In the past week, I have been involved with 3 field situations where dicamba was inadvertently applied to peanut prior to planting. The results were not good. Dicamba is NOT labeled for preplant use in peanut. With that said, here is all I know about how peanuts respond to soil-applied dicamba.
1) This is what soil-applied dicamba injury on peanut looks like. I had to pinch hit that day for Bill “Bob Never Gave Me a Cool Nickname” Starr. I cannot remember for sure but I I think Bill was hunting Sasquatch in Montana or Wyoming????
2) Field studies that I and several others conducted with preplant applications of dicamba way back in the early 2000’s indicated the following:
a) Dicamba at 0.25 lb ae/A (i.e. Clarity @ 8 oz/A or Engenia @ 6.4 oz/A or Xtendimax @ 11 oz/A) applied 7, or 15, or 30 days before planting (DBP) had no effect on yield in 7/7 trials.
b) Dicamba at 0.25 lb ae/A applied 0 DBP (i.e. PRE) caused significant peanut losses in 2/7 field trials. Peanut yield losses in those 2 trials ranged between 36%-76%.
c) Source: Prostko, E.P., T.L. Grey, W.C. Johnson III, D.L. Jordan, W.J. Grichar, B.A. Besler, K.D. Brewer, and E.F. Eastin. 2003. Influence of preplant applications of 2,4-D, dicamba, tribenuron, and tribenuron plus thifensulfuron on peanut. Peanut Science 30:18-22.
3) From Blanchett, B.H., T.L. Grey, E.P. Prostko, and T.W Webster. 2015. The effect of dicamba on peanut when applied during vegetative growth stages. Peanut Science 42:109-120.
4) The most important factors that influence how peanuts will respond to soil-applied dicamba are application rate, soil type, the time interval between application and planting, and irrigation/rainfall. Based upon my experiences with dicamba on peanuts and soybeans, peanuts could be safely planted 14 days + 1″ rainfall/irrigation (0.25 lb ae/A) or 28 days +1″ irrigation/rainfall (0.5 lb ae/A) after a preplant application of dicamba. But, I need to stress again the fact that dicamba is NOT labeled for preplant use in peanut!