Pecan leaves showing a mild form of potentially severe malformation due to the mouse-ear disorder. Image courtesy Bruce Wood, ARS.

Foliar nickel application treats mouse ear   Nickel deficiency causes pecan tree disease

Treatment for Mouse-Eared Pecan Trees Now Licensed

By Sharon Durham
August 30, 2007

A foliar fertilizer developed by Agricultural Research Service (ARS) scientists to alleviate the condition known as "mouse-ear" in pecan trees has been licensed to NIPAN, LLC, of Valdosta, Ga. NIPAN will produce the nickel-based treatment under the trade name NICKEL PLUS. Mouse-ear reduces pecan trees' health and size, makes the trees' limbs brittle, and shrinks nut yields.

The mouse-ear abnormality shows itself as rounded or blunt-tipped leaves. Previously recognized as "little leaf," it's becoming increasingly common in second-generation orchards when pecan trees are replanted. It can also occur in other trees, such as river birch. One treatment of NICKEL PLUS, sprayed on foliage about two weeks after budbreak, is usually sufficient to correct the disorder.

ARS plant pathologist Charles Reilly, nematologist Andrew Nyczepir and Bruce Wood, research leader at the Southeastern Fruit and Tree Nut Research Laboratory in Byron, Ga., determined nickel deficiency to be the cause of mouse-ear. They observed a lack of nickel uptake by affected trees, even when there was an abundance of nickel in the soil. They found that even a severe case of mouse-ear could be corrected by a timely foliar application of nickel liganosulfonate.

Heavy metals such as zinc, manganese, iron, cobalt and copper compete with nickel for uptake channels in the feeder roots of the pecan tree. Additionally, lighter metals such as calcium and magnesium also act to indirectly limit nickel uptake. The researchers found that nickel deficiency had usually been induced by excessive soil or plant accumulation of other elements due to decades of fertilizer applications.

Wood assisted with determining the liquid formulation for NICKEL PLUS, which was developed by NIPAN, LLC. The formulation has now been approved by several state departments of agriculture as a fertilizer for correcting nickel deficiency problems.

The severe form of mouse-ear most commonly occurs in the southeastern Georgia sector of the U.S. pecan belt, but is also found throughout much of the Gulf Coast coastal plain.

ARS is the USDA's chief scientific research agency.