Some responses to a few common questions this week about preplant burndowns:
1) What is the plant-back restriction for field corn following an application of 2,4-D?
Plant-back restrictions for field corn after a burndown application of 2,4-D are 7 days (16 oz/A) or 10-14 days (>16 oz/A)
2) If a grower cannot wait to plant field corn in 7-14 days after an application of 2,4-D, what other burndown options are available?
Roundup (glyphosate) or Gramoxone** (paraquat) + Atrazine 4L (32 oz/A) is my first choice. There are no field corn plant-back restriction for these treatments. Check out the following picture from my burndown plots yesterday in a Tift Co. growers’ field (many thanks to Justin H. and Regan V.).
3) What’s the best option for controlling a failed stand of field corn?
It has been my experience that the best option for controlling a failed stand of field corn is to use Select Max 0.97EC (or other equivalent formulations) @ 6 oz/A + NIS. But, there is a for real 6 day plant-back restriction (field corn) for this treatment. Since many of our current field corn hybrids have tolerance to both Roundup and Liberty, neither of these are great options. Gramoxone has been too inconsistent for me to have much confidence. FYI, it takes about 10-14 days before you really start to observe the full effects of Select Max.
4) What is our current recommended preplant burndown program for peanut?
Roundup or Gramoxone** + Valor @ 2 oz/A + 2,4-D (1 pt/A). An additional 2 oz/A of Valor can be applied at planting. Peanuts can be planted anytime.
**When using Gramoxone on small grain cover crops, applications need to be made when seedheads are present.