After peanuts are put in the ground the calls about weed control start to come in. The biggest issue this year has been that we have not had enough rainfall to activate some of the residual herbicides that were applied. As you tweak your herbicide plan keep plant developmental milestones in mind.
Peanut Plant Development
- Planting to Cracking 7-14 days
- Bloom 30 – 35 days after emergence
- Peak Bloom 60 – 70 days
- Peg appears 7 days after pollination
- Peg enters the soil 10 – 14 days after pollination
- Full size pod 3 to 4 weeks after peg enters soil
As of May 11, 28% of the Georgia peanut crop was reported as planted. Thus, peanut growers should now be evaluating the success of their PRE weed control programs and deciding on the need for early postemergence or “cracking” herbicide applications. Here are a few reminders about cracking sprays:
1) If a peanut grower started clean and used a good residual weed control program (i.e. Prowl or Sonalan + Valor + Strongarm) that was activated with irrigation or rainfall, the need for a cracking spray is questionable. Best thing in this situation is to go to the field and look to see what has escaped or not. If the field is relatively weed-free, a cracking spray may not be justifiable. Growers might consider waiting until 30-40 DAP to pull the trigger earlier on a POST program such as Cadre + 2,4-DB + Anthem Flex or Dual Magnum or Outlook or Warrant or Zidua.
2) If a grower decides to use a cracking spray, I would suggest a combination of paraquat + Storm or Basagran + Anthem Flex or Dual Magnum or Outlook or Warrant or Zidua. Suggested use rates would be as follows:
a) 2 lb ai/gal paraquat = 12 oz/A or 3 lb ai/A paraquat = 8 oz/A
b) Storm 4SL @ 16 oz/A or Basagran 4SL @ 8 oz/A. If a grower wants to make his own “Georgia” Storm then use Ultra Blazer 2SL @ 16 oz/A + Basagran 4SL @ 8 oz/A.
c) Anthem Flex 4SE @ 3 oz/A or Dual Magnum 7.62EC @ 16 oz/A or Outlook 6EC @ 12.8 oz/A or Warrant 3ME @ 48 oz/A or Zidua 85WG @ 1.5 oz/A or Zidua 4.17SC @ 2.5 oz/A.
3) If Dual Magnum or Outlook are used with paraquat + Storm or Basagran, no additional adjuvants are required. If Anthem Flex or Warrant or Zidua are used, a NIS @ 0.25% v/v is suggested.
4) I would prefer peanut cracking sprays to be applied in 15 GPA and tractor speeds of 10 MPH or less to improve spray coverage and reduce the production of dust (which can greatly reduce paraquat efficacy).
5) Given the option of using either an AIXR or TTI spray tip, I would prefer the AIXR tip.
6) If growers use higher rates of paraquat and/or delay paraquat applications past 28 days after cracking (DAC), the risk for yield loss resulting from paraquat injury is increased. Recent results from a 2018 weed-free field trial indicated that paraquat treatments applied ~35 DAC resulted in a 5.5% peanut yield reduction.
Refer to my earlier post for the complete weed control Recommendation sheet: https://site.extension.uga.edu/plowpoints/2020/03/2020-field-corn-peanut-soybean-weed-control/