474 research outputs found

    Handmade clay bricks: chemical, physical and mechanical properties

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    The clay brick masonry that is much used in historical structures often is in a rather poor state of conservation. In order to intervene correctly in these buildings, it is convenient to characterize the old material. For this purpose, a large sample of clay brick specimens from the 12th to 19th century were collected from six Portuguese monasteries, and were characterized chemically, physically and mechanically. A large variability of the properties was found. Additionally, a sample of handmade new bricks, which are commonly used as replacing material, was also analysed. The results were compared to the old bricks and could be possibly adequate as substitution bricks. Still, significant differences were found in chemical composition, and in water absorption and porosity, which are much lower in modern handmade bricks. With respect to mechanical properties, the range of values found in old bricks was rather high and the degree of deterioration exhibited a large scatter, meaning that a conclusion is hardly possible.The authors gratefully acknowledge the Instituto de Gestao do Patrimonio Arquitectonico e Arqueologico (IGESPAR) for providing the old clay bricks used in the present work. The first author acknowledges the partial funding of this work by the FCT through the following scholarships POCTI SFRH/BD/6409/2001 and POCTI SFRH/BPD/26706/2005

    Effect of Insecticides Sprayed on Leaves and Applied via Soil to Aphis illinoisensis Shimer, 1866 (Hemiptera: Aphididae) on Grapevines

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    High infestations by the grapevine aphid Aphis illinoisensis (Hemiptera: Aphididae) have been observedin vineyards in southern Brazil, retarding plant growth and causing premature berry drop. This studyevaluated the effect of insecticides on the control of the species in two experiments carried out in agreenhouse. The first control experiment for A. illinoisensis was conducted with seedlings of Vitis viniferavar. ‘Cabernet Franc’ to assess the effect of azadirachtin (Azamax®) at dosages of 2.4 and 3.6 mL a.i.(active ingredient)/100 L of water, with reapplication seven days after the first application (DAFA). Tocompare its effect, the neonicotinoids imidacloprid (Provado 200 SC®) and thiamethoxam (Actara 250WG®) were sprayed at dosages of 8 mL or g a.i./100 L of water in foliar application without reapplication.The second experiment compared the effect on A. illinoisensis by spraying these neonicotinoids at dosagesof 8 mL or g a.i./100 L in foliar applications and of 0.05 mL or g a.i./100 L applied in the soil. Evaluationswere performed at 0, 1, 5, 7, 10 and 14 DAFA. Imidacloprid and thiamethoxam effectively controlled A.illinoisensis in both forms of application [soil and foliar], while azadirachtin at the dosage of 3.6 ml a.i./100L reapplied seven days after the first application provided 55.7% control. In conclusion, A. illinoisensis canbe controlled effectively by employing neonicotinoids in the soil, while azadirachtin can be an alternativeto reduce infestation pressure

    Avaliação de inseticidas para o controle de Oiketicus kirbyi (Lands-Guilding, 1827) (Lep. Psychidae) em laboratório.

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    Devido à falta de informações sobre o efeito de inseticidas para o controle de O. kirbyi nas culturas da uva e pêssego, este trabalho teve como objetivo avaliar o efeito de lagarticidas sobre a espécie em laboratório (T=24°C±2 e UR 70% ± 10 e fotofase 14 horas).Resumo

    Bioecologia e controle do bicho do cesto Oiketicus kirbyi (Guilding, 1927) (Lepidoptera: Psychidae) em pessegueiro e videira.

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    Este comunicado técnico tem como objetivo apresentar informações sobre a bioecologia do bicho do cesto e estratégias de controle que podem ser empregadas para o manejo da espécie nas culturas do pessegueiro e da videira.bitstream/item/81774/1/cot132-1.pd

    Effect of insecticides sprayed on leaves and applied via soil to Aphis illinoisensis Shimer, 1866 (Hemiptera: Aphididae) on grapevines.

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    High infestations by the grapevine aphid Aphis illinoisensis (Hemiptera: Aphididae) have been observed in vineyards in southern Brazil, retarding plant growth and causing premature berry drop. This study evaluated the effect of insecticides on the control of the species in two experiments carried out in a greenhouse. The first control experiment for A. illinoisensis was conducted with seedlings of Vitis vinifera var. ‘Cabernet Franc’ to assess the effect of azadirachtin (Azamax®) at dosages of 2.4 and 3.6 mL a.i. (active ingredient)/100 L of water, with reapplication seven days after the first application (DAFA). To compare its effect, the neonicotinoids imidacloprid (Provado 200 SC®) and thiamethoxam (Actara 250 WG®) were sprayed at dosages of 8 mL or g a.i./100 L of water in foliar application without reapplication. The second experiment compared the effect on A. illinoisensis by spraying these neonicotinoids at dosages of 8 mL or g a.i./100 L in foliar applications and of 0.05 mL or g a.i./100 L applied in the soil. Evaluations were performed at 0, 1, 5, 7, 10 and 14 DAFA. Imidacloprid and thiamethoxam effectively controlled A. illinoisensis in both forms of application [soil and foliar], while azadirachtin at the dosage of 3.6 ml a.i./100 L reapplied seven days after the first application provided 55.7% control. In conclusion, A. illinoisensis can be controlled effectively by employing neonicotinoids in the soil, while azadirachtin can be an alternative to reduce infestation pressure. Key words: Grapevine aphid, chemical control, pest management, azadirachti

    Susceptibility and Interactions of Drosophila suzukii and Zaprionus indianus (Diptera: Drosophilidae) in Damaging Strawberry.

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    Resumo: Drosophila suzukii (Matsumura) foi recentemente detectado causando danos aos morangos no Brasil. A infestação na cultura de morango frequentemente foi observada conjuntamente com a presença de Zaprionus indianus Gupta. Este estudo investigou a suscetibilidade de morangos em três estágios de amadurecimento para infestação de D. suzukii e Z. indianus e sua interação. Abstracts: Drosophila suzukii (Matsumura) has been recently detected causing damage to strawberries in Brazil. Infestation in strawberry culture has often been observed jointly with the presence of Zaprionus indianus Gupta. This study investigated the susceptibility of strawberries at three ripening stages to infestation of D. suzukii and Z. indianus and their interaction. In the laboratory, strawberries cv. Albion at different ripening stages (green, semi-ripe and ripe) were exposed to D. suzukii and Z. indianus for 24 h in choice and no-choice bioassays. Additionally, we evaluated the effects of mechanical damage incurred artificially or by D. suzukii ovi-position on Z. indianus infestation. In no-choice bioassay, there were no significant differences in fruit susceptibility to D. suzukii infestation at different ripening stages. However, in choice bioassay, D. suzukii adults preferred to oviposit on R fruit. The presence of mechanical damage did not increase susceptibility of fruit to D. suzukii oviposition. For Z. indianus , there was greater susceptibility of R fruit in relation to SR and G fruit in both the choice and no-choice bioassays. There was a significant and positive interaction of mechanical damage and damage caused by D. suzukii to R fruit and infestation by Z. indianus , which was not observed in SR and G fruit. Although infestation of Z. indianus is related to attack damaged or decaying fruit, this work shows that this species has the ability to oviposit and develop in healthy strawberry fruit with and increased infestation level when the fruit has damage to its epidermis
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