ABSTRACT Conyza sp. was the first glyphosate-resistant weed in Brazil’s soybean crop. Synthetic auxin herbicides followed by paraquat has improved the hairy fleabane control, and time of day of herbicide application can affect the control efficacy. There are no studies reporting the effects of the application time of synthetic auxins in tank-mixture with paraquat, or in sequential application with paraquat at two growth stages of hairy fleabane, applied at different times of the day. The herbicides were sprayed during the morning and night. 2,4-D applied alone was more effective applied during the day, while dicamba efficiency was higher when applied at night in the rosette stage. The mixture of 2,4-D and paraquat was more efficient when applied during the night. Tall hairy fleabane were more effectively controlled by dicamba + paraquat as well as any synthetic auxin followed by paraquat. When herbicides were applied at night, efficiency was slightly higher.

ABSTRACT Corn kernels or seeds that remain after harvest can germinate and become a troublesome volunteer plant where bean crops are grown. The objective of this study was to evaluate the effect of time of emergence of volunteer corn on growth parameters, photosynthetic pigments and chlorophyll fluorescence in bean plants, competition for soil and light and light resources. The study was conducted in completely randomised experimental design, in 2×2×2+2 factorial scheme with four replications, involving two bean cultivars in competition with volunteer corn, emerging seven days before and simultaneously with beans, besides the partitioning of the competition by soil and light, just light and two controls without competition. We measured the levels of chlorophyll a, b, total and carotenoids, parameters related to chlorophyll fluorescence and bean growth variables. Volunteer corn was more competitive when it emerged seven days before the beans. When competition was established by light resource, there was a reduction in photosynthetic pigments and morphological variables of the bean plants. When competition by soil and light resources occurred, there was a reduction not only in photosynthetic pigments and morphological characteristics, but also in the chlorophyll fluorescence variables. There were significant correlations between the growth variables of the bean plants and chlorophyll fluorescence, which makes it an important analytical tool for quantifying the stress caused by weeds.

RESUMO Com a intensificação dos sistemas de criação de suínos, no Brasil, a produção de dejetos cresceu consideravelmente, provocando problemas de contaminação da água e solo, devido à sua aplicação inadequada. A compostagem de dejetos líquidos de suínos surge como alternativa para evitar ou reduzir impactos negativos, principalmente para produtores com limitação de áreas físicas, ou que visem ao aumento do número de animais na unidade de produção. Objetivou-se avaliar o efeito de doses de compostagem de dejetos líquidos de suínos nas características agronômicas e produtividade de grãos de painço. O delineamento experimental foi em blocos ao acaso, com quatro repetições e cinco tratamentos, os quais consistiram em testemunha sem adubação, testemunha com adubação mineral (NPK) e doses de compostagem de dejetos líquidos de suínos (4,0 Mg ha-1; 8,0 Mg ha-1; 12,0 Mg ha-1). A compostagem de dejetos líquidos de suínos promoveu incremento na produção de massa seca, número de grãos por planta e produtividade de grãos de painço, em relação às testemunhas sem adubação e com aubação mineral. A resposta do painço para produtividade, nas doses de 8,0 Mg ha-1 e 12,0 Mg ha-1, mostrou-se superior à das testemunhas sem adubação e com adubação mineral recomendada para a cultura, sendo que esta apresenta máxima eficiência agronômica para a dose de 8,0 Mg ha-1.

ABSTRACT With the intensification of pig farming systems, in Brazil, the production of swine waste has increased considerably, leading to water and soil contamination, due to its improper release. Pig slurry composting is an alternative that can be used in order to avoid or reduce negative impacts, especially for producers with physically limited farm areas, or those who intend to increase the number of animals in their production units. This study aimed at evaluating the influence of pig slurry compost doses on the agronomic characteristics and grain yield of proso millet. A randomized blocks design experiment was installed with four replications and five treatments: control without fertilization, control with mineral fertilizer (NPK) and pig slurry compost doses (4.0 Mg ha-1, 8.0 Mg ha-1; 12.0 Mg ha-1). The pig slurry composting increased the dry matter yield, number of grains per plant and grain yield of proso millet, when compared to the control with or without mineral fertilizer. The proso millet yield, at the doses of 8.0 Mg ha-1 and 12.0 Mg ha-1 of pig slurry, was superior than for both the control without fertilization and the control with the recommended mineral fertilizer, with the latter reaching a maximum agronomic efficiency at the dose of 8.0 Mg ha-1.

RESUMO Durante a aplicação de inseticidas, na cultura da soja, forma-se um gradiente vertical de deposição do produto ao longo do dossel, resultando em dificuldades no controle dos percevejos que se encontram nos terços médio e inferior das plantas. Objetivou-se avaliar a sistematicidade do inseticida tiametoxam em diferentes estágios da cultura da soja, utilizando-se o percevejo marrom como bioindicador da ação do inseticida. O estudo combinou locais de aplicação do produto (terço inferior, médio e superior) e de infestação dos percevejos, em cinco fases do estágio fenológico (R2, R3, R4, R5.2 e R6) da cultura da soja. Nos estágios R2 e R5.2, as plantas apresentaram translocação acropetal do produto, sendo o efeito mais pronunciado no estágio R2. Nos estágios R3, R4 e R6, não houve translocação suficiente do produto para o controle dos percevejos. Em todos os estágios, nos tratamentos com exposição direta (mesmo local de infestação e pulverização), houve controle satisfatório dos percevejos.

ABSTRACT During the application of pesticides on soybean fields, a vertical deposition gradient of the product can occur throughout the canopy, resulting in difficulties for controlling stink bugs that are in the middle and lower thirds of plants. This study aimed at evaluating the systemicity of thiamethoxam insecticide in different soybean phenological stages, using brown stink bugs as bioindicators of the pesticide efficacy. The study combined product application sites (lower, middle and upper third) and stink bugs infestation areas at five soybean phenological stages (R2, R3, R4, R5.2 and R6). For the R2 and R5.2 stages, plants presented acropetal translocation of the product, being the effect more evident in the R2 stage. For the R3, R4 and R6 stages, the product translocation was not sufficient for controlling the stink bugs. In all stages, for treatments with direct exposure (same infestation and spraying place), stink bugs were satisfactorily controlled.