Weed control and sensitivity of oats (Avena sativa) with various doses of saflufenacil Nader Soltani * , Christy Shropshire, Peter H. Sikkema University of Guelph Ridgetown Campus, 120 Main Street East, Ridgetown, Ontario, Canada N0P 2C0 article info Article history: Received 13 April 2011 Received in revised form 25 August 2011 Accepted 26 August 2011 Keywords: Density Dry weight Dose response Herbicide sensitivity Oats (Avena sativa L.) Tolerance Yield abstract Saflufenacil is a new herbicide being developed by BASF for broadleaved weed control in maize, soybean and other crops prior to crop emergence. Six field studies were conducted in Ontario, Canada over a three year period (2008e2010) to evaluate the potential of saflufenacil applied pre-emergence (PRE) at various doses for broadleaved weed control in oats. Saflufenacil applied PRE caused minimal visible injury at 1, 2 and 4 weeks after emergence (WAE) in oats. At 4 WAE, the dose of saflufenacil required to provide 95% control of Ambrosia artemisiifolia (common ragweed), Chenopodium album (common lambsquarters), Polygonum convolvulus (wild buckwheat), Polygonum scabrum (green smartweed) and Sinapsis arvensis (wild mustard) was 72 to >100, >100, 74, 58 and >100 g ai ha 1 , respectively. Generally, similar saflu- fenacil dose-response trends were seen at 8 WAE. The doses of saflufenacil required to provide 95% reduction in density and dry weight ranged from 95 to >100 and 42 to >100 g ai ha 1 respectively for A. artemisiifolia, C. album, P . convolvulus, P . scabrum and S. arvensis. Oat yield showed no sensitivity to saflufenacil at the doses evaluated. Based on this study, saflufenacil applied PRE can be safely used in spring planted oats for the control of some troublesome annual broadleaved weeds. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Oats (Avena sativa) are an important spring cereal grown in Ontario. In 2009, growers in Ontario seeded 34,000 ha and produced nearly 80,000 tonnes of oats with a farm gate value of approximately $15,000,000 (McGee, 2011). Weed management is a critical component in successful oat production (Sikkema et al., 2008). Substantial crop yield and associated economic losses can occur if weeds are not adequately controlled. Efficacious pre- emergence (PRE) applied residual broadleaved herbicides with an adequate margin of crop safety that can be tankmixed with glyphosate would allow no-till oat producers to combine two weed control operations in one pass, burndown of emerged weeds prior to seeding and full season residual broadleaf weed control. This would be an additional crop production tactic that would help oat growers to be more competitive in the marketplace. Herbicides available for oats in Ontario have not changed much in recent years (OMAFRA, 2010; Sikkema et al., 2008; Soltani et al., 2006). There have been reports of crop sensitivity in cereals with some of these herbicides (Sikkema et al., 2007). There are currently no soil applied residual herbicides available for broadleaved weed control in oats in Ontario. Availability of new residual herbicides that provide selective and consistent control of annual broadleaved weeds will enable Ontario oat growers to improve their competi- tive edge in the marketplace. More research is needed to determine the efficacy of newly developed herbicides with a novel mode of action in oats. Saflufenacil is a new herbicide being developed for pre-plant burndown and residual broadleaved weed control prior to crop emergence in maize, soybean, sorghum, wheat and other crops (Soltani et al., 2009). Saflufenacil can control troublesome broad- leaved weeds including Abutilon theophrasti (velvetleaf), Ambrosia artemisiifolia (common ragweed), Xanthium strumarium (common cocklebur), Polygonum persicaria (ladysthumb), Amaranthus retro- flexus (redroot pigweed), Amaranthus tuberculatus var. rudis (common waterhemp) and Chenopodium album (common lambs- quarters) including Group 2, 5 and 9 herbicide resistant biotypes (Anonymous, 2008; Liebl et al., 2008). Saflufenacil is a pyr- imidinedione chemical compound that inhibits protoporphy- rinogen-IX-oxidase (PPO). Saflufenacil has both contact and residual activity against susceptible weeds which show injury symptoms within a few hours and die in 1e3 days (Liebl et al., 2008). Saflufenacil is mainly translocated in the xylem and has limited mobility in the phloem (Liebl et al., 2008). Saflufenacil is applied at relatively low doses and has low environmental, toxicological and * Corresponding author. Tel.: þ1 519 6751221; fax: þ1 519 674 1600. E-mail address: nsoltani@ridgetownc.uoguelph.ca (N. Soltani). Contents lists available at SciVerse ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro 0261-2194/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.cropro.2011.08.016 Crop Protection 31 (2012) 45e49