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Fire Blight
I'm very thankful for all the rain we've been getting, but unfortunately it also means that conditions have been optimal for fire blight. Fire blight is a bacteria that infects pears and apples, and is so named because the affected areas look black and shriveled as though they had been burned. Pears are especially susceptible to fire blight, and can be completely killed if left untreated. It usually strikes tender new growth and blossoms, and can be spread by bees and other insects. It spreads rapidly in warm humid weather, so far we've had a very warm and wet spring.

The best solution to this problem is to plant varieties that are resistant to fire blight in the first place. Dr. Ethan Natelson and the Gulf Coast Fruit Study Group (GCFSG) have spent many years researching the best pears varieties for Houston, and I am very grateful to Yvonne Gibbs for taking so much time to share her knowledge with me. You can meet and learn from extremely knowledgeable and experienced fruit growers at GCFSG meetings, and I would recommend that anyone interested in planting a fruit tree attend one. Their research has identified Southern King, Southern Queen, Southern Bartlett, Tennessee, and Acres Home as fire-blight resistant varieties for Houston. Unfortunately these varieties are resistant to fire blight, but not immune to it.

I have Acres Home, Tennhosui, and Southern King pear trees, and this year I grafted on Southern Queen, Southern Bartlett, Tennessee, and Meadows. During one of my routine walks around the yard, I noticed some fire blight on the Acres Home and the Tennhosui. There was no sign of it on any of the other varieties. I immediately grabbed my pruning shrears, sterilized them with alcohol, and pruned out the infected areas. As recommended, I made the pruning cut at least 6-inches below the infection, and sterilized my pruning shears after each cut. According to Urban Harvest, Acres Home tends to get a little fire blight, but it typically doesn't travel down the branches to kill the tree. I cut it out anyway just to be safe, and to get it out of my yard to reduce the chance of re-infection. Sadly, my neighbor has a big neglected pear tree that I'm afraid will always harbor fire blight that can spread to my trees.

While taking the diseased wood over to the trash pile, I noticed more fire blight on my apple trees! The Dorsett Golden and the Anna both had small areas of infection, and one of my Honeycrisp grafts was burned. I again pruned out the affected areas several inches below the infection. With more rain and warm temperatures in the forecast, I decided to be proactive. I swung by Plants for All Seasons, and picked up some Fertilome Fire Blight Spray (it's organic). This spray is 21% streptomycin sulfate, an antibiotic also used to treat tuberculosis and other infections. After the rain last week, Boy #1 and I mixed up a batch and sprayed all the pear and apple trees. Hopefully removing all of the diseased wood and spraying the trees with antibiotic will help protect all of our growing grafts until they get a little bit bigger, and help reduce the chances of fire blight infection.

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Infected branch.
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Burned blossoms.
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Another infected branch.
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Good picture of the infection spreading down a branch.
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Bunch of cut branches.
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Fire Blight Spray
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Boy #1 helping me spray the pear trees.
 


Comments

Dan
03/26/2012 05:33

It's so bad in Austin that the Bradford pear trees have it now. Thanks for the suggestions on varieties. I'm almost at the point of giving up on pears and apples.

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Dallas Fruit Grower
03/28/2012 18:05

That's terrible.

Are you going to spray your neighbor's infected tree too?

It would be nice if the spraying would build up a colony of the helpful antibiotic organisms to prevent future occurrences. I suspect that wouldn't happen from a foliar spray, but I have no idea.

Knock on wood, I have had pretty good success at avoiding fireblight in Dallas -- to date. I have had a few small occurrences but nothing major. Malcolm Beck wrote favorably about Actinovate against cotton root rot in Lessons in Nature, and the maker lists it for use against fireblight as a foliar spray. Consequently, I have always added it granularly when I plant a new tree in the hope that it would serve as a preventative against future problems.

I am no microbiologist, but I wonder if innoculating the soil with the active microorganisms (against cotton root rot) can also serve to innoculate the plant structure and leaves against other bacterial and fungal outbreaks such as fireblight -- or at least help the trees' defenses -- so that foliar sprays are unnecessary.

I don't know the answer. A&M might know the answer off the top of their head. In the meantime, I'll just keep my finger's crossed and wonder whether the actinovate is helping in the soil or it's just dumb luck.

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Lindsey
03/29/2012 15:39

I just found your website. My husband and I JUST (2 weeks ago) planted 6 fruit trees in our suburban backyard. We live in NW Houston as well. We are have only been in Texas 3 years. We came from Michigan and when we went to dig in the ground we were pretty much horrified by the DENSE clay that had not a single bug or living organism to be seen. Anyway, we have some help from a friend who has a lot of fruit tree experience, but I just wanted to thank you for having a site that offers all of this information and experience. I had to laugh about you wanting to plant every square inch of your lot with fruit. I like that idea too! lol Alas, the 6 trees we have planted have already proved to take up much of my morning concern. I have been checking on them every day and truthfully, I do pray for them. If anything is going to survive under my care, I will need to pray! We might have made a bad decision about our orange tree, but I think that the other trees were good varieties?? We have a Dorsett Gold, Anna, then a Fuyu Persimmon, a Texstar Peach, a Rio Red Grapefruit and ... welll the one that might have been not such a good choice but we were won-over by our love for the final product... a Valencia Orange.

Well, I will enjoy reading your website now that I have found it! Thank you for the information....

P.S. I found your website because we are currently looking for a variety of Avacado to plant. It is a tribute tree in honor of my great-grandmother.... and I really want to take the time on this one, (My husband happens to have a trip to San Antonio this weekend if we need to get one of those in Devine) to get the best.

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Jeannette
04/18/2012 20:49

thanks for this post - I had no idea that my 2 year old apple tree had fire blight until I read this. I meant to get out and trim the affected areas two weeks ago and just got around to it today. I was surprised at how much it had progressed in a short span of time. I guess I need to also follow up with a spray to treat the tree.

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Jennie
03/05/2013 07:49

Hi Clayton, I need your opinion on something: I live in Montgomery county and I want to plant a Tennhosui Pear tree but I don't know what pollinator to couple it with. I would prefer something that wont take long to bear fruit of course, but definitely something that is as fire blight resistant as possible. Would Acres Homes Pear do the job? Not sure if the blooming period will allow them to pollinate each other. Thanks for reading.

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Kelly S
06/25/2013 09:19

I planted an Acres Homes pear tree a couple years ago and it's doing great (I live near downtown Houston). But I'm not sure if I should treat it as a European pear that ripens after being harvested or an Asian pear that ripens on the tree. And can you give me some advice on pruning and fertilizing this tree? Thanks!

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