In-season plant tissue testing can be useful in diagnosing nutrient deficiencies in field crops, but it must be used with caution. Extra care is needed this year given the unusual crop planting and growing conditions.
Iowa State University
Mallarino, Antonio and Sawyer, John E., "Tissue Testing for Field Crops Requires Cautious Use and Interpretation" (2019). Integrated Crop Management News. 2554.