An entry written by former 2011-2012 work-study student Katherine that I had squirreled away today. She writes:
Today, we have a lovely purple fungus known as Chondrostereum purpureum or silverleaf fungus. Many thanks to Marianne (aka marcella2/tovje@Flickr) for this wonderful image of Chondrostereum purpureum covered in exuding water droplets (via the UBC Botany Photo of the Day Flickr Pool). Please see a previous Botany Photo of the Day entry on Fomitopsis pinicola for more on guttating fungi.
Some of you may be familiar with Chondrostereum purpureum, or at least the disease it causes in trees (silverleaf), as this fungus can be parasitic on a number of ornamental and/or orchard woody species, particularly those in Prunus (cherries & plums and more), Malus (apples) and Pyrus pears. A clear explanation of silverleaf disease is provided by New Zealand’s Horticulture and Food Research Institute.
Another common name for Chondrostereum purpureum is violet crust, as individuals starts their growth as a crust on exposed sapwood, then develop to be about 3cm in width with a “tough rubbery texture”, according to the Wikipedia entry. Subsequently, the crust “dries out, becomes brittle, and turns a drab brown or beige” with the “infected wood […] stained a darker tint”.
In addition to rosaceous woody plants, Chondrostereum purpureum can also infect many other broad-leaved species (and even a few conifers), giving the species an extensive global distribution (mirroring to a large extent its host plants).
Chondrostereum purpureum is not considered edible. However, it does have an effective economic use in inhibiting resprout and regrowth of cut tree stumps. This application of the fungus can particularly be used by the electrical industry for stumps near power lines. The species is also undergoing testing as a possible control for competing vegetation in conifer plantations by the British Columbia Ministry of Forests and Range (though given how easily fungi spread, one wonders if this could have deleterious effects on the British Columbia orchard industries, even with assurances that this “mycoherbicide is restricted to the target vegetation”).
For those interested, MycoBank.org provides microscopic and spore descriptions for their available cultures of Chondrostereum purpureum.