ARS | Publication request: Response of young bearing pecan trees to spring foliar nickel applications

Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 19, 2010
Publication Date: September 5, 2011
Citation: Wagle, P., Smith, M.W., Wood, B.W., Rohla, C.T. 2011. Response of young bearing pecan trees to spring foliar nickel applications. Journal of Plant Nutrition. 34:1558-1566.

Interpretive Summary: Alternate bearing of pecan is a major production problem for farmers and is potentially influenced by nutrient element stress. Cooperative research established the upper limit for the lower critical level of leaf nickel in pecan farming situations representative of the south central U.S. This information establishes a baseline that enables pecan farmers to better manage orchards to avoid nickel stress and its associated accentuating effects on alternate bearing.

Technical Abstract: The lower critical leaf concentration for nickel (Ni) has not been fully determined for commercial pecan [Carya illinoinensis (Wang.) K. Koch.] orchards. In a two-year study, foliar Ni was applied to orchard trees in early spring beginning at the parachute stage of leaf development and followed by two additional applications at two week intervals. Yield, yield efficiency (ratio of yield to trunk area), trunk growth, leaf area, specific leaf weight, nut weight, nut quality, and kernel percentage were unaffected by treatment. Leaf Ni was increased, but leaf zinc (Zn) and manganese (Mn) concentrations were reduced by foliar Ni application. The lack of a detectable response to Ni treatment indicates that a July leaflet Ni concentration in the control (2.87 µg•g-1) met this pecan orchard’s Ni requirement, establishing a lower critical threshold for leaf Ni than proposed elsewhere.