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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Aplicação de piraclostrobina em genótipos de milho cultivados em safra e segunda safra / Pyraclostrobin application in different corn genotypes cultivated on season and off season

Silva, Andreia Vanessa da 26 August 2016 (has links)
Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-11-28T15:53:24Z No. of bitstreams: 2 Dissertação - Andreia Vanessa da Silva - 2016.pdf: 1619459 bytes, checksum: 11df3f2a6fdab2aebb632cc402194b27 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-11-28T17:24:48Z (GMT) No. of bitstreams: 2 Dissertação - Andreia Vanessa da Silva - 2016.pdf: 1619459 bytes, checksum: 11df3f2a6fdab2aebb632cc402194b27 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-11-28T17:24:48Z (GMT). No. of bitstreams: 2 Dissertação - Andreia Vanessa da Silva - 2016.pdf: 1619459 bytes, checksum: 11df3f2a6fdab2aebb632cc402194b27 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The physiological effects of fungicides from the group of strobilurins were initially described for kresoxim - methyl molecule in wheat crop currently, the effects of strobilurins are reported by several authors in various crops such as soy, beans, tomatoes and corn. In order to evaluate the effects of pyraclostrobin fungicide, which belongs to the group of strobilurins applied at different periods on three corn genotypes. Were conducted two similar experiments, in the agricultural year of 2014/15, one being cultivated on season and other one off season, located in Jataí city, southwest of Goiás State. In both was used randomized blocks in a factorial design 3 x 4 with four replications. The treatments consisted in three corn genotypes and four periods of pyraclostrobin application. Were evaluated: nitrate reductase enzyme activity, chlorophyll index, percentage of senescent leaves, area under the disease progress curve, morphological characteristics, yield components and productivity. The results were submitted to variance analysis and means were compared by Tukey test by 5% probability. Both for the experiment on season as off season there were no interaction between genotype and applications for the variables evaluated, the only interaction was for the area under the disease progress curve cercospora spot in the on season. It was not observed pyraclostrobin application effects on physiology, development and productivity of corn plants grown on season and off season. / Os efeitos fisiológicos dos fungicidas do grupo das estrobilurinas foram inicialmente descritos para a molécula de metil-cresoxima na cultura do trigo, atualmente, os efeitos das estrobilurinas são relatados por vários autores, em diversas culturas, como soja, feijoeiro, tomateiro e milho. Objetivou-se com este trabalho avaliar os efeitos do fungicida piraclostrobina, do grupo das estrobilurinas, aplicado em diferentes épocas sobre genótipos de milho. Foram conduzidos dois experimentos semelhantes, no ano agrícola de 2014/15, sendo um cultivado em primeira safra e o outro em segunda safra, localizados no munícipio de Jataí, sudoeste do estado de Goiás. Em ambos empregou-se o delineamento de blocos ao acaso no esquema fatorial 3 x 4, com quatro repetições. Os tratamentos consistiram de três genótipos de milho e quatro épocas de aplicação de piraclostrobina. Foram avaliadas: atividade enzimática da redutase do nitrato, índice de clorofila, porcentagem de folhas senescentes, área abaixo da curva de progresso da doença, características morfológicas, componentes de produção e produtividade. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Tanto para o experimento de primeira safra quanto de segunda safra não houveram interação entre genótipos e aplicações para as variáveis avaliadas, havendo interação apenas para área abaixo da curva de progresso da doença de mancha de cescoscpora na primeira safra. Não foi observado efeito da aplicação de piraclostrobina na fisiologia, desenvolvimento e produtividade de grãos sobre as plantas de milho cultivados em primeira safra e segunda safra.
12

Avaliação dos efeitos fisiológicos de fungicidas em cultivares de soja de hábito de crescimento determinado e indeterminado / Evaluation of physiological effects of fungicides in soybean cultivars of determined and undetermined habit

José Ari Formiga 24 March 2015 (has links)
Anualmente novas tecnologias são incorporadas a áreas tradicionais e de expansão na produção de grãos no Brasil, sendo a soja [Glycine max (L.) Merrill] a principal cultura. Com vastas áreas e clima favorável, doenças, como a ferrugem asiática (Phakopsora pachyrhizi Sydow & Sydow), foram disseminadas nas principais áreas de produção. Aplicações de fungicidas, do grupo das estrobilurinas associado ao dos triazóis, a partir do florescimento fazem parte do cronograma fitossanitário atual. O objetivo deste estudo foi analisar o efeito fungicida, fisiológico e interação entre piraclostrobina e fluxapiroxade em duas variedades cultivadas de soja de hábitos de crescimento determinado e indeterminado, e alterações nos componentes de produção quando submetidos a aplicações durante todo o ciclo. Foram utilizadas combinações com piraclostrobina + tiofanato-metílico e/ou tiofanato-metílico no tratamento de sementes em conjunto com piraclostrobina, epoxiconazol e fluxapiroxade, em aplicações foliares sendo um tratamento completo, um controle e as demais variações das épocas e dos produtos citados. As variáveis analisadas (número de grãos por vagem, número de vagens por planta, número de nós por planta, estande final de plantas e produtividade de grãos) não variaram entre os manejos estrobilurina/triazol e estrobilurina/carboxamida. Na caracterização dos efeitos fisiológicos, foram utilizados os seguintes parâmetros: condutância estomática, atividade fotossintética, carbono intercelular, transpiração e valor Spad. Os dados não foram consistentes na caracterização dos efeitos fisiológicos e sinérgicos da utilização de fluxapiroxade. / New technologies are incorporated every year to traditional and expansion areas of crop production in Brasil. Soybean [Glycine max (L.) Merrill] is the main crop. With vast areas and favorable weather, diseases as soybean rust (Phakopsora pachyrhizi Sydow & Sydow), were disseminated to the production areas. Fungicide application, strobilurins plus triazoles starting at full flowering its an usual management practice in representative regions. This experiment aimed to evaluate the fungicide effects, physiological alterations and interactions between pyraclostrobin and fluxapyroxad in soybean cultivars of determined and indetermined growth habits, and differences in soybean production compounds when submitted to applications during the cicle. The combinations with pyraclostrobin and thiophanate-methyl and/or thiophanate-methyl in seed treatment together with pyraclostrobin, epoxiconazole and fluxapyroxad, in foliar applications with a complete treatment, control and variations of ingredient actives and timing of application. The analyzed variables such as, pods per plant, nodes per plant, final plant stand and productivity did not varied in different systems with strobilurin/triazole and strobilurin/carboxamides. The following parameters were used for characterizing the physiological effects: stomatal conductance, photosynthetic activity, intercellular carbon, transpiration and Spad value. The results were not consistent to characterize physiological and synergistic effects of the fluxapiroxad.
13

Adaptabilidade de isolados de Monilinia fructicola com diferentes níveis de sensibilidade à azoxistrobina / Fitness of Monilinia fructicola isolates with different levels of sensitivity to azoxystrobin

Isabela Vescove Primiano 23 June 2015 (has links)
O controle da podridão parda do pessegueiro (Monilinia fructicola) é realizado essencialmente por aplicações preventivas de fungicidas, em sua maioria sistêmicos com modo de ação específico. O uso contínuo desses fungicidas pode levar à seleção de indivíduos resistentes ao ingrediente ativo e, consequentemente, à perda da eficiência do controle nos pomares. A evolução da população de isolados resistentes ao longo do tempo, na ausência do fungicida, pode ser prevista com estudos de habilidade competitiva entre isolados resistentes e sensíveis. Portanto, a quantificação da adaptabilidade (fitness) e da estabilidade, necessárias para caracterizar os isolados encontrados em campo, auxiliarão nas estratégias antirresistência. Embora a importância da determinação da adaptabilidade de isolados resistentes seja reconhecida, há poucos métodos descritos para a análise da habilidade competitiva. Assim, esse trabalho verificou a adaptabilidade, a estabilidade e a habilidade competitiva de isolados de M. fructicola com diferentes níveis de sensibilidade à azoxistrobina em experimentos in vitro e em frutos de pêssegos (in natura e enlatado) utilizando metodologias de avaliação diversas. A caracterização dos isolados foi realizada in vitro, in vivo e molecularmente. Foram avaliados o diâmetro da colônia e a esporulação in vitro; o período de incubação e de latência, a incidência e a severidade da doença e a esporulação in vivo dos isolados separadamente. Os dados de esporulação in vitro foram submetidos ao teste de Kruskal-Wallis e os dados de crescimento micelial ao teste de Tukey com 5% de probabilidade. Para a análise dos dados in vivo, utilizou-se a análise multivariada. Dez transferências em meio de cultura sem fungicida foram realizadas para o estudo da estabilidade de dois isolados resistentes (SP08435 e SP09839) e um sensível (PR09638). A esporulação, a porcentagem de germinação de conídios e o diâmetro da colônia dos isolados em meio de cultura com fungicida foram avaliados em quatro transferências (inicial, terceira, sexta e última transferência). A habilidade competitiva foi verificada pela evolução da porcentagem de indivíduos resistentes no tempo entre um isolado resistente (SP09839) e um sensível à azoxistrobina (PR09638). Modelos lineares ou modelos lineares generalizados (GLM) foram utilizados para descrever o progresso da proporção do isolado resistente ao longo do tempo. Os isolados resistentes exibiram esporulação in vitro e taxa de crescimento micelial semelhantes aos sensíveis, além de apresentarem-se no mesmo grupo de similaridade que os isolados sensíveis. Nenhuma mutação no cyt b foi associada à resistência de M. fructicola à azoxistrobina (G143A, G137R, e F129L) e em todos os isolados foi observado o íntron antes do códon 143. Mesmo após 10 transferências em meio de cultura sem fungicida, os isolados resistentes à azoxistrobina não reduziram sua sensibilidade nem sua capacidade de esporulação e crescimento fora do pêssego. Independentemente da metodologia utilizada para avaliar a habilidade competitiva, a resistência à azoxistrobina não correspondeu a um custo adaptativo para M. fructicola, pois a proporção do isolado resistente manteve-se inalterada ao longo das transferências. O uso de pêssego enlatado é recomendado na substituição de frutos in natura para experimentos de habilidade competitiva. / Control of brown rot in peaches (caused by Monilinia fructicola) is mainly by preventive applications of fungicides, mostly single-target site. Repeated use of these fungicides can, however, select for resistant pathogen populations, which may result in failure of disease control. The evolution of resistant isolates in a population over time can be predicted with competitive ability assays between sensitive and resistant isolates. Therefore, studies quantifying pathogen fitness and stability are necessary to characterize field isolates and improve anti-resistant strategies. However, there are limited reports concerning the methodology used in competitive ability assays. This study determined the fitness of M. fructicola isolates with different levels of sensitivity to azoxystrobin in trials in vitro and in vivo (in natura and canned peaches) with different monocyclic components. Isolates characterization were carried out in vitro, in vivo and molecularly. Mycelial growth rate and sporulation were estimated in vitro, and disease incidence, severity, lesion sporulation, incubation and latent period were evaluated in peach fruit for sensitive and resistant isolates. Sporulation in vitro data were analyzed by Kruskal-Wallis test and mycelial growth rate with the Tukey test at 5% probability. For the in vivo experiments, multivariate analysis were carried out. Ten consecutive transfers on non-amended media were conducted to determine the stability of isolates (two resistant and one sensitive). Sporulation, percent spore germination and colony diameter on azoxystrobin amended media were also evaluated four times (the first, the third, the sixth and the last transfer). Competitive ability was investigated by testing the percentage increase of resistant individuals five generations after inoculation with a mix of azoxystrobin sensitive and resistant isolates. The competitive ability of sensitive and resistant isolates were compared with different variables as colony-forming unit and spore germination. Linear or generalized linear models (GLM) were adjusted to compare the progress of resistant isolates over time. All resistant isolates had in vitro sporulation and mycelial growth rate similar to sensitive isolates. All isolates sequenced presented an intron close to codon 143 and did not have any of the point mutations commonly associated with resistance to QoI fungicides (G143A, G137R, and F129L). After 10 transfers in PDA, colony diameter of resistant isolates was not reduced in azoxystrobin-amended media with 1 μg.ml-1 nor was their sporulation in vitro For all parameters used to measure competitive ability, no fitness cost was associated to M. fructicola isolates resistant to azoxystrobin. Canned peach is a viable option for studies aiming to determine fitness cost of resistant isolates.
14

Synergistic effects of mixtures of the kresoxim-methyl fungicide and medicinal plant extracts in vitro and in vivo against Botrytis cinerea

Knowles, Cindy-Lee January 2005 (has links)
Doctor Educationis / The fungus Botrytis cinerea is an opportunistic pathogen on a wide variety of crops, causing a disease known as grey mould through infections via wounds or dead plant parts. Synthetic fungicides for controlling this disease are fast becoming ineffective due to the development of resistance. This, coupled with consumers' world wide becoming increasingly conscious of potential environmental and health problems associated with the build-up of toxic chemicals, (particularly in food products), have resulted in pressure to reduce the use of chemical pesticide volumes as well as its residues. An emerging alternative to random chemical synthesis is the study and exploitation of naturally occurring products with fungicidal properties. One group of compounds known as strobilurins produced by Strobilurus species, woodland basidiomycete fungi, is a good example of this phenomenon. Plants produce an enormous array of secondary metabolites, and it is commonly reasoned that a significant part of this chemical diversity serves to protect plants against plant pathogens. A problem with plant-produced compounds as potential fungicides is that in the natural state, they are generally only weakly active compared to synthetic fungicides. There have been reports on the uses of mixtures of synthetic fungicides for the control of plant pathogenic fungi. When utilized in two-way mixtures, such fungicides may maintain or enhance the level of control of a pathogen at reduced rates for both components utilized in combinations, or alone at normal rates. These studies provide an important precedent for the idea of synergism. For this study, we hypothesize that the addition of plant extracts may enhance the antifungal efficacy of the synthetic strobilurin fungicide, kresoxim-rnethyl against B. cinerea. We selected South African medicinal plant species such as Artemesia afra, Elyptropappus rhinocerotis, Galenia africana, Hypoxis hemerocallidea, Siphonochilus aetheopicus, Sutherlundia frutescence, Tulbaghia violacea and Tulbaghia alliaceae for this study. For the in vitro study, indigenous medicinal plant extracts were prepared at twofold dilution concentrations and combined with kresoxim-rnethyl at concentrations of 0.25 and 0.5% (w/v). The B. cinerea mycelial plug assays showed potent antifungal inhibitory effects with the plant extract and kresoxim-rnethyl mixtures. Further analyses of the mixtures indicate synergistic effects between the fungicide and plant extracts. I surmise that these in vitro effects are also achievable in vivo. Combinations of these agents represent an attractive avenue for the development of new management strategies for controlling B. cinerea in the future. A second study was conducted to analyse the final dose rates for synergistic reactions for combinations of kresoxim-methyl and medicinal plant extracts against B. cinerea in vivo. A series of two-fold concentrations of medicinal plant extracts were combined with kresoxim-methyl to conduct decay inhibition studies on Granny Smith apples. Synergistic effects were observed for many of the kresoxim-methyl and plant extract combinations. I, therefore, came to the conclusion that indigenous South African plant species produce modulators that potentiate the activity of fungicides. Whether these synergistic effects are due to the inhibition of fungal multi-drug resistant pumps require further studies at the molecular level. However, these inhibitory effects are likely to be advantageous for developing fungicide formulations and application strategies with low toxicity effects on the environment. This approach not only makes it possible to reduce fungicide concentrations while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit.
15

Characterization of Fungicide Resistance in Venturia inaequalis Populations in Virginia

Marine, Sasha Cahn 02 May 2012 (has links)
Apple scab (causal organism: Venturia inaequalis) is an economically devastating disease of apples that is predominantly controlled with fungicides. Of the chemical classes currently available, the sterol-inhibiting (SI) and strobilurin (QoI) fungicides are the most commonly used. Recent observations indicate that V. inaequalis populations in Virginia have developed resistance to myclobutanil and other SIs. However, little is known about the frequency and distribution of SI and QoI resistance in Virginia's scab populations. The first objective of this research was to evaluate V. inaequalis populations in Virginia for SI and QoI resistance. Fungal isolates were collected from experimental orchards at the Alson H. Smith Jr., Agricultural Research and Extension Center (AHS AREC) and from commercial orchards in Virginia and Maryland. Sensitivities were determined by assessing colony growth at 19°C on potato dextrose agar (PDA) amended with 0 or 1.0 µg ml-1 of myclobutanil (SI) (N=87) or trifloxystrobin (QoI) (N=25) at 28 days. A range of fungicide sensitivity was observed for both chemical classes. The second objective of this research was to monitor the temporal dynamics of SI resistance over five sequential field seasons. To monitor shoot growth, neon rubber bands were placed over actively growing shoot tips following myclobutanil application or sample collection. Fungal isolates were collected from the same trees from 2007 through 2010 (N=176) and compared with isolates collected from wild apple seedlings (N=3). A continuum of SI resistance was observed for each year, and the V. inaequalis population exhibited a baseline shifted toward reduced sensitivity. The third objective of this research was to examine the spatial distribution of SI fungicide resistance within the tree canopy in a lower-density orchard (less than 150 trees A-1). Leaves collected from larger trees (>8m) in a lower-density orchard at the AHS AREC were analyzed for manganese deposition, pre- and post-mancozeb application. Fungal isolates (N=105) were collected from several locations within the canopy in replicated trees in the same orchard. Weather sensors also monitored the microclimates within those tree canopies. Spray deposition, microclimate and SI resistance were influenced by canopy location. The fourth objective of this research was to investigate potential SI resistance mechanisms. Previously classified isolates were screened for point mutations within the CYP51A1 gene (Appendix C), differences in polymorphic bands (alleles) (Appendix D), and differences in metabolism of myclobutanil (Appendix E). The consensus sequences for the CYP51A1 gene were identical for all isolates tested (N=9), and results from amplified fragment length polymorphism experiment (N=82) were inconclusive. There were, however, significant differences among incubation time and myclobutanil concentration in the bioassay (N=11). Our results indicate that myclobutanil is still an effective compound for control of apple scab in many areas of Virginia. / Ph. D.
16

Beiträge zur Biosynthese von Strobilurin A und Oudemansin A sowie Gewinnung neuer halogenierter Strobilurine durch vorläufer-dirigierte Biosynthese / Contributions to the biosynthesis of strobilurin A and oudemansin A as well as extraction of new halogenated strobilurins by precursor-directed biosynthesis

Thormann, Gerald 26 January 2005 (has links)
No description available.
17

Controle químico de corynespora cassiicola (berk. & curt.) weir em soja / Chemical control of corynespora cassiicola (berk. & curt.) weir in soybean

Stefanelo, Maurício Silva 25 February 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soybean target spot has become important recently, once the disease has generated economic losses to soybean producer, mainly in the Midwest. Therefore, this study aimed to evaluate alternatives managements on soybean target spot. Experiments were conducted in Canarana and Primavera do Leste, Mato Grosso State, in order to evaluate the effect of sowing date, cultivar and fungicide application programs on the severity of target spot. The application programs, that differed in the number of applications and timing of the first spraying, were tested on three soybean cultivars (TMG 7188 RR, TMG 132 RR, M-8766 RR) sown in two seasons (CHAPTER I). The efficiency of fungicides applied at different stages of the crop cycle (vegetative + reproductive, and just at reproductive stage) on cultivar TMG 7188 RR was also tested (Chapter II). Interaction betwen location and treatments was observed for severity of target spot and asiatic rust, as happened to yield. The severity of target spot was higher in the earlier sowing season, unlike soybean asiatic rust. Cultivars were differently susceptible to target spot, showing that choosing cultivar may be a disease management option. Fungicide application at vegetative stage only increased the control of target spot for TMG 132 RR sown in first sowing season in Primavera do Leste. The use of fungicides containing the molecule Fluxapyroxad were more efficient in target spot controlling, regardless of the number of sprays. The correct choice of fungicide, sowing season and less susceptible cultivars are factors to be considered in the management of the target spot in soybean. / A mancha alvo da soja vem ganhando importância nos últimos anos, visto que a doença tem gerado perdas econômicas ao sojicultor, principalmente na região Centro-Oeste do Brasil. Deste modo o presente estudo teve como objetivo avaliar alternativas de manejo da mancha alvo em soja. Experimentos foram conduzidos em Primavera do Leste e Canarana, Mato Grosso, com o intuito de avaliar o efeito da época de semeadura, de cultivares e programas de aplicação foliar de fungicidas sobre a severidade da mancha alvo em soja. Os programas de aplicação, que diferiram quanto ao número de aplicações e época da primeira pulverização, foram testados sobre três cultivares de soja (TMG 7188 RR, TMG 132 RR, M-8766 RR) semeadas em duas épocas (CAPÍTULO I). Também foi testada a eficiência de fungicidas aplicados em diferentes estágios da cultura (vegetativo + reprodutivo; e somente reprodutivo) na cultivar TMG 7188 RR (CAPÍTULO II). Os locais de condução dos experimentos apresentaram interação com os tratamentos para a área abaixo da curva de progresso de mancha alvo e de ferrugem asiática da soja, assim como se deu para a produtividade. A severidade de mancha alvo foi maior nas épocas de semeadura mais precoces, diferentemente do que ocorreu para ferrugem asiática da soja. As cultivares testadas apresentaram diferentes graus de suscetibilidade à mancha alvo, mostrando que a escolha da cultivar é uma opção no manejo da doença. A aplicação de fungicida no estádio vegetativo só apresentou benefício no controle de mancha alvo frente ao programa de aplicação contemplando aplicações apenas no período reprodutivo para o cultivar TMG 132 RR semeado na primeira época no município de Primavera do Leste. A utilização de fungicidas que continham a molécula Fluxapiroxade mostraram-se mais eficientes no controle da mancha alvo, independente do número de pulverizações. A escolha correta do fungicida, bem como a época de semeadura e a utilização de cultivares menos suscetíveis são fatores a serem levados em consideração no manejo da mancha alvo em soja.
18

EFEITO DO ESPECTRO DE GOTAS E IDADE DE TRIFÓLIOS SOBRE A TAXA DE ABSORÇÃO DE FUNGICIDAS EM SOJA / EFFECT OF DROPS SPECTRA AND LEAFLETS AGE ON THE FUNGICIDES ABSORPTION RATE IN SOYBEAN

Lenz, Giuvan 20 October 2010 (has links)
Currently, the Asian soybean rust is the main disease of this crop in Brazil and chemical control, so far, is the only effective measure to reduce losses. The development of control strategies for this disease requires knowledge of how performance of products applied, application technology used as well as their interaction with plants. This work aimed to quantify the effect of large, medium and fine droplet spectra and its interaction with the fungicide absorption rate and leaflets age through indirect measure expressed by the control of Phakopsora pachyrhizi in soybean. The experiment was performed twice and that was first installed in January 2010 and repeated in March this year. The experimental design was composed by completely randomized design with four replications in a factorial (3x3x5x4), which factors were composed of: three spectra drops (large, medium and fine); factor 02: evaluation in different positions of the plant (1º, 3º and 5 leaflets), factor 03: four time periods between the fungicide application and simulated rain (0, 30, 60 and 120 ) and a control with no rain and still a factor 04: control without fungicide applying, Azoxystrobin+Cyproconazole (60+24 g a.i. ha-1) + Nimbus 0.6 L.ha-1, Azoxystrobin (50 g a.i. ha-1) + Nimbus 0.6 L.ha-1 and Cyproconazole (30 g a.i. ha-1). We evaluated the density of droplets per square centimeter, volume median diameter, number median diameter and relative amplitude, disease severity and area under the disease progress curve. It was found that drops with smaller volume median diameter have higher fungicides absorption rates because they provide a greater number of drops per square centimeter and hence larger contact area specific product / plant. Newer leaflets provide more quickly fungicides absorption and therefore, provide a longer delay in disease development. The use of Azoxystrobin + Cyproconazole provided the greatest number of days until the first pustule preview and smaller area under the disease progress curve. The influence of rain has highly dependent on the interval between application of the products and its occurrence, the product applied and tissues age considered. / Atualmente a ferrugem asiática da soja é a principal doença desta cultura no Brasil e o controle químico, até então, é a medida mais eficaz para a redução dos danos causados. O desenvolvimento de estratégias de controle desta doença requer o conhecimento da forma de atuação dos produtos aplicados, tecnologia de aplicação utilizada bem como de sua interação com a planta. Com este trabalho buscou-se quantificar o efeito de espectros de gotas grossas, médias e finas na velocidade de absorção de fungicidas para trifólios de diferentes idades através de medida indireta expressa pelo controle de Phakopsora pachyrhizi na cultura da soja. O experimento foi executado duas vezes sendo que foi instalado primeiramente em Janeiro de 2010 e repetido em Março deste mesmo ano. O delineamento experimental utilizado foi inteiramente casualizado, com quatro repetições, em arranjo fatorial (3x3x5x4), cujos fatores foram compostos por: três espectros de gotas (grossas, médias e finas); fator 02: avaliação em diferentes posições da planta (1º, 3º e 5º trifólios); fator 03: quatro períodos de tempo entre a aplicação de fungicidas e aplicação de chuva simulada (0, 30, 60 e 120 min), mais uma testemunha sem chuva e ainda fator 04: testemunha sem aplicação mais os fungicidas Azoxistrobina + Ciproconazol (60+24 g i.a. ha-1) + Nimbus 0,6 L.ha-1, Azoxistrobina (50 g i.a. ha-1) + Nimbus 0,6 L.ha-1 e Ciproconazol (30 g i.a. ha-1). Avaliou-se densidade de gotas por centímetro quadrado, diâmetro mediano volumétrico, diâmetro mediano numérico e amplitude relativa, severidade da doença e área abaixo da curva de progresso da doença. Verificou-se que gotas de menor DMV apresentam maior velocidade de absorção de fungicidas, pois proporcionam maior número de gotas por centímetro quadrado e conseqüentemente maior área específica de contato produto/planta. Trifólios mais novos absorvem os fungicidas mais rapidamente e, em conseqüência, estabelecem um maior atraso no desenvolvimento da doença. A utilização de Azoxistrobina + Ciproconazol proporcionou o maior número de dias até o aparecimento da primeira pústula e menor área abaixo da curva de progresso da doença. A influência da precipitação possui relação altamente dependente do intervalo entre a aplicação dos produtos e a ocorrência da mesma, do produto que está sendo aplicado e da idade dos tecidos considerados.

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