Avaliação de biótipos de leiteiro com suspeita de resistência a herbicidas inibidores da ALS e Protox

Abstract

Resumo -Objetivou-se com o presente trabalho avaliar a confirmação da ocorrência de resistência de biótipos de leiteiro, oriundos de Rondônia e do Rio Grandes do Sul a herbicidas com diferentes mecanismos de ação, bem como determinar a dose dos herbicidas necessária para redução de 50% na massa seca das plantas (GR50) e para o controle de 50% das plantas de cada unidade experimental (C50). Para tanto foi instalado um experimento em casa de vegetação, em blocos casualizados, com quatro repetições. Os herbicidas utilizados foram: imazethapyr, chlorimuron-ethyl, cloransulam-methyl, saflufenacil, fomesafen e carfentrazone-ethyl. As doses utilizadas foram: 0; 0,5; 2; 8; 16; 32 e 64 vezes a dose comercial. As variáveis avaliadas foram controle do leiteiro aos 07, 14, 21 e 28 dias após a aplicação dos tratamentos (DAT) e também, aos 28 DAT determinou-se a massa seca das plantas. O biótipo do Rio Grande do Sul mostrou sensibilidade aos herbicidas testados, já o de Rondônia apresentou resistência cruzada aos inibidores de ALS (imazethapyr, chlorimuron e cloransulam) e suscetível aos inibidores de PROTOX (carfentrazone, fomesafen e saflufenacil). Palavras-chaves: Euphorbia heterophylla L., Glycine max, plantas daninhasAbstract -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, 1 Recebido para publicação em 28/07/2014 e aceito em 28/06/2015.

MULTIPLE RESISTANCE OF Sagittaria montevidensis BIOTYPES TO ACETOLACTATE SYNTHASE AND PHOTOSYSTEM II INHIBITING HERBICIDES

“…There was no adjustment of the data to the model for the herbicide penoxsulam because the lower rates used in the experiment (0.03x and 1x) provided around 90% control of SAGMO. Prigol et al (2014) reported that Euphorbia biotypes suspected to be resistant to PROTOX and ALS inhibiting herbicides also did no showed data adjustments to the model used in implementing cloransulam-methyl on the weed assessed agreeing with the results of this study.…”

Low level resistance of wild poinsettia biotypes to glyphosate and alternative chemical control

“…Crossed resistance of wild poinsettia has already been shown by other studies MEROTTO, 1999;XAVIER et al, 2013;PRIGOL et al, 2014). Resistance to ALS-inhibiting herbicides was found for chemical groups of imidazolinones, sulfonylureas and triazolopyrimidines (PRIGOL et al, 2014), as observed by this study.…”

“…Crossed resistance of wild poinsettia has already been shown by other studies MEROTTO, 1999;XAVIER et al, 2013;PRIGOL et al, 2014). Resistance to ALS-inhibiting herbicides was found for chemical groups of imidazolinones, sulfonylureas and triazolopyrimidines (PRIGOL et al, 2014), as observed by this study. Unsatisfactory control of biotypes 20.2 and 21.1 by ALS-inhibiting herbicides, associated with low resistance to the herbicide glyphosate, may even hinder its management in soybean crops since their mutual and abusive use may submit wild poinsettia plants to high selection pressure (TREZZI et al, 2011;COSTA;RIZZARDI, 2014).…”

Arg-128-Leu target-site mutation in PPO2 evolves in wild poinsettia (Euphorbia heterophylla) with cross-resistance to PPO-inhibiting herbicides

“…Regardless of the conditions adopted by different laboratories, the resistance levels and crossresistance patterns primarily depend on the population and its resistance mechanism. Euphorbia heterophylla resistant to PPO inhibitors is widespread across Brazilian agricultural areas, especially in the south (Prigol et al 2014;Trezzi et al 2006). Here, we demonstrate that R PPO is resistant to at least three chemical groups of PPO inhibitors (diphenyl ether, pyrimidinedione, and N-phenylphthalimid).…”