Plant Disease Management Handbook

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. Phyllosticta pyrolae and P.

Leaf spot due to a Mycosphaerella sp.

OSU Plant Clinic, 2023.

This leaf spot symptom was caused by Pestalotia sp.

Photo by Ralph S. Byther

See:

Azalea (Rhododendron spp.) - Leaf and Flower Gall

Notice the leaf galls due to Exobasidium sp.

Melodie Putnam, 1998.

As the galls mature they eventually become brown and woody.

Melodie Putnam, 1998.

See:

Greenhouse Plants, Ornamental - Black Root Rot

This "Massachusetts' kinnikinnick had black root rot and chlorotic foliage.

OSU Plant Clinic, 2011.

Cause Both Phytophthora sp. and Pythium sp. have been isolated in the OSU Plant Clinic. Phytophthora cinnamomi has been reported several times and Phytophthora hydropathica has been found both in irrigation water and from root-crowns of wilting plants. Excess water is the most important factor favoring disease development.

Root rots cause non descript symptoms on the above parts of the plant. The plant in this picture has died.

Photo by Jay W. Pscheidt, 1991.

See:

Crabapple (Malus spp.) - Stem Rot

See:

Kalmia (Mountain Laurel) - Leaf Spots

Rhododendron - Ramorum Leaf Blight and Shoot Dieback

Image related to Kalmia (Mountain Laurel)-Phytophthora Blight
Image related to Kalmia (Mountain Laurel)-Phytophthora Blight
Foliar blight on Kalmia caused by Phytophthora syringae.
N. Grunwald.

See:

Azalea (Rhododendron spp.) - Botrytis Petal Blight

Senescent flowers are more likely to develop the gray sporulation of Botrytis.

Jay W. Pscheidt, 2020.

Humid wet conditions encourage development of Botrytis on petals and spent flowers.

Jay W. Pscheidt, 2020.

See:

Rhododendron - Necrotic Ringspot

Image related to Kalmia (Mountain Laurel)-Necrotic Ringspot
Image related to Kalmia (Mountain Laurel)-Necrotic Ringspot
Note the reddish line patterns on the leaves. Plants are very unthrifty.
Photo by Jay W. Pscheidt, 1998.

See:

Rhododendron - Ramorum Leaf Blight and Shoot Dieback

Image shows leaf spot with dark purple boarder and fungal fruiting bodies in the middle but does not indicate what leaf spot organism was found.

OSU Extension Plant Pathology Slide Collection.  

See:

Azalea (Rhododendron spp.) - Cylindrocladium Blight and Root Rot