Peanut weed and disease management trials were conducted at the Oklahoma State University Caddo Research Station near Fort Cobb. Spanish peanut 'Ole' were planted on May 10, 2022, in 36-in rows. Preemergence treatments were applied immediately after planting. The Gramoxone Tolerance, Liberty Tolerance and disease management trials received an overlay of Prowl (1 qt/A) + Valor (2 oz/A) PRE, Cadre (4 fl oz/A) + Butyrac 200 (1 pt/A) + Dyne-Amic (6 fl oz/A) and Select (1 pt/A) + Dyne-Amic (6 fl oz/A) POST. These trials were weed-free, irrigated and maintained throughout the growing season. Trials were visually evaluated for peanut response and weed control or leafspot. Peanut crops were dug, field dried and harvested (10/27/22).

The first trial was established to evaluate the response of peanut to POST applications of Gramoxone alone and in combination with Dual Magnum. Gramoxone was applied at 10.8 (1X) and 21.6 (2X) fl oz/A either alone or in combination with Dual Magnum at 21.3 (1X) and 42.6 (2X) fl oz/A. Applications were made at 14 days after crack (DAC), 28 DAC, or both 14 and 28 DAC. All treatments were applied with Induce (non-ionic surfactant) at 0.25% v/v.

Peanut stands were reduced less than 5% from any of the herbicide treatments applied (Table 1). Initial peanut stunting was 15 to 70% from the POST1 (14 DAC) application timing (Table 2). The most severe stunting occurred from the combinations with Dual Magnum and from the 2X rate applications. This stunting generally subsided and was less than 5% by 79 days after planting (DAP). Initial stunting was less severe from the POST2 (28 DAC) ranging from 3 to 8%. Stunting from a POST1 + POST2 applications was 6 to 26% across the various treatment combinations. Similar to the POST1 timing, injury subsided to 5% or less by 79 DAP. Leaf burn (Table 3) and overall visual injury (Table 4) followed a similar trend to the peanut stunting. All treatments yielded over 5,500 lbs/A (weed-free yield = 5,714 lbs/A) with the exception of two applications of Gramoxone + Dual Magnum, both applied at 2X of the labeled rate which yielded 4,617 lbs/A (Table 4).

The second trial was established to evaluate the effects of preplant and preemergence applications of Liberty (glufosinate) on peanut. Liberty was applied on May 10 at 0, 25, 50 and 75 fl oz/A. Peanut crops were planted immediately prior to the Liberty application or 7 days later. No injury or yield effects were observed from any of the Liberty treatments (Table 5).

 

A trial was established on the Steve King Farm near Eakly to evaluate weed management and peanut response to Anthem Flex combinations. Initial injury (7 days after treatment [DAT]) was between 6 and 10% with all treatments (Table 6). Injury was slightly higher with Anthem Flex compared to Dual Magnum. This is to be expected due to the addition of Aim in the Anthem Flex herbicide. Injury was not visible by 16 DAT with any of the treatments. The only weed in a significant population was volunteer cotton. However, even this population was sporadic across the trial area. It was observed that the addition of Aim to Anthem Flex, equal to a total of 2.0 fl oz/A of Aim,
increased volunteer cotton control. This may be a potential option where Enlist cotton was planted, and a producer would prefer not to apply Gramoxone.

The next weed management trial evaluated various combinations of Prowl, Pursuit and Valor for preemergence weed management in peanut. All PRE treatments were followed with a POST application of 2,4-DB and a POST application of Select. Initial control of Palmer amaranth (Table 7), Texas panicum (Table 8) and ivyleaf morningglory (Table 9) was at least 90% with all treatments 21-27 DAP. These same species were controlled 100%, 58 DAP with Pursuit (4 fl oz/A) + Valor (3 fl oz/A) together or in combination with Prowl H2O (32 fl oz/A). Peanut injury was less than 10% with all treatments applied (Table 10). Peanut yield was over 5,100 lbs/A with the three-way
combination of Prowl H2O + Pursuit + Valor compared to 3,717 lbs/A when no PRE was applied.

The final trial was established to evaluate Lucento based fungicide programs for leafspot. Leafspot was extremely low averaging less than 1 (very few leafspot lesions) on the Florida Leaf Spot Scale the entire growing season. This was true even with the untreated. Due to the low level of leaf spot there were no differences for any of the treatments in level of leafspot or peanut yield (Table 11).

The authors would like to express our gratitude to the Oklahoma Peanut Commission for 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 for allowing us to conduct research on his farm. 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.