Interpretive Summary: Economic losses due to the mouse-ear disorder have become a serious problem in many southeastern orchards. The cause of the disorder has been unknown and there has been no means of control. Preliminary research findings indicate that the cause is due to a nickel (Ni) deficiency. Orchard management strategies are discussed within the context of how to correct and prevent mouse-ear in pecan orchards. This information provides a means of solving the economic harm associated with the mouse-ear disorder of pecan.

Technical Abstract:
The mouse-ear disorder of pecan is a long standing problem that has resisted a solution for nearly a 100 years. Information is discussed relating to how mouse-ear is induced and what orchard managers can do to correct the disorder. Orchard management factors such as soil pH, soil moisture, amount of timing of N applications, zinc application, phosphorous fertilizers, all potentially influence mouse-ear severity. Symptoms implicate a trace micro nutrient deficiency as the primary causal factor. The prime candidates are Cu and Ni. Field and greenhouse results indicate that the problem is in fact due to nickel deficiency.