 Plant Diseases in Arkansas
Fire Blight in Ornamental Pears
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Dr. Steve Vann - Extension Urban Plant
Pathologist
One of the most common plants diseases that we see every spring is a disease
that we see on our ornamental pears. These are very common trees that we see in
a lot of people's home lawns. But it is very susceptible to a disease called
“bacterial fire blight.”
What we see, basically, are the symptoms that occur on the tree. The leaves
will often times fire up, it looks very much like someone put a blow-torch on
the end of the branches. The symptoms are going to occur very randomly on the
tree. And they will die - like you see here - they will brown. Oftentimes, one
of the characteristic symptoms of fire blight will be a crooking of the twig, as
you can see here. Shaped somewhat like a handle on a walking stick.
The bacteria usually enter through the flower and start to kill tissue back,
causing the branches to die back in such a manner here. This can be a very
detrimental disease on our ornamental pears. Supposedly, different varieties
respond differently to the bacteria. However, all of them are susceptible to
some extent.
Supposedly, the Bradford variety tends to be less susceptible to the
bacteria. Given the right environmental conditions the disease can be very
destructive. Usually, infection on the tree takes place during that blooming
window of time - usually during March or late February. This is usually when the
bacteria is brought to the tree, many times by pollinating insects. During the
process of pollination the bacteria is introduced into the flower. At that point
in time, it starts to grow down into the wood. If it's not put in check, the
bacteria will continue to grow down into the tree where you have large sections
of the tree that begin to die out.
To actually confirm diagnosis, a homeowner will really need to bring in a
sample to their local county extension office. To do that, they would need to
select a branch such like this. They should prune that branch in such a manner
as to have both green tissue and dying tissue on that sample. That sample should
be collected, placed in a plastic bag - if it's going to be a few days before
you get into your local extension office you may want to consider putting in a
few sheets of dry paper toweling to keep that sample nice and dry, to keep it
from deteriorating while it's in the refrigerator.
Now, a lot of people ask, “Now what am I going to be able to do about this
particular disease?” And, ideally, for the homeowner, selective pruning is the
most appropriate way to control this particular disease. You need to locate the
dying tissue and go down into the green wood and actually prune that tissue out
of the tree. And that's going to be very difficult, especially if you've got a
twenty or thirty foot tree, as many of them are around the city.
Ideally, if you have a problem with fire blight on many of your ornamental
pears, you may want to consider replacing these trees with something that is not
susceptible.
Announcer
To learn more,
contact your county Extension agent, and follow the links in this section.
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