Peanut Update – 45 DAP

The following update was prepared by Clemson peanut specialist Dan Anco.

Standard Fungicide Programs Begin:  For peanuts that went in the ground on May 1, next week (June 15) will mark 45 DAP. This is when we typically start our standard fungicide applications for disease control. Two of the most common options will be 1.5 pt/A Bravo + 7.2 fl oz/A tebuconazole or one of the Tilt Bravo replacement options copied below from a previous peanut update.  Peanut Money-Maker Production Guide 2016

Boron:  If our soil tests indicated low levels of boron (less than 0.4 lb/A or 0.2 ppm), we can add 1.5 – 2.5 lb/A Solubor, or we can add 2 – 3 lb/A boric acid in with the first fungicide/herbicide application (these ranges provide 0.3 – 0.5 lb boron/A). While we need enough boron to avoid dark and sunken kernel centers (hollow heart), we also need to be careful not to add too much. If we stay under a field total of 0.5 lb/A boron, we will avoid boron toxicity.


Hollow heart from boron toxicity.


Boron toxicity. (Courtesy of Al Cochran)

Nodulation:  If we had inoculation issues, this is also the time where peanut leaves may start to yellow. We can check suspect inoculant issues by using a shovel to dig up plants to see the nodules. This keeps most of the taproot connected. If we simply pull up plants, a good portion of the taproot breaks off and gives us a more limited picture of what’s going on.

If we see about 15 nodules on the taproot 1/8” or bigger, this is good. Less than 10 taproot nodules is borderline, and less than 5 is poor. If there’s only small nodules about 1/16” mostly on the lateral roots, the peanuts have most likely been colonized by Rhizobium bacteria already in the soil and not what we applied in-furrow. If we had an inoculant failure and have nitrogen-deficient peanuts, it can be expensive to deal with. If we find ourselves in this situation, applying ammonium sulfate has typically provided better results than ammonium nitrate. If we have a nitrogen deficiency, I would suggest about 430 lb/A 21% ammonium nitrate (90 lb/A actual nitrogen) be applied as soon as possible. Putting much more than this out may increase yields a little further but overall isn’t projected to payoff so well given where many of this year’s contract prices sit.

Scouting:  This is also a good time to start keeping an eye out for granulate cutworm damage, since they can at times defoliate smaller plants in June. We can also start weekly checks for potato leafhopper feeding damage, which tends to show up first in field borders and on the more susceptible varieties (Bailey, Sullivan, Sugg, and Wynne). If we start seeing damage from one of these pests, we can use one of the recommended options in the Peanut Money-Maker.

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