Mouse-Ear Can Be Defeated
Durham November 22, 2004
Pecan growers battling a tree ailment called "mouse-ear" can now rest
assured that help is on the way, thanks in part to
Agricultural Research Service scientists
who discovered that the condition is caused by a nickel deficiency in the
The ARS discovery has led to a commercial fertilizer application to
control mouse-ear. This growth and development abnormality, recognized as
"little-leaf" in other crops, is becoming increasingly common in
second-generation pecan orchards where new trees are planted.
Nickel deficiency was pinpointed as the problem by research leader
Wood and plant pathologists
Nyczepir at ARS'
Fruit and Tree Nut Research Laboratory in Byron, Ga.
A foliar fertilizer, called NICKEL PLUS, has been developed by NIPAN,
LLC, of Valdosta, Ga. It has been approved by the
Georgia Department of Agriculture as a
fertilizer nutrient that can correct nickel deficiency problems in pecan and
river birch trees. Wood assisted with determining the treatment formulation,
which will be available for distribution next spring.
Wood and his colleagues saw there was a lack of nickel uptake by the
plants even if there was an abundance of nickel in the soil. Heavy metals such
as zinc, manganese, iron, cadmium and copper compete with nickel for uptake
channels in the feeder roots of the pecan tree. Additionally, lighter metals
such as magnesium also act to indirectly limit nickel uptake. It was found that
nickel deficiency had usually been induced by excessive accumulation of other
elements due to decades of fertilizer applications.
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.
The anomaly first appears on the spring flush of shoots. A severe case
of mouse-ear is corrected by a timely foliar application of nickel.
ARS is the USDA's chief scientific