Ash Yellows - Ash Yellows

Jim Olis* and Brian Hudelson, UW-Madison Plant Pathology *Completed as partial fulfillment of the requirements for a BS in Plant Pathology at the University of Wisconsin Madison.
Revised: 4/25/2004
Item number: XHT1079
What is ash yellows? Ash yellows is a chronic, systemic disease that affects ash trees of all ages. White ash is particularly susceptible to ash yellows. Ash yellows occurs in the United States from New York and Pennsylvania west to Minnesota, Iowa, and Arkansas. The organism that causes ash yellows also causes a disease called lilac witchesâ€™-broom.

What does ash yellows look like? Symptoms of ash yellows usually occur within three years of infection. Infected trees typically grow at a much slower rate than non-infected trees, although this may be difficult to detect in a single tree. The rate of growth of an infected tree may be as little as one half that of a healthy tree. Leaves on infected trees are frequently smaller, thinner and lighter green than usual. Often, but not always, affected trees will produce branches in tufts, a symptom that is called â€œbroomingâ€. Eventually, branches in the crown will die and this die-back can continue until the entire crown is dead.

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