Degradation of pesticides present in tomato rinse water by direct photolysis and UVC/H2O2: optimization of process conditions through sequential Doehlert design.

The degradation of three pesticides, azoxystrobin (AZO), difenoconazole (DFZ), and imidacloprid (IMD), commonly found in the tomato rinse water, was studied through UVC (251-257 nm) and UVC/H2O2 photolysis. The results showed that direct photolysis follows pseudo-first-order kinetics, with total AZO and IMD removals within 15 min, using 21.8 and 28.6 W m-2, respectively, while the highest percentage of DFZ degradation was 51.7% at 28.6 W m-2 UVC. The estimated quantum yields were 0.572, 0.028, and 0.061 mol Einstein-1 for AZO, DFZ, and IMD, respectively. With regard to UVC/H2O2, total pesticide removal was achieved after 10 min, while optimal treatment conditions in relation to the pesticide removal rates, estimated through the sequential Doehlert design, were about [H2O2]0 = 130 mg L-1 and 26 W m-2. Cytotoxicity and genotoxicity assays carried out with Allium cepa, for real industrial tomato rinse water sampled from washing belts did not show abnormalities during cell division, with total pesticides degradation after 15 min, demonstrating the potential application of the UVC/H2O2 process as a viable localized treatment with a focus on the possible reuse of treated water.

Use of ozone and detergent for removal of pesticides and improving storage quality of tomato.

The efficiencies of two conventional domestic procedures (immersion in pure water and detergent solution at 0.25 and 1%) and two treatments using ozone (immersion in water with bubbling O3 and immersion in ozonated water, both at 1 and 3 mg L-1) were evaluated for the removal of residues of the fungicides azoxystrobin, chlorothalonil and difenoconazole in tomatoes. The fungicides were sprayed on the fruits at the recommended concentration for the crop. The residues in the tomatoes and in the washing solutions were determined by extraction with low-temperature partition techniques and analysis by gas chromatography. More concentrated solutions were more effective in removing pesticide residues. The water bubbled with ozone at 3 mg L-1 was the most efficient treatment for the removal of fungicides, reaching a reduction of 70-90% of the residues. However, the treatments with the lowest concentration of ozone had lower loss of fruit mass during storage.

Lethal and sublethal toxicity of abamectin and difenoconazole (individually and in mixture) to early life stages of zebrafish.

In recent years, the need for the development of alternative test methods for the conventional acute fish toxicity test (AFT) with adult fish has often been discussed. In addition, concerns have been raised on the potential risks related with environmentally realistic pesticide mixtures since risk evaluations have traditionally been based on individual pesticides. The insecticide/acaricide abamectin and the fungicide difenoconazole are the main pesticides that are intensively used in Brazilian strawberry crop and are hence likely to occur simultaneously in edge-of-field waterbodies. The aim of the present study was therefore to evaluate the lethal and sublethal toxicity of single and mixture exposures of these pesticides to zebrafish early life stages (embryos and juveniles). By comparing the derived toxicity data of the individual compounds with that previously determined for zebrafish adults, the order of life stage sensitivity was juvenile > adult > embryo. The pesticide mixture revealed a dose-level dependent deviation of the independent action model, with antagonism at low dose levels and synergism at high dose levels. Sublethal parameters (especially those related with locomotion) were considerably more sensitive than lethality. Subsequently, the inclusion of sublethal parameters may greatly improve the sensitivity of FET tests and hence its suitability as a substitution of adult fish testing in risk assessment evaluations.

Tratamento químico de sementes sobre o desenvolvimento de mancha marrom em plantas de trigo / Chemical treatment in seeds on the development of the spot blotch in wheat plants

O objetivo do trabalho foi avaliar o efeito dos fungicidas difenoconazole e carboxin + thiram aplicados em sementes de trigo cultivares 'CD 104' e 'OR Mirante', inoculadas com Cochliobolus sativus. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 2x3 (2 cultivares e 2 fungicidas + testemunha sem controle) em sete repetições. O fungo foi isolado e reproduzido em meio de cultura BDA (batata-dextrose-ágar) e, posteriormente, multiplicado em sementes de trigo pré-cozidas, constituindo a fonte de inóculo. As avaliações foram do número de lesões na folha basal de cinco plantas por vaso aos 22, 25, 29, 31, 35 e 38 dias após a semeadura (DAS) e aos 41 dias foram avaliados o comprimento (cm), massa fresca (g) e seca (g) da parte aérea e das raízes. A partir das avaliações do número de lesões, também foi calculada a área abaixo da curva de progresso da doença (AACPD), cujos dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey, a 5% de probabilidade. A cultivar 'CD 104' foi mais suscetível ao patógeno do que 'OR Mirante'; difenoconazole foi eficiente no controle da doença na parte aérea, enquanto carboxin + thiram se igualou à testemunha; os dois fungicidas interferiram negativamente no desenvolvimento das plantas, uma vez que as médias de comprimento, massa fresca e seca da parte aérea e das raízes obtidas das sementes tratadas é inferior à média das sementes não tratadas.

The objective of this research was to evaluate the effect of fungicides difenoconazole and carboxin + thiram applied in seed wheat cultivars 'CD 104' and 'OR Mirante', inoculated with Cochliobolus sativus. The experimental design was completely randomized in a 2x3 factorial design (2 cultivars and 2 fungicides + untreated control) in seven replications. The fungi was isolated and reproduced in PDA culture medium (potato-dextrose-agar) and subsequently multiplied in seeds of wheat pre-cooked and is the source of inoculum. The evaluations were the number of lesions in the basal leaf of five plants per pot at 22, 25, 29, 31, 35 and 38 days after sowing (DAS), and at 41DAS were evaluated the length (cm), fresh weight (g) and dry weight (g) of shoot and root. From the evaluations of the number of lesions was also calculated the area under the disease progress curve (AUDPC). The datas were subjected to analysis of variance and means were compared by Tukey test at 5% probability. The 'CD 104' cultivar was more susceptible to the pathogen than 'OR Mirante'; difenoconazole was efficient to control the disease as carboxin + thiram equaled the witness; both fungicides interfered negatively on plant development, since the average length, fresh weight and dry shoot and root obtained from treated seed is lower than the untreated seeds.

Tratamento químico de sementes sobre o desenvolvimento de mancha marrom em plantas de trigo

The objective of this research was to evaluate the effect of fungicides difenoconazole and carboxin + thiram applied in seed wheat cultivars 'CD 104' and 'OR Mirante', inoculated with Cochliobolus sativus. The experimental design was completely randomized in a 2x3 factorial design (2 cultivars and 2 fungicides + untreated control) in seven replications. The fungi was isolated and reproduced in PDA culture medium (potato-dextrose-agar) and subsequently multiplied in seeds of wheat pre-cooked and is the source of inoculum. The evaluations were the number of lesions in the basal leaf of five plants per pot at 22, 25, 29, 31, 35 and 38 days after sowing (DAS), and at 41DAS were evaluated the length (cm), fresh weight (g) and dry weight (g) of shoot and root. From the evaluations of the number of lesions was also calculated the area under the disease progress curve (AUDPC). The datas were subjected to analysis of variance and means were compared by Tukey test at 5% probability. The 'CD 104' cultivar was more susceptible to the pathogen than 'OR Mirante'; difenoconazole was efficient to control the disease as carboxin + thiram equaled the witness; both fungicides interfered negatively on plant development, since the average length, fresh weight and dry shoot and root obtained from treated seed is lower than the untreated seeds.

O objetivo do trabalho foi avaliar o efeito dos fungicidas difenoconazole e carboxin + thiram aplicados em sementes de trigo cultivares 'CD 104' e 'OR Mirante', inoculadas com Cochliobolus sativus. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 2x3 (2 cultivares e 2 fungicidas + testemunha sem controle) em sete repetições. O fungo foi isolado e reproduzido em meio de cultura BDA (batata-dextrose-ágar) e, posteriormente, multiplicado em sementes de trigo pré-cozidas, constituindo a fonte de inóculo. As avaliações foram do número de lesões na folha basal de cinco plantas por vaso aos 22, 25, 29, 31, 35 e 38 dias após a semeadura (DAS) e aos 41 dias foram avaliados o comprimento (cm), massa fresca (g) e seca (g) da parte aérea e das raízes. A partir das avaliações do número de lesões, também foi calculada a área abaixo da curva de progresso da doença (AACPD), cujos dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey, a 5% de probabilidade. A cultivar 'CD 104' foi mais suscetível ao patógeno do que 'OR Mirante'; difenoconazole foi eficiente no controle da doença na parte aérea, enquanto carboxin + thiram se igualou à testemunha; os dois fungicidas interferiram negativamente no desenvolvimento das plantas, uma vez que as médias de comprimento, massa fresca e seca da parte aérea e das raízes obtidas das sementes tratadas é inferior à média das sementes não tratadas.

Tratamento químico de sementes sobre o desenvolvimento de mancha marrom em plantas de trigo

The objective of this research was to evaluate the effect of fungicides difenoconazole and carboxin + thiram applied in seed wheat cultivars 'CD 104' and 'OR Mirante', inoculated with Cochliobolus sativus. The experimental design was completely randomized in a 2x3 factorial design (2 cultivars and 2 fungicides + untreated control) in seven replications. The fungi was isolated and reproduced in PDA culture medium (potato-dextrose-agar) and subsequently multiplied in seeds of wheat pre-cooked and is the source of inoculum. The evaluations were the number of lesions in the basal leaf of five plants per pot at 22, 25, 29, 31, 35 and 38 days after sowing (DAS), and at 41DAS were evaluated the length (cm), fresh weight (g) and dry weight (g) of shoot and root. From the evaluations of the number of lesions was also calculated the area under the disease progress curve (AUDPC). The datas were subjected to analysis of variance and means were compared by Tukey test at 5% probability. The 'CD 104' cultivar was more susceptible to the pathogen than 'OR Mirante'; difenoconazole was efficient to control the disease as carboxin + thiram equaled the witness; both fungicides interfered negatively on plant development, since the average length, fresh weight and dry shoot and root obtained from treated seed is lower than the untreated seeds.

O objetivo do trabalho foi avaliar o efeito dos fungicidas difenoconazole e carboxin + thiram aplicados em sementes de trigo cultivares 'CD 104' e 'OR Mirante', inoculadas com Cochliobolus sativus. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 2x3 (2 cultivares e 2 fungicidas + testemunha sem controle) em sete repetições. O fungo foi isolado e reproduzido em meio de cultura BDA (batata-dextrose-ágar) e, posteriormente, multiplicado em sementes de trigo pré-cozidas, constituindo a fonte de inóculo. As avaliações foram do número de lesões na folha basal de cinco plantas por vaso aos 22, 25, 29, 31, 35 e 38 dias após a semeadura (DAS) e aos 41 dias foram avaliados o comprimento (cm), massa fresca (g) e seca (g) da parte aérea e das raízes. A partir das avaliações do número de lesões, também foi calculada a área abaixo da curva de progresso da doença (AACPD), cujos dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey, a 5% de probabilidade. A cultivar 'CD 104' foi mais suscetível ao patógeno do que 'OR Mirante'; difenoconazole foi eficiente no controle da doença na parte aérea, enquanto carboxin + thiram se igualou à testemunha; os dois fungicidas interferiram negativamente no desenvolvimento das plantas, uma vez que as médias de comprimento, massa fresca e seca da parte aérea e das raízes obtidas das sementes tratadas é inferior à média das sementes não tratadas.

The impact of fungicides on Nomuraea rileyi (Farlow) Samson epizootics and on populations of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), on soybean / Impacto de fungicidas sobre epizootias de Nomuraea rileyi (Farlow) Samson e sobre populações de Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), em soja

The fungus Nomuraea rileyi (Farlow) Samson is one of the most important natural enemies of soybean caterpillars, mainly under humid weather conditions. Outbreaks of the fungus Microsphaera diffusa Cooke & Peck have demanded fungicide applications on soybeans, which could result in outbreaks of noctuid populations by reduction of the natural inocula of N. rileyi. The recommended fungicides have shown to be detrimental to beneficial fungi, reducing infection, delaying epizootics, and resulting in increased host population densities. In laboratory assays, benomyl, difenoconazole, sulphur and carbendazim affected conidial germination of N. rileyi, being the latter less deleterious. To assess the impact of fungicides used to control M. diffusa, on N. rileyi, two tests were carried on, spraying difenoconazole (75 g a.i./ha) and benomyl (262.5 g a.i./ha) on soybean plots. In the 1997/98 trial, fungicide was sprayed once on soybean plants at R1-R2 developmental stages. In the 1998/99 test, two applications were made, when plants were at V5 and V7 developmental stages, respectively. The number of VBC larvae was significantly higher in the fungicide treated plots than in the control plots. In the 1997/98 test, benomyl treated plots resulted in higher populations of VBC than in the control or in the difenoconazole plots. In the 1998/99 test, VBC population was higher from 7 to 12 days after the first application, and remained high until 19 days after the second application. In general, fungicide treatments delayed the begining of N. rileyi epizootics from 2 to 14 days.

O fungo Nomuraea rileyi (Farlow) Samson é um dos inimigos naturais mais importantes de lagartas da soja, principalmente em condições de tempo úmido. Surtos de oídio têm demandado a aplicação de fungicidas na soja, especialmente nas etapas iniciais do ciclo agrícola, época na qual a interferência sobre N. rileyi pode favorecer a ocorrência de lagarta por redução do inóculo desse fungo. Ensaios de laboratório mostraram que benomil, difenoconazole, enxofre e carbendazim reduziram a germinação de N. rileyi sendo o último menos deletério. Para avaliar o impacto dos fungicidas utilizados no controle do oídio sobre N. rileyi, foram realizadas aplicações com difenoconazole (75 g i.a./ha) ou benomil (262,5 g i.a./ha) em parcelas de soja. No ensaio realizado em 1997/1998 foi realizada apenas uma aplicação de fungicida, estando as plantas no estágio R1-R2. No ensaio realizado em 1998/99 realizaram-se duas aplicações, espaçadas de 19 dias, quando as plantas estavam nos estágios V5 e V7, respectivamente. O número de lagartas foi significativamente maior nas parcelas tratadas com os fungicidas que nas parcelas testemunhas. Em 1997/98, a parcela tratada com benomil apresentou população mais elevada da lagarta-da-soja que nas parcelas testemunhas ou na tratada com difenoconazole. Em 1998/99, a população da lagarta-da-soja foi maior entre o sétimo e décimo segundo dia após a primeira aplicação, e continuou alta até o décimo nono dia após a segunda aplicação. Os fungicidas causaram um atraso de 2 a 14 dias na iniciação da epizootia de N. rileyi.