Patterns of urediniospores release and development of rose apple rust

O objetivo deste trabalho foi avaliar padrões epidemiológicos de campo do fungo (Puccinia psidii Winter) que causa a ferrugem em jambeiro (Syzygium jambos). Entre 29/3 e 31/12/1988, levantou-se a incidência da doença e a população aérea de urediniósporos, na Universidade de Brasília, DF. Avaliaram-se dez plantas, sendo que, entre duas delas, instalou-se uma armadilha Burkard caça-esporos de sete dias. A maior quantidade de urediniósporos capturada foi de 23 de junho a 6 de julho. A principal carga de esporos ocorreu de maio a julho, entre as 10h e as 13 horas. Os maiores números de brotos de jambeiro com pústulas esporulantes ocorreram entre 28 de abril e 20 de julho. O número de brotos terminais infectados foi positivamente correlacionado com a quantidade de esporos. A temperatura (às 12h) foi negativamente correlacionada com a quantidade de urediniósporos dispersos no ar. O número de dias com umidade relativa (UR) do ar (às 24h) ³80% foi positivamente correlacionado com a quantidade de brotos deformados. A quantidade de urediniósporos foi positivamente correlacionada com o número de dias com temperatura £20oC e UR(24h) ³80%. Ao maior pico de urediniósporos capturados precedeu um período sem precipitação, porém com vários dias de UR(24h) ³80% e temperatura £20oC. Estes dados mostraram que a doença foi favorecida por temperaturas £20oC e por UR noturna ³80%.This research was conducted to evaluate some epidemiological features of the rose apple (Syzygium jambos) rust (Puccinia psidii Winter) under field conditions at the Universidade de Brasília, Brasília, DF, Brazil, from March 29 through December 31, 1988. Data for the amount of airborne urediniospores were collected in ten plants, using a Burkard's seven-day volumetric spore trap set between two rose apple trees. Most of the airborne urediniospores were collected between June 23 and July 6, from 10 a.m. to 1 p.m. The major quantity of S. jambos affected shoots occurred between April 28 and July 20. There was a positive correlation between the amount of trapped urediniospores and infected young shoots. A negative correlation was shown between temperature (12h) and number of airborne urediniospores. The number of days with relative humidity (RH) ³80% was positively correlated to the amount of deformed shoots. Also, the amount of urediniospores and infected young shoots were positively correlated to the number of days with night (24h) temperature £20oC or night RH³80%. These data show that this disease was favored by low temperatures (£20oC), high night RH (³80%) and high levels of airborne urediniospores

Development of a locus-specific, co-dominant SCAR marker for assisted-selection of the Sw-5 (Tospovirus resistance) gene cluster in a wide range of tomato accessions

The best levels of broad-spectrum Tospovirus resistance reported in tomatoes thus far are conferred by the Sw-5 locus. This locus contains at least five paralogues (denoted Sw-5a through Sw-5e), of which Sw-5b represents the actual resistance gene. Here we evaluated a panel of seven PCR primer pairs matching different sequences within a genomic region spanning the Sw-5a and Sw-5b gene cluster. Primer efficiency evaluation was done employing tomato isolines with and without the Sw-5 locus. One primer pair produced a single and co-dominant polymorphism between susceptible and resistant isolines. Sequence analysis of these amplicons indicated that they were specific for the Sw-5 locus and their differences were due to insertions/deletions. The polymorphic SCAR amplicon encompass a conserved sequence of the promoter region of the functional Sw-5b gene, being located in the position -31 from its open reading frame. This primer pair was also evaluated in field assays and with a collection of accessions known to be either susceptible or resistant to tospoviruses. An almost complete correlation was found between resistance under greenhouse/field conditions and the presence of the marker. Therefore, this primer pair is a very useful tool in marker-assisted selection systems in a large range of tomato accessions

Identification of resistance to Bean Rugose Mosaic Virus (BRMV) in accesses of common bean germplasm.

The disease known as bean rugose mosaic, also known as ?mosaico-em-desenho? caused by Bean rugose mosaic virus (BRMV), has been recently observed in common bean (Phaseolus vulgaris L.) fields at EMBRAPA Rice and Beans, located in Santo Antonio de Goias, Goias State, Brazil. The importance of this disease increases especially in conditions that enable infection of young plants, when there is the presence of other viruses and under sequential cultivation of susceptible common bean varieties

Additions to the genera Asterolibertia and Cirsosia (Asterinaceae, Asterinales), with particular reference to species from the Brazilian Cerrado

Four new Asterolibertia species and a new variety of Cirsosia splendida, all found on native Cerrado plants, belonging to three host families are described, illustrated and named as: A. bahiensis sp. nov. on Erythroxylum sp. (Erythroxylaceae); A. barrinhensis sp. nov. on Diospyros burchellii (Ebenaceae); A. campograndensis sp. nov. on Hirtella glandulosa (Chrysobalanaceae); A. parinaricola sp. nov. on Parinari obtusifolia (Chrysobalanaceae); and Cirsosia splendida var. laevigata var. nov., showing both sexual and asexual morphs, on H. glandulosa and H. gracilipes (Chrysobalanaceae). Finally, A. licaniae is reported on a new host, H. gracilipes. Keys to all the known species of Asterolibertia and Cirsosia are included

Papaya foot rot reduction under nursery conditions with application of potassium, calcium, or magnesium phosphate

O controle da podridão-do-pé (Phytophthora palmivora) do mamoeiro (Carica papaya) é essencial para reduzir perdas e aumentar a produtividade dos plantios. Sete fosfitos foram avaliados em plântulas (~10cm de altura) de mamoeiro da cultivar 'Tailândia Roxão'. Experimentos foram conduzidos com os seguintes objetivos: determinar a melhor forma de aplicação do fosfito (pulverização ou rega); determinar o melhor período prévio à inoculação do patógeno para aplicação do fosfito; determinar a quantidade de aplicações de fosfito; determinar o efeito de diferentes fosfitos sobre a doença. Os resultados dos testes mostraram que: o método mais adequado para aplicação dos fosfitos foi a pulverização da parte aérea; a aplicação dos fosfitos deve ocorrer com pelo menos 48h antes da inoculação do patógeno; duas pulverizações semanais por três semanas consecutivas antes da inoculação do patógeno reduziram a doença; e fosetyl-Al e todos os fosfitos testados [fosfito A (40% P2O5 + 20% K2O, 150mL p.c. 100L-1), B (40% P2O5 + 20% K2O, 250mL), C (10% P2O5 + 6% Ca, 400mL), D (20% P2O5 + 20% K2O, 200mL), E (40% P2O5 + 6% Mg, 150mL), F (30% P2O5 + 20% K2O, 175mL), G (20% P2O5 + 20% K2O, 200mL)] reduziram a doença. _______________________________________________________________________________ ABSTRACTFoot rot, caused by Phytophthora palmivora, is an important disease of papaya (Carica papaya). Disease control is of extreme importance to reduce losses and to increase productivity. Seven phosphites were tested in greenhouse using papaya seedlings (~ 10cm height) of the cultivar 'Tailândia Roxão'. Experiments were conducted with the following objectives: to determine the most effective method for phosphite application (spray or drench) to reduce disease; to determine the period for phosphite application before pathogen inoculation on plants; to determine the number of phosphite applications; to determine the effects of different phosphites on disease severity. Data from experiments showed that: spraying of aerial plant parts was the most adequate method for phosphite application; phosphites should be applied at least 48h before the inoculation of the pathogen on plants; two weekly phosphite sprays for three consecutive weeks before the pathogen inoculation on plants reduced disease, and; fosetyl-Al and all tested phosphites [phosphite A (40% P2O5 + 20% K2O, 150mL c.p. 100L-1), B (40% P2O5 + 20% K2O, 250mL), C (10% P2O5 + 6% Ca, 400mL), D (20% P2O5 + 20% K2O, 200mL), E (40% P2O5 + 6% Mg, 150mL), F (30% P2O5 + 20% K2O, 175mL), G (20% P2O5 + 20% K2O, 200mL)] reduced disease severity

Novas espécies de Ravenelia sobre leguminosas do Cerrado brasileiro

Four new Ravenelia species were described on native leguminous hosts from the Brazilian Cerrado, as follows: Ravenelia cerradensis sp. nov., R. chapadensis sp. nov., R. mineirosensis sp. nov. and R. emaensis sp. nov. on Chamaecrista clausenii var. cyclophylla, Chamaecriista conferta var. virgata, Anadenanthera colubrina var. colubrina, and on Anadenanthera sp., respectively.Quatro espécies novas de Ravenelia foram descritas em leguminosas do Cerrado brasileiro, a saber: Ravenelia cerradensis sp. nov., R. chapadensis sp. nov., R. mineirosensis sp. nov. e R. emaensis sp. nov. sobre Chamaecrista clausenii var. cyclophylla, Chamaecrista conferta var. virgata, Anadenanthera colubrina var. colubrina e Anadenanthera sp., respectivamente

Hentriacontano: um hidrocarboneto obtido de folhas de Syzygium jambos com efeito estimulante sobre a germinação de urediniósporos de Puccinia psidii

Foi obtido um extrato orgânico de folhas de jambeiro (Syzygium jambos) com um extrator Sohxlet e as frações do extrato foram purificadas através de cromatografia de coluna. O efeito estimulante das frações sobre a germinação de urediniósporos de Puccinia psidii foi avaliado através de um bioensaio em água ágar 2%. Uma fração eluida com n-hexano 100% teve atividade estimulante sobre a germinação que aumentou em até 88%, comparado à testemunha com somente óleo mineral. Esta fração ativa foi caracterizada como um hidrocarboneto através de espectrometria de infra-vermelho e por ressonância nuclear magnética de prótons e de 13C. A análise de espectrometria de massa em cromatógrafo de gás indicou ser a substância estimulante um hidrocarboneto de cadeia longa e não ramificado, com peso molecular 436, correspondendo à fórmula C31H64, denominado hentriacontano. Esta foi a primeira constatação do efeito estimulante deste composto sobre a germinação de esporos de fungos. Estes resultados contribuem para o melhor entendimento do processo de infecção das ferrugens nas plantas hospedeiras.A crude Sohxlet extract from leaves of Syzygium jambos was sequentially fractionated using a silica gel flash column. A bioassay based on the numbers of urediniospores of Puccinia psidii that germinated in 2% water agar detected an active stimulant of germination when the fraction eluted with 100% n-hexane was used. The active fraction induced up to 88% increase in germination when added to a spore suspension in mineral oil. The active fraction was characterized as a hydrocarbon by ¹H nuclear magnetic resonance, 13C nuclear magnetic resonance, and infrared analysis. Gas chromatography-mass spectrometry analysis indicated that the fraction was a long-chain 436 MW hydrocarbon with corresponding to C31H64, namely hentriacontane. This is the first time such a compound proved to be involved with stimulation of fungal spore germination. These results may contribute to better understanding the infection process of rusts

O uso de fosfitos no manejo de doenças fúngicas em fruteiras e soja.

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Uromyces species on leguminous hosts from the Cerrado with description of U. galactiae sp. nov.

Foram estudadas cinco espécies de Uromyces sobre Bauhinia spp. e uma espécie nova em Galactia peduncularis. Uromyces bauhiniae foi encontrada pela primeira vez sobre B. holophylla, onde somente Uromyces floralis havia sido descrita. Uromyces floralis foi estudada sobre B. curvula, hospedeiro inédito no Brasil para esta espécie. Uromyces foveolatus, comum em B. acuruana var. nitida, no cerrado do Mato Grosso e U. goyazensis sobre B. dumosa var. viscidula foram encontradas somente na fase telial em todas as exsicatas examinadas. Uromyces viegasii foi estudada em B. forficata. Uromyces galactiae sp. nov. é o primeiro fungo fitopatogênico associado ao gênero Galactia.Five Uromyces species were studied on Bauhinia spp. and a new species was described on Galactia peduncularis. Uromyces bauhiniae was found for the first time on Bauhinia holophyla, where only U. floralis had been previously described. Uromyces floralis was studied on B. curvula, inedited host in Brazil for that species. Uromyces foveolatus common in B. acuruana var. nitida in the Cerrado of Mato Grosso and U. goyazensis on B. dumosa var. viscidula were both found only in their teleomorphic phase in all exsicates examined. Uromyces viegasii was studied on B. forficata. Uromyces galactiae sp. nov. is the first plant pathogenic fungus found on the Galactia genus