Controle químico de junquinho com resistência cruzada aos herbicidas inibidores da acetolactato sintase (ALS) com diferentes mecanismos de ação

Abstract

The aim of this work was to evaluate the alternative chemical control of Cyperus iria with cross-resistance to ALS-inhibiting herbicides. There were conducted two experiments arrenged in completely randomized design, with four replications. The experiment I consisted of resistant (CYPIR-R), susceptible (CYPIR-S) biotypes and two rice cultivars. The herbicide treatments were: 1) control; 2) imazethapyr (106 g a.i. ha-¹); 3) (imazapyr + imazapic – 73,5 + 24,5 g a.i. ha-¹); 4) bentazone (960 g a.i. ha-¹); 5) propanil (3600 g a.i. ha-¹); 6) bentazone + imazamox (750 + 35 g a.i. ha-¹); 7) bentazone + imazamox (750 + 35 g a.i. ha-¹) + (imazapyr + imazapic – 73,5 + 24,5 g a.i. ha-¹); 8) bentazone (960 g a.i. ha-¹) + (imazapyr + imazapic – 73,5 + 24,5 g a.i. ha-¹); 9) glyphosate (1080 g a.e. ha-¹); 10) propanil + triclopyr (3800 g a.i. ha-¹ + 400 g a.e. ha-¹). The experiment II followed the same procedures, added rates of propanil + triclopyr (1900 g a.i. ha-¹ + 200 g a.e. ha-¹; 2280 g a.i. ha-¹ + 240 g a.e. ha-¹; 2660 g a.i. ha-¹ + 280 g a.e. ha-¹; 3040 g a.i. ha-¹ + 320 g a.e. ha-¹; 3420 g a.i. ha-¹ + 360 g a.e. ha-¹; 3800 g a.i. ha-¹ + 400 g a.e. ha-¹). The variables studied were: visual control at seven, 14, 21 and 28 days after treatments (DAT) and shoot dry mass (SDM) at 28 DAT. The herbicides used, except for ALS-inhibiting in isolation, were efficient in controlling CYPIR-R.