Management of Sagittaria montevidensis resistant to ALS and PSII mechanisms of action with saflufenacil associated with different adjuvants

Abstract

This study aimed at evaluating the effective rates of saflufenacil and adjuvants for controlling Sagittaria montevidensis (sagitaria) populations resistant to ALS and photosystem II (PS II) inhibitor herbicides, and phytotoxicity to the Epagri 108 rice cultivar. Two biotypes of sagitaria (SAGMO) were tested: SAGMO 10 – with cross resistance to ALS inhibitor herbicides, and SAGMO 32 - with multiple resistance to ALS and PSII inhibitor herbicides. Treatments consisted of three different saflufenacil rates: 75; 112.5 and 150 g a.i. ha^-1 with the addition of adjuvants Dash HC^® (0.5% v/v); Assist^® (1% v/v); Iharaguen-S^® (0.5% v/v) or Veget’Oil^® (1 L ha^-1). Evaluation focused on arrowhead control, phytotoxicity and shoot dry weight (DMAP) of the Epagri 108 rice cultivar. The saflufenacil rates of 75 to 150 g a.i. ha^-1 did not provide efficient control for both sagitaria biotypes. Addition of the adjuvants Veget’Oil^®, Assist^® or Iharaguen-S^® to saflufenacil did not alter the control efficiency of herbicide resistant sagitaria populations. The Epagri 108 cultivar presented selectivity to saflufenacil until 150 g a.i. ha^-1, without reducing DMAP. The phytotoxicity caused by saflufenacil, to the rice plants was minimal with the addition of Veget’Oil^®. Rice plants shoot dry matter was not affected, regardless of the adjuvant used. Saflufenacil can be used until the rate of 150 g a.i. ha^-1 associated with adjuvant Veget’Oil^® for the management of sagitaria in rice fields, but it does not provide adequate control of biotypes SAGMO 10 and SAGMO 32.