[jmystro]

When just the leaf blade edge yellows (before turning brown when untreated) is from a lack of potassium. Plants are very potash hungry throughout it’s entire life cycle. When plant roots get hurt, nitrogen and potash are the first signs of an issue as they are needed in the highest amounts. Calcium deficiency shows up as tiny brown looking burn spots. Magnesium deficiency shows as interveinal chlorosis (fancy way of saying yellowing between leaf veins as it looks like tiger strips). Mag has yellowing along entire blade while potash just yellows edge.