RESPONSE OF Sporobolus indicus TO VARYING DOSES OF CLETHODIM: PHYTOTOXICITY AND CONTROL EFFICACY

Abstract

Capeta grass is an invasive grass that is difficult to control in Brazilian pastures, due to its high reproductive capacity, adaptation to adverse conditions and resistance to conventional practices. The herbicide Clethodim has been used to control grasses, but its effectiveness varies according to application conditions. Within this conjecture, the present study aimed to evaluate the efficacy of the herbicide Clethodim in the control of Sporobolus indicus, analyzing its effects on the development and regrowth of the plant. The experiment was conducted at UEMASUL, in a completely randomized design with four treatments (0, 112.5, 225, 375.5 mL ha⁻¹) and five replications. The application was performed with a knapsack sprayer. At 15 days after application, phytotoxicity (EWRC scale) and control efficacy (ALAM scale) were evaluated, with descriptive analysis of the data. An increase in phytotoxicity was observed with the increase of the doses, ranging from mild (T2) to strong (T4). However, control was limited: T2 presented 40% (ineffective), while T3 and T4 reached 48% and 42% (regular control). The best performance occurred at T3, but without proportional gain at higher doses, indicating possible saturation or tolerance of the species. Clethodim promoted only partial control of S. indicus, being insufficient when used alone. The results indicate the need for integrated management strategies, including dose adjustments, association with other methods and consideration of environmental conditions for greater efficacy.