Oregon grape disease

Asked May 2, 2017, 3:13 PM EDT

Hello, I live on 5 acres in rural Central Oregon (Powell Butte). Since moving to this area 2 years ago, I've noticed that the 2 mature Oregon grapes always look moth eaten. They both flower and fruit but look terrible. Can you tell from the photos what the problem is and how to treat? Thank u!

Crook County Oregon horticulture oregon grape

1 Response

Thank you for your Oregon grape question. From your photo it appears that your plants may have necrotic leaf spot, which is caused by fungi. The symptoms are brown necrotic spots on the leaves.

There are garden cultural practices you can implement to help control the problem:

  1. Remove and destroy all infected leaves.

  2. Avoid overhead irrigation or apply to minimize the time that the leaves are wet.

By implementing these practices you will limit the spread of the fungi.

If these cultural practices do not solve your issue, you can consider a chemical control. Bonide Fung-onil Multi-purpose fungicide is recommended. Follow application instructions on the label.

https://pnwhandbooks.org/plantdisease/host-disease/oregon-grape-mahonia-aquifolium-leaf-spot

If you would like to talk with a Master Gardener about your plants, we welcome your home garden questions at the OSU Master Gardener Plant Clinic. You can call the plant clinic at 541-548-6088, or email your questions to the OSU Deschutes County Master Gardener Plant Clinic email: deschutesmg@oregonstate.edu.