Toxicological impact of strobilurin fungicides on human and environmental health: a literature review.

Fungicides are specifically used for controlling fungal infections. Strobilurins, a class of fungicides originating from the mushroom Strobilurus tenacellus, act on the fungal mitochondrial respiratory chain, interrupting the ATP cycle and causing oxidative stress. Although strobilurins are little soluble in water, they have been detected in water samples (such as rainwater and drinking water), indoor dust, and sediments, and they can bioaccumulate in aquatic organisms. Strobilurins are usually absorbed orally and are mainly eliminated via the bile/fecal route and urine, but information about their metabolites is lacking. Strobilurins have low mammalian toxicity; however, they exert severe toxic effects on aquatic organisms. Mitochondrial dysfunction and oxidative stress are the main mechanisms related to the genotoxic damage elicited by toxic compounds, such as strobilurins. These mechanisms alter genes and cause other dysfunctions, including hormonal, cardiac, neurological, and immunological impairment. Despite limitations, we have been able to compile literature information about strobilurins. Many studies have dealt with their toxic effects, but further investigations are needed to clarify their cellular and underlying mechanisms, which will help to find ways to minimize the harmful effects of these compounds.

Characterization of extracellular secondary metabolites in Oudemansiella canarii BRM-044600 displaying antifungal activity against the phytopathogen Sclerotinia sclerotiorum.

White mold disease, caused by the phytopathogen Sclerotinia sclerotiorum, provokes severe productivity losses in several economically important crops. Biocontrol agents, especially antagonist filamentous fungi, are environmentally friendly alternatives to the chemical fungicides used in white mold management. The objective of this study was to screen for basidiomycete fungi capable of inhibiting S. sclerotiorum and investigate their bioactive metabolites responsible for antifungal activities. Two out of 17 tested basidiomycete isolates inhibited the mycelial growth of S. sclerotiorum in pair culture experiments on agar plates, namely Oudemansiella canarii BRM-044600 and Laetisaria arvalis ATCC52088. O. canarii BRM-044600 liquid culture filtrate exhibited the greatest antifungal activity and was selected for further investigation. UHPLC-MS analysis suggests that six putative strobilurins, including strobilurin A and/or stereoisomers of this compound (m/z 259.1299, [M + H]+) and three putative strobilurins with m/z 257.1184 ([M + H]+) are likely responsible for the antifungal activity observed in the culture filtrate. For the first time, this work demonstrated the potential of O. canarii for white mold biocontrol and strobilurin production.

Simultaneous determination of strobilurin fungicides residues in bean samples by HPLC-UV-AD using boron-doped diamond electrode.

The aim of this paper was the development of a method for the determination of six strobilurins (fungicides) using boron-doped diamond (BDD) electrode with amperometric detection (AD) homemade coupled to high performance liquid chromatography (HPLC/UV-Vis). HPLC separation of fungicides was performed in a C18 reverse phase column using both UV and AD detectors at 200 mn and 1.9 V, respectively. The linear range for each strobilurin was from 5 to 15 mg L-1 and the correlation coefficients for all the compounds were above 0.997. Both detectors presented adequate detectability (LOD ranging from 1.33 to 1.57 µg kg-1) respecting the limits pre-established by regulatory agencies. The method was validated presenting good values of recovery and accuracy. In the spiked samples the recoveries ranged from 61.6% (trifloxystrobin) to 98.8% (azoxystrobin) for UV and 62.3% (trifloxystrobin) to 95.2% (azoxystrobin) for AD. In blanks spikes the recovery varied from 77.8% (picoxystrobin) to 88.4% (kresoxim-methyl) for UV and 76.7% (picoxystrobin) to 87.1% (dimoxystrobin) for AD. The method showed good precision (RSD < 10%). The results obtained by amperometric and UV detections were statistically comparable. Seven bean samples were analyzed to detect fungicide residues.

Reduced sensitivity of azoxystrobin and thiophanate-methyl resistance in Lasiodiplodia theobromae from papaya.

Stem-end rot caused by Lasiodiplodia theobromae is one of the most devastating diseases of papaya in northeastern Brazil. It is most effectively controlled by applications of fungicides, including site-specific fungicides at risk for resistance development. This study investigated the molecular mechanisms of reduced sensitivity to the QoI fungicide azoxystrobin and resistance to the MBC fungicide thiophanate-methyl in L. theobromae from Brazilian orchards. The EC50 values for azoxystrobin in sixty-four isolates ranged from 0.36 µg/ml to 364.24 µg/ml and the frequency distribution of EC50 values formed a multimodal curve, indicating reduced sensitivity to azoxystrobin. In detached fruit assays reduced sensitive isolates were not controlled as effectively as sensitive isolates at lowest label rate. Partial fragments were obtained from target genes ß-tubulin (751 bp) and Cytb (687 bp) of isolates resistant to thiophanate-methyl and reduced sensitivity to azoxystrobin. Sequence analysis of the ß-tubulin fragment revealed a mutation corresponding to E198K in all thiophanate-methyl-resistant isolates, while reduced sensitivity to axoxystrobin was not attributable to Cytb gene alterations. The target gene-based mechanism conferring resistance to thiophanate-methyl will likely be stable even if selection pressure subsides. However, the mechanism conferring reduced sensitivity to azoxystrobin is not based on target gene modifications and thus may not be as stable as other genotypes with mutations in Cytb gene.

Accumulation of organic solutes and enzymatic activity in cut roses (Rosaceae) cultivated with physiological effect products in the Sub- Middle São Francisco River Valley / Acúmulo de solutos orgânicos e atividade enzimática em rosa de corte (Rosaceae) cultivada com produtos de ação fisiológica no Vale do Submédio São Francisco

The aim of the present study was to evaluate the accumulation of carbohydrates, protein, and proline as well as the activity of the antioxidant enzymes superoxide dismutase and catalase in the Ambiance cultivar of cut rose plants grown with the application of physiological effect products in the Sub-Middle São Francisco River Valley in Brazil. The experiment was performed under a mesh screen with 50% shading. The experimental design used randomized blocks with four repetitions and six treatments: T1) control (water); T2) boscalid; T3) pyraclostrobin; T4) boscalid + pyraclostrobin (T2 + T3); T5) fluxapyroxad + pyraclostrobin; T6) plant growth regulators 4-(indol-3-yl) butyric acid (IBA) + gibberellic acid (GA3) + kinetin; these treatments were applied every 15 days throughout the crop cycle. To determine the accumulation of solutes and enzymatic activity, 8 leaves was collected every 48 h. Leaves were immediately immersed in liquid nitrogen and frozen until further analysis in the laboratory. Results showed that the product combinations boscalid + pyraclostrobin and fluxapyroxad + pyraclostrobin as well as the plant growth regulators were the treatments with the most consistent responses throughout the evaluated cycle, providing a greater accumulation of solutes in rose leaves, as an osmotic adjustment strategy against stress from high temperatures, particularly when proline accumulation is observed. With regard to enzymatic activity, plant regulators showed more consistent results when compared with other treatments, increasing both superoxide dismutase and catalase activity. The marked accumulation of organic solutes and the high enzymatic activity, particularly of catalase, indicated that rose plants use such mechanisms as a defense against the regions high temperatures.(AU)

Objetivou-se, com este estudo, avaliar o acúmulo de carboidratos, proteína e prolina, bem como a atividade de enzimas antioxidantes superóxido dismutase e catalases em plantas de rosa de corte ‘Ambiance cultivadas sob aplicação de produtos de efeitos fisiológicos no Vale do Submédio São Francisco. O experimento foi realizado em telado com 50% de sombreamento. O delineamento experimental foi em blocos casualizados com quatro repetições e seis tratamentos: T1) testemunha (água); T2) boscalida; T3) piraclostrobina; T4) boscalida + piraclostrobina (T2 + T3); T5) fluxapiroxade + piraclostrobina; T6) regulador vegetal IBA + GA3 + cinetina, aplicados a cada 15 dias durante todo o ciclo da cultura. Para a determinação do acúmulo de solutos e atividade enzimática foram realizadas 8 coletas de folhas a cada 48 horas. As mesmas foram imediatamente imersas em nitrogênio líquido e congeladas para análise posterior em laboratório. Os resultados demonstram que os produtos conjugados boscalida + piraclostrobina, fluxapiroxade + piraclostrobina e os reguladores vegetais foram aqueles com respostas mais consistentes ao longo do ciclo avaliado, propiciando maior acúmulo de solutos nas folhas das roseiras, como estratégia de ajustamento osmótico diante do estresse por temperatura elevada, especialmente quando se observa o acúmulo de prolina. Para a atividade enzimática, os reguladores vegetais apresentam resultados mais regulares quando comparados aos demais tratamentos, aumentando a atividade da SOD e da CAT. O acúmulo acentuado de solutos orgânicos junto com a elevada atividade enzimática, especialmente da CAT, indicam que as roseiras utilizam tais mecanismos como defesa diante das temperaturas elevadas da região.(AU)

Accumulation of organic solutes and enzymatic activity in cut roses (Rosaceae) cultivated with physiological effect products in the Sub- Middle São Francisco River Valley / Acúmulo de solutos orgânicos e atividade enzimática em rosa de corte (Rosaceae) cultivada com produtos de ação fisiológica no Vale do Submédio São Francisco

The aim of the present study was to evaluate the accumulation of carbohydrates, protein, and proline as well as the activity of the antioxidant enzymes superoxide dismutase and catalase in the Ambiance cultivar of cut rose plants grown with the application of physiological effect products in the Sub-Middle São Francisco River Valley in Brazil. The experiment was performed under a mesh screen with 50% shading. The experimental design used randomized blocks with four repetitions and six treatments: T1) control (water); T2) boscalid; T3) pyraclostrobin; T4) boscalid + pyraclostrobin (T2 + T3); T5) fluxapyroxad + pyraclostrobin; T6) plant growth regulators 4-(indol-3-yl) butyric acid (IBA) + gibberellic acid (GA3) + kinetin; these treatments were applied every 15 days throughout the crop cycle. To determine the accumulation of solutes and enzymatic activity, 8 leaves was collected every 48 h. Leaves were immediately immersed in liquid nitrogen and frozen until further analysis in the laboratory. Results showed that the product combinations boscalid + pyraclostrobin and fluxapyroxad + pyraclostrobin as well as the plant growth regulators were the treatments with the most consistent responses throughout the evaluated cycle, providing a greater accumulation of solutes in rose leaves, as an osmotic adjustment strategy against stress from high temperatures, particularly when proline accumulation is observed. With regard to enzymatic activity, plant regulators showed more consistent results when compared with other treatments, increasing both superoxide dismutase and catalase activity. The marked accumulation of organic solutes and the high enzymatic activity, particularly of catalase, indicated that rose plants use such mechanisms as a defense against the region’s high temperatures.

Objetivou-se, com este estudo, avaliar o acúmulo de carboidratos, proteína e prolina, bem como a atividade de enzimas antioxidantes superóxido dismutase e catalases em plantas de rosa de corte ‘Ambiance’ cultivadas sob aplicação de produtos de efeitos fisiológicos no Vale do Submédio São Francisco. O experimento foi realizado em telado com 50% de sombreamento. O delineamento experimental foi em blocos casualizados com quatro repetições e seis tratamentos: T1) testemunha (água); T2) boscalida; T3) piraclostrobina; T4) boscalida + piraclostrobina (T2 + T3); T5) fluxapiroxade + piraclostrobina; T6) regulador vegetal IBA + GA3 + cinetina, aplicados a cada 15 dias durante todo o ciclo da cultura. Para a determinação do acúmulo de solutos e atividade enzimática foram realizadas 8 coletas de folhas a cada 48 horas. As mesmas foram imediatamente imersas em nitrogênio líquido e congeladas para análise posterior em laboratório. Os resultados demonstram que os produtos conjugados boscalida + piraclostrobina, fluxapiroxade + piraclostrobina e os reguladores vegetais foram aqueles com respostas mais consistentes ao longo do ciclo avaliado, propiciando maior acúmulo de solutos nas folhas das roseiras, como estratégia de ajustamento osmótico diante do estresse por temperatura elevada, especialmente quando se observa o acúmulo de prolina. Para a atividade enzimática, os reguladores vegetais apresentam resultados mais regulares quando comparados aos demais tratamentos, aumentando a atividade da SOD e da CAT. O acúmulo acentuado de solutos orgânicos junto com a elevada atividade enzimática, especialmente da CAT, indicam que as roseiras utilizam tais mecanismos como defesa diante das temperaturas elevadas da região.

Chemical control of foliar diseases in soybean depends on cultivar and sowing date / O controle químico de doenças foliares na cultura da soja depende do cultivar e da época de plantio

The aim was to study the effect of early application of two fungicide mixtures on the control of Asian rust and powdery mildew, as well as on grain yield in five soybean cultivars at two sowing dates. The experiment was carried in the experimental area of FAMV/UPF. The cultivars A 4910 RG (super-early), BMX Apolo RR, A 6001 RR and Fundacep 55 RR (early) and Coodetec 214 RR (moderate), established at 13/11/2007 and 3/12/2007 were used. Trifolia of these cultivars were treated twice with the fungicides ciproconazol + azoxystrobin (Priori Xtra®, 0.3 L ha-1 plus Nimbus® adjuvant 0.6 L ha- 1) and epoxiconazol + pyraclostrobin (Opera®, 0.5 L ha-1), in three moments 1: pre-closure of the space between the lines and 21 days after; 2: pre-closure of space between rows and R5.1 stage (10% of beginning seed); and 3: R1 (beginning bloom) and R5.1 stages. The severity (% of affected leaf area) of powdery mildew and number of lesions cm2 of Asian rust were evaluated. After that plants were harvested, the thousand grain weight (g) and grain yield (kg ha-1) were quantified. The experimental design was a split-plot with four replicates, where the main plot were the five cultivars, and the subplots were the control treatment (untreated plants) and the six chemical control programs. Tukey and t-Student tests (p0.05) were used for separation of means of treatments and seasons, respectively. In general terms, foliar application of fungicides controlled both Asian rust and powdery mildew, as well as generated an increase on the thousand grain weight and grain yield. However, there seems to be an interaction among soybean genotypes and sowing date. Thus, our results allow us to infer that the chemical control of leaf diseases in the soybean crop depends of the cultivar and sowing date.

O objetivo foi estudar o efeito da aplicação antecipada de duas misturas de fungicidas no controle da ferrugem asiática e do oídio, bem como no rendimento de grãos em cinco cultivares de soja em duas épocas de semeadura. O experimento foi conduzido no campo experimental da FAMV/UPF. Utilizaram-se as cultivares A 4910 RG (super precoce), BMX Apolo RR, A 6001 RR e Fundacep 55 RR (precoces) e Coodetec 214 RR (moderado), estabelecidas em 13/11/2007 e 3/12/2007. Os fungicidas piraclostrobina + epoxiconazole e azoxistrobina + ciproconzole foram pulverizados duas vezes em 1: pré-fechamento do espaço entre as linhas e 21 dias após, 2: pré-fechamento do espaço entre as linhas e R5.1 (10% de granação), e 3: R1 (início da floração) e R5.1. Avaliaram-se a severidade (% da área foliar afetada) do oídio e o número de lesões cm2 da ferrugem asiática. Logo após as plantas foram colhidas, o peso de mil grãos (g) e rendimento de grãos (kg ha-1) foram quantificados. O delineamento experimental utilizado foi o de parcelas divididas com quatro repetições, onde a parcela principal foram as cinco cultivares, e as subparcelas foram o tratamento controle (plantas não tratadas) e os seis programas de controle químico. Para a separação das médias dos tratamentos e épocas, foram utilizados os testes de Tukey e t-Student (p0.05), respectivamente. De modo geral, a aplicação foliar de fungicidas controlou tanto a ferrugem asiática como o oídio, assim como também gerou um aumento do peso de mil grãos e rendimento de grãos. No entanto, parece existir uma interação entre os genótipos e data de semeadura. Assim, nossos resultados nos permitem inferir que o controle químico das doenças foliares na cultura da soja depende do cultivar e da data de semeadura.