TEXAS A&M AGRILIFE ROLLING PLAINS AGRONOMY PROGRAM

Using Brake (Fluridone) Herbicide Programs

for Weed Control in Peanut 2024

James Grichar (PI) and Emi Kimura (Editor)

Funding source: Texas Peanut Producers Board/National Peanut Board

Funding year: 2024

INTRODUCTION

Brake (fluridone) is a Group 12 herbicide that was developed in the early 1970’s.  It is a pigment inhibitor that has been used extensively to control submerged and floating weeds such as hydrilla [Hydrilla verticillata (L. f.) Royle] in aquatic environments.  This mode of action has been used very little in peanut.  Fluridone was first investigated for use in cotton in the 1970’s and has shown good control of Amaranthus species, especially Palmer amaranth.  However, potential carryover of fluridone to subsequent crops can be a concern.  Research with fluridone during the 1970’s was with rates of 0.26 to 0.8 lb/A and it was found that preplant fluridone applied at 0.26 lb/A provided 89 to 95% control of redroot pigweed (Amaranthus retroflexus L.) and 85 to 100% control of black nightshade (Solanum nigrum L.) in cotton.  Variable control of redroot pigweed was observed when fluridone was applied at 0.09 or 0.18 lb/A (30 to 86% and 61 to 100% control, respectively).  Brake received registration for use in peanut in the latter part of January 2023.  Brake is not a stand alone herbicide and must be included in a program approach.  Also, Brake needs at least 0.5” of rainfall and/or irrigation after applicationto perform up to its potential and will cause some peanut injury in the form of stunting and bleaching especially when higher rates are used and wetter conditions prevail. This research was conducted to evaluate the weed efficacy of Brake programs on weeds commonly found in the south Texas peanut production area.  Of special interest is the ability of Brake to control Palmer amaranth. 

MATERIALS AND METHODS

Field studies were conducted during the 2024 growing season at the Texas A&M Agrilife Research site located near Yoakum in south Texas to evaluate weed control in peanut with Brake herbicide systems.  This study was arranged as a randomized complete block design with 3 replications. An untreated check was included for comparison.  Soils at the Yoakum study site were a Tremona loamy fine sand with pH of 7.6.  Plot size was 2 rows (38” spacing) by 30’ long.  Spray applications were made with a CO₂-pressurized backpack sprayer with a handheld boom equipped with TeeJet DG 11002 spray nozzles calibrated to deliver a total spray volume of 20 gal/A.  This test was planted into excellent moisture on June 27 with SPAN-17 at the rate of 90 lbs/A and was not harvested for yield.  All herbicides were applied preemergence (PRE) on June 28, one day after peanuts were planted.  No rainfall event occurred for over a week after planting with 0.27 inch on July 6, 0.12 in on July 8, and 1.03 in on July 13. 

RESULTS AND DISCUSSION

Peanut injury.  Peanut injury consisted of leaf yellowing or chlorosis.  No stunting was noted.  All herbicide systems which included Brake at 12.0 and 16.0 oz/A rate without Valor resulted in 1 to 6% leaf bleaching when evaluated 18 days after preemergence herbicide treatment (DAT) (Table 1).  Texas panicum control was also excellent (> 96%) at the 18 DAT evaluation (Table 1).  When evaluated 39 DAT all herbicide combinations provided > 80% control (Table 1).  At the 60 DAT evaluation, combinations of Prowl H₂0+ Brake at any rate provided Texas panicum control which ranged from 49 to 77% while all other combinations with Brake provided > 82% control.  At the 95 DAT evaluation, any combinations which contained Prowl H₂0 + Valor + Brake, with the exception of Prowl H₂0 + Valor at 2.0 oz/A + Brake at 8.0 oz/A, provided 78 to 86% Texas panicum control.

Weed control

Smellmelon. When evaluated 35 days after PRE treatment (DAT) Prowl H₂0 alone controlled this weed 99% (Table 1). Prowl H₂0 + Valor systems provided 90 to 93% control, Prowl H₂0 + Brake systems 59 to 80% control, Prowl H₂0 + Dual Magnum + Brake systems 96 to 98% control, and Prowl H₂0 + Valor + Brake systems 65 to 100% control. At the 90 DAT evaluation control was similar to that seen at the 35 DAT evaluation. Typically, Prowl H₂0 will not provide extended control of weeds such as smellmelon as the seeds will germinate after each rainfall and/or irrigation event; however this test area wasirrigated and only 0.48 and 0.34 in of rain was received in July and August, respectively so there was not much moisture available for additional seed germination. In comparison, Prowl H₂0 + Dual Magnum + Brake combinations provided 62 to 84% control.  Prowl H₂0 + Valor at 2.0 oz/A provided 90% control (Table 1).  Large seeded annual grasses such as Texas panicum are difficult to control season-long and may require the use of a graminicide later in the growing season.

Conclusion

As expected, the addition of Brake did not improve Texas panicum control.  Brake is not a stand-alone herbicide and requires the addition of herbicides such as Prowl H₂0, Dual Magnum, or Valor to provide complete and season-long weed control.  Control of large-seeded annual grasses such as Texas panicum may require the use of a postemergence grass herbicide such as Select, Fusilade, or Poast Plus to provide season-long control.  In south Texas, the suggested use rate for Brake will be 8.0 oz/A (0.113 lb ai/A) to avoid any of the late-season yellow flash noted in 2023.