Kinnikinnick (Arctostaphylos uva-ursi)-Leaf Spot

Cause Several fungi have been associated with leaf spots of Arctostaphylos uva-ursi (kinnikinnick or bearberry). Gloeosporium arctostaphyli has been reported from Idaho and Washington. Phyllosticta sp. has been commonly isolated from leaf spots by plant clinics in Oregon and Washington. Mycosphaerella pyrolae (formerly Phyllosticta pyrolae), and P. vaccinii (as well as many other fungi) were most frequently isolated from healthy leaves collected from western Oregon.

Symptoms Gloeosporium arctostaphyli spots are at first purple, then black with purple margins, more distinct from the upper surface.

Cultural control

  • Plant resistant cultivars such as the 'Massachusetts' strain.
  • Avoid overhead watering or limit it to times when the foliage can dry quickly.
  • Rake and destroy fallen leaves. Remove and destroy infected leaves from plants, where practical.
  • Space plantings and prune to improve air circulation.
  • Avoid planting in moist, shady areas if leaf spot is a problem.

References Cooke, W.B. and Shaw, C.G. 1952. Western Fungi. III. Mycologia, 44:795-812.

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.