Emerald Ash Borer Switches Hosts - U of I Extension

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Emerald Ash Borer Switches Hosts

This article was originally published on August 26, 2015 and expired on December 26, 2015. It is provided here for archival purposes and may contain dated information.

Emerald Ash Borer on Native White Fringe Tree

Chionanthus virginicus, commonly known as the white fringe tree, is a small flowering shrub that will cause you to be the envy of the neighborhood for at least four to five days in the spring may be under attack by the dreaded Emerald Ash Borer in the Bloomington Normal area,” states University of Illinois Extension Horticulture Educator, Kelly Allsup. 

 

White fringe trees produce pillars of delicate white and billowy flowers that appear in early spring. Bright blue drupes with white blooms are very attractive to birds when they are ripe. The leaf color becomes vibrant once the temperature cools and days shorten.

 

Closely related to the Ash trees, white fringe tree have now become an alternate host to Illinois’ most detested tree pest, Emerald Ash Borer. “Now that the population of Emerald Ash Borer has decimated the Ash tree population in Bloomington-Normal by killing thousands of trees and their food source, the insects may move to other host plants,” states Allsup.

 

University of Illinois Extension Entomologist Phil Nixon shares the latest research on the evolving Emerald Ash Borer. Emerald ash borer has been found in white fringetree in northern Illinois. Nixon shares “Research conducted by Don Cipollini, Wright State University, and Dayton, OH found characteristic exit holes, larval tunneling damage, or other symptoms in seven of the 16 white fringetrees, Chionanthus virginicus, inspected at the Morton Arboretum on May 29, 2015.”

 

Nixon summarizes, “Dr. Cipollini conducted previous research in Ohio that proved that emerald ash borer is able to infest and complete its life cycle in white fringetree. Emerald ash borer life cycle starts as eggs hatch into larvae that proceed through four larval instars (stages) before forming prepupae, pupating, and emerging as adults. He found that eggs produced larvae that, after 40 days of developing in white fringetree, weighed one-third as much as those from green ash.

 

Dr. Cipollini also tested the closely related Chinese fringe tree, Chionanthus retusus, and devilwood, Osmanthus americanus, as potential hosts. Of the 42 eggs placed on Chinese fringe tree, all of them hatched into larvae that penetrated the stem, but none survived 40 days. All of the larval tunnels were one inch or less in length before the larvae died. Of the 30 eggs placed on devilwood, 24 hatched into larvae that penetrated the stem, with three surviving 40 days. Those surviving larvae weighed one-seventh as much as those from green ash.”

Nixon says, “Both Chionanthus and Osmanthus are closely related to ash (Fraxinus). Of the three non-ash species, white fringe tree is the only one found to support complete development of emerald ash borer to the adult stage. Based on his research and observations, Dr. Cipollini surmises that white fringe tree is attacked when dying and beetles that cannot find suitable ash trees on which to lay their eggs. White fringe tree is apparently attacked in desperation and is not a primary host.”

To properly identify the native fringe tree from the Chinese fringe tree, Clemson University says, “Chinese fringe tree is somewhat taller than white fringe tree, usually growing 15 to 25 feet tall. Their habit is similar to white fringe tree, with a rounded, spreading crown, but is usually less open. Chinese fringe trees bloom at about the same time as the white fringe tree, but their flowers are held in smaller clusters, two to four inches wide and long. Flowers of the Chinese fringe tree have shorter, somewhat wider petals, and flower clusters are denser and held at the ends of the branches. Chinese fringe tree leaves are smaller than those of the native white fringe tree, usually rounded, thick, leathery and glossy. White fringe tree flowers open before the leaves appear, while Chinese fringe tree flowers open after leaves emerge. Chinese fringe tree have insignificant fall color.”

If you suspect emerald ash borer infestations in your white fringe tree please contact your local Extension office.

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Source: Kelly Allsup, Extension Educator, Horticulture, kallsup@illinois.edu

Pull date: December 26, 2015