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Made available in DSpace on 2014-06-11T19:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-29Bitstream added on 2014-06-13T20:09:10Z : No. of bitstreams: 1 perim_l_me_botfca.pdf: 642600 bytes, checksum: 3f26247a69a07b1413c3746c23e76085 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O uso de adjuvantes é adotado em todo o mundo, a fim de melhorar a eficácia das formulações de defensivos agrícolas, independente do tipo de alvo. Existem duas maneiras principais em que adjuvantes podem melhorar o desempenho final do produto. Em primeiro lugar, aumentando a quantidade de ingrediente ativo retido pelo alvo e, por outro, melhorando a sua absorção. O objetivo do presente trabalho foi avaliar os efeitos de óleos minerais e vegetais nas características físicas e químicas da calda de aplicação e na ação do herbicida atrazina (Gesaprim 500® SC). Os tratamentos estudados foram: atrazina, atrazina + Natur’l Óleo®; atrazina + Agr’Óleo®; atrazina + Assist® e testemunhas. Todos os adjuvantes foram acionados na proporção de 0.5% do volume da calda aplicada. As plantas indicadoras utilizadas nos estudos sobre os efeitos dos adjuvantes sobre a ação da atrazina foram: Ipomoea grandifolia,Brachiaria plantaginea, Merremia cissoides e Euphorbia heterophylla. Os parâmetros estudados foram: tensão superficial, pH, efeito do tempo de preparo da calda e do pH sobre a tensão superficial, evaporação da calda, tamanho de gotas, eficácia de controle de plantas daninhas, influência da chuva no controle da atrazina e a velocidade de absorção da atrazina com o uso do fluorômetro. O delineamento experimental utilizado foi em bloco casualizados, com quatro repetições. Portanto com os resultados obtidos pode-se concluir que uso de óleos vegetais ou minerais influenciou positivamente nas características físicas e químicas da calda de aplicação agindo diretamente na ação de herbicidas apresentando uma alta eficiência de controle das espécies estudadas / The adjuvants are used all over the world in order to improve the effectiveness of the herbicides formulations, independent of target. There are two main ways in which adjuvants can improve the performance of the final product. First, increasing the amount of active ingredient retained by the target and secondly, promoting its absorption. The objective of this study was to evaluate the effects of mineral and vegetable oils in physical and chemical characteristics of the application and action of the herbicide Gesaprim 500® (atrazine). The treatments studied were: atrazine; atrazine + Natur'l Óleo®; atrazine + Agr'Óleo®; atrazine + Assist® and check. All adjuvants were used at a rate of 0.5% of the volume of spray applied. The indicator plants used in studies on the effects of adjuvants on the action of atrazine were: Ipomoea grandifolia, Brachiaria plantaginea, Merremia cissoides and Euphorbia heterophylla. The parameters studied were: surface tension, pH, effect of time preparing the solutions and pH on surface tension, evaporation of the solution, droplet size, effective weed control, rain influence in weed control, the active ingredient absorption velocity using the fluorometer method. The experimental design was randomized blocks with four replications. So with the results we can conclude that the use of vegetable or mineral oils had a positive influence on physical and chemical characteristics and at the application acts the treatments showed a highly efficient control of the studied species

The herbicide, Dacthal (dimethyl 2,3,5,6,-tetrachloroterephthalate) is hydrolyzed to give the corresponding diacid and this derivative is a common contaminant in ground water. In the Ontario region of eastern Oregon the use of this herbicide on onions has resulted in the contamination of an aquifer with this derivative. Since movement to groundwater is determined by the hydrolysis of the parent compound to a more soluble derivative. The rate at which this hydrolysis reaction occurs and the stability of the metabolite must be defined. These parameters have been determined using soils from Ontario in which onions had been raised. At room temperature and 50% field capacity, the parent was hydrolyzed rapidly (half-life 16 days) to the diacid derivative. An increase of the incubation temperature to 38°C reduced the hydrolysis rate significantly (half-life 86.8 days). It is assumed that this response reflects reduced microbial activity at the higher temperature. At both temperatures only small amounts of the monoacid intermediate were detected suggesting that the Dacthal monoacid was being hydrolyzed at a faster rate than the parent. It was established that at room temperature, the half-life of the monoacid was only 2.8 days. Over the 300 days the experiments were carried out, little if any degradation of the diacid metabolite could be detected. There was virtually no degradation of the parent over a 60 day period in sterilized soil, suggesting that microbial activity is primarily responsible for this step. By contract, the monoacid was hydrolyzed at comparable rates in sterilized and nonsterilized soil. This study explains why the Dacthal metabolite is a common contaminant in groundwater. The parent is rapidly hydrolyzed to the diacid which is much more water soluble. More important, however, is the persistence of the diacid metabolite in the environment. / Graduation date: 1992

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Thesis (Ph. D.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains x, 170 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Hazard assessment of pesticides in aquatic environments requires accurate predictions of persistence and compartmentalization. A strategy for developing confidence in predictive fate models, such as the Exposure Analysis Modeling System (EXAMS) and the Simplified Lake and Stream Analysis model (SLSA), is to test the models using carefully chosen chemicals in semi-controlled and field situations. An objective of this approach would be to isolate the variability in a particular fate process and thereby assess the ability of an algorithm to model the process. For example, endothall, a relatively watersoluble aquatic herbicide, has essentially a sole fate process, biotransformation. Endothall was used to test the predictive capabilities of EXAMS and SLSA and to identify sources of variance in those predictions.

Please read the abstract in the section 00front of this document. / Dissertation (MSc Agric (Weed Science))--University of Pretoria, 2007. / Plant Production and Soil Science / MSc Agric / unrestricted