Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/15/2003
Publication Date: 12/15/2003
Citation: Wood, B.W., Reilly, C.C., Nyczepir, A.P. 2003. Cu and ni deficiency symptoms and mouse-ear in pecan. Hortscience. 38(5):726. Interpretive Summary: Economic losses due to the mouse-ear disorder has become a serious problem in many southeastern orchards. The cause of the disorder has been unknown and there has been no means of control. Our research has demonstrated that the problem appears to be consistent with that of either a Cu or a Ni deficiency. This knowledge now makes it possible for in depth study into the role of these two metals as a causal factor in mouse-ear.
Technical Abstract: Mouse-ear (ME) is a severe growth disorder affecting pecan [Carya illinooinensis (Wangenh.) K. Koch] trees in certain orchards within the Gulf Coast Coastal Plain of the southeastern U.S. Similar disorders (usually termed "little leaf") appear on certain other deciduous tree species. Our data on pecan implicate a short-term deficiency of physiological availability of CU and/or Ni at bud break, and soon thereafter, as the likely causal factor(s). An evaluation of affected orchards indicate that the disorder is linked to, a) low Cu and Ni availability in certain coils, or b) a Zn induced Cu or Ni deficiency as a result of an accumulation of Zn in old orchards due to decades of foliar Zn applications (thus triggering a replant problem). Because of the difficulty of increasing physiologically available Cu in buds at bud break, foliar application of Cu and Ni in late season (mid October) and early spring (outer-bud-scale-split at bud break) were investigated as approaches to correct the disorder. Timely application of Cu salts in combination with urea or nicotinic acid did not correct Me; however, application of Ni salts generally corrected symptoms. Findings indicate that the disorder appears to be primarily due to a Ni deficiency at bud break. Strategies are presented for management of ME problems in orchards.