Rice ( Oryza sativa L.) response and weed control from tank-mix applications of saflufenacil and imazethapyr

Abstract

Saflufenacil is a new herbicide for broadleaf weed control in various crops. In rice, saflufenacil can be a prospective combination partner to complement the broadleaf weed control of herbicides such as imazethapyr. This study was established to evaluate 1) rice tolerance and 2) weed control of red rice ( Oryza sativa L.) and hemp sesbania ( Sesbania exaltata P. Mill.) to saflufenacil tank-mixed with imazethapyr. The experiment was conducted during 2009 and 2010 at the Texas A&M AgriLife Research and Extension Center located at Beaumont, TX. Treatments included a check, an imazethapyr treatment alone (70 g a.i. ha −1 at the 1- to 2-leaf stage (EPOST) plus 70 g a.i. ha −1 at the 4- to 6-leaf stage (LPOST)), and four saflufenacil doses (12.5, 18.75, 25, and 50 g a.i. ha −1) applied at EPOST and LPOST. Imazethapyr treatment was applied to all saflufenacil treatments. Rice injury increased with doses of saflufenacil and injury up to 83% was observed at 7 DAA when 50 g ha −1 was applied EPOST. Subsequent evaluations indicated less injury over time demonstrating rice recovery from saflufenacil treatments. No injury was observed in the imazethapyr treatment alone. Rice plants seemed to recover faster from LPOST application injury than EPOST. Hemp sesbania control was ≥88% in all saflufenacil treatments in evaluations conducted before harvest indicating effective control throughout the growing season. Red rice control was 100% for all treated plots containing imazethapyr in both years. Therefore, imazethapyr control of red rice was not adversely affected by tank-mixing with saflufenacil. Although injury was significantly higher in the highest doses of saflufenacil, rice yield was not adversely altered by the herbicide treatments. In summary, rice was injured at the highest doses of saflufenacil, but injury did not reduce rice yield. Hemp sesbania was effectively controlled by saflufenacil (>90% on average). No antagonistic interactions between saflufenacil and imazethapyr were observed with red rice control. Saflufenacil appears to be an effective herbicide candidate for broadleaf control in rice.