The following update was prepared by Clemson Peanut Specialist Dan Anco.
There have been some instances of j-rooting and poor vigor this year. Dual has a tendency to get the blame for j-rooting, but often times it is a result of poor seedling vigor. When combined with suboptimal growing conditions, seed with lower vigor have a more difficult time rising to the challenge of good growth. Drought periods the southeast experienced during the 2016 growing season set the stage for less than ideal seed production, and seed lots with lower vigor are one of its symptoms. Even seed that came from irrigated fields can be affected, particularly if excessive water loss through evapotranspiration reduced the effective amount of water that was made available to the crop.
What can we do? Vigor can be a little more elusive to get a feel for before planting than say something like germination. One thing we can try is to obtain the standard germination rate of each individual seed lot and compare that with the cold germination rate for that lot. If there is a wide difference between the two, then this might hint at a lower relative vigor for the lot. More work needs to be done to provide guidance and specifically determine how big of a difference becomes important, and until then this may seem a bit like a guessing game. In the absence of explicit vigor estimates of each lot, another thing we can try if planting conditions allow is to plant slightly shallower (e.g., 1.5 in versus 2 in) in years following stressful years if our seed was sourced from regions affected by drought. Planting into moisture is still more important than starting the seed closer to the surface. These are certainly compromises, and they are no substitution for healthy seed. While most peanut planting in the state is well underway, in future plantings, saving a bit a seed from each lot could be used to check germ and vigor if you have stand issues. As an added reminder, when possible seed stores best in a cool environment protected from the sun or heat for extended periods of time.