Weed Management in Peanuts1
Successful weed control in peanuts involves use of good management practices in all phases of peanut production. Weeds compete with peanuts for moisture, nutrients, and light, with the greatest competition usually occurring during the first six weeks after planting. Although late-season weeds may not be as competitive as early-season weeds, they may interfere with harvesting, and fungicide and insecticide applications.
Crop Rotation
Crop rotation is an important part of a peanut weed control program. Certain broadleaf weeds, which are not easily controlled in peanuts, may be controlled by herbicides that can be used in a preceding crop such as corn. Other benefits of crop rotation may include a reduction in insect, disease, and nematode problems.
Herbicides
Herbicides are one of the most effective methods of weed control in peanuts. Proper weed identification is critical before deciding on the herbicide program for weed management and purchasing herbicides. Once you have determined the weed problem, you can use Tables 2 and 3 to identify the most effective herbicide(s) for certain weeds.
Effective weed control in peanuts is generally obtained by using herbicide programs that consist of a preplant incorporated or preemergence treatment, followed by a cracking/early postemergence treatment and a postemergence treatment. The cracking/early postemergence treatment, if properly timed, is generally the most critical application in a peanut weed control program. Maximum effectiveness will be achieved if the application is timed to the emergence of the weeds or made to weeds less than three inches tall. Follow all label instructions and precautions carefully to avoid crop injury or poor weed control. CAUTION: Peanuts under stress from cold and wet weather, thrips injury, etc., may be subject to injury from early-season herbicide applications.
Table 1 lists herbicide products registered for use in Florida peanut production, their mode of actions group, application rate per acre and per season, reentry interval, and specific comments regarding use. Tables 2 and 3 reflect the performance of these herbicides on several weeds under Florida conditions.
As with all herbicide applications, do not allow spray to drift to cotton, tobacco, or other nearby sensitive crops. Store herbicides behind locked doors in their original containers with intact labels, and keep them separate from seed, fertilizer, and other pesticides.
Replanting intervals occur with certain peanut herbicides. Consult the product label or your county's UF/IFAS Extension office for additional information on next season's crop safety.
Cultivation
Cultivation may be utilized in the early season before peanut plants form a canopy and/or begin to peg. Generally, cultivation is used when herbicides are ineffective; it may also be a component of organic peanut production. Cultivation may also improve the activity of certain herbicides under adverse conditions such as drought. However, cultivation generally results in a flush of weeds and may increase disease problems. If cultivation is necessary, a shallow cultivation (1–2 inches deep) works best with minimal soil movement. This helps to reduce soil thrown onto the peanut foliage, the presence of which may result in increased incidence of stem rot (white mold).
Mowing generally does not result in effective weed control, but it may allow more adequate application of foliar fungicides and insecticide. Mowing is also sometimes used as a last-ditch effort prior to peanut digging and harvest. This approach involves cutting the weed biomass above the peanut canopy. Do not cut the peanut foliage.
