Fireblight spreading

This is scary.


This is climate change


Maybe the Wall street journal, but I wouldn’t give 50 cents a year for the NY times.

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But, the rainy weather could be conducive for fireblight to spread, so it may be worse in the spring than normal, time will tell.


Thank you for sharing this, Mark. It will make me more vigilant with my own trees.

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Excellent article, thanks for posting. Maybe 20 years ago, one of the best days of my life, I ate my way through that Tower Botanical Orchard in Massachusetts. Now I read here it had to be razed, cut down! Oh my! I wonder if they were on M 106? I lost a few trees to blight on M 106 here in Md.

I remember perfect Blue Pearmains all over the ground at the Tower Orchard. Rare tree after rare tree. Hope I’m around when they create a new generation of blight resistant varieties. In the meantime I encourage my friends here to diversify by planting pawpaws, persimmons, figs, blackberries in addition to rolling the dice with a few apples.


Interesting article. Problems with summer rot diseases like Bitter Rot are also getting worse and require more frequent applications of fungicides to manage. Fortunately they just kill the crop and not the tree like FB can!

The computer model that I use to predict Fireblight outbreaks stayed in the “infection” zone about 75% of the time during last year’s bloom period -about 2X or 3X normal. Higher temps combined with more frequent rain created perfect conditions for FB to grow rapidly. I sprayed Strep more often than I was comfortable with, but missed spraying a few key infection days because it was raining.

A while back Penn State published some research on how climate change could impact apple growing. The only positive was that perhaps warmer temps would allow growers to grow more of the very late apples that normally do not ripen properly now.

Roughly two thirds of all eating apples are now grown in Washington state in a climate that only gets about 12 inches of rain each year. We could face a major problem with apples if conditions worsen in that area


Well, there are resistant varieties, and more are being developed. Plus the Geneva rootstocks are supposed to help.

But, with a handfull of mature trees and over 100 three years old and under…I think I saw one limb somewhere with fireblight in 2019.

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Thank you for the article.

@hambone - Tower Hills is about 15 minutes from my home. I’ve been there a few times and seen those old apple trees. I know they conducted tours of the orchard but never got around to join the tour. What a missed opportunity!!! So sad that they were all cut down.

We’ve noticed wet and warm springs in recent years. Last year, it practically rained almost everyday during bloom time.

I wonder what @alan think about this fire blight spreading up north.


A client just sent me the article. I wrote this back to her.

The main problem is that trees on dwarf rootstocks can’t outgrow the disease, I think. I’ve yet to lose a single apple tree to FB in over 25 years of managing hundreds and hundreds of them, including lots of very old trees. Your site is one of the few where I’ve lost a pear to it- most often pear trees survive an attack and grow back completely. However, the commercial industry now mostly grows apples on bushes and not trees.

I manage several sites that get FB strikes on apples, but only on small shoots and I haven’t noticed an increase in the problem in our area- it’s been pretty consistently the same for the last 25 years. There are several other new pests, though.

Cornell pays attention to areas further north that may be seeing FB for the first time. I have noticed when driving upstate orchards with terrible strikes. Maybe because all they are growing is Gala and Honeycrisp.


Thanks for that insight, Alan.

@mamuang: It is very sad about Tower Hills. If I’m reading the article correctly, it sounds like they decided to cut down the old trees as a step toward reconstructing the orchard by regrafting the old varieties on blight-resistant rootstocks. Still very sad to lose the old trees, and if Alan’s thinking is correct, it may even have been a mistake to go with the blight-resistance of the new rootstocks over the presumably greater vigor of the old. Time will tell, I guess, but hopefully the Tower Hills orchard will be back eventually.

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I’m certainly managing a lot of heirloom trees and never have lost one. I have a few over century old trees that occasionally get shoot strikes in summer- lots of strikes, that never get into big wood to make cankers. I have one site with Macouns, Empires, Mutsus, Northern Spies and Cortlandts where there has been two years with major strikes that left lots of cankers in big wood, and yet following years everything healed. I did not remove most of the cankers. They are all on seedling rootstock and are vigorous 35 year old trees.


Alan, my original, ungrafted tree is a Liberty, which I chose partly because it is supposedly FB resistant. My thinking is that if any of my grafts get FB the main tree will be able to cope. Is my logic good there?

I don’t know what the rootstock is. It’s currently about 20 years in the ground and 8 inches in diameter, and is pretty easy to keep back to 12 feet tall, if that tells you anything.

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The logic seems fine to me, but mother nature often defies logic. I really haven’t ever had FB problems on grafted trees so your logic is all we have to go by unless someone else here can speak from experience. I don’t even have any knowledge on what makes one variety more susceptible than another and if resistance is in the big wood or just in the shoots and flowers.

I sure have grafted on a lot of young and very old apple trees at many, many sites but have never had the opportunity of seeing a susceptible graft struck that is on a resistant tree.


Liberty is also CAR resistant.

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There are ways to manage this in pears and apples. First prune out infected branches remembering to disinfect your tools afterwards. Also, you can spray after pruning to help thwart the spread. Fertilome offers a fire blight spray or you could opt for organic with a white vinegar/water mixture. When you first spot branches, then you must act.


I live in Las Cruces, NM. We are usually very dry here but I’ve been fighting fire blight since 2015. It seems I loose more trees in October and November than in the spring. The weather has been getting super humid for us in October -December. It has been very warm in October into 80 degrees. I have more or less about 400 semi-dwarf trees that are 43 years old, most diseased or have issues. They are mostly red delicious with perhaps common delicious and also Jonathan’s. I have an apple buddy grower up north in Belen. She is also having problems with fire blight and something else we are both experiencing. It’s like the trees we prune out fire blight in the winter later end up getting blight again and some turn black…the entire tree. I have fire blight that looks like acid dripped down on one side of the branch. It will bubble and bulge and is like paper coming off. The other side of the branch will be fine. It actually seems sometimes that the trees where the fire blight was not removed ended up doing better but maybe it was because we did not cut far enough past the fire blight. When do you all find it successful to prune out fire blight? Do you prune it out when you see it now matter what time of year or do you wait until dormancy? When is it too early to prune in the winter? Do I need to wait until a month before spring ? Thank you. I don’t know if it’s all fire blight or if there is a secondary infection of some kind of fungus. :frowning: The apples taste so good and we have a sweet spot for growing apples with our climate and elevation. Hope to better and get some help knowing how to best plant and graft.


Search this GF site for " ugly stub Steiner". That’s THE best protocol I know to avoid spreading blight by pruning at the wrong time or in the wrong way. You’ll see an article I posted by Steve Wood, expert. I think @alan brought this to everyone’s attention first.

The gist of the Prof. Steiner Ugly Stub method for me is: do not do normal summer pruning and blight pruning at the same time. Do normal summer pruning only when temperature is over 90 degrees (blight inactive). Prune out blight strikes when you see them, cutting back into at least two year old wood AND leaving an “ugly stub” of 4 to 6 inches that you remove with a flush cut next winter when it’s impossible to spread blight because it’s inactive at low temps. That’s my best understanding.


However, the commercial industry now mostly grows apples on bushes and not trees.

Started planting my orchard 3 years ago, using the open vase design. Primarily, to keep from having to use ladders. My concern is forcing trees that naturally grow a central leader to branch out. Does keeping the trees smaller affect their ability to handle ‘the circumstances of life’ ?

Keeping trees smaller and keeping them horizontal are two different issues. If you keep trees smaller with repeated stub cuts you tend to extend juvenility. More vigorous rootstocks usually require letting the branches grow out further for the trees to become fruitful, but variety is equally important- Goldrush on 111 has similar precosity as Jonagold or Fuji on 26.

For home orchards I recommend more vigorous rootstocks and training them as low as you want but grafting if you want more varieties in less space.

Go to guides and check out my article about pruning by numbers to understand what I’m talking about as far as the effect of pruning.

In my work I often see and manage huge old apple trees on seedling rootstock that were trained into open center trees with scaffolds pulled low repeatedly to create a pedestrian or short ladder tree- but sometimes they have over a 60’ spread.