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Frequently
Asked Questions About Plant Problems
Where
can I go to learn more about Phytophthora ramorum, the cause of
Sudden Oak Death?
These links will help you learn more about the pathogen,
Phytophthora ramorum, commonly referred to as Sudden Oak Death.
I
have a rhododendron that is wilting and dying back. What is wrong
with this plant?
 Plant
problems can have many causes. For example, wilting can be caused
by not enough water or by too much water. Many other factors, such
as environment, cultural care, and the presence of insects or disease,
can affect the health of a plant.
You
will need to provide adequate sample material and an extensive description
of the problem in order to achieve an accurate diagnosis. See plant
problems sampling instructions for further sample submission
information.
I have a lot of problems with my flowering cherry tree in my yard
in Western Washington. Every winter the blossoms die after budding
out and in the summer many of the branches are dead with brown leaves
clinging to the plant. What is happening to the tree?
The damage described sounds typical of the disease brown
rot caused by the fungal pathogen Monilinia. If the problem is indeed
brown rot, refer to the Hortsense
site and from the menu bar, click "Ornamentals", then
"Ornamental cherry", and then "Brown Rot". You
can find more information on this disease as well as management
recommendations. You will want to prune the tree both to remove
dead branches and twigs (also the fungal inoculum that may be present
in the lesions), and to increase air circulation and lower humidity
in the canopy. Prune out all affected twigs several inches below
the area of injury.
Sterilize
your pruning tools between cuts using 10% bleach or 70% ethyl alcohol
(less corrosive to tools than bleach) to avoid spreading the problem.
If possible, avoid getting the leaves wet when watering the trees.
Follow label directions carefully if using fungicides making sure
that the product is labeled for ornamentals in the home landscape.
Every fall, the leaves on my large Western red cedar (Thuja plicata)
in my yard start turning brown and I worry that I am about to loose
it. But then in spring the tree looks very healthy, what is happening?
The
red "flagging" branches observed on the healthy cedars
in fall is normal leaf senescence. For information on what cedar
flagging looks like refer to the WSU
Hortsense web site and from the menu bar, click "Ornamentals",
then "Cedar", and then "Cedar flagging". Double
clicking on image should enlarge picture.
I planted an arborvitae hedge on my property line six years ago.
The plants never really thrived and now it seems as if entire plants
are dead. What could be wrong?
Failure
to thrive and plant death often indicates root problems. Most arborvitae
hedge problems submitted to the Puyallup Plant and Insect Diagnostic
Laboratory appear to have a nonliving origin of damage (such as
overwatering, poor planting technique, etc.) rather than having
been caused by a disease or insect problem. Arborvitaes require
excellent soil drainage and good air circulation around the plants.
We would require more information, as well as a sample of a declining
plant including root material, to help pinpoint the cause of your
arborvitae hedge problem. British Columbia has an excellent bulletin
discussing problems with "cedar" hedges. You can find
this bulletin at Dying
Cedar Hedges– What Is The Cause?
We recently had a large elm tree diagnosed with Dutch elm disease.
We are unable to burn the tree. How can be best dispose of the plant
to prevent the disease from spreading to other elms?
 Chipping
wood into small pieces (below 1 -1 1/2 inches) that will quickly
dry out would probably be a suitable alternative to burning. The
fungal pathogen, Ophiostoma ulmi, should die as the wood dries.
The
main trunk wood should be debarked to prevent the invasion of bark
beetles (carriers of the Dutch elm disease fungus). Beetles do not
feed or lay eggs in or on wood chips, or other wood, once the bark
is removed.
You
could probably also contact your city or county and get a special
burning permit since you are working to stop the spread of the disease.
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