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Control of Cowpeas

Cowpea Control (Prostko)

Every so often, I get a few inquiries about herbicides for the control of cowpea (Vigna unguiculata) (Figure 1). Unfortunately, cowpea (also known southern pea, black-eye pea, or crowder pea) can be a very difficult plant to control and not much research data is out there.  In preparing our UGA Weed Science graduate students for the upcoming 2019 National Weed Science Contest, I was able to collect some good data for various herbicides (Table 1).

In summary, the following herbicides could be used for the control of cowpea depending upon the planted crop:  PRE = Atrazine, Balance Flex (isoxaflutole), and Tricor (metribuzin); POST = Classic (chlorimuron), Engenia (dicamba), Enlist One (2,4-D), Envoke (trifloxysulfruon), Gramoxone (paraquat), Liberty (glufosinate), Osprey (mesosulfuron), Roundup (glyphosate), Sharpen (saflufenacil), and Stinger (clopyralid).

Figure 1.  Cowpea

Table 1.  Cowpea (‘Top Pick Pinkeye Purple’) control with PRE and POST herbicides, TyTy, Georgia, 2019.1

Herbicide Rate/A

(oz)

Application Method

(PRE or POST)

Test 1

Control (%)

Test 2

Control (%)

15 DAT3

(Prostko)

20 DAT

(Culpepper)

14 DAT

(Prostko)

Harness 7EC 22 PRE 0 0 0
Atrazine 4L 64 PRE 100 100 100
Diuron 4L 26 PRE 0 0 0
Valor SX 51WG 3 PRE 0 10 20
Pursuit 2SL 4 PRE 0 8 0
Balance Flexx 2SC 6 PRE 100 100 100
Callisto 4SC 3 PRE 60 65 0
Prowl H20 3.8ASC 48 PRE 0 5 0
Zidua 85WG 1 PRE 0 10 0
Dual Magnum 7.62EC 21 PRE 0 12 0
Spartan 4L 1 PRE 0 0 0
Tricor 4L 24 PRE 100 100 100
Enlist One 3.8SL 13 POST 95 95 100
Buctril 4EC 12 POST 50 70 30
Classic 25DG + COC4 0.5 POST 95 95 85
Select Max 0.97SC + NIS 25 POST 0 10 0
Stinger 3SL 8 POST 95 100 80
Engenia 5SL 6.4 POST 95 95 85
Fusilade DX 2EC + COC 12 POST 0 10 0
Resource 0.86EC + COC 4 POST 0 0 0
Reflex 2SL + NIS 12 POST 50 50 50
Liberty 2.34SL +

N-Pak AMS (2% v/v)

22 POST 100 93 85
Sandea 75DG + NIS 0.66 POST 40 25 30
Osprey 4.5DG + MSO 4.6 POST 70 88 85
Accent 75DG + COC 0.66 POST 65 75 60
Gramoxone 2SL + NIS 32 POST 100 95 90
Facet 75DG + MSO 16 POST 50 60 55
Sharpen 2.85SC + MSO 2.5 POST 95 92 80
Laudis 3.5SC + MSO 3.5 POST 65 68 60
Envoke 75DG + NIS 0.09 POST 85 88 90
Roundup PowerMax 5.5SL 22 POST 100 97 90

1Test 1: Planting Date = May 28; PRE = May 29; POST = June 13 (~8” tall cowpea).

2Test 2: Planting Date = June 17; PRE = June 18; POST = July 8 (~8” tall cowpea).

3DAT = days after POST treatment.

4COC = Agridex @ 1% v/v; NIS = Induce @ 0.25% v/v; MSO = MES 100 @ 1% v/v.