Kelly breaks down his latest tests and shows you what he looks for.  As corn transitions from a slow start to rapid growth, tissue testing becomes a vital part of getting ahead of any potential disease, pest,  and stress issues.  Plants with nutrient deficiencies are more prone to stress.  More stress means lower yields.  Getting the plant the right nutrients before it shows you that it is deficient is key to maintaining strong growth through the entire season.  This is especially true in high population blocks.