Peanut weed management trials were conducted at the Oklahoma State University Caddo Research Station near Fort Cobb. Peanuts were planted on May 8, 2023, in 36-inch rows. Preemergence (PRE) treatments were applied immediately after planting. The volunteer cotton trial received an overlay of Prowl (1 qt/A) + Valor (2oz/A) PRE. All trials received a postemergence (POST) application of Select (1 pt/A) + Dyne-Amic (6 fl oz/A). The preemergence herbicide and Brake tolerance trials received Butyrac 200 (1 pt/A) + Dyne-Amic (6 fl oz/A) POST. These trials were irrigated and maintained throughout the growing season. Trials were visually evaluated for peanut response and weed control. Peanuts were dug, field dried and harvested (10/11/23).

 

The first trial was established to evaluate preemergence herbicides for peanut response and weed control. Preemergence herbicides evaluated included BAS 85001H, a new PPO herbicide for potential use in peanut. Additional herbicides included Valor, Prowl H2O and Pursuit. Peanut stand reduction was 5% or less for all treatments (data not shown). Peanut injury was initially less than 5% for all treatment (Table 1). Peanut injury four weeks after planting (WAP) was greater than 5% with BAS 85001H at 2 fl oz/A and Valor + Pursuit with and without Prowl H2O. Late-season peanut injury was not observed for any treatment. Palmer amaranth (Table 2) and Texas panicum (Table 3) control was at least 98% all season long with all treatments applied. Ivyleaf morningglory (Table 4) control was 100% (2 WAP) and was at least 97% for all treatments except BAS 85001H (0.68 fl oz/A) and Prowl H2O. When evaluated, 12 WAP ivyleaf morningglory control was 99-100% with all Valor + Pursuit combinations. Peanut yields were greater than 4,500 lbs/A for all treatments except where Prowl H2O was applied alone. (Table 1).

 

The second trial evaluated various in-season herbicides to control either Xtend or Enlist volunteer cotton in peanuts. Initial peanut injury was 10% with all Gramoxone and Aim treatments (Table 5). All peanut injury has subsided by four weeks after treatment (WAT). Xtend (dicamba tolerant) volunteer cotton control was 94% (4 WAT) and 83% (9 WAT) with 2,4-DB (Table 6). This compared to no control on Enlist (2,4-D tolerant) volunteer cotton (Table 6). Aim alone or in combination with Anthem Flex controlled 80-88% (4 WAT) and 68-73% (9 WAT) of both Xtend and Enlist volunteer cotton. Anthem Flex alone, which contains a low rate of Aim, only controlled 40-50% of either volunteer cotton. Gramoxone control was 55-69% of both Xtend and Enlist volunteer cotton. Control with Gramoxone was less than expected, which may have been due to the 8 fl oz/A rate. Peanut yields were not affected by any of the treatments applied (Table 5).

 

The third trial evaluated peanut variety response to Brake (fluridone) herbicide applied preemergence. Peanut stand reduction was 5% or less with all treatments applied (data not shown). Peanut stunting was 5% or less season long with Brake on OLé peanut variety (Table 7). Peanut stunting was less than 5% with Span17 peanut variety except with the 1X and 2X rate of Brake (4 WAP). Peanut stunting was 4-6% with the 1X and 2X rate of Brake with Lariat peanut variety.

 

Visual peanut injury (2-4 WAP) was 6-11% for all varieties. Visual peanut injury was 5% or less for all treatments except the 2X rate of Brake with the Lariat variety 8 WAP and injury was less than 5% for all varieties 12 WAP. Peanut yields were not statistically different for any treatments, however, yields of OLé treated with a 2X rate of Brake PRE were less than 5,000 lbs/A.

 

Two additional weed management trials were conducted on-farm. In one trial, weed control was at least 95% (Palmer amaranth, volunteer cotton, annual grass control) with various combinations of Anthem Flex (data not shown). In a second trial, late season of control of Palmer amaranth was poor with various combinations of Cobra applied POST (data not shown).

 

Acknowledgments

The authors would like to express our gratitude to the Oklahoma Peanut Commission and the National Peanut Board for their support of this research. Additionally, we would like to extend our appreciation to the research staff at the Oklahoma State University Caddo Research Station: Bobby Weidenmaier, Brennan Leighton and Harley Houston. We would also like to thank Steve King and Jon Keahey for allowing us to conduct research on their farms. Without the support of these groups and individuals, along with the producers of Oklahoma, the development and results of this research would not be possible.

 

Tables

• Table 1 - Peanut response to preemergence herbicides, Fort Cobb 2023
• Table 2 - Palmer amaranth control with preemergence herbicides, Fort Cobb 2023
• Table 3 - Texas panicum control with preemergence herbicides, Fort Cobb 2023
• Table 4 - Ivyleaf morningglory control with preemergence herbicides, Fort Cobb 2023
• Table 5 - Peanut response to postemergence herbicides, Fort Cobb 2023
• Table 6 - Peanut response to postemergence herbicides, Fort Cobb 2023
• Table 7 - Peanut response to preemergence herbicides, Fort Cobb 2023