Navegando por Autor "Theodoro, José Gabriel Castilho"

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    Efeito de rainfastness nas misturas de herbicidas auxínicos com glyphosate aplicados em plantas com dois estágios diferentes de desenvolvimento
    (Universidade Estadual do Norte do Paraná, 2020-07-31) Theodoro, José Gabriel Castilho; Gandolfo, Marco Antônio; https://orcid.org/0000-0003-2314-3752; http://lattes.cnpq.br/5560552732033631; Gandolfo, Marco Antônio; https://orcid.org/0000-0003-2314-3752; http://lattes.cnpq.br/5560552732033631; Oliveira, Rone Batista de; https://orcid.org/0000-0002-3071-4827; http://lattes.cnpq.br/2379804514613050; Gandolfo, Ulisses Delvaz; https://orcid.org/0000-0001-6131-0289; http://lattes.cnpq.br/8520084377953959
    The occurrence of weeds in agricultural areas is one of the main challenges faced by farmers, with herbicides being the main tool for controlling these plants. Environmental factors, such as the occurrence of rain immediately after spraying the herbicides, can decrease their control efficiency. The objective of this work was to evaluate the effect of simulated rain of 10 mm on the rainfastness of the mixtures of the herbicides 2,4-D + glyphosate and dicamba + glyphosate in the control of the species Amaranthus spp., Commelina benghalensis L., and Glycine max L. at two stages of development (initial stage and final stage). The herbicides used in the mixtures were: dimethylamine salt (DMA806 BR® 670 g L⁻¹), glyphosate potassium salt (Roundup Transorb R®, 480 g L⁻¹), and dicamba (Atectra®, 480 g L⁻¹). The mixtures were sprayed with TTI11002 nozzles (300 kPa) and with a constant application rate of 150 L ha⁻¹. After application, the plants were submitted to simulated rain of 10 mm at different times: 5 minutes (immediate rain); 15 minutes; 30 minutes; 45 minutes; 120 minutes; and 240 minutes. The rain was performed by a rain simulator equipped with three TK-SS stainless steel floodjet deflector nozzles at a vertical distance of 2.0 m from the top of the plants. The pH, density, and surface tension of the two mixtures were also determined. For each mixture, an experiment was carried out in a factorial arrangement of 3 × 2 × 6 (species × stages × rain time) with six replications. Control assessments were visual and performed at 7, 14, 21, 28, 35, and 42 days after application (DAA). Control was determined using the ALAM scale (1974). The occurrence of rain after application of the 2,4-D + glyphosate mixture reduced the control of Glycine max L. and Commelina benghalensis L. Amaranthus spp. plants showed very good control after a 30-minute period without rain. The occurrence of rain after the application of the dicamba + glyphosate mixture reduced the control of Amaranthus spp. and Commelina benghalensis L. Glycine max L. plants showed excellent control regardless of the period of rainfall after application. It is concluded that the reduction in the efficiency of the mixtures with the herbicides 2,4-D + glyphosate and dicamba + glyphosate is dependent on the time of occurrence of rain after application, the weed species, and the stage of development of the plants.