Elm Yellows—Another Diagnostic Indicator

Left: Adding bark section to a jar to detect wintergreen scent. Right: Bark section held in a closed jar for one to two hours. Photos courtesy Joe Boggs

By Joe Boggs and Francesca Peduto Hand, PhD

An interesting chemical reaction that produces methyl salicylate (oil of wintergreen) occurs in the phloem tissue that is colonized by the EY phytoplasma. This provides another diagnostic indicator of EY on American elm. The so-called scratch-and-sniff method of detecting the wintergreen scent involves cutting a section of bark to the white wood near the base of the main stem and placing the sample in a sealed jar. While the wintergreen scent is usually very faint at first, it becomes easily detectable after the sample has been held in the jar for approximately one to two hours.

Death from EY occurs quickly. In fact, trees that appear perfectly healthy with normal twig elongation and leaf expansion early in the growing season are often dead by the end of the season. There are no effective treatments and susceptible trees can become infected regardless of their overall health.

Read the full article: Elm Yellows: The Re-Emergence of an Old Tree Killer

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