Location: Fruit and Nut ResearchTitle: Supplemental foliar nickel and copper applications do not reduce kernel necrosis in pecan trees receiving excess nitrogen Author
Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2010
Publication Date: 9/1/2011
Citation: Wagle, P., Smith, M.W., Wood, B.W., Rohla, C.T. 2011. Supplemental foliar nickel and copper applications do not reduce kernel necrosis in pecan trees receiving excess nitrogen. Communications in Soil Science and Plant Analysis. 42:2219-2228. Interpretive Summary: A recently discovered malady of pecan kernels threatens orchard profitability in the central U.S. pecan producing region. The malady is a darkening (i.e., necrosis) of the lower surface of nut meats. Cooperative research with Oklahoma State University appears to exclude a causal role for either nickel or copper status of the kernel. This research narrows the field of possible causes.
Technical Abstract: Pecan [Carya illinoinensis (Wang.) K. Koch] fruit developed necrotic tissue at the basal end of the kernels (cotyledons) in an orchard receiving unusually high amounts of nitrogen (N) from nitrate contaminated irrigation water. It was hypothesized that increasing canopy nickel (Ni) and copper (Cu) could mitigate negative effects of excess N and reduce the incidence of kernel necrosis. Nickel, copper, and Ni + Cu were tank mixed with zinc (Zn) and applied as a canopy spray application at the parachute stage of leaf development, followed by two additional applications at two week intervals. One study was conducted for two years using the same trees, and a second study was conducted for one year in an adjacent orchard using the same treatments. Foliar nutrient applications effectively increased the leaf concentration of the target nutrients. Results indicated that the amount of kernel necrosis was unaffected by treatment, and no consistent positive results could be attributed to the canopy treatments although N was supplied at abnormally high rates.