Resumo -O método químico de controle de plantas daninhas é o mais utilizado na cultura da cana-de-açúcar, sendo necessários estudos que englobem o efeito destes herbicidas sobre o desenvolvimento de mudas pré-brotadas de cana de açúcar (MPB). O objetivo deste trabalho foi avaliar o efeito da aplicação dos herbicidas ametryn, clomazone, hexazinone + diuron, metribuzin, sulfentrazone e tebuthiuron, isolados e em associação com saflufenacil, no crescimento inicial de mudas pré-brotadas de variedades de cana-de-açúcar. O ensaio foi conduzido em casa de vegetação em delineamento experimental inteiramente casualizado, em esquema fatorial 14 x 2, sendo 14 tratamentos herbicidas e 2 épocas de aplicação após o plantio (3 e 10 DAP), com quatro repetições. Os herbicidas, em suas doses recomendadas, foram aplicados aos 3 ou 10 dias após o transplante das mudas (DAP) das variedades: RB 86 7515, RB 85 5156, RB 96 6928 e RB 97 5201. A porcentagem de fitotoxicidade foi avaliada aos 7, 15, 30 e 60 dias após a aplicação dos tratamentos (DAT). A estatura das plantas, área foliar e biomassa seca da parte aérea foram avaliadas aos 60 DAT. Os herbicidas causaram impacto diferenciado em função das variedades e época de aplicação, todavia, na última avaliação, houve baixa fitotoxicidade na maioria das avaliações. Para a RB 867515 a aplicação dos herbicidas tanto aos 3 como aos 10 DAP foi segura, já para as variedades RB 966928 e RB 975201 a aplicação aos 3 DAP causou menor fitotoxicidade, enquanto, para a RB 855156 foi aos 10 DAP. Conclui-se que as variedades diferem quanto à fitotoxicidade aos herbicidas avaliados, sendo a RB 867515 a mais tolerante e a associação saflufenacil + clomazone e clomazone provocaram maior fitotoxicidade, dentre os tratamentos, nas variedades e épocas estudadas. Palavras-chaves: controle químico; Saccharum officinale; toxicidade Abstract -The chemical weed control is the most used in sugarcane culture, and studies covering the effects of these herbicides on the development of pre-sprouted seedlings of sugarcane. The objective of this work was to evaluate the effect of the herbicides ametryn, clomazone, hexazinone + diuron, metribuzin, sulfentrazone and tebuthiuron isolated and in association with saflufenacil in the initial growth of pre-sprouted seedlings of sugarcane varieties at different times of application.1 Recebido para publicação em 08/12/2016 e aceito em 22/02/2017.
The plants commonly known as morning glory belong to the genera Ipomoea and Merremia and are among the most important weeds in Brazil. Greenhouse studies were conducted in 2016/2017 to compare the susceptibility of different morning glory species-Ipomoea quamoclit, I. nil, I. hederifolia, I. triloba, Merremia aegyptia, and M. cissoides to soil-applied herbicides and to evaluate the effectiveness of these herbicides after periods of drought. In the first experiment, to evaluate the efficacy of each herbicide at pre-emergence stage, a fully randomized 6 (doses) x 6 (species) factorial experimental design with six replicates was used. The herbicides tebuthiuron (3,200; 1,600; 800; 400; 200 and 0.0 g a.i ha-1), amicarbazone (2,100; 1,050; 750; 375; 187 and 0.0 g a.i ha-1), sulfentrazone (1,200; 600; 300; 150 75 and 0.0 g a.i ha-1), mesotrione (240; 120; 60; 30; 15 and 0.0 g a.i ha-1), saflufenacil (200; 100; 50; 25; 12 and 0.0 g a.i ha-1), and imazapic (360; 180; 90; 45; 22 and 0.0 g a.i ha-1) were applied. Ipomoea hederifolia, I. nil, and I. quamoclit were most susceptible to saflufenacil; I. triloba and M. cissoides were most susceptible to tebuthiuron; and M. aegyptia was most susceptible to amicarbazone. Therefore, the best herbicide treatment depends on the species of morning glory. In the second experiment, to determine the effectiveness of herbicides after periods of drought, the treatments were arranged, for each herbicide, in a fully randomized 6 x 5 factorial design with four replicates, six species of morning glory, and five sowing times after periods of drought (0, 15, 30, 45, and 60 days after application (DAA) of the herbicides) relative to the application of the amicarbazone (1,050 g a.i ha-1), imazapic (180 g a.i ha-1), mesotrione (120 g a.i ha-1), saflufenacil (100 g a.i ha-1), sulfentrazone (600 g a.i ha-1), and tebuthiuron (1,600 g a.i ha-1). Herbicide effectiveness after periods of drought began to decrease after 15 days for saflufenacil; 30 days for imazapic, mesotrione, and tebuthiuron; 45 days for amicarbazone; and 60 days for sulfentrazone. Preemergence application of amicarbazone and sulfentrazone exhibited consistent efficacy during the drought periods, satisfactorily controlling the species of morning glory.
Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence Influência da profundidade de semeadura e da quantidade de palha de cana-de-açúcar na emergência de Chloris polydactyla e Eleusine indica e controle por herbicidas aplicados em pré-emergência AbstractThe objective of this study was to evaluate the effect of the sowing depth and amount of sugarcane straw on the soil on the emergence of Chloris polydactyla ('capim-branco') and Eleusine indica (Indian goosegrass) and to determine the efficacy of herbicides applied pre-emergence in the control of these species under different straw amount and rainfall regime conditions. The experiments were conducted in a completely randomized design with four replications. In the first experiment, the effects of six sowing depths (0.5, 1, 2, 4, 8, and 10 cm) and six sugarcane straw amounts (0, 1, 2, 4, 8 and 10 t ha -1 ) were assessed on the emergence of Indian goosegrass and 'capim-branco' in a 6 x 6 factorial arrangement. In the second experiment, the efficacy in the control of these species was evaluated for one control without herbicide and five treatments (indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin, and indaziflam + tebuthiuron) applied pre-emergence over four straw amounts (0, 1, 2, and 4 t ha -1 ) in a 6 x 4 factorial arrangement. This experiment was evaluated under two rainfall regimes in separate experiments (simulation of 20 mm of rainfall 1 or 10 days after herbicide application). The 'capim-branco' showed a marked reduction in emergence beginning at 2 t ha -1 of straw and a 2 cm sowing depth. For the Indian goosegrass, the decline in emergence mainly occurred beginning at 4 t ha -1 of straw and a 4 cm sowing depth. Only some of the Indian goosegrass plants emerged at the greater sowing depths (8 and 10 cm) and straw amounts (8 and 10 t ha -1 ), whereas no emergence of the 'capimbranco' was observed under these conditions. The treatments with sowing at a 1 cm depth and with 0, 1, 2, and 4 t ha -1 of straw provided the highest emergence percentage for the species. Application of the herbicide indaziflam alone was the only ineffective treatment for the control of the weeds regardless of the amount of straw and the water regime used. We concluded that the increase in the sowing depth and the amount of straw significantly reduced the emergence of the species and that the presence of straw and the dry period interfered with the herbicide efficacy. Key words: Indian goosegrass. 'Capim-branco'. Sugarcane. Straw. ResumoObjetivou-se com esse trabalho avaliar o efeito da profundidade de semeadura e da quantidade de palha de cana-de-açúcar sobre o solo na emergência de Chloris polydactyla (capim-branco) e Eleusine indica (capim pé-de-galinha), assim como determinar a eficácia de herbicidas aplicados em pré-emergência no controle dessas espécies, sob diferentes quantidades de palha e regimes de precipitação pluvial. Os experimentos foram real...
A utilização de herbicidas visando a dessecação de culturas agrícolas, especialmente na produção de grãos, trata-se de uma prática recorrente, pois possibilita a antecipação da colheita, o que pode resultar em ganhos financeiros e/ou vantagens em relação a logística de produção. Diante do exposto o presente trabalho teve como objetivo avaliar a eficácia e viabilidade de dois métodos de dessecação da cultura do feijão, através dos seguintes objetivos específicos: (a) Analisar a qualidade dos grãos de feijão após a dessecação e (b) A viabilidade econômica da antecipação da colheita. Para tal realizou-se um experimento em campo em delineamento inteiramente casualizado (DIC), com 6 tratamentos: diquat (450 g i.a./ ha-1), glufosinato de amônio (550 g i.a./ha-1), paraquat (450 g i.a./ha-1), glifosato (960 g i.a./ ha-1), dessecação em terreno e testemunha. Os parâmetros avaliados foram: Qualidade da Dessecação; Velocidade da Dessecação; Viabilidade de Custo da Dessecação, Porcentagem de Germinação, Comprimento do Hipocótilo e Peso de 100 sementes. O herbicida diquat apresentou o melhor desempenho no que tange a antecipação da colheita, 29 dias, sendo que o valor da saca nesse período era de R$ 450,00, em contrapartida o glifosato culminou no menor período de antecipação da colheita, apenas 7 dias. O paraquat foi o tratamento que melhor preservou as características fisiológicas das sementes
Aims: This study aimed to evaluate the control of Eleusine indica Gaertn. and Digitaria insularis (L.) Fedde through the combination of soil cover with green manure straw and herbicides applied in pre-emergence. Study Design: Each weed species was evaluated in different experiments. The experiments were set up in a greenhouse in a completely randomized design and arranged in a factorial scheme (5×4)+2, with four replications. Place and Duration of Study: Center of Agricultural Sciences, São Paulo, Brazil, from May 2019 to May 2020. Methodology: Seeds of Digitaria insularis and Eulesine indica were sown at a depth of 1 cm from the soil surface. Then, the pots were watered, and the straw of Cajanus cajan, Sorghum bicolor, Crotalaria juncea, Crotalaria spectabilis, and Crotalaria breviflora was deposited on the surface. The pre-emergence herbicides trifluralin (900 g ai ha−1), pendimethalin (1200 g ai ha−1), clomazone (1000 g ai ha−1), and s-metolachlor (1920 g ai ha−1) were applied one day after the weed seeds were sown. The percentage of weed control was evaluated at 10, 20, and 30 days after emergence (DAE). The plant shoot was cut at 30 DAE and the weight of dry biomass was determined. The control without herbicide and with soil cover crop and no herbicide and no soil cover were also evaluated. Results: Sorghum bicolor, Cajanus cajan, and Crotalaria breviflora were the most effective in controlling Eleusine indica when no herbicide was applied. Only Sorghum bicolor showed a satisfactory control of Digitaria insularis without the use of chemical management (above 80%). The association of pre-emergence herbicides with soil cover showed high control of weeds. Conclusion: The results showed that the association between chemical and cultural methods is an effective alternative to control Eulesine indica and Digitaria insularis.
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