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The contamination of agricultural soils by microplastics (MPs) has significant implications for herbicide efficacy and soil health. This study investigates the effects of MPs on critical processes such as the sorption, desorption, and degradation of herbicides, highlighting their influence on these compounds’ mobility, persistence, and bioavailability. MPs interact with herbicides through sorption mechanisms, often reducing the availability of these compounds for weed control by retaining them on their surfaces. This sorption not only limits the immediate efficacy of herbicides but also alters their desorption process, resulting in a prolonged release into the soil environment. Additionally, MPs can inhibit microbial activity involved in herbicide degradation, increasing the time degradation of the half-life of these substances and extending their persistence in the environment. These processes collectively enhance the risks of bioaccumulation and environmental contamination. Understanding these interactions is essential for developing strategies to mitigate the impacts of MPs on herbicide performance and promote sustainable agricultural practices.

The interaction of herbicides in the nitrogen cycle and their consequences on soil health and agricultural production are essential topics in agronomic research. In this systematic review article, we have synthesized recent studies on this subject. The results revealed that the indiscriminate use of herbicides can have negative effects on vital processes in the nitrogen cycle, such as reduced enzymatic activity and microbial respiration. Moreover, herbicides alter the soil microbial composition, affecting nitrogen cycling-related activities. Symbiotic nitrogen fixation is also impaired, resulting in a reduction in the population of nitrogen-fixing bacteria and a decrease in the availability of this nutrient in the soil. These effects compromise soil fertility and the release of nitrogen to plants. Therefore, sustainable agricultural practices must be adopted, considering nitrogen cycling efficiency and the preservation of soil and natural resources. This understanding is crucial for guiding appropriate management strategies aimed at minimizing the negative effects of herbicides on the nitrogen cycle and ensuring soil health and agricultural productivity.

The presence of weeds in the sunflower crop is one of the main factors linked to the low increase in productivity of this crop, and to determine the most appropriate management of weeds, it is essential to carry out a diagnosis through the phytosociological survey. The objective of this study was to assess the influence of chemical control on the phytosociological community of weeds in three areas cultivated with sunflower in the Parecis region (Brazil). The areas were treated with 2,4-D + glyphosate for desiccation; S-metolachlor was used for pre-emergence control in the three areas; meanwhile, sulfentrazone and flumioxazin were applied only in one area; and, finally, clethodim was applied for post-emergence weed management. Sampling was carried out at two different times, in the initial and pre-harvest stages (at 35 and 100 days after the emergence of the crop, respectively), using a quadrate, in which weeds were identified and quantified to determine the frequency, relative frequency, density, relative density, abundance, relative abundance, importance index, and similarity index between areas and times. Seventeen weed species were found in the sunflower crop (70.6% dicot and 29.4% monocotyledonous) in the two seasons, grouped into nine botanical families, with Poaceae being the most diverse family. The dicots Tridax procumbens and Acanthospermum hispidium were present in low frequency only in the initial stages of development of the sunflower crop. The weeds with the highest importance index values in the initial and pre-harvest stages were Euphorbia hirta (104 and 91%) and Bidens pilosa (45 and 66%, respectively), both belonging to the dicots group. These two species were present in the two evaluated periods and in the three experimental areas, demonstrating that there was a similarity index between them with values above 93%. These results of the phytosociological study may contribute to determining more efficient management strategies for weed chemical control in the sunflower crop.

The sunflower (Helianthus annuus L.) is an oleaginous plant that shows high suitability for cultivation in Brazil. However, the performance of the crop is influenced by factors such as weed interference, mainly because of the few selective herbicide options. Thus, the objective of this study was to evaluate weed control and selectivity of four pre-emergent herbicides applied to two sunflower cultivars in sandy and clayey soils. Two field experiments were conducted in a randomized block design with a 2 × 6 factorial scheme, two cultivars (CF 101 and M 734) and six treatments with S-metolachlor (1920 g a.i. ha−1), sulfentrazone (150 g a.i. ha−1), flumioxazin (40 g a.i. ha−1), and trifluralin (1780 g a.i. ha−1) and two controls, one with weeding and the other without weeding and without herbicide application, in soils with contrasting textures (sandy and clayey). No injury symptoms were observed in both cultivars, regardless of soil texture. The cultivar M 734 exhibited the highest values of the agronomic parameters evaluated. The treatment with flumioxazin provided control of more than 90% of the weeds in clayey soil and more than 64% in sandy soil. The yield of both cultivars was lower in the sandy soil. Thus, all herbicide treatments were selective for both cultivars tested, since they did not interfere with sunflower grain yield.

Tomatoes are often grown in proximity to other crops such as grain, which can increase their susceptibility to herbicide drift and subsequent crop. Therefore, the objective of this study was to evaluate the effect of simulated herbicide drift on tomato plants. Treatments were established in a 10 × 3 + 1 factorial scheme using a completely randomized design with four replications. The first factor consisted of ten herbicides, while the second was composed by three subdoses (1/4, 1/16, and 1/32) along with an additional treatment without herbicide application. The herbicides 2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, and isoxaflutole caused injury levels greater than 20% or reductions in plant biomass greater than 30% at the lowest subdose. Increasing the subdose resulted in a corresponding increase in injury level and a reduction in biomass. Tomato exposed to hexazinone, diuron, nicosulfuron, and diquat at a subdose of 1/64 exhibited low injury levels and biomass reductions. However, at other subdoses, these herbicides caused significant plant damage. Among the herbicides tested, the auxinic herbicides, particularly dicamba, presented a higher risk for the tomato crop. The documentation and description of the visual symptoms caused by each herbicide applied to tomatoes will aid producers to identify drift problems in the field.

Yellow nutsedge (Cyperus esculentus L.) is cultivated worldwide due to its agricultural and biotechnological potential. In Brazil, it is considered a weed, and we lack studies on its cultivation. Overcoming tuber dormancy is crucial for propagation. This study aimed to assess various dormancy-breaking methods’ effects on tubers and initial plant development. The treatments included gibberellic acid immersion, ethylene exposure, purple nutsedge extract immersion, temperature conditioning, scarification, and bud cutting, along with a control. Scarification resulted in the shortest emergence time (0.904 days) and fastest emergence speed (5.092 tubers/day). Plant development was minimally affected by the treatments, with scarification and gibberellic acid (100 mg L−1) resulting in taller plants (1.19–1.23 times higher than the control). The conditioning at 4 °C and 70 °C proved to be less effective in breaking dormancy. Purple nutsedge extract immersion and bud cutting hindered plant growth. Scarification emerged as the most effective dormancy-breaking method. This study provides insights into the cultivation of yellow nutsedge in Brazil, highlighting the effectiveness of scarification in improving tuber germination and the early growth stages of plants.

Biodegradation studies of herbicides applied to the soil alone and in a mixture are required since herbicides are often used in combinations to control weeds. When herbicides are applied in mixtures, interactions may affect their environmental fate. Thus, the objective of this study was to evaluate the distribution of extractable residue, bound residue, biodegradation, and mineralization of diuron, hexazinone, and sulfometuron-methyl when applied alone and in a mixture in two agricultural soils. Biometric flasks filled with two types of soil (clay and sandy) collected from an area cultivated with sugarcane and treated with 14C-radiolabeled solutions of the herbicides were incubated for 70 d. More 14C–CO2 was released when sulfometuron-methyl and hexazinone were applied in a mixture compared to when applied alone. Being used in a combination did not affect the mineralization of diuron. The soil texture directly influenced the mineralization, bound residue, and extractable residue of the three herbicides. The percentage of extractable residue decreased over time for all herbicides. Hexazinone and sulfometuron-methyl had the highest residue extracted on sandy soil when applied alone. Diuron showed the highest percentage of bound residue. The degradation of the three herbicides was higher in the clay soil regardless of the mode of application, which is related to the higher potential of the bacterial community in the clay soil to mineralize the herbicides.

Brazil stands out in the world for being one of the largest producers and consumers of common beans and cowpeas. However, the cultivation of this agricultural species is exposed to competition with weeds for water, light and nutrients. One of the management methods for weed control is the use of pre-emergent herbicides. Although pre-emergence herbicides are beneficial in controlling weeds, it is important to know the dynamics of these products in the soil, especially their residual effect. Two experiments were carried out to assess the tolerance of bean genotypes to the pre-emergent herbicide S-metolachlor in two Brazilian soils. Bean genotypes have differential tolerance to S-metolachlor when grown in soils with different characteristics. The Vigna spp. were the most affected by S-metolachlor, especially the red Adzuki. Plant growth was more sensitive when grown in sandy soil for most species. Total chlorophyll content was not affected for most genotypes in the two soils evaluated. The differential tolerance of the genotypes in both soils confirms the potential of S-metolachlor to cause damage to the bean crop, especially in sandy soil. The S-metolachlor was efficient in controlling sourgrass and selective to the bean cultivars (Pérola and Talismã) in both soils evaluated. Alexandergrass behaved differently in the soils evaluated, showing tolerance to the application of S-metolachlor when in Oxisol and sensitivity in Ultisol.

The aim of this study was to evaluate the role of rock powder in the phytoremediation of Inceptisol (sandy loam) and Oxisol (clay) contaminated with diuron. Canavalia ensiformis plants were grown in pots containing 7.5 kg of both soils, with doses of 0, 4, and 8 t ha−1 of rock powder. Diuron was applied in doses ranging from 875 to 3500 g of a.i. ha−1. The injury level was assessed at 42 days after emergence (DAE), and the morphological characteristics were assessed at 120 DAE. After phytoremediation, the soil was analyzed using High Performance Liquid Chromatography (HPLC) and by bioassay with cucumber (Cucumis sativus) to detect diuron. In Oxisol, no injury was observed, and the rock powder (4 t ha−1) benefited the growth of C. ensiformis regardless of the dose of diuron. In Inceptisol, the greatest reduction in growth occurred with 3500 g a.i. ha−1 of diuron and 8 t ha−1 of rock powder. Diuron was detected after 120 days in Inceptisol with 2625 g a.i. ha−1 without rock powder and 3500 g a.i. ha−1 with and without rock powder. The cucumber bioindicator in Inceptisol showed an increase in the level of injury as the dose of diuron increased. The rock powder favored the growth of C. ensiformis and was able to phytoremediate high concentrations of diuron, which supports the safe use of this herbicide for weed control, minimizing environmental impacts.

Sulfometuron-methyl is a broad-spectrum herbicide, used throughout Brazil; however, its environmental impacts in biochar (BC) amended soils is not fully understood. Biochar is known to enhance soil quality but can also have undesired effects such as altering the bioavailability and behavior of herbicides. Microbial communities can degrade herbicides such as sulfometuron-methyl in soils; however, they are known to be affected by BC. Therefore, it is important to understand the tripartite interaction between these factors. This research aimed to evaluate the sorption-desorption and biodegradation of sulfometuron-methyl in Amazonian soils amended with BC, and to assess the effects of the interactions between BC and sulfometuron-methyl on soil bacterial communities. Soil samples were collected from field plots amended with BC at three doses (0, 40 and 80 t ha−1) applied ten years ago. The herbicide sorption and desorption were evaluated using a batch equilibrium method. Mineralization and biodegradation studies were conducted in microcosms incubated with 14C-sulfometuron-methyl for 80 days. Systematic soil sampling, followed by DNA extraction, quantification (qPCR) and 16S rRNA amplicon sequencing were performed. The presence of BC increased the sorption of the herbicide to the soil by 11% (BC40) and 16% (BC80) compared to unamended soil. The presence of BC also affected the degradation of 14C-sulfometuron-methyl, reducing the mineralization rate and increasing the degradation half-life times (DT50) from 36.67 days in unamended soil to 52.11 and 55.45 days in BC40 and BC80 soils, respectively. The herbicide application altered the bacterial communities, affecting abundance and richness, and changing the taxonomic diversity (i.e., some taxa were promoted and other inhibited). A tripartite interaction was found between BC, the herbicide and soil bacterial communities, suggesting that it is important to consider the environmental impact of soil applied herbicides in biochar amended soils.

A dificuldade no manejo de plantas daninhas presentes no girassol cresce em concomitância com a expansão da cultura, principalmente em virtude das poucas opções de herbicidas seletivos. Nesse sentido, o objetivo dessa pesquisa foi avaliar a seletividade das cultivares de girassol Olisun 3 e ADV 5504 a herbicidas aplicados em pré-emergência da cultura em condições de campo. O delineamento experimental utilizado foi feito em blocos ao acaso com esquema fatorial 2 × 6 em quatro repetições, sendo dois cultivares (Olisun 3 e ADV 5504) e seis tratamentos herbicidas (sulfentrazone 600 g i.a. ha-1, s-metolachlor 1920 g i.a. ha-1, trifluralin 1780 g i.a. ha-1, prometryn 1000 g i.a. ha-1, flumioxazin 40 g i.a. ha-1 e testemunha sem aplicação de herbicidas). Sintomas de fitointoxicação (média de 6,92 e 10,96%) nas plantas foram observados 7 DAA. A cultivar ADV 5504 apresentou valores superiores de fitointoxicação (14,75%) para o herbicida s-metolachlor. A Olisun 3 exibiu o maior diâmetro de caule (23,32 mm) quando foi utilizado o prometryn. Para altura de inserção de capítulo, a ADV 5504 apresentou valor superior (1,16 m) e o herbicida s-metolachlor não afetou tal variável, com valor (1,15 m) estatisticamente semelhante à testemunha. A produtividade dos dois cultivares foi semelhante estatisticamente (1891,28 e 2025,91 kg ha-1). Todos os herbicidas pesquisados foram seletivos para ambas as cultivares Olisun 3 e ADV 5504, não interferindo na produtividade final de grãos do girassol. Portanto é possível recomendar esses produtos para o controle das plantas daninhas nessa cultura.

The objective of this study objective was to evaluate the selectivity of pre-emergence applications the herbicide clomazone cotton seeds treated with dietholate and zinc acetate. The 4 x 2 factorial arrangement was adopted (4 seed treatment methods and 2 clomazone dosages), distributed in a randomized block design with 4 repetitions. In treatments where dietholate and zinc acetate were applied, rates of 0.4 kg ha-1 and 8 ml per kg of seeds were used respectively. The clomazone rates used refer to 0.8 and 1.0 kg ha- 1. The cotton cultivar used was the Fiber Max 966 LL. Independent of treatment, all seeds were treated with tiametoxam insecticide and fludioxonil + metalaxyl-M fungicide at rates of 2.24 and 0.08 + 0.03 g per kg of seed, respectively, to control pests early and limit losses caused by pathogens in germination and seedling emergence. Dietholate and zinc acetate treatment had greater initial effect on cotton plants at 21, 30 and 45 days after application. In phytointoxication symptoms were observed for treatment with dietholate and zinc acetate during the evaluation periods. Seeds treated with dietholate, dietholate and zinc acetate or zinc acetate alone provided a higher number of bolls and seed cotton production compared to the control.

O objetivo do trabalho foi identificar a comunidade infestante de plantas daninhas em áreas de pastagens no município de Nova Olímpia, MT. O levantamento foi realizado nos meses de fevereiro e março de 2012, em que foram analisadas 10 propriedades, tendo cada uma 10 parcelas de 25 m². Nas parcelas foram realizadas a contagem e identificação das espécies daninhas. Os dados foram analisados por meio de cálculo de densidade, frequência, abundância, densidade relativa, frequência relativa, abundância relativa, índice de valor de importância (IVI) e índice de similaridade. Foram encontradas 31 espécies de plantas daninhas distribuídas em 16 famílias botânicas, sendo, Asteraceae (4), Papilionoideae (4) Poaceae (4) e Malvaceae (3) as mais representativas em números de espécies. As espécies mais ocorrentes foram Sida carpinifolia (IVI = 38,50), Sida spp. (IVI = 36,26), Chenopodium ambrosiodies (IVI = 21,06) e Sida cordifolia (IVI = 19,71). Foi encontrada similaridade expressiva entre as propriedades sendo que as propriedades 6 e 8 se destacaram com índice de similaridade de 78,26%.

The infestation of weeds is a major biotic factor in the agroecosystem of cane sugar that may interfere in development and crop productivity. This study aimed to evaluate the potential for leaching and residual effects of the herbicide amicarbazone in contrasting soils. Samples were Quartzarenic Neosol (NR – sandy texture) and Red Latosol (LR – clay texture). For the leaching potential, after application of herbicide amicarbazone (NR 1.05 kg ha-1 and LR 1.40 kg ha-1), layers of 0, 20, 40, 60, 80 and 100 mm of water were applied to soil columns. We evaluated the residual effect after the permanence of the herbicide in soil of clay texture and sandy for periods of 0, 25, 50, 75 and 100 days after application (DAA) of amicarbazone (0, 1.05, 1.40 kg ha-1) treatments. The amicarbazone started showing high leaching from the 60 mm layer of water in sandy texture soils, evidencing a shorter residual effect. In clay soil, slides from 20 to 80 mm of water reduced the biomass until a depth of 5-10 cm, with the use of this herbicide. Based on these results, we conclude that the amicarbazone showed higher leaching and lower residual effects in sandy soil. The residual effect of amicarbazone was prolonged as the content of clay and organic matter present in the soil increased. A infestação de plantas daninhas é um dos principais fatores bióticos presentes no agroecossistema da cana-de-açúcar que têm a capacidade de interferir no desenvolvimento e na produtividade da cultura. O trabalho teve como objetivo avaliar o potencial de lixiviação e efeito residual do herbicida amicarbazone utilizado na cultura da cana-de-açúcar, em solos contrastantes. Para tanto, utilizaramse amostras de Neossolo Quartzarênico (NR – textura arenosa) e Latossolo Vermelho (LR – textura argilosa). No potencial de lixiviação, após a aplicação do herbicida amicarbazone (NR 1,05 kg ha-1 e LR 1,40 kg ha-1), foram aplicadas lâminas de 0, 20, 40, 60, 80 e 100 mm de água nas colunas de solos. Avaliou-se o efeito residual, após a permanência do herbicida no solo de textura argilosa e arenosa, por períodos de 0, 25, 50, 75 e 100 dias após a aplicação (DAA) de amicarbazone (0; 1,05; 1,40 kg ha-1) nos tratamentos. O amicarbazone apresentou elevada lixiviação a partir da lâmina de 60 mm de água em solos de textura arenosa, constatando menor efeito residual. Em solo argiloso, lâminas de 20 a 80 mm de água reduziram a biomassa até a profundidade de 5-10 cm, com o uso deste herbicida. Com base nos resultados, conclui que o amicarbazone apresentou elevada lixiviação e menor efeito residual em solo arenoso. O efeito residual do amicarbazone foi prolongado conforme o aumento do teor de argila e matéria orgânica presente no solo.

Objective to evaluate the leaching of the hexazinone and admixed with diuron, in soil of contrasting textures, in soil columns under different rainfall. The following soils were used: Red Latosol - LV, of clay texture and Quartzarenic Neosol - NQ, sandy texture. The experimental units were constituted by PVC columns filled with soil, at rates of hexazinone (LV - 375 g ha -1 and NQ - 225 g ha -1 ) and hexazinone + diuron (LV - 396 + 1,404 g ha -1 and NQ - 264 + 936 g ha-1 ). The factorial 6 x 6 in randomized block design, with three replications was adopted. Factor A evaluated the precipitation of 0, 20, 40, 60, 80, and 100 mm; factor B analyzed the depths (0-5, 5-10, 10-15, 15-20, 20-25 and 25-30 cm) column. Posteriorly the rain simulation the columns were longitudinally opened and along these were sown Cucumis sativus. Independent of soil texture, the hexazinoneand mixture hexazinone + diuron did not exceed 10-15 cm layer of soil, the layer of 0 mm. The hexazinone and diuron + hexazinone mixture showed phytotoxicity of species bioindicator in the layer of 20-25 cm in LV, and reaching up to 25-30 cm in NQ, the greatest layer simulated. It was concluded that there was no difference in leaching potential of hexazinone when mixture with diuron in soils with distinct textures, however the clay textural composition, organic matter content of soil and rainfall influenced the leaching. = Objetivou-se avaliar a lixiviação do hexazinone isoladamente e da mistura com o diuron, em solos de texturas contrastantes, em colunas de solos sob diferentes precipitações. Utilizou-se um Latossolo Vermelho – LV, de textura argilosa e um Neossolo Quartzarênico – NQ, de textura arenosa. As unidades experimentais foram constituídas por colunas de PVC preenchidas com solos, nas doses de hexazinone (LV - 375 g ha -1 e NQ - 225 g ha -1 ) e hexazinone + diuron (LV - 396 + 1.404 g ha -1 e NQ - 264 + 936 g ha -1 ). Adotou-se o esquema fatorial 6 x 6 no delineamento em blocos casualizados, com três repetições. No fator A foram avaliadas às precipitações de 0, 20, 40, 60, 80 e 100 mm, e o fator B as profundidades (0-5, 5-10, 10-15, 15-20, 20-25 e 25-30 cm) das colunas. Posteriormente a simulação da chuva as colunas foram abertas longitudinalmente e ao longo dessas foram semeados Cucumis sativus . Independente da textura do solo, o hexazinone e a mistura hexazinone + diuron não ultrapassaram a camada de 10-15 cm do solo, na lâmina de 0 mm. O hexazinone e a mistura hexazinone + diuron apresentaram fitotoxicidade da espécie bioindicadora na camada de 20-25 cm em LV, e chegando até 25-30 cm no NQ, na maior lâmina simulada. Concluiu-se que não houve diferença no potencial de lixiviação do hexazinone quando em mistura com o diuronnos solos com texturas distintas, entretanto a composição textural argilosa, teor de matéria orgânica do solo e precipitaçõespluviométricas influenciou a lixiviação.

Weed reduce yield and quality of cotton fiber, because this culture has slow growth in the early stages of its cycle. Thus, the objective of this present work to evaluate weed control and selectivity of herbicides applied pre- and post-emergence, in density cotton. Ten treatments with herbicides fomesafen, clomazone, diuron, prometryne, trifloxysulfuron-sodium, pyrithiobac-sodium, S-metolachlor and fluazifop-butyl, applied in mixture or sequential, and a control without herbicide were evaluated. The experiments were performed simultaneously with the same treatments in district of Deciolândia, municipality of Diamantino - MT, with a variety Fabermax 966 and in municipality of Sapezal - MT, with a variety DP 604. During thedevelopment of culture, phytointoxication and control levels at 7, 14 and 28 days after application (DAA); stand and height at 28 DAA; number of apples at 145 DAA and productivity of cotton in seed at 160 DAA were evaluated. Independent of the varieties of cotton, all treatments caused phytointoxication early, only treatments 4, 5 and 6 of experiment 1 did not differ from the control in productivity, but the other did not affect productivity, stand, plant height, number of bolls, and provide effective control of weeds, being selective in cotton. The mixture fomesafen + prometryne applied in pre-emergence, was also selective varieties of cotton Fabermax 966 and DP 604, however fomesafen is not registered for the crop. = As plantas daninhas reduzem a produtividade e a qualidade da fibra do algodoeiro, pelo fato desta cultura apresentar crescimento lento nos primeiros estádios de seu ciclo. Assim, objetivou-se com o presente trabalho avaliar o controle de plantas daninhas e a seletividade de herbicidas, aplicados em pré e em pós-emergência, no algodão adensado. Foram testados 10 tratamentos com os herbicidas fomesafen, clomazone, diuron, prometryne, trifloxysulfuron-sodium, pyrithiobac-sodium, S-metolachlor e fluazifop-butil, aplicados em mistura ou sequencial, além da testemunha sem aplicação de herbicida. Osexperimentos foram realizados simultaneamente com os mesmos tratamentos, no distrito de Deciolândia, município de Diamantino - MT, com a variedade Fabermax 966 e no município de Sapezal - MT, com a variedade DP 604. Durante o desenvolvimento da cultura, foram realizadas avaliações de fitointoxicação e níveis de controle aos 7, 14 e 28 dias após a aplicação (DAA); estande e altura aos 28 DAA; número de maçãs aos 145 DAA e produtividade do algodão em caroço aos160 DAA. Independentes das variedades de algodoeiro, todos os tratamentos avaliados causaram fitointoxicações iniciais,apenas os tratamentos 4, 5 e 6 do experimento 1 não diferiram da testemunha na produtividade, porém os demais não afetaramnegativamente a produtividade, estande, altura de plantas, número de maçãs, além de proporcionar controle efetivo de plantas daninhas, sendo seletivos ao algodoeiro. A mistura fomesafen + prometryne aplicada em pré-emergência, foi seletiva as variedades de algodoeiro Fabermax 966 e DP 604, entretanto o fomesafen não é registrado para a cultura.

A cultura do algodão tem grande importância econômica e social, visto que é a fibra mais utilizada no setor têxtil. Contudo, apresenta alta sensibilidade a plantas daninhas e há poucos herbicidas seletivos à cultura. Neste contexto objetivouse com este trabalho avaliar a seletividade de herbicidas aplicados em pré-emergência na cultura do algodão. Os herbicidas alachlor, S-metolachlor, diuron, prometryne, trifluralin e oxyfluorfen foram aplicados isoladamente e em misturas sobre a variedade FMT-701, nas localidades de Diamantino-MT e Campos de Júlio-MT. O delineamento experimental utilizado foiem blocos casualizados com 16 tratamentos e 4 repetições. Para avaliar a seletividade foram realizadas avaliações de alturaaos 36, 66 e 150 dias após a aplicação (DAA), fitointoxicação aos 14, 21, 29 e 36 DAA, estande aos 21 e 49 DAA, número de maçãs aos 141 DAA e produtividade do algodão em caroço aos 193 DAA. Os resultados indicaram que grande parte dos tratamentos causou injúrias na fase inicial da cultura e alguns tratamentos também proporcionaram menor altura de plantas em determinadas avaliações. Verificou-se ainda que os tratamentos não proporcionaram diferença significativa no estande de plantas, no número de maçãs e nem na produtividade de algodão em caroço, evidenciando que todos os tratamentos avaliados podem ser utilizados no manejo de plantas daninhas.The culture of the cotton has great economic and social importance, because it is the fiber more frequently used in the textile section. However, the crop has high sensibility to weed and there are few selective herbicides for this crop. In this context, the objective of this study was to evaluate the selectivity of applied herbicides in pre-emergency on the culture of the cotton. The herbicides alachlor, S-metolachlor, diuron, prometryne, trifluralin and oxyfluorfen were separately applied and in mixtures with the variety FMT-701, in the places of Diamantino-MT and Campos de Júlio-MT. The experimental delimitation used was randomized blocks with 16 treatments and 4 repetitions. To evaluate the selectivity of the evaluations the height of the plants were observed 36, 66 and 150 days after the application (DAA), phytotoxicity to 14, 21, 29 and 36 DAA, stand to 21and 49 DAA, number of apples to 141 DAA and productivity of the cotton in pit to 193 DAA. The results indicate that great part of the treatments provided damage during the initial phase of development and some treatments also resulted in the reduced height of plants at certain periods of evaluation. It was verified that the treatments did not provide significant difference in the stand of plants, in the number of apples and nor in the cotton productivity in pit, evidencing that all the appraised treatments can be used for weed control.

Objetivou-se avaliar a seletividade de herbicidas para plantas de pinhão manso. O trabalho foi dividido em dois experimentos realizados em casa de vegetação e campo. Nos dois experimentos foram avaliados os mesmos tratamentos químicos, dispostos em delineamento experimental de blocos casualizados, com cinco repetições. Estudaram-se dezoito herbicidas: bentazon (0,72 kg i.a. ha-1), atrazine (4,00 kg i.a. ha-1), nicosulfuron (0,06 kg i.a. ha-1), oxyfluorfen (1,44 kg i.a. ha-1), isoxaflutole (0,15 kg i.a. ha-1), sethoxydim (0,37 kg i.a. ha-1), glyphosate + imazethapyr (0,53 + 0,09 kg i.a. ha-1), imazethapyr (0,10 kg i.a. ha-1), mesotrione (0,19 kg i.a. ha-1), acifluorfen + bentazon (0,25 + 0,60 kg i.a. ha-1), glyphosate (1,80 kg i.a. ha-1), imazamox (0,04 kg i.a. ha-1), diuron (3,20 kg i.a. ha-1), ametryn (3,00 kg i.a. ha-1), amicarbazone (1,40 kg i.a. ha-1), profoxydim (0,17 kg i.a. ha-1), bentazon + imazamox (0,60 + 0,03 kg i.a. ha-1) e flumioxazin (0,03 kg i.a. ha-1), além das testemunhas (arranquio manual das plantas daninhas e sem manejo). Para a aplicação dos tratamentos em casa de vegetação, as plantas apresentavam de 4 a 6 folhas desenvolvidas, enquanto no experimento a campo apresentavam de 10 a 12 folhas desenvolvidas. Foram avaliados as notas de fitointoxicação, a altura da planta e o diâmetro do caule aos 7, 14, 21, 28 e 35 dias após a aplicação (DAA) dos herbicidas, em casa de vegetação e campo. Com base nos resultados obtidos concluiu-se que, independentemente do experimento, os tratamentos com glyphosate e diuron e ametryn causaram danos tóxicos severos às plantas de pinhão manso até aos 35 DAA. Por outro lado, evidenciou-se a seletividade dos herbicidas profoxydim, imazamox, mesotrione, acifluorfen + bentazon, sethoxydium, oxyfluorfen, sethoxydim e nicosulfuron, com potencial para utilização na cultura do pinhão manso.

O aumento no uso de herbicidas, aliado ao emprego inadequado dessas moléculas, aumentou também as preocupações com os riscos de contaminação ambiental, bem como com seus efeitos sobre os seres humanos e animais. Objetivou-se com este trabalho avaliar o potencial de lixiviação de herbicidas utilizados na cultura da cana-de-açúcar, em solos contrastantes. Utilizaram-se amostras de Neossolo Quartzarênico (NR - textura arenosa) e Latossolo Vermelho (LR - textura argilosa). Após a aplicação dos herbicidas ametryne (NR 1,60 kg ha-1 e LR 2,40 kg ha-1), clomazone (NR 0,90 kg ha-1 e LR 1,10 kg ha-1) e diuron (NR 1,60 kg ha-1 e LR 3,20 kg ha-1) foram irrigadas lâminas de 0, 20, 40, 60, 80 e 100 mm de água nas colunas de solos. Resultados indicam que o ametryne, em amostras NR apresentou movimentação até a camada de 5-10 cm quando aplicado lâminas de 20 e 40 mm de água. Evidenciou-se que o clomazone, independente do solo, não ultrapassou a camada de 0-5 cm nas lâminas de 0 e 20 mm de água e 5-10 cm de profundidade nas lâminas acima de 40 mm de água. Com lâminas de até 80 mm, o diuron lixiviou somente nas camadas de 0-5 cm de profundidade no LR. Conclui-se que o potencial de lixiviação do ametryne e diuron foi influenciado pela textura do solo juntamente com o teor de matéria orgânica, o mesmo não ocorreu para o clomazone.

Objetivou-se avaliar a lixiviação do hexazinone isoladamente e da mistura com o diuron, em solos de texturas contrastantes, em colunas de solos sob diferentes precipitações. Utilizou-se um Latossolo Vermelho – LV, de textura argilosa e um Neossolo Quartzarênico – NQ, de textura arenosa. As unidades experimentais foram constituídas por colunas de PVC preenchidas com solos, nas doses de hexazinone (LV - 375 g ha-1 e NQ - 225 g ha-1) e hexazinone + diuron (LV - 396 + 1.404 g ha-1 e NQ - 264 + 936 g ha-1). Adotou-se o esquema fatorial 6 x 6 no delineamento em blocos casualizados, com três repetições. No fator A foram avaliadas às precipitações de 0, 20, 40, 60, 80 e 100 mm, e o fator B as profundidades (0-5, 5-10, 10-15, 15-20, 20-25 e 25-30 cm) das colunas. Posteriormente a simulação da chuva as colunas foram abertas longitudinalmente e ao longo dessas foram semeados Cucumis sativus. Independente da textura do solo, o hexazinone e a mistura hexazinone + diuron não ultrapassaram a camada de 10-15 cm do solo, na lâmina de 0 mm. O hexazinone e a mistura hexazinone + diuron apresentaram fitotoxicidade da espécie bioindicadora na camada de 20-25 cm em LV, e chegando até 25-30 cm no NQ, na maior lâmina simulada. Concluiu-se que não houve diferença no potencial de lixiviação do hexazinone quando em mistura com o diuron nos solos com texturas distintas, entretanto a composição textural argilosa, teor de matéria orgânica do solo e precipitações pluviométricas influenciou a lixiviação.

As plantas daninhas reduzem a produtividade e a qualidade da fibra do algodoeiro, pelo fato desta cultura apresentar crescimento lento nos primeiros estádios de seu ciclo. Assim, objetivou-se com o presente trabalho avaliar o controle de plantas daninhas e a seletividade de herbicidas, aplicados em pré e em pós-emergência, no algodão adensado. Foram testados 10 tratamentos com os herbicidas fomesafen, clomazone, diuron, prometryne, trifloxysulfuron-sodium, pyrithiobac-sodium, S-metolachlor e fluazifop-butil, aplicados em mistura ou sequencial, além da testemunha sem aplicação de herbicida. Os experimentos foram realizados simultaneamente com os mesmos tratamentos, no distrito de Deciolândia, município de Diamantino - MT, com a variedade Fabermax 966 e no município de Sapezal - MT, com a variedade DP 604. Durante o desenvolvimento da cultura, foram realizadas avaliações de fitointoxicação e níveis de controle aos 7, 14 e 28 dias após a aplicação (DAA); estande e altura aos 28 DAA; número de maçãs aos 145 DAA e produtividade do algodão em caroço aos 160 DAA. Independentes das variedades de algodoeiro, todos os tratamentos avaliados causaram fitointoxicações iniciais,apenas os tratamentos 4, 5 e 6 do experimento 1 não diferiram da testemunha na produtividade, porém os demais não afetaram negativamente a produtividade, estande, altura de plantas, número de maçãs, além de proporcionar controle efetivo de plantas daninhas, sendo seletivos ao algodoeiro. A mistura fomesafen + prometryne aplicada em pré-emergência, foi seletiva as variedades de algodoeiro Fabermax 966 e DP 604, entretanto o fomesafen não é registrado para a cultura.

Objetivou-se com este trabalho avaliar a eficiência do bispyribac-sodium como maturador químico na cultura de cana-de-açúcar variedade RB86-7515. O ensaio foi realizado no delineamento em blocos casualizados, esquema com parcelas subdivididas e 4 repetições. Os tratamentos principais (maturadores) foram compostos por testemunha T1 (sem aplicação), T2, T3, T4, T5, T6 (20; 22; 24; 26 e 28 g ha-1 de bispyribac-sodium, respectivamente), T7 (15 g ha-1 de sulfometuron-methyl) e T8 (200 g ha-1 de ethyl-trinexapac). Os tratamentos secundários (subparcelas) corresponderam às épocas de amostragens aos 15; 30; 45; 60 e 75 dias após a aplicação (DAA) dos maturadores. Foram considerados os parâmetros fitointoxicação, produtividade de colmos, brotações laterais, sólidos solúveis (%Brix), pol da cana (%Pol) e açúcares totais recuperáveis (ATR em kg t-1). Os maturadores foram seletivos, onde não foi constatado fitointoxicação, independente do tratamento. Para as variáveis produtividade de colmos, Brix e ATR, não houve diferença significativa entre os diferentes tratamentos químicos. Elevados índices de brotações laterais foram obtidos nos tratamentos com o bispyribac-sodium aos 60 e 75 DAA. Todos os tratamentos com maturadores apresentaram incrementos significativos nos índices de Brix e Pol, sem que houvesse decréscimo na produtividade e induziram ao aumento no teor de ATR aos 45; 60 e 75 DAA, em relação à testemunha. O bispyribac-sodium, assim como o sulfometuron-methyl e ethyl-trinexapac foram eficientes na melhoria da qualidade tecnológica e apresentam potenciais para serem utilizados como maturadores na cultura da cana-de-açúcar.