Eficácia e seletividade de herbicidas isolados e em associações no cafeeiro
Data
2017-03-28
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Universidade Federal de Lavras
Resumo
O controle químico é o principal sistema de manejo de plantas daninhas na cafeicultura. Contudo, poucos herbicidas são eficientes e ao mesmo tempo seletivos ao cafeeiro. Em função disto, objetivou-se com este trabalho avaliar a eficiência sobre as principais plantas daninhas e a seletividade de herbicidas aplicados isoladamente e em associações no cafeeiro. Foram conduzidos dois experimentos em blocos ao acaso com quatro repetições no município de Carmo de Minas (MG) em plantio comercial da cultivar Catucaí Amarelo 20/15 para avaliação da eficácia do controle químico no manejo de plantas daninhas na entrelinha da cultura. Primeiramente, realizou-se a identificação das espécies de plantas daninhas por meio do perfil fitossociológico e, posteriormente, foram utilizadas aplicações em pós-emergência dos herbicidas saflufenacil (49 g ha -1 ) e pyrazosulfuron-ethyl (15 g ha -1 ) isolados e em associações com glyphosate (1080 g ha -1 ) ou sethoxydim (184 g ha -1 ), acrescidos de imazethapyr (100 g ha - 1 ) ou chlorimuron-ethyl (15 g ha -1 ) ou flumioxazin (120 g ha -1 ), respeitando a presença de mecanismos de ação diferentes em todas as associações. Foram realizadas avaliações de porcentagem de controle aos 14, 21 e 28 dias após aplicação (DAA) dos tratamentos. As espécies de plantas daninhas com maior importância foram: Digitaria horizontalis, Spermacoce latifolia, Amaranthus retroflexus, Commelina benghalensis e Bidens pilosa. De maneira geral, as associações entre herbicidas, principalmente as que continham glyphosate, se mostraram mais eficientes aos 28 DAA que as aplicações isoladas e em misturas contendo sethoxydim. O segundo experimento (de seletividade) foi conduzido no setor de cafeicultura do Departamento de Agricultura da Universidade Federal de Lavras (MG). Foram utilizadas mudas de cafeeiro cultivar Topázio MG 1190 em delineamento blocos ao acaso com quatro repetições, em que, foram aplicados diretamente sobre as folhas das mudas os herbicidas isolados saflufenacil (49 g ha -1 ), pyrazosulfuron-ethyl (15 g ha -1 ), imazethapyr (100 g ha -1 ), chlorimuron-ethyl (15 g ha - 1 ), iodosulfuron-methyl (3,5 g ha -1 ), metsulfuron-methyl (6 g ha -1 ) e sethoxydim (184 g ha -1 ), este último foi utilizado nas associações com os seis primeiros herbicidas. Foram avaliados os sintomas de fitotoxidade aos 7, 14, 21, 28, 35, 42 e 49 dias após a aplicação (DAA) e aos 65 DAA foram determinadas as características morfológicas. Observou-se que os herbicidas pyrazosulfuron-ethyl, sethoxydim isolados e a mistura entre ambos não causaram sintomas de fitotoxidez até os 49 DAA e não influenciaram nas características morfológicas e variáveis fisiológicas, ou seja, foram seletivos aos cafeeiros jovens. Sintomas de fitotoxidez leves foram observados nas aplicações isoladas de imazethapyr e chlorimuron-ethyl aos 7 DAA e de iodosulfuron-methyl aos 14 DAA. Com o uso desses três herbicidas, o caule apresentou menor diâmetro aos 65 DAA em relação à testemunha. As associações entre chlorimuron-ethyl e iodosulfuron-ethyl com sethoxydim promoveram sintomas de fitotoxidez aos 7 DAA e menor diâmetro de caule respectivamente. O saflufenacil isolado e em mistura com sethoxydim provocaram sintomas de fitotoxidez visual das folhas e menor diâmetro de caule em comparação à testemunha, já o metsulfuron-methyl foi responsável por fitotoxidez tardia e interferiu negativamente no crescimento dos cafeeiros jovens
Chemical control is the main weed management system in coffee cultivation. However, few herbicides are efficient and at the same time selective to coffee trees. The objective of this work was to evaluate the efficiency of herbicides applied alone and in associations and the their selectivity in the main weeds presents in coffee trees. Two experiments were carried out in randomized blocks with four replications in the municipality of Carmo de Minas (MG - Brazil) in a commercial plantation of the cultivar Catucaí Amarelo 20/15 to evaluate the effectiveness of chemical control in the weed management in the crop line. Firstly, the weed species were identified through the phytosociological profile and, afterwards, post-emergence herbicides saflufenacil (49 g ha -1 ) and pyrazosulfuron-ethyl (15 g ha -1 ) were isolated and in association with glyphosate (1080 g ha -1 ) or sethoxydim (184 g ha -1 ), plus imazethapyr (100 g ha -1 ) or chlorimuron-ethyl (15 g ha -1 ) or flumioxazin (120 g ha -1 ), respecting the presence of different mechanisms of action in all associations. Percentage of control evaluations were performed at 14, 21 and 28 days after application (DAA) of the treatments. The most important species of weeds were: Digitaria horizontalis, Spermacoce latifolia, Amaranthus retroflexus, Commelina benghalensise Bidens pilosa. In general, associations between herbicides, especially those containing glyphosate, were more efficient at 28 DAA than isolated applications and mixtures containing sethoxydim. The second experiment (of selectivity) was conducted in the coffee sector of the Department of Agriculture of the Federal University of Lavras. Coffee cultivars Topázio MG 1190 were used in a randomized complete block design with four replicates, in which the isolated herbicides saflufenacil (49 g ha -1 ), pyrazosulfuron-ethyl (15 g ha -1 ), imazethapyr (100 g ha -1 ), chlorimuron-ethyl (15 g ha -1 ), iodosulfuron-methyl (3.5 g ha -1 ), metsulfuron-methy (6 g ha -1 ), the latter was used in the associations with the first six herbicides. The phytotoxicity symptoms were evaluated at 7, 14, 21, 28, 35, 42 and 49 days after application (DAA), at 65 DAA the morphological characteristics and physiological variables of gas exchange were determined. It was observed that the herbicides pyrazosulfuron-ethyl, sethoxydim isolated and the mixture between them did not cause symptoms of phytotoxicity up to 49 DAA and did not influence the morphological characteristics and physiological variables, that is, they were selective to the young coffee plants. Mild phytotoxicity symptoms were observed in the isolated applications of imazethapyr and chlorimuron-ethyl at 7 DAA and iodosulfuron-methyl at 14 DAA. With the use of these three herbicides, the stem had a smaller diameter at 65 DAA than the plant without the application. The associations between chlorimuron-ethyl and iodosulfuron-ethyl with sethoxydim promoted phytotoxicity symptoms at 7 DAA and smaller stem diameter respectively. The saflufenacil isolated and in mixture with sethoxydim caused symptoms of visual phytotoxicity of the leaves and smaller diameter of stem in comparison to the control. Methsulfuron-methyl was responsible for late phytotoxicity, negatively interfering with growth and negatively affected the growth of young coffee trees.
Chemical control is the main weed management system in coffee cultivation. However, few herbicides are efficient and at the same time selective to coffee trees. The objective of this work was to evaluate the efficiency of herbicides applied alone and in associations and the their selectivity in the main weeds presents in coffee trees. Two experiments were carried out in randomized blocks with four replications in the municipality of Carmo de Minas (MG - Brazil) in a commercial plantation of the cultivar Catucaí Amarelo 20/15 to evaluate the effectiveness of chemical control in the weed management in the crop line. Firstly, the weed species were identified through the phytosociological profile and, afterwards, post-emergence herbicides saflufenacil (49 g ha -1 ) and pyrazosulfuron-ethyl (15 g ha -1 ) were isolated and in association with glyphosate (1080 g ha -1 ) or sethoxydim (184 g ha -1 ), plus imazethapyr (100 g ha -1 ) or chlorimuron-ethyl (15 g ha -1 ) or flumioxazin (120 g ha -1 ), respecting the presence of different mechanisms of action in all associations. Percentage of control evaluations were performed at 14, 21 and 28 days after application (DAA) of the treatments. The most important species of weeds were: Digitaria horizontalis, Spermacoce latifolia, Amaranthus retroflexus, Commelina benghalensise Bidens pilosa. In general, associations between herbicides, especially those containing glyphosate, were more efficient at 28 DAA than isolated applications and mixtures containing sethoxydim. The second experiment (of selectivity) was conducted in the coffee sector of the Department of Agriculture of the Federal University of Lavras. Coffee cultivars Topázio MG 1190 were used in a randomized complete block design with four replicates, in which the isolated herbicides saflufenacil (49 g ha -1 ), pyrazosulfuron-ethyl (15 g ha -1 ), imazethapyr (100 g ha -1 ), chlorimuron-ethyl (15 g ha -1 ), iodosulfuron-methyl (3.5 g ha -1 ), metsulfuron-methy (6 g ha -1 ), the latter was used in the associations with the first six herbicides. The phytotoxicity symptoms were evaluated at 7, 14, 21, 28, 35, 42 and 49 days after application (DAA), at 65 DAA the morphological characteristics and physiological variables of gas exchange were determined. It was observed that the herbicides pyrazosulfuron-ethyl, sethoxydim isolated and the mixture between them did not cause symptoms of phytotoxicity up to 49 DAA and did not influence the morphological characteristics and physiological variables, that is, they were selective to the young coffee plants. Mild phytotoxicity symptoms were observed in the isolated applications of imazethapyr and chlorimuron-ethyl at 7 DAA and iodosulfuron-methyl at 14 DAA. With the use of these three herbicides, the stem had a smaller diameter at 65 DAA than the plant without the application. The associations between chlorimuron-ethyl and iodosulfuron-ethyl with sethoxydim promoted phytotoxicity symptoms at 7 DAA and smaller stem diameter respectively. The saflufenacil isolated and in mixture with sethoxydim caused symptoms of visual phytotoxicity of the leaves and smaller diameter of stem in comparison to the control. Methsulfuron-methyl was responsible for late phytotoxicity, negatively interfering with growth and negatively affected the growth of young coffee trees.
Descrição
Dissertação de Mestrado defendida na Universidade Federal de Lavras
Palavras-chave
Controle químico, Plantas daninhas, Fitotoxidez
Citação
RODRIGUES, R. J. A. Eficácia e seletividade de herbicidas isolados e em associações no cafeeiro. 2017. 108 f. Dissertação (Mestrado em Agronomia - Fitotecnia) - Universidade Federal de Lavras, Lavras. 2017.