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During the different stages of its development, wheat is possible infected by many plant pathogens. One of the most common is Zymoseptoria tritici, the causal agent of the disease called Septoria Tritici Blotch (STB). The most common strategy in the Z. tritici disease management is treating plants with fungicides. Unfortunately, this plant pathogen as many others evolved resistance towards some of the most commonly used fungicidal classes. The aim of this study was to detect the resistance of Z. tritici to strobilurin fungicide azoxystrobin. During the April 2017, around 300 plant samples were collected from 11 geographical regions in the Czech Republic. From those plant samples, 52 monosporic Z. tritici isolates were obtained and tested for the presence of the resistance. The fungicide resistance was measured and detected by laboratory agar dilution biotest and molecular methods as a CAPS marker (Cleaved Amplified Polymorphic Sequences) and qPCR (Quantitative Polymerase Chain Reaction). By agar dilution biotest, resistance to azoxystrobin was confirmed in 54% of total 52 analysed isolates. By CAPS marker analysis, the presence of G143A mutant allele of the mitochondrial cytochrome b gene, linked to the fungicide resistance, was confirmed in all selected isolates marked as resistant in the biotest. The DNA of one infected leaf sample collected from the field marked as 17Zt212 was isolated and tested by the qPCR method. In the field sample (17Zt212), the 4% of the Z. tritici population was found to be resistant to fungicide azoxystrobin.

Made available in DSpace on 2017-07-25T19:29:48Z (GMT). No. of bitstreams: 1 CarlosASchipanski.pdf: 743340 bytes, checksum: 82ebbcfc2be8edf6e9fe39a210220464 (MD5) Previous issue date: 2011-04-29 / The aim of this study was to evaluate the effects of fungicides and resistance inducer acibenzolar-S-methyl applied as seed treatment associated with foliar applications sprays of fungicides in corn on the control of common rust of corn, caused by the fungus Puccinia sorghi. To achieve this objective to experiments were carried out. On the first experiment, the P. sorghi was inoculated in the laboratory and the effects of the following fungicides were evaluated: fluquinconazol (10 g ia/60.000 seed 1), flutriafol (3 g ai), azoxystrobin (15 g ia), carbendazin ( 10 g ia), carbendazin + thiram (9 + 21 g ia), carboxin + thiram (12 + 12 g ia), fludioxonil + metalaxyl - m (3 + 7.5 g ia) fludioxonil + mefenoxam + thiabendazole (1 + 6 +0.8 g ia), difenoconazole (6 g ia), acibenzolar-s-methyl (12.5 g ia) and thiophanate methyl +fluazinam (14 + 2.1 g ia). After inoculation, the plants were assessed to count the number of lesions at 7, 14 and 21 days after inoculation (DAI), fresh and dry weight, root length and shoot at 21 DAI. After the assessments it was observed that the fungicides azoxystrobin and fluquinconazol had the highest levels of control of the disease, and the levels of control from the other products tested varied from 23.7 to 49.9% control. No effects of these products were observed on the green and dry weight, length of roots and shoots of maize plants. In the second experiment conducted under field conditions, the effects of the following fungicides were evaluated: fluquinconazol (10 g ia/60.000 seed-1), azoxystrobin (15 g ia) carbendazin (10 g ia) in seed treatment in combination with foliar fungicides sprays. At the V4 stage, the fungicides azoxystrobin (60 g ai ha-1) and azoxystrobin + cyproconazole (60 +24 g ai ha-1) were used and at the V9 stage azoxystrobin + cyproconazole (70 + 28 g ai ha-1). The treatments were combined in a 4x3x2 factorial structure, with 24 treatments and four replications. The rust severity assessments levels started after sowing and the plumule leaf emergence, considering as 1 (full emergence of the plumule leaf above ground), 7, 14, 21, 28, 35 , 42, 49, 56 days after emergence (DAE), severity of common rust at the stages VT, R3 and R5, plant height at 21 and 28 DAE, incidence of stalk rot and mold grains, the 1000 grain weight, final stand and productivity. A significant effect of the fungicides azoxystrobin, fluquinconazol and carbendazin as seed treatment on reducing the severity of common rust of corn until 56 DAE. The treatment with azoxystrobin presented a better result. However, the effect of the seed treatment was suppressed at the 28 DAE when associated with the foliar sprays. The foliar sprays in V4 stage reduced the severity of the common rust and no differences between the fungicides azoxystrobin and azoxystrobin + cyproconazole were oberved. The spray with azoxystrobin + cyproconazole in V9 stage also contributed to the decrease of the disease severity. A greater reduction of disease severity was observed when the sprays were done at the V4 and V9 stages. No treatment effect was observed on the incidence of stalk rot, grain molds, final stand, southern rust and gray leaf spot severity. Only the carbendazin fungicide seed treatment presented a significant effect in relation to the yield. / O objetivo deste trabalho foi avaliar os efeitos dos fungicidas e do indutor de resistência acibenzolar-S-methyl aplicados via tratamento de sementes e posteriormente da associação dos fungicidas nas sementes às aplicações de fungicidas foliares na cultura do milho sobre o controle da ferrugem comum, causada pelo fungo Puccinia sorghi. Para cumprir tal objetivo foram montados dois experimentos. No primeiro, a P. sorghi foi inoculada em condições de laboratório e foram testados o efeito do tratamento de sementes com os fungicidas fluquinconazole (10 g i.a./60.000 sementes-1), flutriafol (3 g i.a.), azoxystrobin (15 g i.a.), carbendazin (10 g i.a.), carbendazin + thiram (9 + 21 g i.a.), carboxin + thiram (12 + 12 g i.a.), fludioxonil + metalaxyl – m (7,5 + 3 g i.a.), fludioxonil + mefenoxam + thiabendazole (1 +0,8 + 6 g i.a.), difenoconazole (6 g i.a.), thiophanate methyl + fluazinam (14 + 2,1 g i.a.) e do indutor de resistência acibenzolar-S-methyl (12,5 g i.a.). Após a inoculação das plantas foram realizadas as avaliações de contagem de número de lesões aos 7, 14 e 21 dias após a inoculação (DAI), peso verde, peso seco e comprimento de raízes e parte aérea aos 21 DAI. Foi observado que os fungicidas azoxystrobin e fluquinconazole apresentaram os maiores níveis de controle da doença, e os demais produtos testados apresentaram valores entre 23,7 49,9% de controle. Não foi observado efeito dos produtos sobre o peso verde, peso seco e comprimento tanto de raízes quanto de parte aérea das plantas de milho. No segundo experimento, realizado em condições de campo, foram avaliados a eficácia dos fungicidas fluquinconazole (10 g i.a./60.000 sementes-1), azoxystrobin (15 g i.a.) e carbendazin (10 g i.a.) via tratamento de sementes em associação com aplicações foliares de fungicidas, sendo no estádio V4 os fungicidas azoxystrobin (60 g i.a. ha-1) e azoxystrobin + ciproconazole (60 +24 g i.a. ha-1) e no estádio V9 os fungicidas azoxystrobin + ciproconazole (70 +28 g i.a. ha-1). Os tratamentos foram combinados em um esquema fatorial 4x3x2, totalizando 24 tratamentos com 4 repetições. Após a semeadura, aguardou-se a emergência da folha plumular e iniciaram-se as avaliações de severidade (%) de ferrugem comum do milho aos 1 (emergência total da folha plumular acima do solo), 7, 14, 21, 28, 35, 42, 49, 56 dias após a emergência (DAE), severidade de ferrugem comum nos estádios VT, R3 e R5, altura de plantas aos 21 e 28 DAE, incidência de colmos doentes e grãos ardidos, peso de 1000 grãos, estande final e produtividade. Foi observado efeito dos fungicidas azoxystrobin, fluquinconazole e carbendazin via tratamento de semente sobre a redução da severidade de ferrugem comum do milho até os 56 DAE e o azoxystrobin foi superior aos demais. No entanto, quando associado às aplicações foliares o efeito dos fungicidas via tratamento de sementes foi suprimido aos 28 DAE. As aplicações foliares em V4 reduziram a severidade de ferrugem comum e não se observou diferença entre os fungicidas azoxystrobin e azoxystrobin ciproconazole. A aplicação de azoxystrobin ciproconazole em V9 também contribuiu para a redução da severidade da doença e quando ambas as aplicações foram combinadas notou-se uma redução ainda maior. Não foi observado efeito dos tratamentos sobre a incidência de colmos doentes e grãos ardidos, estande final, severidade de ferrugem polissora e cercosporiose. Em relação à produtividade, somente o fungicida carbendazin via tratamento de sementes apresentou resposta significativa.

Azoxystrobin (AZY), a systemic broad-spectrum fungicide, is applied on crops to control soil-borne pathogenic fungi. This study aimed to determine the effects of AZY on non-target plant species and Glomus intraradices Schenck & Smith, an arbuscular mycorrhizal fungus (AMF) associated with plants' roots. We hypothesized that AZY negatively affects AMF viability; and that, if the plants were dependent on this symbiosis, AZY exerts an indirect detrimental effect on plant growth. To test this, three mycotrophic (Phalaris arundinacea L., Solidago canadense L., Geum canadense Jacq.) and one non-mycotrophic (Chenopodium album L.) native plant species were subjected to five AZY doses with or without AMF. Plants were grown for 60 days in a greenhouse, in individual pots, (4 plants X 2 AMF X 5 AZY X 6 replicates), and mesocosms (1 mes. X 2 AMF X 5 AZY X 6 replicates), and harvested 30 days after spraying, and dry mass was taken. Fresh root samples were used for microscopic assessment of AMF colonization. The results from the individual pot experiment show that the effects of AZY on biomass varied across plant species. AZY led to a significant increase in shoot and root mass of P. arundinacea, and a decrease in shoot mass of AMF inoculated G. canadense. The presence of AMF resulted in a significant increase in root and shoot mass of P. arundinacea, and an increase in root mass of S. canadense and shoot mass of C. album. In the mesocosm experiment AZY did not have a significant effect on the measured parameters, although the presence of AMF significantly increased root, shoot, and total dry mass of G. canadense and P. arundinacea. Conversely, AMF significantly decreased shoot and total dry mass of S. canadense. The results suggest that both direct and indirect effects should be taken into account when assessing the impact of pesticides on non-target plant species.

Azoxystrobin (AZY), a systemic broad-spectrum fungicide, is applied on crops to control soil-borne pathogenic fungi. This study aimed to determine the effects of AZY on non-target plant species and Glomus intraradices Schenck & Smith, an arbuscular mycorrhizal fungus (AMF) associated with plants' roots. We hypothesized that AZY negatively affects AMF viability; and that, if the plants were dependent on this symbiosis, AZY exerts an indirect detrimental effect on plant growth. To test this, three mycotrophic (Phalaris arundinacea L., Solidago canadense L., Geum canadense Jacq.) and one non-mycotrophic (Chenopodium album L.) native plant species were subjected to five AZY doses with or without AMF. Plants were grown for 60 days in a greenhouse, in individual pots, (4 plants X 2 AMF X 5 AZY X 6 replicates), and mesocosms (1 mes. X 2 AMF X 5 AZY X 6 replicates), and harvested 30 days after spraying, and dry mass was taken. Fresh root samples were used for microscopic assessment of AMF colonization. The results from the individual pot experiment show that the effects of AZY on biomass varied across plant species. AZY led to a significant increase in shoot and root mass of P. arundinacea, and a decrease in shoot mass of AMF inoculated G. canadense. The presence of AMF resulted in a significant increase in root and shoot mass of P. arundinacea, and an increase in root mass of S. canadense and shoot mass of C. album. In the mesocosm experiment AZY did not have a significant effect on the measured parameters, although the presence of AMF significantly increased root, shoot, and total dry mass of G. canadense and P. arundinacea. Conversely, AMF significantly decreased shoot and total dry mass of S. canadense. The results suggest that both direct and indirect effects should be taken into account when assessing the impact of pesticides on non-target plant species.

Azoxystrobin (AZY), a systemic broad-spectrum fungicide, is applied on crops to control soil-borne pathogenic fungi. This study aimed to determine the effects of AZY on non-target plant species and Glomus intraradices Schenck & Smith, an arbuscular mycorrhizal fungus (AMF) associated with plants' roots. We hypothesized that AZY negatively affects AMF viability; and that, if the plants were dependent on this symbiosis, AZY exerts an indirect detrimental effect on plant growth. To test this, three mycotrophic (Phalaris arundinacea L., Solidago canadense L., Geum canadense Jacq.) and one non-mycotrophic (Chenopodium album L.) native plant species were subjected to five AZY doses with or without AMF. Plants were grown for 60 days in a greenhouse, in individual pots, (4 plants X 2 AMF X 5 AZY X 6 replicates), and mesocosms (1 mes. X 2 AMF X 5 AZY X 6 replicates), and harvested 30 days after spraying, and dry mass was taken. Fresh root samples were used for microscopic assessment of AMF colonization. The results from the individual pot experiment show that the effects of AZY on biomass varied across plant species. AZY led to a significant increase in shoot and root mass of P. arundinacea, and a decrease in shoot mass of AMF inoculated G. canadense. The presence of AMF resulted in a significant increase in root and shoot mass of P. arundinacea, and an increase in root mass of S. canadense and shoot mass of C. album. In the mesocosm experiment AZY did not have a significant effect on the measured parameters, although the presence of AMF significantly increased root, shoot, and total dry mass of G. canadense and P. arundinacea. Conversely, AMF significantly decreased shoot and total dry mass of S. canadense. The results suggest that both direct and indirect effects should be taken into account when assessing the impact of pesticides on non-target plant species.

Gaeumannomyces tritici is a soil-borne, highly destructive, wheat root pathogen, causing take-all disease. Some modern, elite, winter wheat cultivars possess a genetic trait promoting low take-all inoculum build-up (LowTAB). This leads to reduced disease if wheat is grown in the same field the next year. This PhD aimed to test if genetics (LowTAB) and chemistry will individually or synergistically influence take-all fungal inoculum build-up in first wheats as methods to control second wheat take-all disease. The underlying mechanism, epidemiology, agronomy and genetics of the TAB (take-all build-up) trait in eight first wheat field trials was investigated. This identified two minor QTLs conferring the LowTAB trait, in a doubled haploid mapping population. This PhD also confirms the highly complex cultivar-year-field interactions that underpin this trait. Root phenotyping experiments in the field and laboratory highlight that the TAB trait is not likely to be the result of root system architecture variation. Future field trials are planned to confirm the QTLs identified and to test for links between TAB and root-soil-microbial interactions. The effect of foliar applied chemistry (fungicide: Amistar, active ingredient: azoxystrobin and plant growth regulator: Moddus, a.i. trinexapac-ethyl) combined with genetics (TAB) on first wheat take-all inoculum build-up and second wheat disease was investigated. To complement this, laboratory screens were performed checking for common target site mutations to the azoxystrobin fungicide, in new and historic G. tritici isolates. For the first time, legacy effects of first wheat foliar chemistry on second wheat disease were identified, however no synergy with genetics were found. Early first wheat Amistar sprays reduced second wheat take-all disease, whilst later sprays and plant growth regulator, Moddus; had no effect. However, first wheat inoculum reduction by Amistar, could not be directly linked to the second wheat disease outbreaks observed. No evidence of fungicide resistance was found in 40 UK isolates, thus the varied efficacy of Amistar is linked to soil dose rate at the different application times. The collective PhD findings of the effect of first wheat chemistry and genetics make a significant contribution to the control of take-all disease in commercial second wheat crops.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-17T14:46:49Z No. of bitstreams: 1 Cicero Nicolini.pdf: 204101 bytes, checksum: 7157eb0dfbcf608b64b0ae9bbbaf5c05 (MD5) / Made available in DSpace on 2017-02-17T14:46:49Z (GMT). No. of bitstreams: 1 Cicero Nicolini.pdf: 204101 bytes, checksum: 7157eb0dfbcf608b64b0ae9bbbaf5c05 (MD5) Previous issue date: 2008-03-03 / The Alternaria black spot is one of the most common and destructive diseases of brassica species. This disease can be caused by several species of Alternaria, although A. brassicicola is predominant species in both conventional and organic crops in Brazil. Since commercial cultivars of brassica with acceptable levels of disease resistance are not available, the disease control in conventional production system is based on the fungicide applications, while in the organic production system the disease control on relays on cultural methods. The objective of this study is to assess the sensitivity of 112 isolates of A. brassicicola to fungicide groups: benzimidazoles (carbendazim), dicarboximides (iprodione), triazoles (tebuconazole) and strobilurines (azoxystrobin). The isolates were evaluated in vitro to obtain the concentration capable of inhibiting 50% of the mycelial growth (CL50) and separated in four classes depending on the sensibility to the tested fungicides. All the isolated of A. brassicicola were sensitive the iprodione, with CL50 values below to 0.1 mg i.a./L. Most of the isolates originating from conventional (92.9%) and organic (96.4%) were middling resistant the azoxystrobin, while an isolated (CFM-576) was highly resistant. In relation to tebuconazole, only isolated sensitive (42.9%) and lightly resistant (57.1%) were observed. There was nosignificant difference between the isolates of A. brassicicola originated either from conventional or organic systems and brassica types regarding the levels of sensitivity to the fungicides. / A alternariose é uma das doenças foliares mais comuns e destrutivas das brássicas, podendo ser causada por várias espécies de Alternaria, embora A. brassicicola seja a espécie predominante em plantios convencionais e orgânicos no Brasil. Como inexistem cultivares comerciais de brássicas com níveis aceitáveis de resistência à doença, no sistema de produção convencional o controle da doença se baseia na aplicação de fungicidas, enquanto no sistema orgânico em métodos culturais. O presente trabalho teve como objetivo avaliar a sensibilidade de 112 isolados de A. brassicicola oriundos de cultivos convencionais e orgânicos de brássicas a fungicidas dos grupos dicarboximidas (iprodione), triazóis (tebuconazole) e estrobilurinas (azoxystrobin). Os isolados foram avaliados in vitro visando obter a concentração capaz de inibir 50% do crescimento micelial (CL50) e separados em quatro classes dependendo da sua sensibilidade aos fungicidas testados. Todos os isolados de A. brassicicola foram sensíveis a iprodione, com valores de CL50 inferiores a 0,1 mg i.a./L. A maioria dos isolados oriundos de cultivos convencionais (92,9%) e orgânicos (96,4%) se comportou como medianamente resistente a azoxystrobin, enquanto um isolado (CFM-576) foi altamente resistente. Em relação a tebuconazole, foram constatados somente isolados sensíveis (42,9%) e ligeiramente resistentes (57,1%). Não foi encontrada diferença significativa quanto à sensibilidade aos fungicidas testados entre os isolados de A. brassicicola oriundos de cultivos convencionais e orgânicos, bem como, coletados de diferentes tipos de brássicas.

<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.