Technical Abstract: The nutritional physiology of essential micronutrients in pecan, especially that of nickel, is a limiting factor in optimization of physiological efficiency of orchard enterprises. Knowledge by farmers and extension specialists about the role of nickel, a newly recognized micronutrient, is meager. This review summarizes situations where nickel influences mouse-ear and orchard replant maladies affecting many orchards. This information assists in recognition and correction of nickel deficiency in orchards, thus, helping to maximize profitability.