Leaf dieback on onion caused by bacterial bulb rot.

Above brown soil stands an onion plant with many firm, tall leaves. While most leaves are thick and healthy, two inner leaves are completely withered and yellow. A few leaves near the base of the plant show some yellowing and drooping. Credit: Brenna J. Aegerter, UCCE San Joaquin County
Credit: Brenna J. Aegerter, UCCE San Joaquin County