Bad - Shriveled Walnut meats

Asked October 16, 2015, 10:42 AM EDT

What casues English walnuts to have shriveled nut meats?

Upon cracking /shelling of our walnuts, we are finding a good portion of our harvested English walnuts have uneatable- black shriveled nut meats . what causes this and how do we prevent?

Tuscola County Michigan

1 Response

Black shriveled walnut meat is commonly caused by the Walnut husk fly. This insect lays its eggs into ripening husk. Young larvae feed on the husk causing the husk to blacken and it will stain the meat inside. Nuts will shrivel when there is a heavy infestation. Purdue Extension has a bulletin on this subject and states in it that sanitation is part of the solution. Pickup all fallen nuts as soon as they drop and dispose of the bad ones. The larvae leave the damaged nuts and overwinter in the soil, so quick disposal may help reduce their numbers. See the following articles from Extension on managing this pest: