Esta pesquisa foi conduzida na ESALQ, Piracicaba-SP e na Universidade Federal de Mato Grosso do Sul, em Dourados-MS, 1983 a 1986, com objetivo de se estudar a ação de herbicidas graminicidas, aplicados em pós-emergência, na cultura da soja, época de aplicação dos produtos, doses e espécies de gramíneas controladas. Os herbicidas utilizados foram: sethoxydim, diclofop-methyl, fluazifop-butil, haloxifop-methyl, chcorazifop-propanyl, quisalofop-ethyl; avaliando-se os efeitos na planta a nível de campo e na semente colhida. Verificou-se que os herbicidas estudados não provocam injúrias morfológicas e não alteram a qualidade fisiológica. A melhor época de aplicação dos herbicidas pesquisado é dos 20 aos 25 dias após a semeadura da cultura, ou seja, do quinto para o sexto trifólio da soja, época em que germinaram a maioria das gramíneas. A aplicação nesta época permite por parte de alguns herbicidas uma ação residual em pré-emergência, mantendo o solo livre de plantas daninhas. Os herbicidas mais eficazes foram: fluazifop-butil, haloxifop-methyl e quizalofop-etyl nas doses de 0,65; 0,24 e 0,14 Kg/ha, respectivamente

The present research was carried out at Escola Superior de Agricultura "Luiz and at Universidade Federal de Queiroz", in Piracicaba-SP de Mato Grosso do Sul, in Dourados-MS, from 1983 to 1986. Its aim was to study the effects of post-emergency herbicides of graminicide action in soybean The study focused: when to apply the products, their doses, species of grasses which were controled and the effects of the herbicides sethoxydim, diclofop-methyl, fluazifop-butil, haloxyfop-methyl, chlorazifop-propynil and quizalofop-ethyl. The observations were made in plants in the outdoors and in picked up suds studied through laboratory tests. To do so, experimental essays were develop in the field, in a greenhouse and in laboratories of analysis of seeds. After accomplishing the work, it was verified that the herbicides studies did not cause morphologic injuries, non did they alter the physiologic quality of the soybean seeds. The best time to apply the herbicides 20 to 25 days after planting the crop, that is, fifth to the sixth trefoid of the soybean. was from from the This time corresponds to that when most graminious have already spruted without having reached the staze of resistency to the chemical control of the tested products. Besides, it was allowed a residual action, in a pre-emergency basis, of some herbicides, such as haloxifop-methyl and chlorazifop- -propynil, keeping the soil free from weeds until it has been covered by the culture. The most effective herbicides were: fluazifop-butil, haloxyfop-methyl and quizalofop-ethyl in doses of 0,65, 0,24 and 0,14 kg/ha, respectively