The following is from Dr. Balota's chapter in 2021 Virginia Peanut Production Guide (Publication SPES-274NP) relative to inoculant performance.

Poorly inoculated fields usually will not show any yellowing until about 45 DAP.  Inoculation can be checked by using a shovel to uproot plants. Simply pulling up plants will cause the lower taproot to break off and result in a low count. The presence of large (1/8” or larger) nodules on the taproot indicates successful inoculation. An average of 15 large nodules per taproot at 45 DAP is considered good; less than 10 per taproot is marginal and less than 5 indicates poor inoculation. If only small (1/16”) nodules are present and these are mostly on the lateral roots rather than on the taproot, the plant has probably only been colonized by native Rhizobium bacteria, not the applied inoculants.