Weed Control J 2026; 25: e202600893

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Ambrosia sp.: dose-response to glyphosate

DOI: 10.7824/wcj.2026;25:00893

Abstract:

Farmers have reported difficulty in controlling Ambrosia sp., observing uncontrolled plants in soybean fields even after post-emergence glyphosate application. The aim of this study was to evaluate the response of Ambrosia sp.to different rates of the herbicide glyphosate. The experiment was conducted in duplicate in a greenhouse at the Federal University of Santa Catarina, Curitibanos campus, between September and December 2022, using a completely randomized design with four replications. The treatments consisted of the application of nine increasing rates of the herbicide glyphosate (0; 93.75; 187.5; 375; 750; 1500; 3000; 6000; 12000 g ae ha⁻¹) when the Ambrosia sp. plants had between 4 to 8 true leaves. The following parameters were evaluated: height; percentage of control; and final above-ground dry matter mass. The results indicated growth inhibition, resulting in reduced height for rates starting from 1500 g ae ha⁻¹ in Ambrosia sp.. The evaluation of final above-ground dry matter mass showed a reduction between 73 and 95%, depending on the dose applied. Even the high rates used were not able to achieve excellent control (>90%) of the species.