Sebastian County Home & Garden
Trees
Homeowner Fire Blight Control
Chances are you reading this because the limbs of your pear or apple tree are
beginning to turn brown and die. This is caused by the bacterium
Erwinia amylovora. We call this disease Fire Blight and no amount of
fungicide will stop it. These “burnt” symptoms are most apparent in
early summer after the infection has already spread. This is how fire
blight got its name.
If it is mid-summer and you are in a panic, this is how you can control the
disease from this point:
If it is summer and temperatures are over 90F then remove infected branches
8” to 12” past the infection. Clean your pruners after each cut with
Lysol, alcohol, or a bleach solution. When the temperature is over 90F,
bacterial growth is inhibited, but if it is spring and a very pleasant
temperature, RUN—DON’T WALK!–CUT OUT THE INFECTION NOW! Don’t be
afraid to cut large branches and limbs. If you leave sick wood, you will
have to deal with it next year, too and may lose the entire tree.
Check in fall after leaves have fallen off for any “holdovers” that you
missed. Cut these out. Remove fallen leaves from under tree.
Now in spring, as buds swell, spray with a copper spray. Get good
coverage. This will slow down the spread of bacteria that you missed.
Do not mix copper and oil sprays. Don’t apply copper after flowering; if
copper is applied after flowering to fruit, it will cause the fruit to russet
like a potato.
When the flower buds are just beginning to open, but before they do all the
way, spray with streptomycin. Repeat every week until flowering is done.
There are more scientific ways to time your sprays, but this is easiest.
If you are growing pears, watch out for the “rat-tail” blooms (a smaller, second
flowering). These are the most sensitive part and temperatures are warmer
then. Spray them with streptomycin, too. If you have a problem
with scab, you may spray with a fungicide, too.
Keep your eyes open for shoot tips, especially on suckers, that are just
barely wilting. This is an early sign of Fire Blight. New growth in
the spring should never wilt. If it does, it’s fire blight. If you
miss it, you will know all about it in June. If the infection is bad
enough that you are getting information from me, you will be fighting an uphill
battle, so be mentally prepared for the possibility of losing the entire tree.
An easy way to deal with these wilted suckers is to remove the entire sucker.
Mechanical injuries to limbs have been shown to increase the incidence of
this disease, so try to minimize damage.
Note: The best control of Fire Blight is not to get it.
Replant with resistant varieties!
Resistant Pear varieties: Kieffer, Moonglow, Maxine, Starking
Delicious. Comice and Seckel are susceptible, but occurrence is uncommon.
Bartlett is extremely susceptible to fire blight. It is not recommended.
Resistant Apple varieties: Arkansas Black, Empire, William’s Pride, Red
Delicious, Gold Rush.
Figure 1. Blight on blossoms. |
Figure 2. Blight on young shoot tips. |
| Figure 3. A severely infected tree. |
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Dustin Blakey, Sebastian County Extension Agent – Agriculture
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