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Weed Control in Perennial Peanut

Brent Sellers and Jason Ferrell

Introduction

Perennial peanut has been called "Florida alfalfa" because it is a high-quality forage legume that performs well in tropical climates of the Deep South. Perennial peanut is highly palatable to most livestock, and bloating is not a problem as it is with many legumes. For these reasons, perennial peanut has filled a niche in the high-quality legume hay market.

In the past, weed control has been a difficult issue to overcome with this crop because very few herbicides could be used. The Florida Department of Agriculture and Consumer Services concluded that the following expanded list of herbicides can be used on perennial peanuts. However, it must be noted that this is a Florida ruling. Producers in Alabama, Georgia, or other states must check with their local regulatory agencies to ensure that these products can be used in their states.

After numerous field trials, we have compiled the herbicides that can be applied to perennial peanut without risk of adverse effects. This list contains very few products, but if used properly they should improve control of some troublesome weed species.

Tables

Table 1. 

Recommended herbicides for perennial peanuts.

Trade name and broadcast rate/A

Common name

Remarks

2,4-D amine Weed Killer

(EPA 1386-43-72693)

1 pt/A

2,4-D

(0.5 lb)

For control of many annual broadleaf species such as Mexican tea (Jerusalem oak), pigweeds, Spanish needle, etc. Can be applied any time during the season as long as the 30-day restriction on hay cutting is observed. May lead to slight yield decrease in 'Florigraze', but 'Arbrook' is more tolerant. Mixing 8 fl. oz of 2,4-D amine Weed Killer with 4 fl. oz of Impose has been found to be an effective combination.

NOTE: 2,4-D amine Weed Killer is the product that has been officially approved for use. Take care to use this particular product rather than other non-approved 2,4-D herbicides.

Impose

4 fl. oz/A

imazapic

Impose is highly effective on crabgrass, nutsedges, johnsongrass, and numerous broadleaf weeds. This herbicide should always be applied with a surfactant. There are no grazing or haying restrictions for this herbicide. Other herbicides with the same active ingredient, such as Cadre, cannot be legally applied to perennial peanuts.

Select Max

or TapOut

16–32 fl. oz/A

clethodim

Select Max will provide excellent control of annual and perennial grasses, but will not control any broadleaf weeds. Select Max can be applied up to 32 fl. oz/A in a single treatment, but should not exceed a total of 64 fl. oz/A/year. This product requires the addition of a surfactant or crop oil, and haying or grazing must be delayed for 40 days after application.

Clethodim 2EC

(Several brands)

6–16 fl. oz/A

clethodim

Apply 6–16 oz/A, plus crop oil at 1%, for control of annual or perennial grasses. For common bermudagrass control, two applications of 16 oz/A, made 2–4 weeks apart, will be required. Do not exceed greater than 32 oz/A/season and do not harvest within 40 days of application.

GlyStar Plus

glyphosate

Preplant. Apply as a broadcast application at 16 to 64 oz/acre prior to planting rhizomes.

Dormant season. Apply 32 to 48 oz/acre as a broadcast application in a minimum of 15 gallons of water per acre. Do not make more than one dormant application per year. Do not apply to crop that is transitioning into spring greenup.

In-season wiper applications. Dilute to 50% concentration for use in a wiper applicator. Remove livestock prior to application and wait 14 days prior to grazing livestock or harvesting. Ensure that there is sufficient weed growth to minimize contact with the perennial peanut.

In-season broadcast applications. Use broadcast applications where a wiper cannot be used at a rate of 12 to 32 oz/acre in a minimum of 15 gallons of water per acre. Use lower application rates where the perennial peanut stand is less than 3 years old and not before it is one year old. Well established stands tolerate higher rates. Do not apply if yield reduction cannot be tolerated. A second application can be applied 28 days after the first application, but do not exceed 48 oz/acre for all in-season applications. Do not graze or harvest for 56 days after in-season broadcast applications.

NOTE: Only this formulation of glyphosate is currently labeled for perennial peanut in Florida per the GlyStar Plus supplemental label. Additional restrictions for using this product are found on the supplemental label.

Velpar L

1 pt/A

hexazinone

On established stands, apply 1 pt/A for control of winter weeds when perennial peanut is dormant. If weeds are emerged at time of application, use surfactant at 1 pt/100 gal. If perennial peanut is not dormant during the time of the application, expect injury and yield loss. During the season, Velpar can be applied after hay removal, but before perennial peanut regrowth has occurred. In this situation, no surfactant is needed, but weed control is often marginal. If peanuts have leafed out, expect moderate to severe injury.

Note: Velpar is toxic to certain hardwood species, particularly oaks. Application near the root zone of sensitive trees can result in tree death. Therefore, be cautious when applying near field borders where desirable trees are growing.