Gall-like structures on leaves
Click on images for larger versions
The mystery pest appears to be the work of a fungus in the genus Exobasidium, a group of parasitic fungi. While berry production in the area examined will certainly be reduced this year, it probably won’t have serious longer term impacts. The outbreak may be related to the unusually wet weather over last few weeks. With a little citizen science/use of iNaturalist, we can track its occurrence in the Backlands.
UPDATE July 4, 2023. Already a report has come in that the mystery pest is abundant on black huckleberry to the south and southwest of Osprey Trail area. See comment.
By David Patriquin
In a nutshell: most of the Black Huckleberry (Gaylusaccia bacatta) plants I looked at yesterday (July 2), between downpours, within 300 m or so of the trailhead for the Osprey Trail were heavily infected by a mystery pest that causes pinkish galls to form on leaves and distorts fruit (berry) development of black huckleberry (Gaylussacia baccata). I found very few plants with normal berries.
Visually, these structures and deformations look very much like the work of a fungus in the genus Exobasidium, a group of parasitic fungi* so that’s a tentative ID; confirmation by experts is still required to confirm it as such and identify it to the species level.
Many species of Exobasidium are pathogens on plants of the heath family (Ericaceae). Heath family species are prominent on the whaleback outcrops and associated low areas of the McIntosh Run barrens. Besides the huckleberries, blueberries, leatherleaf, sheep laurel (lambkill), crowberries, bearberry, foxberry and teaberry are members of the Heath family; so are our garden rhododendrons and azaleas.
* This possible ID was suggested to me by Sean Basquill, Ecosystem Scientist with Nova Scotia NRR. Continue reading
