Due to its antimicrobial properties propolis has been utilised by man for millennia, however, only recently has its use as an agricultural antimicrobial agent been tested. The capacity of this product to activate plant defence mechanisms is highly promising, due to the large number of substances in its composition. Therefore, the objective of this study was to evaluate the effect of different concentrations and application times of ethanol extracts of propolis (EEP) on powdery mildew (Podosphaera fuliginea) in cucumber crops, to establish the most suitable method for control and whether or not there is potential to induce plant defence mechanisms. The experiment was conducted in pots in a greenhouse. A completely randomised experimental design was employed, using a 6x3 factorial consisting of six concentrations (0; 0.5; 1; 2; 4 and 8%) and three EEP application times (24 hours before pathogen inoculation, 24 hours after pathogen inoculation and at the onset of first symptoms of the disease), replicated four times. Evaluations for disease incidence and severity were made weekly. The experiment was repeated for a second crop, following the same methodology established in the first. We also evaluated the effect of different EEP concentrations on the activation of plant defence mechanisms, through the induction of phytoalexins in soybean (Glycine max) cotyledons. A significant interaction was observed between the factors (application time x concentration) for disease incidence. For the area under the disease progress curve (AUDPC) for severity there was no interaction observed between the factors, however, we observed significant differences for the two factors separately. The AUDPC for incidence was less for the application 24 hours after pathogen inoculation, principally at the highest concentration. The 8% concentration of EEP controlled disease severity by 31.33 and 43.68% for the first and second crops, respectively. The application of the concentrations 24 hours before and 24 hours after pathogen inoculation showed less AUDPC for severity, but this difference was not significant for either crop. The EEP induced increasing phytoalexin levels in soybean cotyledons as the applied EEP concentration increased. Ethanol extracts of propolis could have potential for the control of powdery mildew, principally in cucumbers, through the preventive application of an 8% concentration.

-Canola is an oilseed winter plant, constituting an alternative to crop rotation. It presents socioeconomic value for the production of vegetable oil for human consumption, biodiesel and animal food formulation. The evaluation of canola seed viability is routinely performed by germination test, which can be extended for up to 14 days if it is necessary to overcome dormancy. The objective of this study was to establish criteria for conducting a tetrazolium test in canola seeds, determining viability groups. Four lots of seed were used, placed between soaked paper to hydrate for 16 hours at 20 °C. In the coloration step, after preliminary tests, the following combinations of tetrazolium salt concentration, temperature and incubation period were tested: 0.5 and 1.0% at 30 °C; 0.2, 0.5 and 1.0% at 40 °C for two, four and six hours. It was concluded that the evaluation of viability of canola seeds by the tetrazolium test is effective upon hydration of the seeds between papers for 16 hours at 20 °C, coloration by immersion in 0.5% tetrazolium solution for six hours, at 40 °C and two viability groups were established and illustrated.Index terms: Brassica napus L. var oleifera, physiological quality, germination, dormancy.Critérios para execução do teste de tetrazólio em sementes de canola RESUMO -A canola é uma planta oleaginosa de inverno, constituindo-se alternativa para a rotação de culturas. Apresenta valor socioeconômico pela produção de óleo vegetal para consumo humano, biodiesel e formulação de ração animal. A avaliação da viabilidade de sementes de canola é realizada rotineiramente pelo teste de germinação, que pode se estender por até 14 dias se houver a necessidade de superação da dormência. O objetivo do trabalho foi estabelecer critérios para condução do teste de tetrazólio em sementes de canola, determinando grupos de viabilidade. Utilizaram-se quatro lotes de sementes, colocadas para hidratar entre papel umedecido por 16 horas, a 20 °C. Na etapa de coloração, após testes preliminares, foram avaliadas as seguintes combinações de concentração do sal de tetrazólio, temperatura e período de incubação: 0,5 e 1,0% a 30 °C; 0,2; 0,5 e 1,0% a 40 °C, durante duas, quatro e seis horas. Conclui-se que a avaliação da viabilidade das sementes de canola por meio do teste de tetrazólio é eficiente mediante hidratação das sementes entre papel por 16 horas a 20 ºC, coloração por imersão em solução de tetrazólio a 0,5%, durante seis horas, a 40 °C, sendo estabelecidos e ilustrados dois grupos de viabilidade.Termos para indexação: Brassica napus L. var oleifera, qualidade fisiológica, germinação, dormência.

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-The identification of brown rot control derivatives has been the focus of intense research owing to the negative effects of the unrelenting usage of fungicides. Brown rot, caused by Monilinia fructicola, is an important post-harvest disease of peaches. The goal of this study was to estimate the optimum sample size of peaches in order to assess the average lesion size and the influence of different plant extracts on the fruits. Three preparation forms (FPE) were evaluated, as well as another seven forms of application (FAE) of canola and mustard extracts on peaches, with applications of the pathogen's inoculum. Five fruits were utilized in five repetitions per treatment. Evaluation involved measurement of the fruits' lesioned areas. The necessary sampling size was determined for estimation of the averages for each treatment and experiment. For measurement of the lesion size, 99 fruits in FPE and 23 fruits in FAE were sufficient for estimating the average with an estimation error of 10%. Based on the same estimation error, the sampling size is contingent on the extracts (canola, and mustard), batches of fruits, forms of extraction, and extract application on the fruits.Keywords: Monilinia fructicola. Experimental Precision. Sample Size. Post-harvest. PLANO AMOSTRAL PARA A AVALIAÇÃO DA SEVERIDADE DE PODRIDÃO-PARDA EM PÊSSEGOS SUBMETIDOS A DIFERENTES EXTRATOS VEGETAISRESUMO -Devido aos efeitos da utilização indiscriminada de fungicidas, diversos estudos vêm sendo desenvolvidos na busca por formas alternativas de controle da podridão-parda, causada por Monilinia fructicola, em pós-colheita de pêssego. O objetivo deste estudo foi estimar o tamanho ótimo de amostra para avaliar a média do tamanho da lesão pêssegos e a influência de diferentes extratos vegetais nos frutos sobre o tamanho de amostra. Foi conduzido um experimento de três formas de preparo (FPE) e outro experimento de sete formas de aplicação (FAE) de extratos de canola e mostarda sobre pêssegos, com posterior aplicação do inóculo do patógeno. Foram usados cinco frutos em cinco repetições por tratamento. As avaliações foram feitas através da medição da área da lesão nos frutos. Foi determinado o tamanho de amostra necessário para a estimacão da média para cada tratamento e cada experimento. Para a mensuração do tamanho da lesão, 99 frutos em FPE e 23 frutos em FAE são suficientes para a estimação da média com um erro de estimação de 10% da média. Usando um mesmo erro de estimação, o tamanho de amostra (número de frutos) depende dos extratos (canola e mostarda), lotes de frutos e formas de extração e de aplicação dos extratos nos frutos.Palavras-chave: Monilinia fructicola. Precisão experimental. Tamanho de amostra. Pós-colheita.

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