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Resistência de cultivares de arroz a Rhizoctonia solani e Rhizoctonia oryzae
Prabhu Anne Sitarama,Filippi Marta Cristina,Silva Gisele Barata da,Santos Gil Rodrigo de
Pesquisa Agropecuária Brasileira , 2002,
Abstract: Isolados de Rhizoctonia solani e Rhizoctonia oryzae, agentes causais da queima-da-bainha e mancha-da-bainha, respectivamente, foram coletados em lavouras de arroz irrigado no Estado do Tocantins. O objetivo deste trabalho foi avaliar a resistência de 12 cultivares de arroz a essas doen as, sob condi es artificiais de inocula o, em casa de vegeta o. N o houve correla o entre resistência das cultivares a R. oryzae e R. solani quanto ao comprimento da les o na bainha infectada pelo método de palito de dentes. A rela o entre tamanho da les o na bainha e folha foi linear e significativamente negativa (r = -0,66, P<=0,05), indicando que n o há rela o entre resistência das cultivares na bainha e nas folhas a R. solani. Entre as cultivares precoces, Labelle apresentou maior grau de suscetibilidade em todos os métodos de inocula o. A área sob a curva de progresso da doen a baseada na altura da les o no colmo e o método de inocula o utilizando casca e gr o de arroz foram mais adequados para a determina o da resistência entre as cultivares. Diferen as significativas entre as cultivares de ciclo médio n o foram observadas. As folhas apresentaram resistência à infec o por R. oryzae nos testes de inocula o utilizando discos de micélio.
Seedling Blight of Festuca arizonica Caused by Rhizoctonia solani  [PDF]
Mopuri N. Reddy, Stanley H. Faeth
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.21006
Abstract: We report here a damping-off disease occurring at the seedling stage of the grass Festuca arizonica (Arizona fescue) that is caused by the soil-borne fungal pathogen Rhizoctonia solani.
Biological control of Rhizoctonia solani on potato by Verticillium biguttatum
E Demirci, C Eken, E Dane
African Journal of Biotechnology , 2009,
Abstract: Ten isolates of Verticillium biguttatum were obtained from sclerotia of Rhizoctonia solani on potato tubers in Erzurum, Turkey. The interaction between V. biguttatum and R. solani was studied in vitro and in vivo. V. biguttatum isolates affected R. solani by antibiosis and parasitism. All isolates of V. biguttatum inhibited the growth of R. solani colony. After the coiling around of R. solani hyphae, V. biguttatum hyphae penetrated host cell walls and grew within the hyphae. Viability of hyphae and sclerotia of R. solani was reduced by V. biguttatum isolates. V. biguttatum also significantly reduced the disease severity of R. solani on potato sprouts in pot experiments. This is the first report of V. biguttatum from sclerotia of R. solani in Turkey.
Reaction of melon genotypes to Rhizoctonia solani
Michereff, Sami J;Andrade, Domingos EGT;Sales Júnior, Rui;
Horticultura Brasileira , 2008, DOI: 10.1590/S0102-05362008000300022
Abstract: the intensive exploration of melon (cucumis melo l.) crops in the brazilian northeast favors the occurrence of root diseases such as the rhizoctonia canker, caused by rhizoctonia solani. twenty melon genotypes were challenged against the pathogen isolates rs-9 and rs-10 aiming at selecting those potentially useful for breeding programs and/or integrated disease management. seeds were planted in infested soil (50 mg of colonized rice grains kg-1 of soil). disease severity was assessed 15 days after inoculation, by means of a disease scale from 0 to 4, used later to cluster genotypes in five classes. none of the genotypes presented immune-like reaction to r. solani, independent of the pathogen isolate. disease severity ranged from 6.2 to 85.4% and from 7.8 to 85.2%, for isolates rs-9 and rs-10, respectively. when both isolates were considered simultaneously, genotypes sancho, af-1805, athenas, af-682, torreon, and galileo were highly resistant. genotypes sancho and af-1805 had the lowest disease severity levels in relation to isolate rs-9, and genotype gold pride, in relation to rs-10. these genotypes differed significantly from the others, within isolates. therefore, they are potential sources of resistance to r. solani and should be considered as a priority planting choice in infested areas.
Parasitism of Rhizoctonia solani by strains of Trichoderma spp.
Melo, Itamar Soares de;Faull, Jane L.;
Scientia Agricola , 2000, DOI: 10.1590/S0103-90162000000100010
Abstract: rhizoctonia solani causes serious diseases in a wide range of plant species. the fungus trichoderma has been shown to be particularly effective in the control of the pathogen. thus, this research was carried out to screen fourteen trichoderma strains against r. solani in vitro. all strains tested inhibited the growth of r. solani. three t. koningii strains produced toxic metabolites with strong activity against r. solani, inhibiting the mycelial growth by 79%. t. harzianum, th-9 reduced the viability of sclerotia of r. solani by 81.8% and t. koningii, tk-5 reduced by 53%. electron microscopic observations revealed that all t. harzianum strains interacted with r. solani. th-9 grew toward and coiled around the host cells, penetrating and destroying the hyphae. penetration of host cells was apparently accomplished by mechanical activity.
Parasitism of Rhizoctonia solani by strains of Trichoderma spp.  [cached]
Melo Itamar Soares de,Faull Jane L.
Scientia Agricola , 2000,
Abstract: Rhizoctonia solani causes serious diseases in a wide range of plant species. The fungus Trichoderma has been shown to be particularly effective in the control of the pathogen. Thus, this research was carried out to screen fourteen Trichoderma strains against R. solani in vitro. All strains tested inhibited the growth of R. solani. Three T. koningii strains produced toxic metabolites with strong activity against R. solani, inhibiting the mycelial growth by 79%. T. harzianum, Th-9 reduced the viability of sclerotia of R. solani by 81.8% and T. koningii, TK-5 reduced by 53%. Electron microscopic observations revealed that all T. harzianum strains interacted with R. solani. Th-9 grew toward and coiled around the host cells, penetrating and destroying the hyphae. Penetration of host cells was apparently accomplished by mechanical activity.
Patogenicidade de Rhizoctonia solani em morangueiro
Tanaka, Maria Aparecida de Souza;Ito, Margarida Fumiko;Passos, Francisco Antonio;
Bragantia , 1995, DOI: 10.1590/S0006-87051995000200010
Abstract: rhizoctonia solani was consistently associated with strawberry plants in nurseries or in fruit production fields, with symptoms of progressive decline, stunt, reddening of leaflets, petioles and runners, besides dry rots of the crown apex, estipules and base of the petioles. these plants showed frequently roots with necrotic lesions. fusarium spp. and pythium spp. also were isolated from the diseased plants. this study was conducted to determine the role of each referred fungus on the disease and to investigate a possible interaction between them. for this purpose, r. solani, pythium sp. and fusarium sp., alone or combined one with other, were inoculated in strawberry plants, in the greenhouse. the results showed that only when r. solani was present, there was an identical reproduction of the symptoms observed in the field. fusarium and pythium, nevertheless, were reisolated from root lesions, indicating the possibility of its involvement with the disease, increasing the symptoms of decline under field conditions.
Infection process in sheath blight of rice caused by Rhizoctonia solani  [cached]
AMITA SINGH, RASHMI ROHILA, S. SAVARY L. WILLOCQUET and U.S. SINGH
Indian Phytopathology , 2012,
Abstract: When Rhizoctonia solani is inoculated on inner surface of rice sheath it first colonized the surface before producing the infection structures like lobate appressoria, bulbous appressoria and infection cushion. The most frequent penetration was by hyphal tips followed by lobate apressoria. Colonization of epidermal and mesophyll cells was both intra- and inter-cellular. Intra
Resistência física de bainhas de plantas de arroz supridas com silício e infectadas por Rhizoctonia solani Physical resistance of leaf sheaths of rice plants supplied with silicon and infected by Rhizoctonia solani
Daniel Augusto Schurt,Fabrício ávila Rodrigues,Ricardo Dutra Reis,Wiler Ribas Moreira
Tropical Plant Pathology , 2012, DOI: 10.1590/s1982-56762012000400008
Abstract: Este trabalho objetivou associar a deposi o de silício (Si) nas bainhas de plantas de arroz ao aumento da resistência física à infec o por Rhizoctonia solani. Plantas das cultivares suscetíveis BR-Irga 409 e Labelle foram cultivadas em solu o nutritiva contendo (+Si) ou n o (-Si) Si. A concentra o de Si nas bainhas das plantas supridas com Si e inoculadas com R. solani aumentou significativamente em rela o às plantas n o supridas com Si reduzindo o comprimento relativo da les o às 96 horas após inocula o (hai). Houve diferen a significativa entre os tratamentos -Si e +Si quanto à for a necessária para uma agulha metálica atravessar as bainhas às 48 e 72 hai. A maior resistência física às 24 hai deve-se ao fato de que R. solani estava crescendo sobre o tecido sem destruí-lo, o que p de ser comprovado pela ausência de sintomas. Após esse período, a resistência diminuiu devido ao rápido crescimento de R. solani. Entretanto, nas bainhas de plantas supridas com Si, a for a necessária para a agulha penetrar foi maior às 48 e 72 hai. A resistência das bainhas de plantas supridas com Si à infec o por R. solani pode ser explicada, em parte, pela maior resistência física decorrente da deposi o desse elemento. This study aimed to associate the silicon (Si) deposition on sheaths of rice plants with an increase in physical resistance against infection by Rhizoctonia solani. Plants from the susceptible cultivars BR-Irga 409 and Labelle were grown in nutrient solution containing (+Si) or not (-Si) Si. Si concentration on sheaths of plants supplied with Si and inoculated with R. solani significantly increased compared to plants non-supplied with Si, reducing the relative lesion length at 96 hours after inoculation (hai). There were significant differences between -Si and +Si treatments for the force required of a metal needle to pass through the sheaths at 48 and 72 hai. The greater physical resistance at 24 hai was due to the fact that R. solani was growing on sheath tissue without destroying it, which could be proved by the absence of symptoms. After this period, the resistance decreased due to the rapid R. solani growth. However, on sheaths of plants supplied with Si, the force required for the needle to penetrate was higher at 48 and 72 hai. The sheath resistance of plants supplied with Si to infection by R. solani can be explained partly by the greater physical resistance due to Si deposition.
Susceptibility of leguminous green manure species to Rhizoctonia solani and Sclerotium rolfsii
Paula Júnior, Trazilbo José de;Teixeira, Hudson;Vieira, Rogério Faria;Lehner, Miller da Silva;Lima, Renan Cardoso de;Queiroz, Telma Fallieri Nascimento;
Summa Phytopathologica , 2011, DOI: 10.1590/S0100-54052011000400012
Abstract: we studied the susceptibility of species used as green manure in common bean fields to root rot (rhizoctonia solani) and southern blight (sclerotium rolfsii). seeds of crotalaria breviflora, canavalia ensiformis, cajanus cajan, dolichos lablab, stizolobium cinereum, s. aterrimum, and the bean cvs. "pérola", "valente" and "carnaval" were sown in soil infested by either r. solani ag-4 or s. rolfsii in greenhouse. the emergence of d. lablab seedlings in soil infested by r. solani dropped to 62%. c. breviflora, c. ensiformis and cv. "valente" presented the lowest root rot severity. the pathogen s. rolfsii drastically reduced seedling emergence in all species; no c. cajan and s. cinereum seedling emerged. all plant species presented high southern blight severity. we conclude that leguminous crops are not suitable as green manure for areas of bean cultivation with high r. solani and s. rolfsii populations.
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