Rhododendron leaves turning yellow

Asked October 22, 2017, 6:56 PM EDT

Dear OSU Extention experts, I planted a PJM rhododendron this spring. Now i noticed its leaves are turning yellow. Next to this rhododendron, i have a mapple tree which leaves don't look healthy either and plants under the mapple tree are turning yellow too, including groundcovers. What might cause this occurence? Is there something i should do about it? Thank you very much in advance for your advice. Anuška

Benton County Oregon trees and shrubs diagnosis of plant problems horticulture

1 Response

Hello. I wish that you had told me if these photos were recently taken. There is a pest that has been attacking rhododendron shrubs. It has a very distinctive stippling presentation on the leaves. The photo of that shrub is showing some damage to to some of the leaves that may be from this pest. It is difficult to tell from the photo. The other photos look more like seasonal changes to me but it is hard to tell. Both the maple and the sumac are deciduous and should be dropping their leaves soon. Changes in appearance are not unusual this time of year for those two plants. From the photos it is difficult to tell anything else. I suggest that you take samples from all three plants to the Master Gardener help desk for a closer examination of them. The rhodie should not have those bright yellow leaves so take some of them as well as some of the other leaves that show signs of pigmentation changes. The Master Gardener Help Desk is located in the Benton County OSU Extension Office, address is 4077 SW Research Way in Corvallis. Be sure to call first to ensure that a Master Gardener is on duty Phone number is 541-766-6750.