Atualmente a soja é uma das principais culturas de interesse econômico cultivadas no Brasil, sendo que o país configura como o segundo maior produtor da oleaginosa, ficando atrás apenas da produção obtida pelos Estados Unidos da América. Para se proteger essa alta produtividade e manter o Brasil em um cenário econômico competitivo, os produtores brasileiros utilizam diversos defensivos agrícolas. Destes, os fungicidas são principalmente utilizados de maneira preventiva, ou seja, sem a presença do patógeno alvo, isso ocorre principalemnte devido ao modo de ação dos princípios ativos disponíveis comercialmente na atualidade. Essa utilização preferencial de fungicidas de maneira preventiva, fez com que crescesce também o interesse pelo estudo dos efeitos, sejam eles positivos ou negativos, na fisiologia e bioquímica das plantas cultivadas. O presente experimento foi instalado em casa de vegetação no município de Holambra-SP, tendo por objetivo avaliar os efeitos fisiológicos e bioquímicos provocados pela aplicação dos fungicidas benzovindiflupir+azoxistrobina (STL+AZT) e protioconazol+trifloxistrobina (PTZ+TFS), na cultura da soja. O delineamento experimental foi o de blocos casualizados contando com seis repetições cada. Os tratamentos com fungicidas utilizados foram: [T1] controle (testemunha); [T2] plantas que receberam aplicação de STL+AZT (30 + 60 g de ingrediente ativo por hectare), com adição do adjuvante Nimbus a 600 ml por hectare, conforme recomendação do fabricante; [T3] plantas que receberam aplicação de PTZ+TFS (70 + 60 g de ingradiente ativo por hectare), com adição do adjuvante Aureo a 400 ml por hectare, confrome recomendação do fabricante. Foram realizadas duas aplicações, sendo a primeira 42 dias após a emergência das plantas, quando estas se encontravam na fase de início de florescimento (R1) e a segunda com 15 dias de intervalo da primeira. Os tratamentos foram avaliados atraves de trocas gasosas, fluorescência da clorofila a e enzimas do sistema antioxidante. Não foram observadas alterações significativas na eficiência quântica potencial (Fv/Fm) e eficiência quântica máxima (Fv\'/Fm\') do fotossistema II (PSII) para nenhum dos fungicidas testados. Entretanto observou-se que a utilização de PTZ+TFS reduziu de maneira significativa no rendimento quântico efetivo do PSII (ΦPSII), na taxa aparente de transporte de elétrons (ETR) e na proporção de centro de reações do PSII \"abertos\" (qP), sendo que reduções na condutância estomática (gs), transpiração (E), taxa de assimilação de CO2 (A) e na velocidade máxima de carboxilação da rubisco (Vcmáx) também foram observadas quando se aplicou esse fungicida. Além das reduções observadas, constatou-se também que esse fungicida provoca uma elevação da temperatura foliar (Tf). Além dessas alterações fotoquímicas, foi também observado um aumento da atividade das enzimas dismutase da superoxido (SOD) e glutationa redutase (GR). Em contrapartida a utilização de STL+AZT aumentou ΦPSII, ETR e qP, assim como elevação em gs, E, Vcmáx e consequentemente em A também foram observados. / Currently soybean is one of the main crops of economic interest cultivated in Brazil, and the country is the second largest producer of this oilseed, behind only of the production obtained by the United States of America. In order to protect this high productivity and keep Brazil in a competitive economic scenario, brazilian growers use several agricultural pesticides. Among these pesticides, fungicides are mainly used in a preventative way, that is, without the presence of the target pathogen, this is mainly due to the mode of action of the currently commercially available active ingredients. This preferential use of preventative fungicides has also increased the interest in studying the effects, whether positive or negative, on the physiology and biochemistry of cultivated plants. The present experiment was carried out in a greenhouse in the municipality of Holambra-SP, Brazil, to evaluate the physiological and biochemical effects of the fungicides benzovindiflupir + azoxystrobin (STL+AZT) and prothioconazole + trifloxystrobin (PTZ +TFS) on soybeans. The experimental design was a randomized block design with six replicates each. The treatments with fungicides used were: [T1] control (control); [T2] plants receiving STL + AZT (30 + 60 g of active ingredient per hectare), with addition of the Nimbus adjuvant at 600 ml per hectare, according to the manufacturer\'s recommendation; [T3] plants receiving PTZ + TFS (70 + 60 g active in per hectare), with addition of the Aureo adjuvant at 400 ml per hectare, according to the manufacturer\'s recommendation. Two applications were performed, the first was 42 days after the emergence of the plants when they were in the begning of flowering (R1) and the second after 15 days of the first one. The treatments were evaluated through gas exchange, chlorophyll a fluorescence and antioxidant system enzymes. No significant changes were observed in the potential quantum efficiency (Fv/Fm) and the maximum quantum efficiency (Fv\'/Fm\') of photosystem II (PSII) for none of the fungicides tested. However, it was observed that the use of PTZ+TFS significantly reduced the effective quantum yield of PSII (ΦPSII), the apparent electron transport rate (ETR) , and reductions in stomatal conductance (gs), transpiration (E), CO2 assimilation rate (A) and the maximum rate of carboxylation of rubisco (Vcmáx) were also observed when applying this fungicide. In addition to the observed reductions, it was also verified that this fungicide causes a rise in leaf temperature (Tf). In addition to these photochemical alterations, an increased activity of the enzymes superoxide dismutase (SOD) and glutathione reductase (GR) was also observed. In contrast, the use of STL + AZT increased ΦPSII, ETR and qP, as well as elevation in gs, E, Vcmax and consequently in A were also observed.

<p>Frogeye leaf spot (FLS) is a foliar disease in soybean (<i>Glycine max</i> (L.) Merr.) caused by the fungal pathogen <i>Cercospora sojina</i> Hara. FLS is commonly found in hot and humid regions of the southern United States but has become more common in the North Central states. Foliar application of quinone outside inhibitor (QoI) fungicides has been one of the major tools used in the management of this disease, but QoI-resistant <i>C. sojina</i> isolates have been already confirmed in 21 states, including Indiana. We hypothesized that resistant populations of <i>C. sojina</i> to QoIs fungicides are widespread in Indiana and that sexual reproduction is occurring within <i>C. sojina</i> populations, likely contributing to the dissemination of fungicide resistance. The main objectives of this research were to determine the distribution of QoI-resistant <i>C. sojina</i> isolates on soybean from Indiana and to evaluate <i>C. sojina </i>populations for potential sexual reproduction. In the summer of 2019 and 2020, 406 isolates of <i>C. sojina </i>were collected from 32 counties across Indiana and screened for QoI-fungicide resistance using a PCR-RFLP method. An i<i>n vitro </i>fungicide sensitivity test was performed on a subset of isolates to evaluate the sensitivity of <i>C. sojina</i> isolates to azoxystrobin, pyraclostrobin, picoxystrobin, and prothioconazole. A discriminatory dose of picoxystrobin (QoI) and prothioconazole (demethylation inhibitor- DMI) were established at 1 μg/ml and 10 μg/ml, respectively, to distinguish between QoI-resistant and sensitive isolates and to identify a reduction in sensitivity to DMI fungicides, respectively. Discriminatory doses were estimated by testing five concentrations (0.001, 0.01, 0.1, 1, and 10 µg/ml) of each fungicide. QoI-resistant isolates were found in 29 out of the 32 counties. Two hundred and fifty-one (251) out of the 406 isolates (61.8%) were confirmed as QoI-resistant. Partial nucleotide sequences of the cyt <i>b</i> gene from four resistant and four sensitive <i>C. sojina</i> isolates corroborated the presence and absence of the G143A mutation, respectively. Results from the sensitivity assays with azoxystrobin and pyraclostrobin discriminatory doses supported the findings from the PCR-RFLP assay as all QoI-resistant mutants were inhibited less than 50% when exposed to these doses. Results from this study indicated that QoI-resistant <i>C. sojina</i> isolates are spread throughout Indiana and that prothioconazole (DMI) could be a potential supplemental or alternative fungicide to control FLS. Additionally, mating type distribution was determined in 43 <i>C. sojina</i> populations for assessment of potential sexual reproduction. Fifteen (15) populations did not deviate significantly from the expected 1:1 ratio, suggesting potential for cryptic sexual reproduction in these populations, but further research on genetic diversity is required to verify these results. </p> <p> </p>

Sour rot of tomatoes, caused by Geotrichum candidum, occurs in the field and postharvest settings regularly, although postharvest losses are severe only in some years on the Eastern Shore of Virginia (ESV) and other tomato production regions. Fungicide products and cultural control methods are tested for efficacy utilizing a traditional wounding technique that does not properly reflect natural sour rot infections. A new inoculation technique was optimized for G. candidum using negative pressure to infiltrate the tomato stem scar with pathogenic spores. This new method creates consistently high rates of infection and more successfully creates infections in mature green and breaker fruit. The population of G. candidum on the Eastern Shore of VA (ESV) was characterized using multilocus sequencing technique. The resulting phylogenetic tree defines four distinct groups, including two with uncommon loci that distinguish them from the majority of the population. Thirty-seven G. candidum isolates were inoculated to media amended with ten fungicides and antimicrobial compounds commonly used in tomato production and postharvest treatments. Propiconazole and tebuconazole completely inhibited growth of all colonies. Cultivar trials were conducted to determine if resistance or tolerance to G. candidum occurs. Ten commonly grown round and Roma cultivars on the ESV were similarly susceptible to G. candidum, even at low inoculum levels. Field and postharvest surveys of sour rot on tomato fruit attempted to correlate disease incidence with weather conditions in order to better understand the cause of sporadic infection. Few patterns were seen consistently throughout harvest periods and years. Rainfall was positively correlated with disease 2-3 days before surveys and temperature was negatively correlated with disease 5-7 days before surveys. No in-field weather conditions were correlated with postharvest disease incidence. Greenhouse trials were conducted to assess the influence of water congested tomato fruit on susceptibility to sour rot. Tomato plants were exposed to water inundation to mimic rainfall and varying levels of irrigation, both in order to congest tomato fruit. Though water congestion was achieved, tomato fruit were equally susceptible to sour rot infections. / Ph. D.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The soybean cultivars reaction to the causal agent of asian rust (Phakopsora pachyrhizi Syd. & P. Syd.) and mixing responsiveness of DeMethylation Inhibitor (DMI) and Quinone outsite Inhibitor (QoI) fungicides are important factors to be determined for the management of the pathogen. The activity of these fungicides sprayed on the leaves depends on the amount that it reaches the biochemical action site and the compound efficacy. Thus, the proportion of leaf deposit that it enters the leaf, the rate of entry and dissipation in the leaf tissue are determinant for the activity and diseases residual control after the occurrence of a wash. The chapter I objective was to evaluate the reaction of fifteen soybean cultivars to the causal agent of soybean rust and the responsiveness mixing Active Ingredients (AI) epoxiconazole (EPOX) + pyraclostrobin (PYR) and prothioconazole (PROT) + trifloxystrobin (TRIFL). The parameters evaluated were the latency period, residual control, progression and the Area Under the Disease Progress Curve (AUDPC). In the Chapter II, the EPOX and PYR persistence associated with mancozeb (Mz) was determined under greenhouse conditions in two commercial soybean cultivars. Artificial washes were used to determine the concentration of the remaining AI on the foliar tissues after the spraying. For this purpose, the leaves were washed with water at 0.17, 1, 2, 4, 48, 96, 192 h after the fungicide spraying and immediately collected. The EPOX and PYR concentrations were also determined on leaves at 12, 16 and 20 days after spraying. Through the high performance liquid chromatographic analysis and the experimental design, it was possible to measure the EPOX and PYR concentrations penetrated and it dissipated in whole-plant leaves, associated or not to mancozeb. The influence of the interaction between leaflets age and cultivars in the EPOX and PYR concentration on leaves after the spraying was also evaluated. Due to the scarcity of detailed studies on the performance of site-specific fungicides associated with multisite fungicides, in the Chapter III was investigated the asian rust severity and the residual control of the EPOX and PYR mixture associated mancozeb. In the chapter I, it was verified that the responsiveness of DMI and QoI mixtures to P. pachyrhizi is different among the cultivars. The greatest residual control of the pathogen in the different cultivars was through of the PROT + TRIFL spraying. In the chapter II, it was verified that mancozeb influences the persistence of DMI and QoI fungicides in soybean cultivars. The EPOX penetration rate in the cultivars was faster without the association of mancozeb to the fungicide (DMI + QoI). The association of mancozeb to the fungicide (DMI + QoI) reduced the penetration rate of PYR in DM 6563 RSF IPRO cultivar. The PYR concentration in leaves of the two cultivars at 48 h after spraying was similar by the association or not of the fungicide with mancozeb. The cultivars showed different AI penetration rates in leaves. It was observed a reduction of the AI concentrations in the foliar tissues after 48 h of the spraying, evidencing a dissipation process of the AI, after this time. The association of mancozeb to the fungicide (DMI + QoI) only influenced the persistence of PYR at 16 days after spraying in DM 6563 RSF IPRO cultivar. The dissipation rate of PYR is different between the leaves cultivars. The penetration of the AI is greater in younger leaves than in older leaves. The concentrations of PYR in soybean leaves were higher than EPOX at different sampling times, after the fungicide spraying. In the chapter III, it was verified that mancozeb associated with EPOX + PYR in spray solution increases the residual control of P. pachyrhizi and it reduces the disease severity. / A reação de cultivares de soja ao agente causal da ferrugem asiática (Phakopsora pachyrhizi Syd. & P. Syd.) e responsividade de mistura de fungicidas Inibidores da DesMetilação (IDM) e Inibidores da Quinona oxidase (IQo) são importantes fatores a serem determinados para o manejo do patógeno. A atividade desses fungicidas pulverizados na folha depende da quantidade que atinge o local de ação bioquímico e da eficácia do composto. Assim, a proporção do depósito foliar que entra na folha, a taxa de entrada e sua dissipação no tecido foliar são determinantes para a atividade e residual no controle das doenças após a ocorrência de uma lavagem. O capítulo I teve como objetivo avaliar a reação de quinze cultivares de soja ao agente causal da ferrugem asiática e responsividade da mistura dos ingredientes ativos (IA) epoxiconazol (EPOX) + piraclostrobina (PIR) e protioconazol (PROT) + trifloxistrobina (TRIFL). Os parâmetros avaliados foram o período de latência, residual de controle, progresso e a área abaixo da curva de progresso da doença (AACPD). No capítulo II, a persistência de EPOX e PIR associadas com mancozebe (Mz) em duas cultivares comerciais de soja foi determinada em condições de casa de vegetação. Lavagens artificiais foram utilizadas para determinar a concentração dos IA remanescentes nos tecidos foliares após a pulverização. Para isso, as folhas foram lavadas com água 0,17, 1, 2, 4, 48, 96, 192 h após a pulverização do fungicida e imediatamente coletadas. As concentrações de EPOX e PIR também foram determinadas em folhas aos 12, 16 e 20 dias após a pulverização. Através da análise cromatográfica liquida de alta eficiência e do desenho experimental foi possível mensurar as concentrações de EPOX e PIR penetradas e dissipadas em folhas de planta inteira, associadas ou não à mancozebe. A influência da interação de idade de trifólios e cultivares sobre as concentrações de EPOX e PIR após a pulverização também foi avaliada. Devido à escassez de estudos detalhados sobre o desempenho dos fungicidas sítio-específicos associados aos fungicidas multissítios, no capítulo III foi investigado a severidade de ferrugem asiática e o residual de controle da mistura de EPOX e PIR associada ao mancozebe. No capítulo I foi verificado que a responsividade de misturas de IDM e IQo à P. pachyrhizi é distinta entre as cultivares. O maior residual de controle do patógeno nas diferentes cultivares foi através da pulverização de PROT + TRIFL. No capítulo II foi verificado que mancozebe influencia a persistência de fungicidas IDM e IQo em cultivares de soja. A taxa de penetração de EPOX nas cultivares foi mais rápida sem a associação de mancozebe ao fungicida (IDM + IQo). A associação de mancozebe ao fungicida (IDM + IQo) reduziu a taxa de penetração de PIR na cultivar DM 6563 RSF IPRO. A concentração de PIR em folhas das duas cultivares às 48 h após a pulverização foi semelhante pela associação ou não do fungicida com mancozebe. As cultivares apresentaram diferentes taxas de penetração dos IA em folhas. Observou-se uma redução das concentrações dos IA nos tecidos foliares após 48 h da pulverização, evidenciando um processo de dissipação dos IA, após esse tempo. A associação de mancozebe ao fungicida (IDM + IQo) somente influenciou a persistência de PIR aos 16 dias após a pulverização na cultivar DM 6563 RSF IPRO. A taxa de dissipação de PIR em folhas é diferente entre as cultivares. A penetração dos IA é maior em folhas mais novas do que em folhas velhas. As concentrações de PIR em folhas de soja foram superiores que EPOX nos diferentes tempos de coletas, após a pulverização do fungicida. No capítulo III foi verificado que mancozebe associado com EPOX + PIR em calda de pulverização aumenta o residual de controle de P. pachyrhizi e reduz a severidade da doença.