Eficácia de herbicidas aplicados em área total ou na linha de plantio de cana-de-açúcar
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Data
2021-07-12
Autores
Copetti, Bárbara Marcasso
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Universidade Estadual Paulista (Unesp)
Resumo
A aplicação de herbicida na cultura da cana-de-açúcar é realizada sobre um colchão de palha de 10 a 12 t ha-1, proveniente da colheita mecanizada. Em algumas áreas, o afastamento da palha da linha da cana tem por finalidade diminuir a incidência de cigarrinhas das pastagens (Mahanarva fimbriolata), uma vez que não mais se beneficiará do abrigo propiciado pela palha. Entretanto, a densidade de palha nas entrelinhas do canavial será maior porque recebe a palha retirada da linha. Nesse cenário, é importante entender se a palha depositada na entrelinha constitui em barreira física capaz de conter o desenvolvimento das plantas daninhas. Também é necessário entender a resposta dos herbicidas quando aplicados em área total ou apenas na linha descoberta da cultura. Por isso, dois trabalhos foram realizados em épocas diferentes (época seca e chuvosa) cujo objetivo foi estudar a eficácia de controle proporcionada por herbicidas quando aplicados em área total e localizados na linha de cultivo em soqueiras de cana-de-açúcar, após a remoção da palha oriunda da colheita sobre a linha da cultura. Para isso, foram semeadas nas áreas sob a palha da cana-de-açúcar as seguintes plantas daninhas: Urochloa decumbens, Digitaria horizontalis, Panicum maximum, Merremia aegyptia, Ipomoea hederifolia e Ricinus communis. Antes da semeadura foi realizada a retirada da palha das parcelas e, então, as sementes foram dispostas em faixas por toda a parcela (linha e entrelinha da cana) e, posteriormente, a palha foi recolocada na parcela e foi feito o afastamento da palha da linha da cana, garantindo o acúmulo de palha na entrelinha da cultura. Na sequência, foi feita a aplicação em área total e na linha da cana nas parcelas. O delineamento do primeiro trabalho, instalado na época seca, foi em blocos casualizados com 16 tratamentos em quatro repetições, arranjados em esquema fatorial 7x2 com duas testemunhas adicionais. No segundo, instalado na época úmida, o delineamento foi em blocos casualizados com 12 tratamentos em quatro repetições, arranjados em esquema fatorial 5x2 com duas testemunhas adicionais. No primeiro fator alocou-se as associações de herbicidas e no segundo fator as modalidades de aplicação dos herbicidas: em área total e localizada sobre a linha da cultura após remoção da palha. No primeiro experimento, em todos os tratamentos obteve-se controles maiores que 90,31% das espécies infestantes, enquanto no segundo experimento os tratamentos começaram a apresentar diminuição no controle a partir dos 90 DAA. Em relação à modalidade de aplicação, em ambos a aplicação de herbicida na linha da cana proporcionou controle menor quando comparado à aplicação na área total da parcela. Conclui-se, dessa forma, que mesmo com a prática do afastamento e acúmulo de palha na entrelinha da cana-de-açúcar, independente da época de aplicação de herbicida no ano, a aplicação em área total ainda é a melhor forma de controle das plantas daninhas.
The application of herbicide in the sugarcane crop is carried out on a straw mattress of 10 to 12 t ha-1, from mechanized harvesting. In some areas, the removal of straw from the sugarcane line is intended to reduce the incidence of leafhoppers in pastures (Mahanarva fimbriolata), since it will no longer benefit from the shelter provided by the straw. However, the density of straw between the rows of the cane field will be higher because it receives the straw removed from the row. In this scenario, it is important to understand whether the straw deposited between the rows constitutes a physical barrier capable of containing the development of weeds. It is also necessary to understand the response of herbicides when applied in the total area or just in the uncovered line of the crop. Therefore, two studies were carried out at different times (dry and rainy season) whose objective was to study the control effectiveness provided by herbicides when applied in total area and located in the cultivation line in sugarcane stumps, after removal of straw from the harvest on the crop line. For this purpose, the following weeds were sown in the areas under sugarcane straw: Urochloa decumbens, Digitaria horizontalis, Panicum maximum, Merremia aegyptia, Ipomoea hederifolia and Ricinus communis. Before sowing, the straw was removed from the plots and then the seeds were arranged in strips throughout the plot (cane row and row) and then the straw was replaced in the plot and the straw was removed from the plot. sugarcane line, ensuring the accumulation of straw between the crop lines. Subsequently, application was made in the total area and in the line of the sugarcane in the parcels. The design of the first work, installed in the dry season, was in randomized blocks with 16 treatments in four replications, arranged in a 7x2 factorial scheme with two additional checks. In the second, installed in the wet season, the design was in randomized blocks with 12 treatments in four replications, arranged in a 5x2 factorial scheme with two additional checks. In the first factor the associations of herbicides were allocated and in the second factor the modalities of application of the herbicides: in total area and located on the crop line after straw removal. In the first experiment, in all treatments, controls greater than 90.31% of the weed species were obtained, while in the second experiment, the treatments began to show a decrease in the control after 90 DAA. In relation to the modality of application, in both, the application of herbicide in the sugarcane line provided less control when compared to the application in the total area of the plot. It is concluded, therefore, that even with the practice of removal and accumulation of straw between the rows of sugarcane, regardless of the time of herbicide application in the year, application in the total area is still the best way to control the weeds.
The application of herbicide in the sugarcane crop is carried out on a straw mattress of 10 to 12 t ha-1, from mechanized harvesting. In some areas, the removal of straw from the sugarcane line is intended to reduce the incidence of leafhoppers in pastures (Mahanarva fimbriolata), since it will no longer benefit from the shelter provided by the straw. However, the density of straw between the rows of the cane field will be higher because it receives the straw removed from the row. In this scenario, it is important to understand whether the straw deposited between the rows constitutes a physical barrier capable of containing the development of weeds. It is also necessary to understand the response of herbicides when applied in the total area or just in the uncovered line of the crop. Therefore, two studies were carried out at different times (dry and rainy season) whose objective was to study the control effectiveness provided by herbicides when applied in total area and located in the cultivation line in sugarcane stumps, after removal of straw from the harvest on the crop line. For this purpose, the following weeds were sown in the areas under sugarcane straw: Urochloa decumbens, Digitaria horizontalis, Panicum maximum, Merremia aegyptia, Ipomoea hederifolia and Ricinus communis. Before sowing, the straw was removed from the plots and then the seeds were arranged in strips throughout the plot (cane row and row) and then the straw was replaced in the plot and the straw was removed from the plot. sugarcane line, ensuring the accumulation of straw between the crop lines. Subsequently, application was made in the total area and in the line of the sugarcane in the parcels. The design of the first work, installed in the dry season, was in randomized blocks with 16 treatments in four replications, arranged in a 7x2 factorial scheme with two additional checks. In the second, installed in the wet season, the design was in randomized blocks with 12 treatments in four replications, arranged in a 5x2 factorial scheme with two additional checks. In the first factor the associations of herbicides were allocated and in the second factor the modalities of application of the herbicides: in total area and located on the crop line after straw removal. In the first experiment, in all treatments, controls greater than 90.31% of the weed species were obtained, while in the second experiment, the treatments began to show a decrease in the control after 90 DAA. In relation to the modality of application, in both, the application of herbicide in the sugarcane line provided less control when compared to the application in the total area of the plot. It is concluded, therefore, that even with the practice of removal and accumulation of straw between the rows of sugarcane, regardless of the time of herbicide application in the year, application in the total area is still the best way to control the weeds.
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Saccharum officinarum, Resíduos de culturas agrícolas, Botânica econômica