Dying kinnikinnick/bearberry

Asked June 3, 2018, 9:12 PM EDT

I have a yard full of kinnikinnick that was planted last year (early spring 2017.) It was establishing well and sending out lots of new growth last summer. Now, much of the new growth has died and about a 30% of the plants are completely dead or mostly dead. They were planted in fill, which around here is sand. Is the sand causing them to die? I was so encouraged by the vigorous growth only to see most of it die over the winter. The plants that remain are showing vigorous growth again. We did fertilize last fall. Do I need to have the landscaper dig them up and start over with decent soil? All the dead parts/plants are black. Thank you for your time. Kate

Clatsop County Oregon horticulture

1 Response

Manzanita (Arctostaphylos manzanita)-Leaf Spots is a fungal disease, which I believe is the problem. There could be as many as 15 different fungi, which have been reported from the Pacific Northwest. For all these foliage diseases; however, airborne or water-splashed spores infect young leaves during wet weather, often in spring.

Symptoms of this disease Gloeosporium arctostaphyli (rust) are spots that at first are purple, then black with purple margins, more distinct from the upper surface. The rust disease alternates between spruce and various species of bearberry including manzanita. The plant eventually turns black and dies. Remove all dead and infected plants to avoid further disease. Plant resistant cultivars such as the 'Massachusetts' strain. Avoid overhead watering or limit it to times when the foliage can dry quickly, which is impossible in the winter. Replant in the Spring when it is dry and amend the soil to help establish the plants before winter. Space plantings to improve air circulation and avoid planting in moist, shady areas.

References:

https://pnwhandbooks.org/plantdisease/host-disease/kinnikinnick-arctostaphylos-uva-ursi-leaf-spot

https://pnwhandbooks.org/plantdisease/host-disease/manzanita-arctostaphylos-manzanita-leaf-spots