Peanut Response to Simulated Drift Rates of Glufosinate

Abstract

Utilization of glufosinate resistant corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] is becoming increasingly important in weed management strategies, especially where glyphosate resistance is a major problem. However, glufosinate drift to adjacent non‐tolerant crops and direct application to sensitive crops are concerns. Research was conducted to determine peanut (Arachis hypogaea L.) yield response to glufosinate applied at rates ranging from 0.015 to 0.48 lb ai/acre when peanut was 4 to 6 inches in diameter. Visible injury increased and pod yield decreased relative to non‐treated peanut when glufosinate was applied at approximately 0.08 lb/acre (approximately one sixth the manufacturer's suggested use rate for most crops). Cubic functions were significant when plotting visible injury and percent reduction in pod yield versus glufosinate rate, and visible injury and pod yield were negatively correlated (P < 0.0001, r2 = −0.845). These results suggest that early season visible injury three weeks after application is a relatively good predictor of yield loss when glufosinate injury occurs in peanut.

Growth and yield response of peanut to simulated drift of glufosinate at vegetative and reproductive growth stages

“…These results indicate a reduction in peanut canopy and yield with increasing visual injury following glufosinate application. This observation is consistent with that made by Jordan et al (2011) who noted that visible injury at 3 WAT and peanut yield were negatively correlated ( r 2 = −0.845). Based on the highest observed values for r 2 in this study, the best timing for assessing potential yield reduction based on injury was between 2 and 4 WAT with r 2 values of 0.80 and 0.85, respectively (Table 2).…”

“…Injury symptoms following peanut exposure to glufosinate were similar to those reported in previous studies (Johnson et al 2012; Jordan et al 2011; Prostko et al 2013). Injury was characteristic of contact herbicides that manifested as necrosis, leaf bronzing, and plant stunting.…”

“…These results are consistent with those reported by Johnson et al (2012) that peanut injury increased from 40% to 100% as the glufosinate rate increased from 16 to 302 g ha −1 . Similarly, Jordan et al (2011) reported that visible injury increased relative to nontreated peanut when glufosinate was applied at 36 g ha −1 (approximately one-sixth of the manufacturer's suggested use rate for most crops).…”

“…Few studies have addressed the effects of simulated drift rates of glufosinate on peanut. Jordan et al (2011) reported a 14% peanut yield reduction when glufosinate was applied at 135 g ha -1 , but yield reduction increased to 74% when the herbicide was applied at 538 g ha -1 . Similarly, Johnson et al (2012) reported a 25% peanut yield reduction from glufosinate at 123 g ha -1 , but the reduction increased to 75% when glufosinate was applied at 302 g ha -1 .…”

The Effect of Dicamba on Peanut When Applied During Vegetative Growth Stages

“…Glufosinate also caused 75 yield loss to peanut when applied less than a normal rate of 538 g ai ha -1 . Glufosinate at 135 and 76 269 g ai ha -1 applied three weeks after emergence (WAE) caused yield loss of 14 and 51% 77 respectively in North Carolina (Jordan et al, 2011). Visual estimates of peanut injury and 78 peanut yield indicated a significant negative correlation.…”