Cause Unknown, possibly genetic. Generally not considered a major economic problem. Found throughout the Willamette Valley in Oregon.
Symptoms Yellow blotches on needles of any age. If needles appear speckled, blotches may be small. Yellow blotches also may be large but do not cross the midrib. If needles appear yellow with a drab green midrib, blotches may have merged or coalesced. All variations of needle symptoms may appear on the tree at the same time. Affected needles generally fall off and can cause defoliation in severe cases. Affected trees usually are scattered within a plantation; the disease does not seem to spread within the plantation. Some trees may grow out of the syndrome and look fine 2 to 3 years later. Other trees may be affected each year.
Cultural control None known. Wait to see whether the tree improves. If tree is affected year after year, remove and destroy.
Reference Chastagner, G.A. 1997. Christmas Tree Diseases, Insects, and Disorders in the Pacific Northwest: Identification and Management. Washington State University Cooperative Extension. MISC0186.