Evaluation of wild poinsettia biotypes with suspicion of resistant to ALS and Protox inhibitors herbicides

Abstract

The objective of the present study was to evaluate the confirmation of occurrence of wild poinsettia resistance, coming from Rondônia and Rio Grande do Sul, to herbicides with different mechanisms of action, and to determine the dose of herbicides required for 50% reduction in the dry mass of plants (GR₅₀) and for the control of 50% of these plants in each experimental unit (C₅₀). Therefore, an experiment was conducted over greenhouse conditions, in randomized block design with four replications. The herbicides used were: imazethapyr, chlorimuron-ethyl, cloransulam-methyl, saflufenacil, fomesafen, and carfentrazone-ethyl. The doses used were: 0; 0.5; 2; 8; 16; 32 and 64 times the commercial dose. The variables evaluated were control of wild poinsettia at 7, 14, 21, and 28 days after treatments (DAT), and also at 28 DAT was determined the dry mass of plants. The Rio Grande do Sul biotype showed sensitivity to the herbicides tested, at meantime the Rondônia biotype presented cross-resistance to ALS-inhibitors (imazethapyr, chlorimuron, and cloransulam), and susceptibility to PROTOX-inhibitors (carfentrazone, fomesafen, and saflufenacil).