@alan
You might recall that I owned a fruit tree nursery. Among my inventory were rows of pear trees in 7 and 15 gallon pots. I could pick out the fireblight susceptible cultivars by row. I had two pest control advisors, both PhDs in plant pathology from UCR. I did not video our discussions.
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Iâm only speaking from my experience. This spring I had very warm weather, frequent rain, and high humidity. This is typical for me in Virginia. Prompt removal of leaves and vigorous removal of any FB branches proved very helpful. I had blackened leaves with no other involvement which did not appear to be FB. They were not dissimilar with the photo presented.
I may be obsessed but I walk my trees daily and try to respond as soon as I see anything that could be a strike. I was curious how coastal areas would be more subject to FB than in my location. I thought insects and rapid growth especially at bloom were the main culprits. I have not considered leaf damage as an entry point although I understand that may be possible.
If you learned something from them please explain what it was, donât just dismiss another personâs approach by saying they are wrong- that isnât helpful.
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Apparently there was a misunderstanding. Deleted my previous reply as iâm not sure what the information was from UC Davis. We deal with fireblight a lot at times here. I am sure whatever we think we know about fireblight there are things we donât know. Itâs a very mysterious disease showing up in my orchard again this year after nearly 5 years of mostly silence. Lost several half trees i amputated after the strikes. 1 tree the strikes happened in a day by the next day green jade pear was dead to the ground. It was a purchased tree so unlike the ones that are grafted well above the ground it wasnât. Fireblight appears to be associated with insects such as locusts, japanese beetles etc. .
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Fireblight comes in the winter. It infects dormant wood buds and to some degree is hosted in bark fissures. The malady to new growth occurs as it emerges from the infected node during the growth season although it typically is not noticeable until summer. Magnitude of the damage is related to the pathogen activity that season and the resistance (if any) of the host plant. Callery pears are notorious hosts, as is pyracantha. Treatment of any kind after bud break is futile - antibiotics must be applied in late winter. Cutting back affected growth is ok for aesthetic purposes but if one node on your tree has it, then they likely all have it. Please refer to a licensed plant pathologist for further information.
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Hereâs another opinion. Fire Blight Management Guidelines--UC IPM
It certainly doesnât come in the winter in most of the country. You donât have winter by my def. It is your rain season.
I used to have a great link by one of the countryâs foremost experts on the disease who recommended cutting strikes back to stubs during the growing season and then removing the rest during dormancy when FB is inactive. This was to avoid creating entrance wounds into larger wood when the bacteria is active. It seems to have been taken off-line. However, the link I provided does recommend removing it as you see it.
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That was my experience, I got rid of the whole tree and the dirt too. I had mine in container, no barks either.
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Thanks for the explanation in California your trees dont sleep so fireblight always keeps multiplying at a faster rate. Fireblight only attacks growing tissue As @Alan mentioned we remove infected tissue we want no overwintering infection to reinfect the orchard next year. If we do things right we can reduce fireblight with infected branch removal and copper sprays. Many times an antibiotic spray is needed to ensure there is no new infection. We spray in spring and fall. Both copper and fertilome are specifically for fighting bacteria like fireblight. Here is more about the infection and how to counter it Cutting Fire Blight Strikes | WSU Tree Fruit | Washington State University
Update:
The point Richard is making is valid he is basically saying what we know bacteria are always there just like bacteria are in our stomach some good some bad. What pear doesnât have a few fireblight bacteria. Specifically he said âthe phylum under the bark is alive, and the budwood phylum is (mostly) what the pathogen infects. They only travel while the plants are dormant and they donât care about winter temperatures. The new, damaged growth we are removing does not contain the pathogen - but the nodes they emerged from doâ which is true enough once the infection is systemic. Callery rootsock or kieffer,orient, burford, warren, hood, ayers etc. are not bothered by the bacteria. Like when we get sick one person dies from an illness another shows no symptoms.
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Clark, it seems to me that if the FB bacteria was âalways thereâ removing strikes would be pointless from a treatment perspective and we wouldnât talk so much about pollinators being vectors. Nor would we have to time anti-biotic sprays so precisely when trying to control it.
As I understand It, it doesnât live within the wood waiting to infect as your gut analogy suggests, it comes from the outside and once it gets into big wood, there is no treatment.
All I do is remove strikes, as much for cosmetics as treatment- my customers donât want to look at the sagging burned leaves. Like you, I find the disease to be entirely unpredictable in my region, with one orchard getting hit while another one mile away does not. I donât have to spray for it in my business. I once considered spraying a badly struck orchard with a growth inhibitor but the customer had relatively shallow pockets and couldnât afford for me to cut out all the cankers either, which had moved into larger wood. If I had done the spray I probably would have thought it successful because there was no FB there the next season or the 10 following ones
I seldom lose trees to it and rarely even have to remove whole scaffold limbs to the disease, but I donât use fully dwarfing rootstocks or grow a lot of susceptible pear trees in the same orchard. I remember a few years back driving way upstate NY and seeing apple orchards really terribly affected by the disease.
Unlike the common literature descriptions as in the one your link provides, Iâve never seen infected blossoms and every FB siege has come later in the season to young, flowerless shoots. I later found out that this is called shoot blight and it is by far the most common type of infections we get here in lower NY state and nearby CT. Maybe that is why FB so seldom kills the trees I manage- perhaps the infection spreads more when it begins at near first growth. By the time the tips of growing shoots are infected the trees may have gathered more reserve energy that could help the tree wall off infection from entering larger wood.
It is a poorly understood disease, and I donât know if any meaningful research has been done specifically about shoot blight. Iâm guessing it is either leaf hoppers or aphids that are its primary vectors and they can be controlled by late spring sprays.
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Please provide a link that states this based on research, it contradicts what I have consistently read about the disease- that it attacks new growth during spring via insect vectors, so Iâm very interested.
You and Richard are both correct in my opinion As an example wild callery and many other pears may very well have a systemic fireblight infection. @Richard has a hood pear in close proximity to neglected callery that are infected and showing infection. In this case fireblight is ever present.
On the other hand if an infected callery beside one of your orchards has the fireblight bacteria your trees are not infected. In this case you quickly remove leaves and branches to prevent the spread of the infection in your orchard where there is no fireblight. The way we know this to be true is by variety grown. A susceptible variety dies to the ground from a systemic fireblight like my green jade did this year.
In the south there is an ever present fireblight at most locations. Ayers, warren , hood, orient, kieffer, and many others are grown that are highly resistant to fireblight.
Fireblight spreads by oozing lesions in such orchards or from nearby hosts that have cankers in branches and trunks. Looking at the bark in orchards like thst you can see the infection Fire Blight - Limb & Trunk - Ontario AppleIPM. The orchards always have the bacteria present and active. The hard part is not every infection is visible. Burford shows no symptoms whatsoever but plant a bartlett beside it you will know you have a problem. Bosc is a great pear for many reasons but its a master of identifying hard to diagnose viruses and other things and its highly susceptible to fireblight. On the other hand not every pear shows it has stony pit virus like bosc does as an example.
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And I keep asking you to provide any reference in the literature that suggests cases of âchronic fire blightâ. All fire blight is systemic, but that doesnât seem to be what you are referring to. But that isnât even the subject I have questioned Richard about- so you have me doubly confused. Richard has said two things I disagree with, one, that he apparently doesnât believe cutting out FB strikes has any efficacy and that any licensed plant pathologist would agree with him, and also that in CA trees become infected during winter when they arenât actively growing (leaves and/or flowers).
This link along with the others youâve provided have not referred to chronic fire blight either. Cut and paste what you think does- Iâve been wrong before on a regular basis, but, in this case, I havenât been able to figure out where that is.
I honestly donât care about being right, but itâs important to me that people, as much as possible, keep facts straight on this forum. One of my favorite things is to be proven wrong because then Iâm learning something.
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This article is great at explaining the illness and how it overwinters but itâs a little outdated. As an example many experts no.longer believe in dissenfecting tools. These people who treat fireblight all say there is no cure only control of fireblight once itâs infected the tree. We have years without fireblight here.
Fire Blight: Symptoms, Causes & Treatment - Independent Tree, Northeast Ohio
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Many types of apple trees are susceptible to fire blight. If you plan to plant an apple tree, look for disease-resistant varieties (see the list later in this article).
WHICH PLANTS GET FIRE BLIGHT?
Fire blight affects a lot of plants in the rose family (Rosaeae) which, as you probably guessed, includes roses. The rose family also includes the genera Pyrus (pears) and Prunus. Within the genus Prunus are apples, peaches, cherries, plums, raspberries, and other valuable fruiting crops.
While many species are susceptible, fire blight is especially damaging to apples and pears.
WHAT SHOULD I DO IF MY TREE HAS FIRE BLIGHT?
First, be certain that the problem has been correctly diagnosed.
If you think your trees have fire blight but arenât sure, the Certified Arborists at Independent Tree in Newbury, Ohio can help. Give us a call at 440-276-0785; weâre happy to discuss the symptoms or inspect your tree to provide a diagnosis. Youâll learn on the spot what to do and all that is involved in treating fire blight.
Certified Arborists are specially trained to identify and treat tree diseases. Our goal is to be minimally invasive with any treatments and to protect the health of your trees. At the same time, a good professional will be honest about the outcome of all potential treatments.
TREATMENT OPTIONS FOR FIRE BLIGHT
If you want to treat your trees and shrubs yourself, pruning and spraying are the two most common approaches.
SPRAY TREATMENTS
The anti-bacterial spray that is most widely used is called Bordeaux mixture. It was created in the 19th century in the wine-growing region of France with the same name and has been used ever since. Bordeaux is a mixture of water, copper sulfate, and lime (hydrated lime is calcium hydroxide, not the fruit).
One of the benefits of using Bordeaux mixture rather than a straight copper-based spray is that the Bordeaux mixture sticks to trees during rainy weather while copper sprays wash off. This makes timing your spraying easier because the weather only needs to be clear for as long as it takes the spray to dry.
For a homeowner, there are drawbacks to making and applying the Bordeaux mixture yourself. They include:
- Timing. The full-strength spray is best applied in winter before spring bud break, as it can damage leaves and buds. Dormant season is the usual time to spray, but you can spray a weaker solution in spring to avoid bud damage. For more details, see our article on the proper timing for spring treatments.
- Repetition. Youâll most likely have to spray repeatedly during the year.
- Mixing. To get the most effective spray, youâll want to mix it just before use. Premixed concentrates are fine but may have sat for some time and become less effective.
- Agitating. You have to keep the ingredientsâ particles suspended in water so that they are evenly distributed and do not clog your sprayerâs nozzle.
- Protection. Youâll need to wear a protective breathing mask while making the mixture, and will want to wear protective gear while spraying it. Sulfur = rotten egg smell!
- Application. You need to reach all parts of your trees, which may have reached their mature height and spread. This may be impossible from the ground without special high-pressure equipment.
- Effectiveness. Spraying is not entirely effective, especially when all parts of the tree are not completely drenched during treatment.
Spraying is usually combined with pruning, as spraying prevents new infections but does not cure existing damage.
PRUNING OUT DISEASED WOOD
Youâll want to prune out all damaged foliage and branches, disinfecting your pruning tools between each cut, including if youâre pruning in winter. A tool with the fire blight bacterium on it is a perfect vehicle for transferring the disease directly to healthy tree tissue.
Remember that each pruning cut, even those done perfectly, is a wound to the tree. Pruning out fire blight damage during the growing season can leave wounds open to many pathogens that would not be as active during the dormant season. If you do prune, do it as minimally as possible.
Remember to include suckering growth at a treesâ trunk base when pruning, as the graft union (where the variety of tree meets the standard rootstock it was grafted onto) can also be infected by fire blight. Most fruit trees grown in northeast Ohio are grafted onto a hardier rootstock.
Pruning out fire blight generally involves making cuts below the extent of visible canker damage, as the bacterium has almost certainly penetrated internal tissue beyond the edges of the canker. Youâll also want to cut back to the right place on your branches. For details on how and where to cut, see our article on pruning tips.
OTHER FIRE BLIGHT CONTROL OPTIONS
Other important measures include reducing fertilization that generates a lot of spring growth that can become infected. If your trees need fertilizing, you can apply a mild, slow-release fertilizer in the fall, or better yet, rely on your well-amended soil and organic layer of mulch (be sure to apply it properly!) to provide sufficient nutrition to your trees.
And always, always remove and discard diseased fruit and fallen debris from the tree or the ground. Place them in a plastic bag, seal it, and dispose with your regular trash. Do not compost diseased material as itâs unlikely to fully kill the fire blight-causing bacteria.
SHOULD YOU TREAT FIRE BLIGHT YOURSELF?
Tree care professionals are experienced in treating disease, up to date on best practices for both spraying and pruning, and have the specialized equipment needed to properly apply disease treatments.
If your fire blight is severe, it will be more effective to have it professionally treated. Tree care crews will prune out diseased tissue, spray as needed (during the appropriate timeframe), and remove all infected material from your garden, and can schedule return visits to check on the effectiveness of treatment. This is especially useful if you have full-size, mature apple or pear trees, whose crowns may be 20 feet or more off the ground.
HARD CHOICES
Thereâs no cure for fire blight, only control.
Sometimes a fire blight infection is so severe that removing the infected tree or trees is the only solution. When infection and internal damage reach a certain point, treatments are no longer effective, and the ease with which fire blight spreads makes infected trees a risk factor for all surrounding trees and plants that are susceptible to fire blight.
The good news is that once an infected tree is removed, its fire blight bacteria are also removed. You can safely plant another apple or pear tree thatâs healthy and free of disease and you can specifically choose a fire blight-resistant cultivar! It will take another vector to bring fire blight back to your garden, and small areas of new infections are much easier to control.
FIRE BLIGHT RESISTANT TREES
The table below is taken from Ohio State University Extension.
Table 3. Relative susceptibility of common apple and pear cultivars to fire blight
Highly Susceptible Moderately Susceptible Moderately Resistant
Apple
Beacon Dutchess Jonafree
Cortland Empire Melrose
Fuji Golden Delicious Northwestern Greening
Gala Haralson Nova Easygro
Granny Smith Jonagold Prima
Idared Jonamac Priscilla
Jonathan Jerseymac Quinte
Lodi Liberty Red Delicious
Monroe McIntosh Red Free
Mutsu (Crispin) Minjon Sir Prize
Paula Red Northern Spy Pristine
Rome Beauty Novamac Liberty
Wayne Spartan Goldrush
Wealthy Honeycrisp Enterprize
Yellow Transparent Braeburn Sundance
Ginger gold Winsap/Staymen strains Williams Pride
Pear
Aurora Maxine Kieffer
Bartlett Seckel Magness
Bosc Beurre DâAnjou Moonglow
Clappâs Favorite Harrow Delight
Red Bartlett Honeysweet
Reimer Red Blakeâs Pride
Starkrimson
Pollinator bees are important for the health of your fruit trees
PROTECT OUR POLLINATORS
One very important consideration in the spread and control of fire blight is pollinating bees. Bees can carry fire blight bacteria from flower to flower the same way they carry pollen. Removing flowering fruit trees to control fire blight reduces food sources for bees. On the other hand, keeping untreated or poorly treated diseased trees ensures the spread of fire blight to neighboring trees, resulting in more fruit trees being cut down, further reducing the pollinatorsâ food sources.
IN SUMMARY
Keeping your fruit trees healthy with a proactive tree health care plan is the responsible thing to do. Or, if your trees become infected, treat the outbreak quickly and professionally to minimize damage and prevent spreading fire blight. Itâs vital that we keep habitat and food sources for bees healthy, especially when we enjoy the fruits of their labor each year"
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Maybe we just arenât clearly communicating. Yes, I know that as long as there are active cankers on a tree, bacteria are surviving, but the bacteria does not live in healthy trees asymptomatically, or at least none of the many links you have posted seem to suggest this.
This is why it is suggested that cankers be mechanically removed. Oh and while there are active cankers on the tree there can be inoculum in wood a slight distance beyond the cankers, whence the directive that one needs to cut a short distance beyond visible infection when cutting out cankers or dead shoots.
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@alan (â but the bacteria does not live in healthy trees asymptomatically,â)
On page 68 of the article I linked aboveâŚ
https://naldc.nal.usda.gov/download/CAT79714375/PDF
(âWe (508y511) discovered thati/. amylovora may live for long periods as residents in or on apparently healthy pear and apple tissues without producing blight symptoms. â)
The way I understand the references ,/ studies in this part of the paper is ; fire blight bacteria can be resident host on / in host plants , sometimes causing disease , sometimes. Not.
It seems you will find it where you look .( where you try to culture it from ?) may be more abundant than we can see, from visual inspection? Then something ? Enables it to cause disease .?
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Fireblight is slow to give up its secrets, at least in how to deal with it. Resistant trees? Liberty and Enterprise have been the two most susceptible in my orchard this year, with Liberty still suffering in the middle of the hot, dry summer, while previously susceptible varieties have almost no strikes. To prune out immediately, leave an ugly stub, disinfect or not? The advice is inconsistent, if not contradictory. The only thing Iâve found that reduces spring infection is frequent streptomycin sprays during bloom. I do prune out strikes because in my climate you can see the strikes oozing some liquid, which appears to rapidly spread infection if not removed. If possible pruning back into second or third year wood seems to slow the infection.
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Yes @Richard was right on that part where he said its dormant which is why itâs the mystery disease. Just like good and bad gut bacteria in people. Thatâs not to say it doesnt spread externally it does do that too. Some orchards are constantly spreading infection. The interesting unknown is what triggered it in my orchard this year? There are no cankers i remove trees if they need it. There is no way to know at this time if @alan orchard has trees with dormant fb. There are trees that the bark changes color slightly they have fb but it never is on the outside. Older trees have less vigor and less fireblight damage
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I wonder if FB is spread by the birds or bees in my yard, is it possible.
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Squirrels appear to spread it on my trees or at least open them up to infection when they climb the trees to get at the fruit. They scratch the bark with their claws and break branches, which likely gives the bacteria an entry point. I noticed the branches that were getting robbed by squirrels getting fireblight this year, while untouched trees or branches were spared.
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