Herbicide Rates

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I have received several questions about rates of residual herbicides at planting and once peanuts emerge. There are a lot of ways to approach this. For me, I prefer going with full rates for PRE applications. For example, 1.3 pints of Dual Magnum, 2 pints of generic metolachlor, 3 pints of Warrant, 21 oz Outlook. The 1X rate for our peanuts for Valor SX is 2 oz/acre. Farmers can certainly go with 0.5X PRE and 0.5X early POST. No problems there, I just prefer the full rate each time and then apply a full rate of another herbicide at the next timing. Yes, this is more expensive, but seldom does a weed control program fail to pay for itself. There is sticker shock but weed control is essential. I would not put more than 2/3X metolachlor (whatever formulation) PPI, and if you have growers putting out laybys, 0.5 or 2/3X is sufficient.

I had a question about using Pursuit, Strongarm and Dual as a PRE treatment. The peanut tolerance would be fine but that is expensive. In this case the grower was following peanuts with soybean so I recommended Cadre or Impose POST and leave off the Pursuit. Pursuit is just marginal and expensive.

I have become less of a fan of the true cracking treatment because it is hard for growers to get this applied. Acres are too many. I prefer growers apply a full rate of say metolachlor and Valor SX PRE (I would like to see Prowl PPI) and then apply paraquat plus Basagran plus residual 2 weeks after peanuts emerge. In some cases with good rainfall the PREs may hold well past this 2-3 week window, but not always. Based on our work you can add acephate to the mix and minimize thrips feeding. You will get a little more burn with the residual but when the Basagran is included (0.5 pints/acre) injury will be very transient. BUT, if the peanuts have significant thrips damage, say 1.5 or more on our 5 point scale, do not spray paraquat. Get the acephate out as quickly as you can, let the peanuts recover, and move to an herbicide program that is more effective on bigger weeds if that is the case. We reduce yield every time we spray paraquat when the thrips have injured the peanuts.

Article first appeared as North Carolina Peanut Note (PNNC-2015-035)

Written By

Dr. David JordanExtension Peanut Specialist (919) 515-4068 david_jordan@ncsu.eduCrop and Soil Sciences - NC State University
Updated on Feb 19, 2016
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