Walnut blight, sunburn, and damage caused by walnut husk fly and codling moth all have similar symptoms and may be confused. All have black sunken lesions. Walnut blight lesions are always dry. Husk fly damage remains soft, unsunken, and smooth. Symptoms caused by walnut blight and walnut husk fly may cover the entire husk. Sunburn damage is generally restricted to the side of the husk that is exposed to the sun. Husks or bark may be bleached or cracked. Codling moth damage can be distinguished from the others by the presence of frass left by the moth larva.
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