River Birch Nutritional Problems

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A rare micro nutrient deficiency  in river birch causes a symptom called mouse ear because the leaves become very small and have a curled upper edge.

During the summer of 2012, which was hot and dry, I observed river birch trees (Betula nigra) in northeast Florida with symptoms I had not seen previously. The leaves of new growth were smaller about 1/4 their normal size with a distorted, somewhat rolled distal end. Severely affected branches can defoliate and eventually die.

At first I suspected herbicide damage. But after seeing the problem on nearby properties that did not have the same landscape maintenance company, I ruled out herbicide as the cause.

I then remembered an obscure micro nutrient deficiency. It has a name — mouse ear. This rare micro nutrient deficiency is normally found on river birch nursery stock  and less frequently in the field. This micro nutrient deficiency is more commonly found on pecan trees but I have not seen it on pecan trees in northeast Florida.

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Once treated for the micro nutrient deficiency, the new flush of growth had normal sized leaves within four weeks following treatment. The chlorosis cleared up shortly after the photo was taken.

I found the appropriate micro nutrient product and appliced it as a foliar spray and a soil drench. Within four weeks new growth had begun to emerge without the mouse ear symptoms.