Cause Many fungi are reported including Dasyschypha sp., Phyllosticta pyrolae, and Pestalopezia sp. The OSU Plant Clinic has identified Phyllosticta sp. most often. Phyllosticta pyrolae and P. vaccinii (as well as many other fungi) were most frequently isolated from healthy leaves collected from western Oregon. Elsinoe ledi will cause a disease called spot anthracnose.
A survey of the fungi associated with severe leaf spots on salal growing on southern Vancouver Island, BC found Alternaria sp., Monochaetia sp., Pestalotiopsis spp., Phoma sp., Phomopsis sp., Phyllosticta pyrolae, and Valdensia heterodoxa (formerly Valdensinia heterodoxa) as the most common.
Phytophthora ramorum (Sudden Oak Death) can also produce necrotic leaf spots and petioles on salal and other Gaultheria sp. This is a quarantined pest so if you suspect you have seen a P. ramorum-infected plant in Oregon, call the Invasive Species Hotline, 1-800-INVADER (1-800-468-2337).
Most fungal leaf spots are favored by wet weather that keeps leaves wet for extended periods of time. They generally survive unfavorable conditions in plant debris.
Symptoms Phyllosticta leaf spots are nearly circular and brown with pale centers. Spots may start as a small water-soaked or pinhead-size spot. Generally, spots are only a few millimeters wide in nature but can enlarge and coalesce in cold storage. Small, black, fruiting bodies (pycnidia) develop in the spots' centers. Can also produce a stem lesion.
Spot anthracnose is grayish white with a red-brown border and purple margin.
Valdensinia leaf spot - A brown, necrotic leaf spot with concentric rings. Mature infections are characterized by sclerotia on the host veins, followed by leaf death and defoliation.
- Remove infected, dead, and dying leaves on and near plants.
- Avoid overhead irrigation or apply such that plants are not wet for extended periods of time.
Chemical control Fixed coppers may be useful, but no chemicals are labeled specifically for this crop.
References Osterbauer, N.K., Lane, S., and Trippe, A. 2014. Phytophthora ramorum identified infecting eastern teaberry (Gaultheria procumbens) plants shipped to Oregon. Plant Health Progress 15:9.
Petrini, O., Stone, J., and Carroll, F.E. 1982. Endophytic fungi in evergreen shrubs in western Oregon: a preliminary study. Canadian Journal of Botany, 60:789-796.
Shamoun, S.F., Countess, R.E., and Vogelgsang, S. 2000. The mycobiota of salal (Gaultheria shallon) collected on Vancouver Island and the exploitation of fungal pathogens for biological control. Canadian Journal of Plant Pathology 22:192.