases caused by Phytophthora cinnamomi. Disease suppression mechanisms include antibiosis, competition, hyperparasitism, and induced systemic resistance. Although abiotic factors may influence disease suppression, the latter is often based on microbial interactions—the two common mechanisms being general for pythium (Pythium spp.) and phytophthora root rot (Phytophthora spp.) and specific for rhizoctonia (Rhizoctonia solani). The discovery of disease suppression agents in compost led to the development of biocontrol agent-fortified compost during the last decade of the 20th century. The suggested recommendations for future research and extension outreach may include 1) development of methods to manage bacterial and viral diseases through the use of compost; 2) exploration of the potential effects of fortified compost on insect pests suppression; 3) improvement of inoculation methods of composts with biocontrol agents to produce consistent levels of disease suppression at the commercial scale; 4) development of effective fortified compost teas for suppressing foliar diseases; 5) education of compost producers on methods of production of fortified compost that suppress specific diseases; and 6) education of end-users on uses of fortified compost and its by-products.
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Dissertations / Theses on the topic "Disease suppression; Rhizoctonia solani"

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Fang, Lynn. "Biological Indicators Of Compost-Mediated Disease Suppression Against The Soilborne Plant Pathogen Rhizoctonia Solani." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/456.

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Compost can suppress soilborne plant pathogens that cause significant damage on globally important food crops. However, reports of plant pathogen suppression are inconsistent likely because there are no established standards for feedstock material, application rate, and maturity age upon application. Excellent results can be achieved in greenhouse trials, but field applications are much less reliable. Disease suppression occurs through the activity of biocontrol organisms (direct antagonism), and general microbial competition. Biocontrol species are hypothesized to colonize the pile during the curing phase, but single species may not be as important as microbial consortia. Substrate composition during maturation may give rise to a suppressive microbial community. More research is needed to understand the relationships between feedstock, maturity, and production process on compost microbial ecology. The thesis had two main objectives: 1) identify biological indicators in compost that could (a) characterize maturity, process, and feedstock, and (b) predict disease suppression against R. solani, and 2) identify bacterial and fungal community composition and/or structure that is associated with suppression of soilborne disease. Rhizoctonia solani is a facultative saprophytic fungus and soilborne plant pathogen that attacks many globally important food crops and turfgrass. Prior research suggests that managing carbon quality and compost maturity will alter relative competition between biological control microbes and the R. solani pathogen. The pathogen is responsible for economic losses to organic vegetable production in Vermont and there are no available methods to manage the disease that meet organic certification. R. solani on radish was chosen as a model system given its global importance, competitiveness affected by carbon quality, and lack of disease management options for organic production. Compost samples were most abundant in the bacterial phyla Proteobacteria and Bacteroidetes, and known biocontrol species were not detected in abundance. Compost samples did not differ significantly in fungal community composition, suggesting a dominance effect from the native soil fungal community. Overall, anaerobic digestate and vermicompost were most suppressive against R. solani. Thermophilic composts were not very suppressive overall, though a specially made hardwood bark compost was comparable to the suppressiveness of vermicompost application. Ecoenzyme analysis was able to integrate information on environmental substrate composition, microbial nutrient acquisition, and microbial community metabolism, offering the best view of current ecological conditions in compost. Ecoenzyme analysis showed that the most suppressive composts, anaerobic digestate and vermicompost, were most nutrient limited. All compost samples were severely nitrogen (N) limited, and anaerobic digestate and vermicompost were severely limited in both N and phosphorus (P). The additional P limitation may support non-pathogenic species to outcompete R. solani. The key to disease suppression may lie in matching up the ecology of the plant pathogen with the ecology of biocontrol, which may be engineered in compost.
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Nanayakkara, Chandrika Malkanthi Hewawasam. "Bacterial biocontrol and soil solarization strategies for suppression of Rhizoctonia solani on rice." Thesis, University of Aberdeen, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424985.

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Use of known antagonists and antagonistic, endophytic bacteria was investigated to screen a successful antagonist for the fungal strains R. solani AG 2-1, R. solani AG 4 and R. solani AGSL01.   Reputed antagonists used in the study; Bacillus subtilis MBI 205,  B. subtilis MBI 600, Pseudomonas fluorescens B5 and P. corrugate R. 117 were capable of suppressing the fungus in dual cultures. Manipulation of soil factors to reduce pre-plant density of R. solani sclerotia involved a laboratory experiment followed by two field experiments.  In the laboratory study, the effect of constant soil temperatures was investigated by incubating sclerotia at 30, 35, 40, 45 and 50°C.  Sclerotia were counted into lots of 100, placed in polyester mesh bags (85 μm pore size, 10 x 10 cm dimension) at depths of 5 and 10 cm in rice field soils contained in plastic containers (20x20x18 cm).  Total loss of viability was observed on day 1, day 8 and day 28 at 45°C, 40°C and 35°C, respectively.  Loss was even detected within 6.00 h at 50oC. Field experiments of soil solarization (carried out at The Regional Agricultural Research Institute (RARI), Bombuwela, Sri Lanka) were conducted during the fallow periods between the two main cropping seasons in 2003.  During the trials, the effect of polythene mulching, straw incorporation and their combined effect on the viability of sclerotia were investigated.  Sclerotia (lots of 100) were buried at depths of 5 and 10 cm and the soil temperature was recorded at 8.00, 11.00, 14.00 and 17.00h daily at both depths.  During the field trials, at both depths, the effect of treatment over time was noted on percentage recovery and viability of sclerotia (p<0.001).  The results showed a drop in mean percentage recovery of less than 50% during the first week of both trials.  Germination was markedly reduced to less than 10% by the first week in all the treatments.  Depth of burial and straw incorporation had no effect.  In solarized plots, a significant increase in soil temperature at both soil depths was observed between 14.00 and 17.00h.  Average temperatures of 40°C and 34°C were observed for solarized and non-solarized plots, respectively.  The study therefore has identified a practical, low cost and environmentally friendly method of control, and the use of polythene five weeks prior to rice seed sowing is recommended to minimise sheath blight and other diseases caused by similar soil-borne fungal pathogens.
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Kabir, Nasreen Zahan. "Selection of effective antagonists against Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29726.pdf.

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Kabir, Nasreen Zahan. "Selection of effective antagonists against Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27351.

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Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato, overwinters as sclerotia on potato tubers. To develop a biocontrol strategy based on the prevention of the sclerotial germination, an isolation of microorganisms colonizing sclerotia of infected potato tubers (cultivars Norland, Atlantic and Souris), was conducted. In vitro screening was used to select effective antagonistic fungi against Rhizoctonia solani. Fifty fungal isolates were selected in order to cover all identified genera and potato variety and examined for their ability to inhibit germination of sclerotia which were incubated with the test fungus for 14 days. Twenty-four (24) fungal isolates were retained based on their ability to reduce sclerotial viability by more than 50% as compared with 100% viability of untreated sclerotia. These 24 isolates were further examined for their ability to protect Table beet seedlings against the pathogen in greenhouse soils. Based on their ability to protect Table beet seedlings from Rhizoctonia infections and to increase the number of secondary roots and root length isolates, F2, F11, F132, F158, and F258 were screened and test their efficacy to increase beet seed germination in field soils. (Abstract shortened by UMI.)
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Chung, Young Ryun. "Suppression of Rhizoctonia solani and its interaction with Trichoderma hamatum in bark compost container media /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487586889189028.

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Brewer, Marin Talbot. "Effects of Biological Control and a Ryegrass Rotation on Rhizoctonia Disease of Potato." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/BrewerMT2003.pdf.

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Ali, Md Ansar. "Biological variation and chemical control of Rhizoctonia solani causing rice sheath blight disease in Bangladesh." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480682.

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Sykes, Virginia Roseanna. "Use of digital image analysis to identify Rhizoctonia solani and Rhizoctonia zeae resistance in Festuca arundinacea plant introductions." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/42769.

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Brown patch, caused by Rhizoctonia solani Kuhn, is an important disease on tall fescue (TF, Festuca arundinacea Schreb, synonym Schedonorus phoenix (Scop.) Holub). Rhizoctonia zeae Voorhees, a related pathogen, causes similar symptoms. Confusion over which Rhizoctonia species is causing symptoms and subjective visual evaluations of disease severity may contribute to variability in observed BP resistance of TF cultivars at multiple locations. The objectives of this study were to develop an objective digital image analysis (DIA) method for evaluating disease and to use DIA to screen tall fescue plant introductions (PIs) for resistance to R. solani and R. zeae. There was a strong correlation (r2 = 0.97) between actual disease severity, measured by applying lesioned tissue of a known area to healthy leaves, and DIA calculated disease severity using scanned images of individual leaves (DIA-IL). The accuracy and precision of visual evaluations and DIA evaluations of entire plants (DIA-WP) were evaluated using DIA-IL as a standard of accuracy. Accuracy of DIA-WP was not significantly different from visual evaluation accuracy. Precision was significantly higher for DIA-WP. Evaluation of PIs and putatively BP resistant TF cultivars for resistance to R. solani and R. zeae using DIA-WP identified clones within each PI that ranked high for resistance to R. solani or R. zeae. No clones were identified with high resistance to both R. solani and R. zeae. Improved precision of DIA evaluation methods and inclusion of R. zeae in BP resistance breeding may decrease variability of TF cultivar performance across locations.
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Maios, Claudia. "Expression of defence-related genes in sugar beet plants infected with Rhizoctonia solani and treated with benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH)." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99349.

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The chemicals inducers SA, BABA, and BTH were tested as seed treatment and soil drench on a partial-resistant cultivar of sugar beet grown in sand infested with the Rhizoctonia solani AG 2-2IIIB. In another series of experiments, BTH was applied as soil drench on sugar beet plants inoculated with R. solani. The chemical inducers were ineffective in reducing pre-emergence damping-off and post-emergence plant mortality. Despite these results, treatment with BTH altered the levels of expression ratios of four defence encoding genes associated with systemic resistance: chitinase, peroxidase, chalcone isomerase, and chalcone synthase. BTH sensitised sugar beet plants without the necessity of R. solani infection to up-regulate substantially the transcript level ratios of chalcS and chit3, while levels of chalcI were down-regulated levels below 1. Of interest, was the significant increase of transcript levels of chit3 in sugar beet plants infected with R. solani and treated with BTH. In conclusion, sugar beet plants were capable of over expressing selected genes in response to a chemical inducer, but contrary to what had been reported, gene activation in sugar beet as a result of BTH treatment does not confer disease resistance against R. solani.
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Liu, Yangxi. "Rhizoctonia Solani Damping-Off of Sugarbeet: Effect of Plant Growth Stage on Disease Severity and Management Using Penthiopyrad." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27901.

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Rhizoctonia solani is the most damaging pathogen on sugarbeet (Beta vulgaris L.) in North Dakota and Minnesota. Research was conducted to evaluate penthiopyrad for controlling R. solani and determine when the plants are most susceptible to infection. Penthiopyrad applied in-furrow and as a soil drench resulted in significantly higher percent survival than the positive control whereas penthiopyrad applied in a band was ineffective at controlling R. solani. Penthiopyrad can also be used as a seed treatment at the 14 g rate to provide effective control of R. solani. Sugarbeet plants, irrespective of their inherent level of resistance, were easily infected by R. solani up to three weeks after planting, even longer for susceptible varieties, highlighting the need for additional protection in the form of seed treatment or fungicide application that may be required to protect vulnerable sugar beet planted in fields with a history of the disease.
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Books on the topic "Disease suppression; Rhizoctonia solani"

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Rhizoctonia species: Taxonomy, molecular biology, ecology, pathology, and disease control. Dordrecht: Kluwer Academic, 1996.

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Sneh, B., S. Jabaji-Hare, S. M. Neate, and G. Dijst. Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Springer London, Limited, 2013.

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(Editor), B. Sneh, S. Jabaji-Hare (Editor), S. M. Neate (Editor), and G. Dijst (Editor), eds. Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Springer, 1996.

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Gleń-Karolczyk, Katarzyna. Zabiegi ochronne kształtujące plonowanie zdrowotność oraz różnorodność mikroorganizmów związanych z czernieniem pierścieniowym korzeni chrzanu (Atmoracia rusticana Gaertn.). Publishing House of the University of Agriculture in Krakow, 2019. http://dx.doi.org/10.15576/978-83-66602-39-7.

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Horseradish roots, due to the content of many valuable nutrients and substances with healing and pro-health properties, are used more and more in medicine, food industry and cosmetics. In Poland, the cultivation of horseradish is considered minor crops. In addition, its limited size causes horseradish producers to encounter a number of unresolved agrotechnical problems. Infectious diseases developing on the leaves and roots during the long growing season reduce the size and quality of root crops. The small range of protection products intended for use in the cultivation of horseradish generates further serious environmental problems (immunization of pathogens, low effectiveness, deterioration of the quality of raw materials intended for industry, destruction of beneficial organisms and biodiversity). In order to meet the problems encountered by horseradish producers and taking into account the lack of data on: yielding, occurrence of infectious diseases and the possibility of combating them with methods alternative to chemical ones in the years 2012–2015, rigorous experiments have been carried out. The paper compares the impact of chemical protection and its reduced variants with biological protection on: total yield of horseradish roots and its structure. The intensification of infectious diseases on horseradish leaves and roots was analyzed extensively. Correlations were examined between individual disease entities and total yield and separated root fractions. A very important and innovative part of the work was to learn about the microbial communities involved in the epidemiology of Verticillium wilt of horseradish roots. The effect was examined of treatment of horseradish cuttings with a biological preparation (Pythium oligandrum), a chemical preparation (thiophanate-methyl), and the Kelpak SL biostimulator (auxins and cytokinins from the Ecklonia maxima algae) on the quantitative and qualitative changes occurring in the communities of these microorganisms. The affiliation of species to groups of frequencies was arranged hierarchically, and the biodiversity of these communities was expressed by the following indicators: Simpson index, Shannon–Wiener index, Shannon evenness index and species richness index. Correlations were assessed between the number of communities, indicators of their biodiversity and intensification of Verticillium wilt of horseradish roots. It was shown that the total yield of horseradish roots was on average 126 dt · ha–1. Within its structure, the main root was 56%, whereas the fraction of lateral roots (cuttings) with a length of more than 20 cm accounted for 26%, and those shorter than 20 cm for 12%, with unprofitable yield (waste) of 6%. In the years with higher humidity, the total root yield was higher than in the dry seasons by around 51 dt · ha–1 on average. On the other hand, the applied protection treatments significantly increased the total yield of horseradish roots from 4,6 to 45,3 dt · ha–1 and the share of fractions of more than 30 cm therein. Higher yielding effects were obtained in variants with a reduced amount of foliar application of fungicides at the expense of introducing biopreparations and biostimulators (R1, R2, R3) and in chemical protection (Ch) than in biological protection (B1, B2) and with the limitation of treatments only to the treatment of cuttings. The largest increments can be expected after treating the seedlings with Topsin M 500 SC and spraying the leaves: 1 × Amistar Opti 480 SC, 1 × Polyversum WP, 1 × Timorex Gold 24 EC and three times with biostimulators (2 × Kelpak SL + 1 × Tytanit). In the perspective of the increasing water deficit, among the biological protection methods, the (B2) variant with the treatment of seedlings with auxins and cytokinins contained in the E. maxima algae extract is more recommended than (B1) involving the use of P. oligandrum spores. White rust was the biggest threat on horseradish plantations, whereas the following occurred to a lesser extent: Phoma leaf spot, Cylindrosporium disease, Alternaria black spot and Verticillium wilt. In turn, on the surface of the roots it was dry root rot and inside – Verticillium wilt of horseradish roots. The best health of the leaves and roots was ensured by full chemical protection (cuttings treatment + 6 foliar applications). A similar effect of protection against Albugo candida and Pyrenopeziza brassicae was achieved in the case of reduced chemical protection to one foliar treatment with synthetic fungicide, two treatments with biological preparations (Polyversum WP and Timorex Gold 24 EC) and three treatments with biostimulators (2 × Kelpak SL, 1 × Tytanit). On the other hand, the level of limitation of root diseases comparable with chemical protection was ensured by its reduced variants R3 and R2, and in the case of dry root rot, also both variants of biological protection. In the dry years, over 60% of the roots showed symptoms of Verticillium wilt, and its main culprits are Verticillium dahliae (37.4%), Globisporangium irregulare (7.2%), Ilyonectria destructans (7.0%), Fusarium acuminatum (6.7%), Rhizoctonia solani (6.0%), Epicoccum nigrum (5.4%), Alternaria brassicae (5.17%). The Kelpak SL biostimulator and the Polyversum WP biological preparation contributed to the increased biodiversity of microbial communities associated with Verticillium wilt of horseradish roots. In turn, along with its increase, the intensification of the disease symptoms decreased. There was a significant correlation between the richness of species in the communities of microbial isolates and the intensification of Verticillium wilt of horseradish roots. Each additional species of microorganism contributed to the reduction of disease intensification by 1,19%.
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Book chapters on the topic "Disease suppression; Rhizoctonia solani"

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Rothrock, Craig S. "Cotton Diseases Incited by Rhizoctonia Solani." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 269–77. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_24.

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Weinhold, Albert R., and James B. Sinclair. "Rhizoctonia Solani: Penetration, Colonization, and Host Response." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 163–74. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_14.

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Lootsma, M. "Suppression of Rhizoctonia Solani on Potato by Mycophagous Soil Fauna." In Plant Production on the Threshold of a New Century, 401–3. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1158-4_46.

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Neate, Stephen M., and Johannes H. M. Schneider. "Sampling and Quantification of Rhizoctonia Solani in Soil." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 185–95. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_16.

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Carling, Donald E. "Grouping in Rhizoctonia Solani by Hyphal Anastomosis Reaction." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 37–47. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_3.

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Rubio, Victor, Stellos M. Tavantzis, and Dilip K. Lakshman. "Extrachromosomal Elements and Degree of Pathogenicity in Rhizoctonia Solani." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 127–38. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_11.

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Keijer, Jaap. "The Initial Steps of the Infection Process in Rhizoctonia Solani." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 149–62. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_13.

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O’Brien, Philip A. "Identification and Detection of Rhizoctonia Solani Using Serological and DNA Marker Techniques." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 177–83. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_15.

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Savary, S., and T. W. Mew. "Analyzing Crop Losses Due to Rhizoctonia Solani: Rice Sheath Blight, a Case Study." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 237–45. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_21.

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Elad, Yigal. "Bacterial and Fungal Cell-Wall Hydrolytic Enzymes in Relation to Biological Control of Rhizoctonia Solani." In Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, 455–62. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2901-7_41.

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Conference papers on the topic "Disease suppression; Rhizoctonia solani"

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Bredehoeft, Mark, and Chris Dunsmore. "PCC for enhancement of sugar beet production and evaluation of Rhizoctonia disease suppression." In American Society of Sugarbeet Technologist. ASSBT, 2011. http://dx.doi.org/10.5274/assbt.2011.53.

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McGrath, J. Mitchell, and Suba Nagendran. "Discovery of resistance to seedling disease caused by Rhizoctonia solani AG2-2, description of the host-pathogen interaction, and development of a seedling disease screening nursery." In American Society of Sugar Beet Technologist. ASSBT, 2007. http://dx.doi.org/10.5274/assbt.2007.55.

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Belyakova, N. V., E. A. Vorobyova, and V. A. Sivolapov. "MOLECULAR-GENETIC ANALYSIS OF PHYTOPATHOGENS IN STANDS OF THE VORONEZH REGION." In Modern machines, equipment and IT solutions for industrial complex: theory and practice. Voronezh State University of Forestry and Technologies named after G.F. Morozov, Voronezh, Russia, 2021. http://dx.doi.org/10.34220/mmeitsic2021_29-33.

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This paper presents the results of DNA diagnostics of phytopathogens in the Voronezh region. DNA diagnostics was carried out step by step: isolation of total DNA from the sample by CTAB method, amplification of marker regions of phytopathogenic organisms using primers ITS1 and ITS4, electrophoretic separation of the obtained amplicons in 2% agarose gel followed by staining with ethidium bromide, determination of the nucleotide sequence of the amplified loci ABI Prism 310. The study identified the following plant diseases: Sphaeropsis sapinea, Rhizoctonia solani, Cladosporium herbarum. Along with this, we identified the Neocatenulostroma pathogen, which had not previously been found in the territories under its jurisdiction. This disease cannot be determined by phenological signs. The degree of infection by pathogens ranged from 15 to 40%. At present, the problem of protecting plants from diseases is especially urgent. It has been established that the greatest damage to forestry activities is caused by fungal and infectious diseases. At the same time, among phytopathogens, about 97% are fungal infections, 2% are bacterial and 1% are viral.
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Reports on the topic "Disease suppression; Rhizoctonia solani"

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Hoitink, Harry A. J., Yitzhak Hadar, Laurence V. Madden, and Yona Chen. Sustained Suppression of Pythium Diseases: Interactions between Compost Maturity and Nutritional Requirements of Biocontrol Agents. United States Department of Agriculture, June 1993. http://dx.doi.org/10.32747/1993.7568755.bard.

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Several procedures were developed that predict maturity (stability) of composts prepared from municipal solid wastes (MSW). A respirometry procedure, based O2 uptake by compost, predicted (R2=0.90) the growth response of ryegrass in composts and an acceptable level of maturity. Spectroscopic methods (CPMAS13-NMR and DRIFT spectroscopy) showed that the stabilizing compost contained increasing levels of aromatic structures. All procedures predicted acceptable plant growth after approximately 110 days of composting. MSW compost suppressed diseases caused by a broad spectrum of plant pathogens including Rhizoctonia solani, Pythium aphanidermatum and Fusarium oxysporum. A strain of Pantoea agglomerans was identified that caused lysis of hyphae of R. solani. Evidence was obtained, suggesting that thermophilic biocontrol agents also might play a role in suppression. 13C-NMR spectra revealed that the longevity of the suppressive effect against Pythium root rot was determined by the concentration of readily biodegradable carbohydrate in the substrate, mostly present as cellulose. Bacterial species capable of inducing biocontrol were replaced by those not effective as suppression was lost. The rate of uptake of 14C-acetate into microbial biomass in the conducive substrate was not significantly different from that in the suppressive substrate although specific activity was higher. The suppressive composts induced systemic acquired resistance in cucumjber roots to Pythium root rot and to anthracnose in the foliage. Composts also increased peroxidase activity in plants by the conducive substrate did not have these effects. In summary, the composition of the organic fraction determined bacterial species composition and activity in the substrate, which in turn regulated plant gene expression relative to biological control.
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Hoitink, Harry A. J., Yitzhak Hadar, Laurence V. Madden, and Yona Chen. Sustained Suppression of Pythium Diseases: Interactions between Compost Maturity and Nutritional Requirements of Biocontrol Agents. United States Department of Agriculture, June 1993. http://dx.doi.org/10.32747/1993.7568746.bard.

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Several procedures were developed that predict maturity (stability) of composts prepared from municipal solid wastes (MSW). A respirometry procedure, based O2 uptake by compost, predicted (R2=0.90) the growth response of ryegrass in composts and an acceptable level of maturity. Spectroscopic methods (CPMAS13-NMR and DRIFT spectroscopy) showed that the stabilizing compost contained increasing levels of aromatic structures. All procedures predicted acceptable plant growth after approximately 110 days of composting. MSW compost suppressed diseases caused by a broad spectrum of plant pathogens including Rhizoctonia solani, Pythium aphanidermatum and Fusarium oxysporum. A strain of Pantoea agglomerans was identified that caused lysis of hyphae of R. solani. Evidence was obtained, suggesting that thermophilic biocontrol agents also might play a role in suppression. 13C-NMR spectra revealed that the longevity of the suppressive effect against Pythium root rot was determined by the concentration of readily biodegradable carbohydrate in the substrate, mostly present as cellulose. Bacterial species capable of inducing biocontrol were replaced by those not effective as suppression was lost. The rate of uptake of 14C-acetate into microbial biomass in the conducive substrate was not significantly different from that in the suppressive substrate although specific activity was higher. The suppressive composts induced systemic acquired resistance in cucumjber roots to Pythium root rot and to anthracnose in the foliage. Composts also increased peroxidase activity in plants by the conducive substrate did not have these effects. In summary, the composition of the organic fraction determined bacterial species composition and activity in the substrate, which in turn regulated plant gene expression relative to biological control.
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Kloepper, Joseph W., and Ilan Chet. Endophytic Bacteria of Cotton and Sweet Corn for Providing Growth Promotion and Biological Disease Control. United States Department of Agriculture, January 1996. http://dx.doi.org/10.32747/1996.7613039.bard.

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Endophytes were isolated from 16.7% of surface-disinfested seeds and 100% of stems and roots of field-growth plants. Strains from Israel with broad-spectrum in vitro antibiosis were mainly Bacillus spp., and some were chitinolytic. Following dipping of cut cotton roots into suspensions of these strains, endophytes were detected up to 72 days later by isolation and by autoradiograms of 14C-labelled bacteria. Selected endophytes exhibited biological control potential based on significant reductions in disease severity on cotton inoculated with Rhizoctonia solani or Fusarium oxysporum f. sp. vasinfectum as well as control of Sclerotium rolfsii on bean. Neither salicylic acid nor chitinase levels increased in plants as a result of endophytic colonization, suggesting that the observed biocontrol was not accounted for by PR protein production. Some biocontrol endophytes secreted chitinolytic enzymes. Model endophytic strains inoculated into cotton stems via stem injection showed only limited movement within the stem. When introduced into stems at low concentrations, endophytes increased in population density at the injection site. After examining several experimental and semi-practical inoculation systems, seed treatment was selected as an efficient way to reintroduce most endophytes into plants.
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Shtienberg, Dan, William Fry, Amos Dinoor, Thomas Zitter, and Uzi Kafkafi. Reduction in Pesticide Use in Plant Disease Control by Integration of Chemical and Non-Chemical Factors. United States Department of Agriculture, May 1995. http://dx.doi.org/10.32747/1995.7613027.bard.

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The long term goal of this research project was to improve control efficiency of Alternaria diseases while reducing fungicide use, by integration of chemical and non-chemical factors. Non-chemical factors were genotype resistance, age-related resistance and fertilizers. The Specific objectives were: 1) To quantify changes in resistance among genotypes and over time in terms of disease development and specific phases of the disease cycle; 2) To quantify the effects of fertilizers applied to the foliage alone, or in combination with a fungicide, on disease development; 3) To quantify the relative contribution of genotype resistance, age-related resistance and fungicide type to the reduction of disease development; 4) To develop a strategy for integration of chemical and non-chemical factors which will achieve optimal disease suppression. The influence of physiological age of cotton plants and of the individual leaves, on disease incidence and on the rate of lesion expansion of A. macrospora was examined on leaves sampled from the field. Both parameters increased with the physiological age of individual leaves but were not affected by the age of the whole plant. The hypothesis that enrichment of the foliage with nitrogen and potassium may enhance host resistance to Alternaria and thus reduce disease severity, was examined for potato and tomato (A. solani ) and for cotton (A. macrospora ). Under controlled environment conditions, application of urea or KNO3 resulted in some reduction in disease development; however, foliar application of both nutrients (8-10 sprays in total) did not affect Alternaria severity in the field. Systemic fungicides against Alternaria (e.g. , tebuconazole and difenoconazole) are more effective than the commonly used protectant fungicides (e.g. mancozeb and chlorothalonil). Concepts for the integration of genotype resistance, age-related resistances and fungicide for the suppression of Alternaria diseases were developed and evaluated. It was found that reduction in host resistance, with age and among genotypes, can be compensated for by adjusting the intensity of fungicide applications, i.e. by increasing the frequency of sprays and by spraying systemic fungicides towards the end of the season. In, moderately resistant cultivars protection can be achieved by spraying at longer intervals than susceptible cultivars. The concepts for integration were evaluated in field trials for cotton, potatoes and tomatoes. By following these concepts it was possible to save up to five sprays out of 8-10 in a growing season.
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Thomashow, Linda, Leonid Chernin, Ilan Chet, David M. Weller, and Dmitri Mavrodi. Genetically Engineered Microbial Agents for Biocontrol of Plant Fungal Diseases. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696521.bard.

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The objectives of the project were: a) to construct the site-specific integrative expression cassettes carrying: (i) the chiA gene for a 58-kDa endochitinase, (ii) the pyrrolnitrin biosynthesis operon, and (iii) the acdS gene encoding ACC deaminase; b) to employ these constructs to engineer stable recombinant strains with an expanded repertoire of beneficial activities; c) to evaluate the rhizosphere competence and antifungal activity of the WT and modified strains against pathogenic fungi under laboratory and greenhouse conditions; and d) to monitor the persistence and impact of the introduced strains on culturable and nonculturable rhizosphere microbial populations in the greenhouse and the field. The research generally support our concepts that combining strategically selected genes conferring diverse modes of action against plant pathogens into one organism can improve the efficacy of biological control agents. We hypothesized that biocontrol agents (BCAs) engineered to expand their repertoire of beneficial activities will more effectively control soilborne plant pathogens. In this work, we demonstrated that biocontrol activity of Pseudomonas fluorescens Q8r1-96 and Q2-87, both producing the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) effective against the plant pathogenic fungus Rhizoctonia solani, can be improved significantly by introducing and expressing either the 1.6-kb gene chiA, encoding the 58-kDa endochitinase ChiA from the rhizosphere strain SerratiaplymuthicaIC1270, or the 5.8-kb prnABCDoperon encoding the broad-range antibiotic pyrrolnitrin (Prn) from another rhizosphere strain, P. fluorescens Pf-5. The PₜₐcchiAandPₜₐcprnABCDcassettes were cloned into the integrative pBK-miniTn7-ΩGm plasmid, and inserted into the genomic DNA of the recipient bacteria. Recombinant derivatives of strains Q8r1-96 and Q2-87 expressing the PₜₐcchiA or PₜₐcprnABCD cassettes produced endochitinase ChiA, or Prn, respectively, in addition to 2,4-DAPG, and the recombinants gave significantly better biocontrol of R. solani on beans under greenhouse conditions. The disease reduction index increased in comparison to the parental strains Q8r1-96 and Q2-87 to 17.5 and 39.0% from 3.2 and 12.4%, respectively, in the case of derivatives carrying the PₜₐcchiAcassette and to 63.1 and 70% vs. 2.8 and 12,4%, respectively, in the case of derivatives carrying the PₜₐcprnABCDcassette. The genetically modified strains exhibited persistence and non-target effects comparable to those of the parental strains in greenhouse soil. Three integrative cassettes carrying the acdS gene encoding ACC deaminase cloned under the control of different promoters were constructed and tested for enhancement of plant growth promotion by biocontrol strains of P. fluorescens and S. plymuthica. The integrative cassettes constructed in this work are already being used as a simple and efficient tool to improve biocontrol activity of various PGPR bacteria against fungi containing chitin in the cell walls or highly sensitive to Prn. Some parts of the work (e. g., construction of integrative cassettes) was collaborative while other parts e.g., (enzyme and antibiotic activity analyses) were fully synergistic. The US partners isolated and provided to the Israeli collaborators the original biocontrol strains P. fluorescens strains Q8r1-96 and Q2-87 and their mutants deficient in 2,4-DAPG production, which were used to evaluate the relative importance of introduction of Prn, chitinase or ACC deaminase genes for improvement of the biocontrol activity of the parental strains. The recombinant strains obtained at HUJI were supplied to the US collaborators for further analysis.
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