"Cracking" Time Tips for Peanuts (Prostko)

Many peanut growers are likely to begin or already have begun treating their fields with early-postemergence ("cracking") applications of Gramoxone (paraquat).  Here are a few tips for success as well as some pictures from "cracking" treatments that I applied just last week:

1) Cracking applications can be applied from peanut emergence up until 28 days after cracking. Cosmetic injury (stunting and leaf necrosis) should be expected.  Generally, this injury will not result in peanut yield loss as long as the label is followed (i.e. application rate and time).  Here is the Gramoxone label for those that might (should) be interested:

https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/ Gramoxone_SL _3.0 _Label1de.pdf

2) 15 GPA and coarse droplets (VMD₅₀ ≥ 270 microns) are preferred. Gramoxone is NOT LABELED for aerial applications when applied postemergence in peanuts.

3) The UGA recommended treatment (without walking the field) is as follows:  Gramoxone 3SL @ 8 oz/A + Storm 4SL @ 16 oz/A + 1 Group 15 herbicide (either Anthem Flex 4SE @ 3 oz/A or Dual Magnum 7.62EC @ 16 oz/A or Enversa 3ME @ 48 oz/A or Outlook 6EC @ 10.5 oz/A or Warrant 3ME @ 48 oz/A or Zidua 4.17SC @ 2.5 oz/A). I do not have a Group 15 preference.  Anthem Flex will cause more cosmetic injury due to one of its active ingredients (carfentrazone, trade name: Aim).

4) NIS @ 0.25% v/v (32 oz/100 gals) should be included except when Dual Magnum or Outlook are used. Both of these herbicides are EC formulations (oil-based) and therefore have adjuvant-like properties.

5) Growers can make their own Storm (aka "Georgia" Storm) by tank-mixing Ultra Blazer 2SL @ 16 oz/A + either Basagran 4SL @ 8 oz/A or Basagran 5SL @ 6.4 oz/A.  This is a more appropriate ratio for south Georgia and also will be slightly cheaper.  

6) Gramoxone mixing order (from label):

4.4.3 GRAMOXONE SL 3.0 IN TANK MIXTURES: 1. Fill spray tank 1/2 full with clean water or other approved carriers such as clear liquid fertilizer. 2. Add nonionic surfactant to tank 3. Begin tank agitation and continue throughout mixing and spraying. 4. Add dry formulations (WP, DF, etc.) to tank. 5. Add liquid formulations (SC, EC, L, etc.) to tank. 6. Add Gramoxone SL 3.0 to tank. 7. Add crop oil concentrate or methylated seed oil to tank where/if needed. 8. Fill remainder of spray tank

7) Some field pictures from earlier today.  Treatments were applied 4 days ago:

 

Crying Wolf with Valor? (Prostko)

Not sure what's going over the last few days in the peanut patch but I have received numerous inquires about Valor applications ahead of the anticipated rainfall over the next few days.  Here are some reminders to share with overly concerned growers:

1) I have been working with Valor since 1997.  Since that time, I have NO data that proves that when injury occurs, peanut yields are significantly reduced after a labeled/recommended application (3 oz/A within 48 hours after planting, at least 1.5" planting depth).

2) Valor does NOT effect peanut seed germination and radical development.  Recent UGA thermogradient studies indicated that when there is direct peanut seed exposure to Valor at field application rates, there in NO impact on germination and radicle development (Source: Peanut Science (2020) 47:89-93).

3) From 2017-2019, I conducted field trials to evaluate the potential effects of high moisture conditions on peanut response to Valor.  During those trials, peanuts were exposed to 8.0-11.3" of rainfall/irrigation in the first 30 DAP.  Yields were NOT reduced in any year (Source: Peanut Science (2021) 48:113-117). Here is some data for the "Doubting Thomas": 

Figure 1. Peanut yield response to Valor under high moisture conditions in 2018 (UGA Ponder Farm, Ty Ty).  Peanuts were planted 2" deep and Valor was applied 48 hours after planting.  3 oz/A is the labeled and recommended use rate.  

4) Peanuts are most likely to be injured by Valor when higher rates are applied, applications are delayed past 48 hours after planting, peanuts are planted too shallow, and heavy rainfall occurs as the peanuts begin to emerge (i.e. cracking).  Irrigation immediately after application will not prevent Valor injury when heavy rainfall events occur at cracking.

5) Here is an injury picture from some work I did way back in 2009.  Pretty bad but NO yield loss!

Figure 2.  Valor injury 17 DAP (Attapulgus, 2009).  5.44" total rainfall from 

planting until picture was taken. Valor was applied the same day as planting, 

1.75"  planting depth.