Elm Phloem Necrosis
caused by Mycoplasma

This disease kills more elms than Dutch elm disease in many urban areas. It is prevalent in the eastern half of the nation. The disease is common on winged and American elms, but attacks all elms.

Identification:

Mycoplasma, which are microscopic plants, cannot be field identified. Consult a specialist.

Injury:

Symptoms appear initially on one branch or a small portion of the crown. Leaves wilt, become chlorotic, and their margins curl upwards. Defoliation follows, and the crown appears bushy. Defoliation and death can occur in a few weeks. Some of the brown, wilted leaves persist, separating these symptoms from Dutch elm disease. This disease is identified by the butterscotch discoloration of the inner bark of the host tree. A wintergreen odor can sometimes be smelled after placing the affected bark in a vial or plastic bag.

Biology and History:

Leafhoppers that have previously fed on infected elms transmit the mycoplasma to healthy elms.