Earlier today I had a question about peanuts with a light green cast and whether one should consider a nitrogen application. My recommendation is that when peanuts are 45 days old (45 days after emergence,) dig up roots and assess nodulation. If the canopy is light green in color, this could reflect rapid growth or wet/cloudy weather. The solution to the latter is drier fields and not applied nitrogen. If peanuts are turning yellow, there may be an issue with nodulation. While peanuts will have hundreds of nodules on roots by the end of the season, if the taproot has less than 15 nodules about 45 days after they emerge, application of nitrogen might be warranted.