“J-Rooting” is not uncommon to see in peanut fields even when plants are growing well.  When seed quality is poor, especially when stress occurs (cool temperatures, for example) J rooting can be very prominent. Historically, herbicides like metolachlor and S-metolachlor (Dual Magnum) have been blamed for J rooting, but work by UGA has demonstrated that this herbicide is not the culprit.  The following images are from Rocky Mount and the show J rooting but stands are relatively good and peanuts are growing well.