Red Stain in Boxelder

Boxelder, Acer negundo, is sometimes identified by a red stain in the wood. The presence of the stain does not seem to harm the structure of the wood. In fact, some people find the stain interesting and incorporate it into woodworking projects. The color of the stain can range from light pink to dark red. When exposed to the light, the color of the stain fades over time.

It has been reported that the stain is caused by the infection of the fungus Fusarium reticulatum. A recent study, however, gives evidence that the cause of this staining may be related to nonspecific causes, particularly wounding caused by environmental factors, insect injury, or sapsucker injury.

Two researchers at the University of Minnesota, Andrea Morse and Robert Blanchette, performed a series of experiments to investigate the cause of the red stain in boxelder. They inoculated trees with various fungi, and also wounded trees without inoculating to serve as experimental controls.

They were not able to isolate Fusarium reticulatum from red-stained tissue. In addition observing the red stain in trees inoculated with various fungal species, they also observed red staining in the trees that were only wounded, but not inoculated with fungi. The researchers speculate that boxelder trees produce the red stain in response to nonspecific wounding.

In the future, the researchers would like to learn more about the composition of the red stain, and the function it serves in the tree. They would also like to learn more about how certain organisms, such as fungi, seem to enhance the production of red stain.

This article originally appeared in the April 1, 2003 issue, p. 35.

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