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L’étude de la structure génétique des populations d’agents pathogènes à grandes échelles reste très important dans la contexte de nouvelles invasions. Puccinia striiformis f.sp. tritici (PST), responsable de la rouille jaune du blé, constitue un modèle fongique d’intérêt pour les études d’invasion étant donné sa capacité de migration et l’apparition récurrente de nouvelles souches localement. Nous avons analysé la structure des populations de PST à l’échelle mondiale, à l’aide de marqueurs microsatellites sur un échantillon de 409 isolats issus des six continents. Les génotypes ont été répartis en six groupes génétiques correspondant à leur origine géographique. Les analyses indiquent une forte hétérogénéité géographique de diversité génotypique, avec des signatures de recombinaison dans les régions de l'Himalaya (Népal et Pakistan) et à proximité en Chine. La structure reste clonale pour les populations des autres régions. L’assignation des isolats aux différents groupes génétiques a permis de déterminer l’origine des invasions (récentes ou anciennes). Ainsi, les souches agressives adaptées à de hautes températures, répandues de par le monde depuis 2000, sont originaires de Mer rouge-Moyen Orient ; les isolats d'Amérique du Nord et du Sud et d’Australie proviennent d’Europe du Nord-Ouest. Par ailleurs, les isolats d'Afrique du Sud appartiennent au groupe génétique de la zone méditerranéenne. La subdivision marquée entre les différentes zones géographiques indique qu’elles ne sont pas fortement marquées par les migrations récentes. De plus, les voies de migration identifiées attestent de l'importance des activités humaines dans la dispersion de PST à longue distance. La biologie des populations des zones les plus diverses (Chine et Pakistan) a été finement étudiée à l’aide d‘échantillonnages réalisés deux années consécutives. Une population échantillonnée en 2004 et 2005 dans la vallée de Tianshui, (province de Gansu, Chine), s’est révélée très diverse, fortement recombinante et non structurée spatialement et temporellement. L’observation de clones identiques entre les deux échantillons temporels a permis de développer un estimateur du taux de sexualité, i.e. du rôle relatif de la reproduction sexuée par rapport à celui de la reproduction asexuée dans le maintien de la population. Ce taux de reproduction sexuée est estimé à 74 %, alors que la taille efficace de la population est de 1735, ce qui donne les premières indications du rôle du cycle sexué. L’échantillonnage réalisé au Nord du Pakistan a permis de décrire quatre groupes génétiques ayant tous une grande diversité génotypique et une structure recombinante. Le très faible taux de ré-échantillonnage de génotypes identiques au cours de deux années suggère le rôle prédominant de la reproduction sexuée dans le maintien temporel des populations locales. La forte diversité génétique et génotypique, la signature de recombinaison et la capacité à la reproduction sexuée de PST dans la région himalayenne suggèrent que cette zone est le centre d'origine potentielle de PST. Les analyses d’approximations bayésiennes confirment la thèse d’une dispersion à partir de l’Himalaya vers les autres régions du monde. La variabilité pour la capacité à produire des téleutosores, spores indispensables à l’initiation de la phase sexuée, a été analysée (56 isolats mondiaux), et s’avère liée à la variabilité génotypique et au taux de recombinaison. Ce résultat conforte la thèse de l'apparition de la sexualité dans la zone himalayenne et à proximité de cette zone et de la perte de sexualité lors de migrations dans les zones où l’hôte alternant est absent et où le cycle épidémique est essentiellement asexué. La description de l'origine, des voies mondiale de migration de PST ainsi que de son centre de diversité contribue à la compréhension du potentiel évolutif de PST et à la construction de stratégies de gestion de lutte contre l’agent pathogène. / Analyses of the large-scale population structure of pathogens enable the identification of migration patterns, diversity reservoirs or longevity of populations, the understanding of current evolutionary trajectories and the anticipation of future ones. A detailed analysis of populations in centre of diversity should enable to infer the adaptive capacity of the pathogen and identify potential sources for new invasions. Puccinia striiformis f.sp. tritici (PST) is the causal agent of wheat yellow/stripe rust, and despite a worldwide distribution, this fungus remains a model species for invasion studies, due to its long-distance migration capacity and recurrent local emergence of new strains. Little is known about the ancestral relationship of the worldwide PST population with unknown center of origin. We used multilocus microsatellite genotyping to infer the worldwide population structure of PST and the origin of new invasions, analysing a set of isolates representative of sampling performed over six continents. Bayesian and multivariate clustering methods partitioned the isolates into six distinct genetic groups, corresponding to distinct geographic areas. The assignment analysis confirmed the Middle East-Red Sea Area as the most likely source of newly spreading, high-temperature-adapted strains; Europe as the source of South American, North American and Australian populations; and Mediterranean-Central Asian populations as the origin of South African populations. The existence of strong population subdivision at worldwide level shows that major genetic groups are not markedly affected by recent dispersal events. However, the sources for recent invasions and the migration routes identified emphasize the importance of human activities on the recent long-distance spread of the disease. The analyses of linkage disequilibrium and genotypic diversity indicated a strong regional heterogeneity in levels of recombination, with clear signatures of recombination in the Himalayan (Nepal and Pakistan) and near-Himalayan (China) regions and a predominant clonal population structure in other regions. To explain the variability in diversity and recombination of worldwide PST populations, we assessed their sex ability in terms of telial production, the sex-specific structures that are obligatory for PST sexual cycle, in a set of 56 isolates representative of these worldwide geographical origins. We confirmed that the variability in genotypic diversity/ recombination was linked with the sex ability, pinpointing the Himalayan region as the possible center of origin of PST, from where it then spread worldwide. The reduced sex ability in clonal populations certainly reflects a loss of sexual function, associated to migration in areas where sexual alternate host is lacking, or not necessary for the completion of epidemic cycle. Approximate Bayesian computation analyses confirmed an out of Himalaya spread of PST, with Pakistan and China being the most ancestral population. A detailed analysis of Pakistani population at regional level revealed the existence of a strong population subdivision, a high genotypic diversity and the existence of recombination signature at each location reflecting the role of sexual recombination in the temporal maintenance at local level. A time spaced sampling of PST in the valley of Tianshui (China) inspired the development of a new estimator, allowing to quantify the relative contribution of sexual reproduction and effective population size on the basis of clonal resampling within and between years. A sexual reproduction rate of 74% (95% confidence interval [CI]: 38-95%) and effective population size of 1735 (95% CI: 675-2800) was quantified in Chinese PST population. The description of the origin and migration routes of PST populations worldwide and at its centre of diversity contributes to our understanding of PST evolutionary potential, and is helpful to build disease management strategies.

A ferrugem alaranjada da cana-de-açúcar, causada pelo fungo Puccinia kuehnii, apesar de ser centenária, foi detectada no Brasil apenas no final de 2009, após causar uma grande epidemia na Austrália em 2000. Pela recente detecção, não há estudos que comparam as populações brasileiras de P. kuehnii e a reação, em condições controladas, de importantes variedades de cana-de-açúcar ao patógeno. Assim, este trabalho analisou e comparou o comportamento de variedades de cana-de-açúcar inoculadas com seis diferentes populações de P. kuehnii coletadas em diferentes locais no Brasil, além de verificar a variabilidade patogênica e genética destas populações. Para isso, inoculou-se populações de P. kuehnii coletadas em Piracicaba (SP), Araras (SP), Ribeirão Preto (SP), Paranacity (PR), Nova Alvorada do Sul (MS) e Dourados (MS). As variedades de cana-deaçúcar utilizadas foram: SP89-1115, SP81-3250, RB85-5156, RB86-7515, RB92- 5211, RB96-6928, CTC 3, CTC 6, CTC 8, CTC 9, CTC 13, CTC 15 e CTC 18. Em todas as inoculações avaliaram-se os períodos de incubação e de latência da doença, a severidade, o número total de pústulas e a porcentagem de pústulas abertas. Além disso, as regiões ITS e IGS de todas as populações de P. kuehnii foram sequenciadas e comparadas entre si e com sequências do patógeno da Austrália, Papua Nova Guiné, Indonésia, Filipinas, Japão, China, Guatemala, Panamá, Jamaica, Costa Rica, Nicaraguá, México e Estados Unidos. Os resultados mostraram que a porcentagem de pústulas abertas é o melhor parâmetro para separar e classificar as variedades de cana-de-açúcar quanto ao grau de resistência ao patógeno. O período de incubação da doença variou de 7 a 10 dias e o período de latência, de 9 a 19 dias. As populações de P. kuehnii não constituem diferentes raças virulentas e a população coletada em Araras (SP) é uma raça mais agressiva do patógeno. Para as regiões IGS e ITS, as seis populações de P. kuehnii utilizadas apresentam sequências idênticas entre si e entre todas as sequências de P. kuehnii do continente americano depositadas no \"GenBank\". Para estas duas regiões, as populações utilizadas no trabalho diferem de sequências da Austrália, China, Filipinas, Havaí (EUA), Indonésia, Japão, Papua Nova Guiné e Samoa. A disseminação do patógeno além da Ásia e Austrália parece ter ocorrido após a epidemia da doença na Austrália em 2000. No entanto ainda não se sabe ao certo como o patógeno teria chegado à América em 2007 e à África em 2011. / Despite being a century disease, sugarcane orange rust, caused by the Puccinia kuehnii, was only reported in 2009 Brazil, after having caused an epidemic in Australia in 2000. Because it was recently detected in Brazil, there are no studies that compare P. kuehnii populations in Brazil and the reaction, under controlled conditions, of important sugarcane varieties to the pathogen. This study compared the performance of sugarcane varieties inoculated with six different populations of P. kuehnii collected in different sites in Brazil. We also studied the pathogenic and genetic variability of these pathogens populations. In order to carry out this study, P. kuehnii populations were collected in the municipalities of Piracicaba (SP), Araras (SP), Ribeirao Preto (SP), Paranacity (PR), Nova Alvorada do Sul (MS), and Dourados (MS). The sugarcane varieties used were: SP89-1115, SP81-3250, RB85- 5156, RB86-7515, RB92-5211 RB96-6928, CTC 3, CTC 6, CTC 8, CTC 9, CTC 13, CTC 15, and CTC 18. For all inoculations, we evaluated the incubation period, latent period, disease severity, total number of pustules, and percentage of open pustules. Furthermore, the ITS and IGS rDNA regions of all P. kuehnii populations were sequenced and compared with sequences from Australia, China, Costa Rica, Guatemala, Indonesia, Jamaica, Japan, Mexico, Nicaragua, Papua New Guinea, the Philippines, Panama, and the United States. The results showed that the percentage of open pustules is the best parameter to separate and classify the resistance of sugarcane varieties to the pathogen. The incubation period of the disease ranged from 7 to 10 days and the latent period from 9 to 19 days. There are no P. kuhenii virulent races and the population collected in Araras (SP) is a more aggressive race. For the IGS and ITS regions, the six P. kuehnii populations have identical sequences which were identical to all P. kuehnii sequences found in the American continent deposited at the GenBank accession. The P. kuehnii used in this study is different from populations found in Australia, China, Hawaii (USA), Indonesia, Japan, Papua New Guinea, the Philippines, and Samoa. The pathogen dissemination over Asia and Australia seems have occurred after the 2000 epidemic in Australia. However, it is unknown still how the pathogen reached America in 2007 and Africa in 2011.

Made available in DSpace on 2014-06-11T19:28:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-04-22Bitstream added on 2014-06-13T20:58:40Z : No. of bitstreams: 1 takahashi_ss_me_botfca.pdf: 389279 bytes, checksum: 9ed3412d5f2a78f13dd658cd0b6e19b9 (MD5) / O conhecimento das perdas causadas por doenças no campo é considerado um dos mais importante fatores no manejo integrado de doenças em Eucalyptus. A ferrugem do eucalipto, causada pelo fungo Puccinia psidii Winter, também conhecida como ferrugem das Mirtáceas, é considerada uma das mais recentes enfermidades em plantas com menos de dois anos de idade. Desde meados da década de 80 tem sido registrado índices severos da doença, nas regiões Sudeste e Nordeste do Brasil. Apesar de alguns grupos de pesquisadores terem desenvolvido importantes trabalhos sobre o assunto, as informações a respeito dos danos causados pela doença continuam com lacunas. Deste modo, mais informações a respeito da doença, principalmente sobre sua epidemiologia, são necessários na escolha do melhor método de controle a ser adotado. Dentro desse contexto o presente trabalho objetivou: comparar o índice de infecção de duas regiões de plantio, analisar a distribuição temporal da doença e determinar os danos causados pela ferrugem em plantios de Eucalyptus spp. Para comparação de duas regiões de plantio distintas do Estado de São Paulo: Vale do Paraíba e Ribeirão Preto, em relação à ocorrência da ferrugem do eucalipto, calculou-se o índice de infecção a partir de um modelo matemático proposto por Ruiz et al. (1989). O índice de infecção foi estimado, a partir de dados climáticos diários de temperatura e período de molhamento foliar, para cada região durante os anos de 1993 a 1997. A partir dos resultados a região do Vale do Paraíba destacou-se, em termos de condições climáticas, como favorável à ocorrência da ferrugem em eucalipto, enquanto o contrário foi verificado para a região de Ribeirão Preto. Devido ao alto índice de ocorrência da ferrugem na região do Vale do Paraíba, também foram avaliados o aspecto temporal e os danos causados pela doença... / The most important fact about integrated management in Eucalyptus is to know how much the loss caused by diseases in the field is, in other words, the quantification of the production damage and its consequences. The eucalyptus rust, also known as Mirtaceas rust, is considered one of the most recent illness in trees that are younger than two-year-old. Since the mid-80s severe indices of disease incident have been registered on the southeastern and northeastern Brazilian regions. Despite some research groups have developed important works on the subject, the available informations are still very uncertain. Thus, more studies about the disease, mainly on epidemiology, are necessary to choose which disease control method will be taken. In this context, the present work objectived: to compare the infection index between two planting region in São Paulo State, to analysis the disease temporal distribution and to estimate the damage caused by rust in Eucalyptus grandis plantation. The infection index was estimated from Ruiz et al. (1989) mathematical model for to compare two distincts regions in São Paulo State: Vale do Paraíba and Ribeirão Preto. The infection index, from diary climatic data of temperature and wet leaf period, was estimated among 1993 and 1997 for each region. The Vale do Paraíba region became apparent in the eucalyptus rust occurrence, while in the Ribeirão Preto the opposite region was verified. Also temporal analysis and loss assesment were made due the high eucalyptus rust intensity in the Vale do Paraíba region. Experiments were carried out in three environments: Guararema, São José dos Campos and Taubaté, in the Vale do Paraíba region, conducted in 1997 until 2001. Each environment had two experiments with two different ages, where five Eucalyptus grandis genotypes were evaluated, depending on the site... (Complete abstract, click eletronic address below)

The object of this diploma essay is to evaluate selected breeding material sensitivity to attack of crown rust and grass rust. Research was realized in cooperation with Breeding Station Větrov, located in altitude 630 meters above sea level, district of Tabor. Attack of the plants was rated according to scale used by UKZUZ1-9. During vegetation period attacked parts of the plants were collected for specific rust diagnosis. The results were evaluated using statistical data elaboration.

Made available in DSpace on 2016-12-08T16:44:42Z (GMT). No. of bitstreams: 1 PGPV12MA104.pdf: 3071931 bytes, checksum: 12c25e131b1ed773136ed462f974fe61 (MD5) Previous issue date: 2012-07-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The rust (Puccinia hemerocallidis Thuem) is the main disease of daylily. In Brazil, there are no registered fungicides to control this disease and there are no studies indicating the more resistant cultivars. The study aimed to verify, on field conditions, the effectiveness of fungicides mixtures and rock dust on the control of rust and on the agronomic characteristics of five cultivars the daylily, identify the resistance degree of this cultivars to rust, as well to verify, in vitro, the efficacy of seven fungicides and rock dust on the germination inhibition of P. hemerocallidis urediniospore. The experiments were conducted at the Center of Agroveterinaries Sciences, CAV/UDESC in Lages, SC. On field conditions evaluated the cultivars Cora Offer, Daniela Esther Nass, Hariet, Margaret Mee and São Paulo and the products rock dust, pyraclostrobin + epoxiconazole, trifloxystrobin + tebuconazole, picoxystrobin + cyproconazole and azoxystrobin + cyproconazole. The fungicides were applied every thirty days for a total of three applications and the rock dust was applied every seven days for a total of thirteen applications. Weekly were quantified the incidence and severity of rust on leaves and through these data were calculated the Area Under Disease Progress Curve (AUDPC). It was also evaluated number of leaves, of flowers and of tillers. It was observed that all mixtures of fungicides reduced the disease incidence and severity, as well, delayed leaf senescence process. The mixtures pyraclostrobin + epoxiconazole, trifloxystrobin + tebuconazole and picoxystrobin + cyproconazole provided higher number of flowers the plants. The rock dust reduced the severity of the disease, but had lowest control in relation to fungicides mixtures, besides had not increased in none agronomic characteristics. The cultivar Daniela Esther Nass had the lowest incidence and severity of rust and the smallest reduction in number of leaves. The cultivar Daniela Esther Nass was classified as moderately resistant/resistant to rust, the Cora Offer as moderately susceptible/ susceptible, the Hariet and Margaret Mee as susceptible, and São Paulo as very susceptible. In the in vitro assay were evaluated the products azoxystrobin, picoxystrobin, pyraclostrobin, trifloxystrobin, cyproconazole, epoxiconazole, tebuconazole and rock dust at concentrations of 0, 0.01, 0.1, 1, 10 and 100 mg L-1. The products were diluted and mixed in a water-agar media, and stored at 4°C for 24 hours. Was added 0.5 mL of a suspension containing urediniospore of P. hemerocallidis and the incubation was at 22°C, in the dark, for 6 hours. The IC50 values were within the range of 0.01 to 0.1 mg L-1 for fungicides of the strobilurin chemical group; between 0.1 and 1 mg L-1 to tebuconazole; between 1 and 10 mg. L-1 to epoxiconazole, and between 10 and 100 mg. L-1 to cyproconazole and rock dust. The CI100 was observed only in fungicides azoxystrobin and picoxystrobin. It was concluded that all fungicides of the strobilurin chemical group and tebuconazole showed highly toxicity to urediniospores of the P. hemerocallidis, and fungicides epoxiconazole and cyproconazole, such as the rock dust had moderately toxicity this pathogen / A ferrugem (Puccinia hemerocallidis) é a principal doença do hemerocale. No Brasil, não há fungicidas registrados para o controle desta doença e também não há trabalhos indicando quais as cultivares mais resistentes. O trabalho teve como objetivos verificar, a campo, a eficácia de mistura de fungicidas e do pó de rocha no controle da ferrugem e nas características agronômicas de cinco cultivares de hemerocale, identificar o grau de resistência destas cultivares à ferrugem e também verificar, in vitro, a eficácia de sete fungicidas e do pó de rocha na inibição da germinação de uredosporos de P. hemerocallidis. Os experimentos foram conduzidos no Centro de Ciências Agroveterinárias, CAV/UDESC, em Lages, SC. A campo, avaliou-se as cultivares Cora Offer, Daniela Esther Nass, Hariet, Margaret Mee e São Paulo e os produtos pó de rocha, piraclostrobina + epoxiconazol, trifloxistrobina + tebuconazol, picoxistrobina + ciproconazol e azoxistrobina + ciproconazol. Os fungicidas foram aplicados a cada trinta dias, num total de três aplicações e o pó de rocha a cada sete dias, num total de treze aplicações. Semanalmente quantificou-se a incidência e a severidade da ferrugem em folhas e através destas calculou-se a Área Abaixo da Curva de Progresso da Doença (AACPD). Avaliou-se ainda o número de folhas, de flores e de afilhos. Observou-se que todas as misturas de fungicidas reduziram a incidência e a severidade da ferrugem, bem como retardaram o processo de senescência das folhas. As misturas piraclostrobina + epoxiconazol, trifloxistrobina + tebuconazol e picoxistrobina + ciproconazol propiciaram maior número de flores as plantas. O pó de rocha reduziu a severidade da doença, mas apresentou menor controle em relação as misturas de fungicidas, além disso, não apresentou incremento em nenhuma característica agronômica. A cultivar Daniela Esther Nass apresentou a menor incidência e severidade à ferrugem e a menor redução no número de folhas. A cultivar Daniela Esther Nass foi classificada como moderadamente resistente/resistente à ferrugem, a Cora Offer como moderadamente suscetível/suscetível, a Hariet e a Margaret Mee como suscetíveis, e a São Paulo como altamente suscetível. No ensaio in vitro foram avaliados os produtos azoxistrobina, picoxistrobina, piraclostrobina, trifloxistrobina, ciproconazol, epoxiconazol, tebuconazol e pó de rocha nas concentrações de 0; 0,01; 0,1; 1; 10 e 100 mg.L-1. Os produtos foram diluídos e misturados em meio de ágar-água e armazenadas a 4ºC durante 24 horas. Adicionou-se 0,5 mL de uma suspensão contendo uredosporos de P. hemerocallidis e a incubação foi a 22ºC, no escuro, durante 6 horas. As CI50 ficaram num intervalo entre 0,01 e 0,1 mg.L-1 para os fungicidas do grupo químico das estrobilurinas; entre 0,1 e 1 mg.L-1 para o tebuconazol; entre 1 e 10 mg.L-1 para o epoxiconazol; e entre 10 e 100 mg. L-1 para o ciproconazol e o pó de rocha. A CI100 foi observada apenas nos fungicidas azoxistrobina e picoxistrobina. Todos os fungicidas do grupo químico das estrobilurinas e o tebuconazol apresentaram elevada fungitoxicidade a uredosporos de P. hemerocallidis; e os fungicidas ciproconazol e epoxiconazol, bem como o pó de rocha apresentaram ação moderadamente fungitóxica a este patógeno

A ferrugem alaranjada da cana-de-açúcar, causada pelo fungo Puccinia kuehnii, apesar de ser centenária, foi detectada no Brasil apenas no final de 2009, após causar uma grande epidemia na Austrália em 2000. Pela recente detecção, não há estudos que comparam as populações brasileiras de P. kuehnii e a reação, em condições controladas, de importantes variedades de cana-de-açúcar ao patógeno. Assim, este trabalho analisou e comparou o comportamento de variedades de cana-de-açúcar inoculadas com seis diferentes populações de P. kuehnii coletadas em diferentes locais no Brasil, além de verificar a variabilidade patogênica e genética destas populações. Para isso, inoculou-se populações de P. kuehnii coletadas em Piracicaba (SP), Araras (SP), Ribeirão Preto (SP), Paranacity (PR), Nova Alvorada do Sul (MS) e Dourados (MS). As variedades de cana-deaçúcar utilizadas foram: SP89-1115, SP81-3250, RB85-5156, RB86-7515, RB92- 5211, RB96-6928, CTC 3, CTC 6, CTC 8, CTC 9, CTC 13, CTC 15 e CTC 18. Em todas as inoculações avaliaram-se os períodos de incubação e de latência da doença, a severidade, o número total de pústulas e a porcentagem de pústulas abertas. Além disso, as regiões ITS e IGS de todas as populações de P. kuehnii foram sequenciadas e comparadas entre si e com sequências do patógeno da Austrália, Papua Nova Guiné, Indonésia, Filipinas, Japão, China, Guatemala, Panamá, Jamaica, Costa Rica, Nicaraguá, México e Estados Unidos. Os resultados mostraram que a porcentagem de pústulas abertas é o melhor parâmetro para separar e classificar as variedades de cana-de-açúcar quanto ao grau de resistência ao patógeno. O período de incubação da doença variou de 7 a 10 dias e o período de latência, de 9 a 19 dias. As populações de P. kuehnii não constituem diferentes raças virulentas e a população coletada em Araras (SP) é uma raça mais agressiva do patógeno. Para as regiões IGS e ITS, as seis populações de P. kuehnii utilizadas apresentam sequências idênticas entre si e entre todas as sequências de P. kuehnii do continente americano depositadas no \"GenBank\". Para estas duas regiões, as populações utilizadas no trabalho diferem de sequências da Austrália, China, Filipinas, Havaí (EUA), Indonésia, Japão, Papua Nova Guiné e Samoa. A disseminação do patógeno além da Ásia e Austrália parece ter ocorrido após a epidemia da doença na Austrália em 2000. No entanto ainda não se sabe ao certo como o patógeno teria chegado à América em 2007 e à África em 2011. / Despite being a century disease, sugarcane orange rust, caused by the Puccinia kuehnii, was only reported in 2009 Brazil, after having caused an epidemic in Australia in 2000. Because it was recently detected in Brazil, there are no studies that compare P. kuehnii populations in Brazil and the reaction, under controlled conditions, of important sugarcane varieties to the pathogen. This study compared the performance of sugarcane varieties inoculated with six different populations of P. kuehnii collected in different sites in Brazil. We also studied the pathogenic and genetic variability of these pathogens populations. In order to carry out this study, P. kuehnii populations were collected in the municipalities of Piracicaba (SP), Araras (SP), Ribeirao Preto (SP), Paranacity (PR), Nova Alvorada do Sul (MS), and Dourados (MS). The sugarcane varieties used were: SP89-1115, SP81-3250, RB85- 5156, RB86-7515, RB92-5211 RB96-6928, CTC 3, CTC 6, CTC 8, CTC 9, CTC 13, CTC 15, and CTC 18. For all inoculations, we evaluated the incubation period, latent period, disease severity, total number of pustules, and percentage of open pustules. Furthermore, the ITS and IGS rDNA regions of all P. kuehnii populations were sequenced and compared with sequences from Australia, China, Costa Rica, Guatemala, Indonesia, Jamaica, Japan, Mexico, Nicaragua, Papua New Guinea, the Philippines, Panama, and the United States. The results showed that the percentage of open pustules is the best parameter to separate and classify the resistance of sugarcane varieties to the pathogen. The incubation period of the disease ranged from 7 to 10 days and the latent period from 9 to 19 days. There are no P. kuhenii virulent races and the population collected in Araras (SP) is a more aggressive race. For the IGS and ITS regions, the six P. kuehnii populations have identical sequences which were identical to all P. kuehnii sequences found in the American continent deposited at the GenBank accession. The P. kuehnii used in this study is different from populations found in Australia, China, Hawaii (USA), Indonesia, Japan, Papua New Guinea, the Philippines, and Samoa. The pathogen dissemination over Asia and Australia seems have occurred after the 2000 epidemic in Australia. However, it is unknown still how the pathogen reached America in 2007 and Africa in 2011.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Among the major diseases with potential for reducing the final yield of maize (Zea mays) are common rust (Puccinia sorghi), and Spot Blotch (Exserohilum turcicum). Seed companies offer hybrids with levels of disease resistance in the shoots, however, these have demonstrated the need for alternatives that help to maintain the low rate progress of diseases. Given the potential of triazole and strobilurin disease control in the culture and the need to integrate control practices, this study evaluated the effects of times and frequency of application of mixtures of triazoles + esbrubilurinas in hybrids with different levels of resistance. Through two experiments in 2007/2008 and 2009/2010 seasons, the experimental design was randomized block in factorial arrangement (3x4x3) with four replications. In a total of two experiments were used four hybrids; Pioneer 32R21, Pioneer 32R48 and 32R22 and Pioneer NK Penta; three fungicides, azoxystrobin + Ciproconazol (at 200 g/L + 80 g/L + Mineral oil 0.5% v / v) + Pyraclostrobin Epoxiconazol (at 133 g/L + 50 g/L), + picoxystrobin Ciproconazol (at 200 g/L + 80 g/L + Mineral oil 0.5% v / v) at doses of 0.3 L/ha, 0.75 L/ha and 0.3 L/ha respectively, plus a control without fungicide. The fungicides were applied in three application programs: at the time of seven leaves fully exposed, at tasseling and combination between the two periods, 7 sheets + tassel. The variables were the AUDPC for rust and leaf spots calculated from four disease severity, grain weight, grain yield and rate of SPAD. It was found that triazole + strobilurin have a suppressive effect on the AUDPC of disease. Also there was significant correlation between SPAD index, grain weight and grain yield, being indicative of a physiological effect that contributes to the grain weight and the final yield. / Entre as principais doenças com potencial de redução no rendimento final da cultura do milho (Zea mays) estão a ferrugem comum (Puccinia sorghi) e a helmintosporiose (Exserohilum turcicum). Empresas produtoras de sementes oferecem híbridos com níveis de resistência a doenças de parte aérea, no entanto, estes têm demonstrado necessidade de alternativas que auxiliem a manutenção da baixa taxa de progresso das doenças. Tendo em vista o potencial dos triazóis e das estrobilurinas no controle das doenças na cultura e a necessidade de integrar práticas de controle, este trabalho objetivou avaliar os efeitos das épocas e da frequência de aplicação de misturas de triazois + esbrubilurinas em híbridos simples com diferentes níveis de resistência. Foram realizados dois experimentos nas safras 2007/2008 e 2009/2010, dispostos em delineamento experimental de blocos ao acaso, arranjo fatorial (3x4x3), com quatro repetições. No total dos experimentos foram usados 4 híbridos; Pioneer 32R21, Pioneer 32R48 e NK Penta e Pioneer 32R22, três fungicidas; Azoxistrobina + Ciproconazole (200 g L-1 + 80 g L-1 + Óleo mineral 0,5% v/v), Piraclostrobina + Epoxiconazole (133 g L-1 + 50 g L-1), Picoxistrobina + Ciproconazole (200 g L-1 + 80 g L-1 + Óleo mineral 0,5% v/v), nas doses de 0.3 L ha-1, 0,75 L ha-1 e 0,3 L ha-1 respectivamente, mais um tratamento testemunha sem fungicida. Os fungicidas foram aplicados em três programas de aplicação: na época de 7 folhas totalmente expostas, no pendoamento e combinação entre as duas épocas, 7 folhas + pendoamento. As variáveis foram a AACPD para Ferrugem e Helmintosporiose, calculada a partir de quatro avaliações de severidade, peso de mil grãos, rendimento de grãos e índice de SPAD. Verificou-se que triazóis + estrobilurinas apresentam efeito supressor sobre a AACPD das doenças. Também observou-se significativa correlação entre índice de SPAD, peso de mil grãos e rendimento de grãos, sendo um indicativo de efeito fisiológico, com contribuição no peso de mil grãos e no rendimento final.