Peanut Weed Control Update for May 23 (Prostko)
1) Rainfall events on Mother’s Day Weekend (May 9-13) caused some Valor related peanut problems in many areas of south Georgia (Figure 1). Since I have addressed this issue numerous times in other blogs, I feel no need to bloviate any further. But, this problem should not be a surprise to anyone who has ever used Valor in the past. Valor injury will almost always happen when rainfall events occur from cracking up until about 2-3 weeks later. Historically, this injury has been cosmetic only and not resulted in reduced peanut yields.
|Figure 1. Valor injury at UGA Ponder Farm, May 14, 2019.|
2) Cracking/EPOST applications of paraquat mixtures or solo applied Storm or Ultra Blazer should be delayed as late as possible in peanut fields suffering from Valor injury. I would argue that if Valor injury has occurred, then good weed control has also occurred and a cracking treatment might not really be needed. Paraquat treatments can safely be applied in peanuts up to 28 days after cracking.
3) Common paraquat mixtures include paraquat + Storm or Basagran + Dual Magnum or Warrant or Zidua. I have no preference between Dual Magnum, Warrant or Zidua. There is no need for additional adjuvants with Dual Magnum mixes but a NIS (0.25% v/v) should be used in Warrant or Zidua + paraquat tank-mixes. FYI, I am not a huge fan of paraquat + Dual Magnum or Warrant or Zidua without any Basagran/Storm due to greater injury potential that might reduce yields (especially under these lava-like weather conditions). Also, paraquat without Basagran/Storm is not very effective on smallflower mg (Figure 2).
|Figure 2. Smallflower morninglory|
3) With paraquat mixes, I prefer Storm (bentazon + acifluorfen) over Basagran (bentazon) due to the variety of weeds that can occur in any given peanut field in Georgia. My typical recommended use rate of Storm in EPOST paraquat tank-mixes is 16 oz/A. If need be, growers can make their own “Georgia” Storm by mixing 16 oz/A of Ultra Blazer 2SL + 8 oz/A of Basagran 4SL (yes, this is a slightly hotter mix than 16 oz/A of Storm).
4) It is very hot and very dry right now. Non-irrigated growers who were planning on using paraquat tank-mixes after peanut emergence might want to re-considering their options. Why? Rainfall/irrigation is critical in helping peanut plants recover from paraquat injury. I do not think that irrigated growers need to worry about this issue since they can help the peanut plants recover from paraquat injury with well-timed irrigation events.
5) When paraquat + Storm/Basagran + Dual/Warrant/Zidua mixtures are applied in peanut, there is no need to be a great ID’er of weeds since these mixes control just about everything (small grasses and small broadleaf weeds). But, if a non-irrigated grower decides to go with something other than paraquat mixtures (which is fine), such as Ultra Blazer or Strongarm or Cadre or 2,4-DB, they better know what is in the field since these herbicides are not as broad spectrum. I am not comfortable with very early applications of Cobra unless the peanut plants have reached the 6 true leaf stage.
6) No matter what I say or do, if it don’t rain, it don’t matter! (That’s a famous quote from former UGA Extension Peanut Specialist, Dr. John Baldwin)