Avaliação do controle de plantas daninhas por herbicidas em calda armazenada utilizando índices espectrais

Abstract

The storage of phytosanitary product spray during application occurs in the field for several reasons. Staying in the spray tank can influence effectiveness. Understanding the timing and factors for use in these conditions requires evaluation methodologies for decision making. In this sense, this work was carried out with the objective of evaluating the effect of storing spray solutions containing a herbicide mixture on the effectiveness of weed control through visual methods and remote sensing techniques. For this, two experiments were set up in a subdivided plot scheme with 4 randomized blocks. In the first, 4 herbicide sprays were in the plots, in the subplot 8 aging seasons and in the subsubplot 7 efficacy evaluations. In the second, 4 doses of a herbicide spray were allocated in the plots, 8 aging seasons in the subplot and 7 efficacy evaluations in the subplot. The data were submitted to analysis of variance with the outcomes for significant interactions; Pearson's correlation of visual scores was applied with the indices: Triangular Green Index (TGI) in the first experiment and Normalized Difference Vegetation (NDVI) in the second experiment was applied. For both experiments, there was no significant interaction for the aging of herbicide sprays, which favors their storage; the adjustment of the regression models for the TGI index in the correlation with the visual grades was decreasing along the evaluations, while the NDVI index was increasing; for the second experiment, the dose between half and maximum recommended by the manufacturers of the mixture glyphosate + dicamba was sufficient to control weeds. The evaluated herbicide sprays were stored without prejudice to effectiveness; better results were obtained in evaluating the chemical control by the TGI index in the initial phase after herbicide application, while the NDVI performed better at the end under different plant biomass conditions.