Ash Leaf Rust

Early infection lesion of ash leaf rust on white ash. The small yellow-orange pustules will develop into aecia and will produce aeciospores, the spore stage that then infects the host marsh grasses.

Early infection lesion of ash leaf rust on white ash. The small yellow-orange pustules will develop into aecia and will produce aeciospores, the spore stage that then infects the host marsh grasses.
Photo: Maine Forest Service Forest Health and Monitoring Division

A close view of an early ash leaf rust lesion on the leaf vein. Lesions can occur on green stems, petioles, or leaves.

A close view of an early ash leaf rust lesion on the leaf vein. Lesions can occur on green stems, petioles, or leaves.
Photo: Maine Forest Service Forest Health and Monitoring Division