Native Plants

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Thursday - January 16, 2014
From: Beaverton, OR
Region: Northwest
Topic: Diseases and Disorders, Shrubs
Title: Care for California lilacs from Portland OR
Answered by: Barbara Medford
QUESTION:
Hi There, We live in the Portland Oregon area, so temps are moderate and winters are wet. We have several California Lilacs that are about 7ft in height and have created the perfect screen. Love these shrubs, but just noticed that on most of them (6 or 7) the leaves have started to brown and are now falling off (started to notice this all in late December). I also noticed an extremely strong fragrance coming from the shrubs (like a combination of cinnamon and alcohol but gone bad..hard to describe). I had actually thought it was a neighbor cooking for the holidays, but realized today it was my shrubs. I don't have a green thumb, so not sure at all what to do. Any thoughts on what might be causing this? My initial thought was verticillium wilt. It would be horrible to lose all 9/10 shrubs this winter. Any help will be GREATLY appreciated!ANSWER:
We always like to begin by discovering if the plant in question is native to North America and also to the area in which it is being grown; in your case, Multnomah County, on the northern border of Oregon with Washington State. Since we had nothing with the name "California Lilac" as the common name in our Native Plant Database, we next searched the Internet on that name and got this page from Laspilitas Nursery California Lilacs referring to California Lilacs as Ceanothus spp. On that same search, we found this article from SF Gate How to Care for California Lilacs, which used the same designation - Ceanothus spp. This usually means that there are several species of that genus growing in different areas.
So, we tried searching our Native Plant Database on Ceanothus, learning there are 26 members of that genus native to North America and 6 to Oregon. The one we chose to use as an example is Ceanothus sanguineus (Oregon teatree), which according to this USDA Plant Profile Map is native to Multnomah County. If you follow that plant link to our webpage on the plant, you will see that another of its common names is "Wild Lilac" so we feel we are on the right track. We have no pictures of this particular species in our Native Plant Image Gallery, so here are some pictures from Google.
We found no information in our own database on the symptoms you have described, but suggest you read the articles from SF Gate and Las Pilitas for some clues. We also urge you to compare the growing conditions in your garden with those described as optimum for Ceanothus. We did note in the Las Pilitas article that heavy watering and fertilizing are not recommended. Since we are gardeners, not entomologists, we suggest you contact Oregon State University Extension for the Portland Metro Area. Generally, these university extension programs are closer to the area and more knowledgeable in the conditions there. That home page also has a link to the Portland Metro Area Master Gardener Program.
These people are trained, on-the-ground gardeners who may very well have encountered the very same problem you have. Either site should be able to help you diagnose the problem, and if it proves to be a pest or disease, give you guidance in treating it.
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