Abstract Background The presence of straw on the soil contributes to the management of weeds in several production systems and this understanding needs to be extended to annual crops under no-tillage systems. Objective This study aimed to evaluate the effect of covering the soil with 5 Mg ha-1 of maize straw on the germination and growth of Digitaria insularis, Conyza spp., Bidens pilosa, Amaranthus hybridus, Euphorbia heterophylla, and Eleusine indica. Methods For this purpose, completely randomized design was used with sixteen and third two replicates. Four assays were conducted between the years 2019 and 2020 in a greenhouse. The number of emerged seedlings was evaluated at 7, 14, and 21 days after sowing (DAS) and the shoot dry weight of the seedlings and the correlation between these variables were evaluated at 21 DAS. Results The covering of the soil with straw decreased the weed infestation of all species, except E. heterophylla, which presented positive correlation for the variables evaluated, denoting that the straw had no effect on the germination and growth of this species. The variables evaluated showed no correlation for the other species, denoting that the soil cover with straw suppress the germination and growth of plants. Conclusions We conclude that soil cover with 5 Mg ha-1 of maize straw is a tool for the control of weeds of the species evaluated, except E. heterophylla, and an option for integrated weed managements that can complement the residual effect of herbicides.

Abstract Background Dicamba is a herbicide with a moderate volatility profile and low dose effects on broadleaf weeds. Dicamba volatility can be strongly reduced with formulation technology and volatilization reducers. Objective This literature review on the dicamba herbicide aims to present new perspectives for its use, characteristics, volatilization risks, technologies to mitigate these risks and the main methods used to assess volatility in Brazil and worldwide. Conclusions Dicamba volatility can be mitigated with appropriate formulations and/or the use of adjuvants to reduce volatility. There has been an evolution in adapting new salts and technologies to reduce dicamba volatility. There are different methods of evaluating herbicide volatility, in particular, for the quantification of volatilized dicamba either in laboratory or field studies. Available methods can be fast and consistent and can assess volatilization from different surfaces, weather conditions and technologies to reduce volatilization. Under some conditions it is desirable to combine this method with bioassays.

Abstract The use of herbicides is essential to preserve the productivity and efficiency of crops in land use and growth factors. The general public has questioned the use of herbicides and pesticides, even when used rationally and following the procedures approved by regulatory agencies. It is essential to present accurate information about these products’ use and the risk associated with this use in this context. The mean dose and the Environmental Impact Quotient (EIQ) continuously decreased as a function of the year of release of new active ingredients with herbicidal action in Brazil, which indicates that the new products are more efficient and present lower risks to the environment, farmworkers and consumers. The mean EIQ for each herbicide application in soybean, maize, sugarcane, and cotton has decreased in Brazil. The proportion of herbicides in the number of applications has decreased compared to other classes of pesticides, except for cotton. The risk of products decreased over time, with continuous reductions in EIQ values per unit of the treated area; the EIQ values determined per production remained stable despite the increased complexity of pest management, which caused an increase in the number of applications.

Abstract Background: The use of commercial mix and tank mix with two or more herbicides is a widespread practice. However, despite its several possible benefits, little is known about its effect on the behavior of the molecules in the soil, which can increase or reduce the leaching potential of these molecules. Objective: This study evaluated the leaching potential of the herbicides diuron and sulfentrazone applied, using commercial mix and tank mix, in soils with different textures. Methods: The herbicides diuron (1,750 g ha-1) and sulfentrazone (875 g ha-1) were applied in three soils with different textures (clayey, medium, and sandy), using a commercial mix (Stone®) and a tank mix (Herburon 500 BR + Boral®). Subsequently, the treated soils were reconstituted in soil columns subjected to rainfall simulations with accumulated rainfall volumes of 40, 80, and 120 mm; the leached solutions were collected and analyzed by LC-MS/MS. Results: The results indicated a low descending movement of diuron in the three soils evaluated, when applied using commercial and tank mixes with sulfentrazone. Higher rainfall volumes (80 and 120 mm) were required to increase the diuron movement (≈20% of diuron applied). Sulfentrazone showed a high leaching potential in the soils, whereas the tank mix increased the leaching potential in sandy soil with the rainfall depths of 80 and 120 mm. Conclusions: The formulations did not affect the leaching potential of the herbicides in clayey and medium soil. However, the tank mix promoted greater leaching of the herbicides in the sandy soil when compared to the commercial mix.