Assessing the effect of using stored spray solutions in weed control efficacy by remote sensing

Abstract

The preparation and handling of herbicide spray mixtures, encompassing aspects like storage time and efficacy assessment methods, presents significant challenges in Brazilian agriculture. This study aimed to evaluate the impact of storage duration on the efficacy of spray mixtures containing dicamba and glyphosate, assessed through both remote sensing and conventional visual methods. The experiment was conducted in a randomized block design with four replicates, employing a split-plot scheme where plots received one of four herbicide spray mixturess, subplots eight storage periods, and sub subplots were assessed at seven distinct time points. Results indicated that glyphosate and dicamba spray mixtures maintained their herbicide efficacy even after being stored for up to 28 days. While efficacy varied across the tested rate, one specific combination (1,400 g ha^-1 glyphosate + 624 g ha^-1 dicamba) consistently provided the highest weed control. The peak efficacy of the glyphosate and dicamba mixture was observed at approximately fourteen days after application. Furthermore, the Normalized Difference Vegetation Index (NDVI) proved advantageous by providing earlier detection of new weed emergence compared to visual assessment.