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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Abies, Plant diseases--Diagnosis, Trees--Diseases and pests

Can I attempt to diagnose a diseased tree online? We're getting more brown spots on our grand fir and I would like to try to figure out what is wrong.


You can attempt it, but you will not know for certain based solely on a comparison of symptoms. You can certainly get an idea of what the potential problems could be. Try the Pacific Northwest Disease Management Handbook online---it has excellent photos. Search for fir.

There are several possibilities with brown spots as symptoms, especially:
*needle casts (there are 3 kinds)
*web blight
*current season needle necrosis
*shoot blight
*Grovesillea canker
*interior needle blight

The best way to diagnose a problem is to bring photos of the affected tree along with samples (if you can reach them) to your local county extension agent or Master Gardener diagnostic clinic.

Date 2017-02-16
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Plant Answer Line Question

Keywords: Burl, Abies, Sequoia

I would like to remove a burl from one of my fir trees. Can I do this without causing harm to the tree?


I was unable to find any information on the incidence of burls (lignotubers) on fir trees (Abies), but I did locate information about redwood (Sequoia sempervirens) burls from a version of The Sempervirens Fund website which is no longer available:

About Redwood Burl
by Chris Brinegar, PhD

"The swollen tissue at the base of some redwood trees is commonly known as a "burl" although scientifically it is referred to as a lignotuber (from the Latin for "woody swelling"). All redwoods have lignotuber tissue but not all have large visible burls. Lignotuber tissue is derived from cells that exist in the tree's seedling stage and then proliferate near the base of the tree as it ages. Buds form within the woody burl and remain dormant until stimulated to grow by damage to the main trunk (usually by fire or logging). The resulting shoots grow rapidly using carbohydrates stored in the surrounding cells and minerals transported through the parent tree's root system. Lignotubers can also form their own roots.

Lignotubers are responsible for vegetative (clonal) reproduction common in redwoods. Without this mode of propagation, the redwood forest would appear far different than it does currently. The second and third-growth redwoods in our coastal forests were generated vegetatively after 19th and 20th century logging of the original forests. If redwoods were solely dependent on reproduction from seed, their numbers would only be a small fraction of what we see today.

Most people think of burl as the "sliced redwood" sold in gift shops and roadside stands, but they do not realize that many of these burls were obtained illegally. There is a growing black market for burl with much of it coming from unscrupulous dealers who harvest it from healthy redwoods on protected forestland. In some cases, removing burl can kill a tree or, at the very least, deface it and reduce its reproductive potential.

Burls can be planted under the appropriate conditions to allow the shoots to form roots and then grow into trees, but the typical buyer of a redwood burl places it in water, watches the shoots grow, then disposes of it after the shoots die from lack of nutrients. If you are determined to grow a redwood tree we suggest that you purchase a small seed-derived tree from a reputable nursery rather than trying to grow one from a burl that may have been acquired through questionable methods."

According to the information here, it seems that by removing a burl, you may risk harming or killing the tree. You might want to contact a certified arborist in your area, and ask them what they recommend. Here is a link to the website of the Pacific Northwest chapter of the International Society of Arboriculture, where you can find lists of certified arborists.

Date 2017-05-12
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Plant Answer Line Question

Keywords: Abies, Trees--Diseases and pests

We planted a young Fraser fir last March. It has a lot of new growth, but has developed some dead-looking tips here and there that are a reddish rust color. I am wondering if we have a serious problem or should I just remove the affected tips and not worry about it? I have noticed a lot of trees this summer on my travels out through the Cumberland-Enumclaw area that look a similar cinnamon color and are totally dead!


The problem you describe could be the result of drought injury, or it could be one of several rust and fungal diseases which affect fir trees. Was the tree watered well after planting? Here is information on drought injury from Oregon State University's plant disease database. Excerpt:

Drought injury usually progresses from the top of the tree downward and from the outside to the inside of the crown. Top dieback and branch death may be common. Defoliation of the mid-crown or loss of needles at the base and tip of shoots can also occur in Douglas-fir. Older needles commonly turn yellow and are shed prematurely. Roots may be alive even though the entire above-ground parts are dead. Winter injury, gopher and root weevil problems can produce similar symptoms.

Your description also sounds like the symptoms of Phytophthora, a fungal disease which is common in our area. Excerpt:

Phytophthora root rot is usually a problem only in areas with poor drainage or where flooding occurs. The fungus attacks the roots, which rot and die. The infection moves up into the crown, where the cambium (soft inner bark) turns reddish-brown or caramel in color instead of the normal white to greenish color. Older trees may develop cankers on the trunk, which are a dark reddish-brown when cut. The cankers may be accompanied by split bark and oozing pitch. Lower branches wilt, turn dark red, and die back. Younger trees are often killed outright, while infected mature trees may show wilting, branch dieback, and/or gradual decline.

Missouri Botanical Garden's Integrated Pest Management site has information and includes an image of Fraser fir suffering from Phytophthora.

The Connecticut Agricultural Experiment Station has published a guide entitled "Recognizing and Managing Phytophthora Root Rot and Other Conifer Diseases" which may be of use to you. (Caution: this is a large file!)

I recommend taking a sample of one of the cinnamon-colored branches to a Master Gardener Clinic, and also taking photos of the whole tree, so that you can have the problem diagnosed. If you are near Enumclaw, the Pierce County Master Gardeners offer diagnostic clinics.

Date 2017-02-11
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Plant Answer Line Question

Keywords: Abies, Edible wild plants, Pseudotsuga menziesii, Ethnobotany

There seems to be a new fad of local foragers making tea from the needles of Douglas fir and Grand fir. I am guessing there are Native American origins to this practice. How safe is it, especially in an urban environment? Are there supposed to be benefits to drinking this kind of infusion?


There is a deep tradition of ethnobotanical uses of various parts of both Douglas fir (Pseudotsuga menziesii) and Grand fir (Abies grandis). Nancy Turner's book, Thompson Ethnobotany: Knowledge and Usage of Plants by the Thompson Indians of British Columbia (Royal British Columbia Museum, 1990) says that "a beverage tea was made by boiling Douglas-fir twigs with their needles. This tea was said to have tonic and diuretic properties."

Turner says there is a great deal of confusion surrounding both the English common names and Thompson Indian names for various fir species. This makes it difficult to know which species were intended for which uses. An infusion made from the boughs of a species that might be Grand fir (Abies grandis) "could be drunk for any illness." In Ethnobotany of Western Washington (University of Washington Press, 1973), author Erna Gunther notes both distinctions and confusions between Abies grandis and Pseudotsuga menziesii: according to the Green River informant she consulted, tribe members boiled Grand fir needles as a tea to treat colds, but a Swinomish informant believed Grand fir and Douglas fir to be the same species.

Douglas fir and Grand fir are not mentioned in Toxic Plants of North America (George Burrows and Ronald Tyrl, Wiley-Blackwell, 2013), but a plant's absence from a list of toxic plants does not mean that it is risk-free. Common sense says it would be best not to gather needles from urban trees that are not your own, since there is no way of knowing whether those trees might have been sprayed with pesticides, or exposed to air pollutants.

According to Stephen Facciola's Cornucopia II: A Source Book of Edible Plants (Kampong Publications, 1998), tea made from young foliage and twigs of Pseudotsuga menziesii is both refreshing and high in vitamin C. He says that the young branch tips of various species of Abies, including A. grandis, are used as a tea substitute.

I could not find reliable information about the recommended quantities of needles to water, ideal length of boiling time, or chemical properties of needles used for tea. Elise Krohn, author of Wild Rose and Western Red Cedar: The Gifts of the Northwest Plants (self-published in 2007) has information on her Wild Foods and Medicines blog about "making evergreen tree tip tea." My advice would be to proceed with caution and consult a medical professional in case a coniferous tisane might have potential interactions with other substances. (Even a popular beverage like Earl Grey tea can be problematic due to the Citrus-derived bergamottin which interacts with some medications).

Date 2017-01-06
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Garden Tip

Keywords: Plant and garden societies, Chamaecyparis, Picea, Tsuga, Abies, Dwarf conifers and shrubs, Conifers

The Pacific Northwest is an excellent climate for growing evergreens because our winters are generally mild. We can grow far more species than just Douglas Firs and Red Cedars, and in city gardens dwarf conifers are much more suitable. Explore the wide world of conifers, plants that produce cones, by joining the American Conifer Society. Membership costs $25 per year which includes a nice quarterly journal with color photos. Their website has a database with descriptions and photos, as well as information on becoming a member. Call (410) 721-6611 to join.

Favorite four conifers as voted on by members of the American Conifer Society:

  1. Picea orientalis 'Skylands'
  2. Abies koreana 'Silberlocke'
  3. Tsuga canadensis
  4. Chamaecyparis obtusa 'Nana Lutea'

Date: 2007-04-03
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August 01 2017 12:36:01