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Understanding Fire Blight

by Guest Author on 09/03/2010
Fire_blight

[Guest blog post by Judy]

Hello, my fellow fruit-lovers!

It has been very cool and wet here this past spring and summer. Of course, these are ideal conditions for bacterial diseases to infect our fruit trees, as well as other trees and shrubs. Since bacterial diseases are so common among fruit trees, I thought you home growers might like some background on one of the most prevalent bacterial diseases affecting apple and pear trees – Fire Blight. I am also going to give you some ideas on how to fight this disease!

Fire Blight is a contagious, systemic, bacterial disease. This means that bacteria (erwinia amylovora) attacks the blossoms and then moves up the twigs and branches (through the tree system). The name “Fire Blight” comes from the scorched appearance of the leaves and bark. Affected areas appear black, shrunken and cracked. Blossoms will turn brown, wilt and die about 1-2 weeks after infection occurs.

Fire Blight also exhibits an amber-colored ooze (which is heavy with bacteria) from the bark of the tree. When the temperature begins to climb between 60°-80°F, it brings the bacteria out of dormancy and creates optimal conditions for spreading the disease. Bees, insects, birds, splashing rain, and wind easily spread Fire Blight disease.

Along with apple and pear trees, Fire Blight affects quinces and other members of the Rosaceae family (including most common rose varieties and raspberries).

But, we donʼt want to turn this into a science class! So letʼs move on to how to handle Fire Blight.

Cultural practices. Any excessive amount of new growth on your tree is easily susceptible to Fire Blight infection. To avoid this, we recommend feeding with a low-nitrogen fertilizer. Be sure to also remove any suckers– as young, tender growth, they will also be vunerable to infection.

Chemical. A good Fire Blight Spray can control infections and should be applied every 7-10 days (from bloom time through the spring storm period). Removing the blighted wood from infected shrubs and trees can help save them. Prune off all infected branches at least 10-12 inches behind the blighted area. Burn the affected branches, if possible.

Clean up. Be sure to do a complete clean-up around your trees when fall rolls around. Collect all pruning debris, any mummied fruit, and leaves. Move them away from the trees and burn them. This will prevent the bacteria from over-wintering in the debris.

**Because Fire Blight is highly contagious, take care to disinfect tools. Sterilize the tools in a household bleach solution (ten parts water to one part bleach). Dip clippers between cuts. Be sure to wipe clippers dry to prevent corrosion. Alternatively, you can use alcohol wipes to clean your clippers between cuts, both protecting your trees and your tools.

There’s not one single practice that will insure complete control of Fire Blight. When we’re dealing with Fire Blight here at Stark Bro’s, we prune out the blighted areas immediately and do a thorough clean-up to prevent re-infection and minimize spreading. Your best defense is a combination of cultural, chemical and clean-up control methods.

I hope this information gives you a good understanding of Fire Blight and helps to make your fall, winter and spring productive and disease-free!

– Judy

41 comments on “Understanding Fire Blight

  1. Pingback: 8 New Fall Must-Have’s | Growing with Stark Bro's

  2. Larry on said:

    In addition, Ag extension recommends using a basic copper sulfate solution in dormancy. Do you recomment that? and do you have a recipe for a basic copper sulfate solution.
    Finally, I have a number of apple and pear trees from Starkbrothers. I lost a seckel pear to fire blight. Do you have a replacement variety of seckel pear that is more resistant to fire blight?

    Larry

    • Judy on said:

      Hi Larry,
      A copper sulfate spray is good in dormancy, but we usually recommend using a combination of Dormant Oil and Lime Sulfur during dormancy. This combination will kill fungus, and the dormant oil will smother any eggs that are laid. One thing that will really help with all insects and diseases is a thorough fall cleanup. After your tree goes dormant, remove all mummied fruit from the tree and the ground. Rake away all pruning debris and leaves from your fruit trees, then burn all of it!

      Actually, the Seckel pear tree is moderately resistant to fire blight. Following a good spray schedule, and doing fall maintenance (pruning, clean-up) will certainly help keep your fruit trees insect and disease free. :)

  3. Cynthia Holder on said:

    I had this issue hit my apple, pear and raspberries. I tried to buy the Streptomycin spray to kill the bacteria and was told that it has been pulled off the market because of regulations. Do you know about this and if so what do we do now?

    • Judy on said:

      Hi Cynthia, boy, that is tough, having fire blight affect your trees! I don’t know if where you live the Streptomycin has been pulled off the shelves, but, we still carry Fertilome Fire Blight Spray (main ingredient: Streptomycin) and it has not been restricted to any states. Check your local garden store for Fire Blight spray. If you can’t find Fire Blight Spray, get a Copper Spray. That will work very well, also.

      Good luck with your fruit trees! If anything else comes up, just give us a shout. :)

      Judy

  4. cheryl on said:

    I by mistake got shipped a pear tree with several varieties of pear on the same tree. A couple varieties of the pears were very susceptible to fire blight. You really have to cut back and get everything out. I sprayed with a copper spray last fall and think it really helped. It was a pretty dry year too. I don’t think there is alot you can do if you have a variety that is very suspeptible to fire blight. I would cut the tree totally down but it’s a good poll. for other pear trees.

    How about an article on Brown Rot. I think I have the most problem with Brown Rot on fruit and can you get Brown Rot on the bark of the trees?

    • Judy on said:

      Hi Cheryl,

      One thing that helps a lot to retard any fungal disease is to do a complete fall clean-up. After your tree goes dormant, remove all mummied fruit from the tree and the ground, and rake up all pruning debris and leaves. Then burn all of it! This removes locations for over-wintering fungal spores. Infections from fruit may advance into wood causing small cankers.

      Keep your eyes open for a blog post about Brown Rot, we’ll have one up soon. :) We appreciate you taking the time to visit http://www.starkbros.com/blog!

  5. Pat Wood on said:

    Stark could do an invaluable service for us small growers by showing a photo of some common bacterial/fungicidal diseases along with the most effective remedies. This kind of information is essential to being a successful small orchard owner.
    Thanks for any assistance.

    • Meg on said:

      Thank you for your insight, Pat! We’ll be working on incorporating your suggestion into our future blog posts. If there is any disease in particular you’d like for us to cover, please let us know! :)

  6. JIM OQUINN on said:

    QUESTION? i HAVE LOST A NUMBER OF TREES, STRAWBERRIES, AND BLACKBERRIES IN VARIOUS PLACES IN MY YARD. CAN THE SOIL BE INFECTED?

    • Judy on said:

      Hello Jim,

      I am so sorry to hear about the loss of your plants and trees. It could be caused by infected soil, or it could be weather-related. If you were in an area that received a great deal of rain and had a very cool spring, that could cause a lot of problems as well. Your County Extension Agency should be able to help you with some good localized information and a soil test, if you would like one. Or if you prefer, you can e-mail me at info@starkbros.com. (Please include your zip code in your e-mail, as well as describing what trees/plants you have lost.) Don’t give up on growing, the answer is out there ~ and we will find it!

  7. Ken Kegley on said:

    I had a late hatch of San Jose Scale and it really made a mess couldn’t sell a 1/3 of the apples never had that happen.Apples ripened a month early here. I stopped spraying then all of a sudden there were all these scale flying around.I sprayed oil and lime sulfur this spring.but now I’m lost

    • Judy on said:

      Hello Ken! Control is aimed at the overwintering immature scales and at the San Jose Scale crawlers.

      - Spray the tree(s) with All Seasons® Dormant Oil before buds swell in the spring.
      - Be on the “look out” for crawlers to appear in the latter part of summer.
      - Spray with an insecticide containing diazinon (has been restricted from home use) or chlorpyrifos (Dursban) when crawlers appear. There are several pyrethroids and permethrin-based insecticides which you can use in place of diazinon (I recommend Rotenone-Pyrethrins Spray) when crawlers appear.
      - If there are recurring events later, you can use the same treatment method to rid your garden area of the scale.

      I hope this information helps you rid your apple orchard of San Jose Scale!

  8. jim turner on said:

    I have a damson plum tree that has black, corky growths on several limbs, which I cut off but the growths still persist. What is this & can the tree be saved? Is it a danger to nearby peachtrees? thanx for your feedback:)

    • jim turner on said:

      Has no one read my post? Will appreciate a response, thanx:)

      • Meg on said:

        Hi Jim, I am so sorry for the delayed response, as I had the information & completely forgot to post it for you! Please accept my apologies.

        It sounds like your plum tree has Black Knot (a disease we’ll be posting on in the near future). To control Black Knot, the important 1st step is pruning the infected branches & removing them from the growing area. (All black knot pruning should be done in late winter, before any new growth is present.)

        Pruning debris (leaves, cut branches, mummied fruits) should also be removed from the growing area & immediately burned. If burning is not possible, you can bury the removed knots in 1+ foot of compacted soil. The reason for burning/burying? Knots are capable of reproducing & releasing spores, which will re-infect tree. We want to avoid the cycle. :) Removing all sources of infectious spores from the area is really necessary.

        Also! …Fungicide spray can work defensively against black knot, but it won’t be very effective if the pruning & complete clean-up are ignored.

        Again, I’m truly sorry it’s taken me awhile to post this info for you! I hope it helps revive your plum tree, & watch for our blog post on the topic in the future. :) Best wishes, Jim!

  9. jim turner on said:

    thanx for your reply, meg..I am going to try your suggestions tomorrow. It is March 13, Sunday. Looking forward to new posting

  10. steven osborne on said:

    My keifer pear tree has been fully infected by fire blight, I was wondering if I could do anything to save it.

    • Sarah on said:

      Hi there, Steve. If you have been fertilizing your tree, I would recommend holding off on the fertilizer until your fire blight issues are under control. As it states, the excessive new growth encouraged with fertilizers high in nitrogen will be susceptible to infection.

      Prune out any and all infected limbs a few inches below the visible signs of infection, cleaning/disinfecting the pruners between each cut (mandatory to avoid reinfecting the tree) like is mentioned here, burn anything you prune off so that it isn’t lying on the ground ready to reinfect your pear, and be sure to use something like Ferti-Lome® Fire Blight Spray to control the disease.

      You did say the tree is “fully infected” so if it is that bad it may be beyond saving. If there is a chance it has not been overtaken by fire blight, it may take a lot of effort, but you should be able to save your tree.

  11. Glenda on said:

    I have two apple trees that I planted last year. The new leaves would curl up and turn brown. Also, some of the older leaves would do the same. I have been thinking that it was fire blight. However, the leaves and stems never turned black, only brown and withered. Someone told me that fire blight always turns the tips black. Is this true? I have a ton of new trees coming this spring, including other apples, cherries, plums, and peaches. I am wondering if I should just remove the two trees in question before my new shipment comes in or if it will be possible to save them.

    • Sarah on said:

      Hello Glenda :) The best way to tell if your current trees are infected with fire blight (and aren’t suffering from something like a nutrient deficiency or mites instead) would be to see pictures of what you’re experiencing.

      If you could please send photos to info@starkbros.com we will be able to better identify what is wrong with the trees. Be sure to mention whether the trees in question hold onto their brown leaves or if the leaves drop off the tree. It would greatly help us help you solve this! :)

  12. Doug on said:

    Our two Thirty five foot Cleveland pears, exactly ten years old, are full of Fire blight. By the time I got any answers of what this condition was, There is no pruning back 12 inches to prune out the bad diseased starts. There are so many within inches of the main limbs that I am afraid it’s too late. Plus the fact of reaching the upper parts of the tree would be impossible without a bucket truck. We just are devastated about this, they are beautiful trees, almost perfect in shape and fullness and bloom so well. Our county ext. agent says Sprays do nothing to cure they just prevent. Pruning out is the only chance, and that is slim to none.

    • Sarah on said:

      I’m sorry to hear your Cleveland ornamental pear trees have fire blight, Doug. :( Years ago it wasn’t found in ornamental pears but over time we have even found it in our own Cleveland pears growing here. Fire blight sprays are a control, not a cure, but (combined with the pruning the tree needs) it is the best bet for your trees.

      I would recommend hiring a licensed tree professional to help you save your Cleveland pear trees, especially since they are so tall and pruning isn’t something you feel is possible. It sounds like you care for your trees and I think it would be better for you (and them) to have them professionally cared for than to watch them suffer. :)

  13. Erin on said:

    I have an apple tree in my small (8 tree) orchard that has black soot down the trunk..and assume this is fire blight…would you consider this tree a loss? should I just remove the tree? I also question 2 adjacent trees- the branches appear fine, but where the trees were pruned up along the truck appear to be black…should I hold off on adding any trees to the orchard this year?

    • Sarah on said:

      Hi Erin! Since Fire Blight tends to present in the flowers/leaves/limbs of the susceptible trees, the fact that the trunk is the only thing with the sooty appearance leads me to believe it is not Fire Blight affecting your trees. If you could take some photos of the trees and the black soot appearance on their trunks [and send them to info@starkbros.com] we might get a better idea of what it is so that we can advise you accordingly. :)

  14. Jakeru on said:

    Hey everyone! My father is growing a bunch of Asian pear and sweet cherry trees on our farm in Pineville Missouri (southwest MO) and we’ve run across what seems to be a strange pest that we can’t identify.
    It’s a styrofoam-like dark grey or dark brown shiny thumb-nail sized blob that attaches only to the smaller twigs on the trees and it wraps around the twigs almost completely but not entirely. It’s sort of crusted to the twig and the underside seemed to had little circles which could potentially be seeds or spores or something. There are often multiple twigs infected per tree and each twig that is infected generally has more than one of these small whealts. The things can be removed manually with relative ease.
    The Asian pear trees seem uneffected but still infected by their presence but the sweet cherry trees seem to be suffering, but it could just be due to heat stress and the Japanese beetles.
    Any help identifying or treating would be appreciated! Thanks!

    • Sarah on said:

      Hi there! I am very curious about this occurrence you’re seeing on your cherry trees, Jakeru. It sounds like it could be residue from where a pest infested the twigs, but I don’t want to be wrong and be misinterpreting something like black knot (which wouldn’t be controlled with a pesticide). Would you be able to send us any photos of this on the cherry trees? If so, you can email us at info@starkbros.com and we would be glad to look into this issue for you. :)

      The heat and Japanese beetles would definitely explain the stress on the Asian Pear trees and the sweet cherry trees as well. This has been an increasingly rough growing season.

  15. Sissy on said:

    We have had a Bartlett pear tree for 10 years and it never bloomed until this year ( 2012 ). had lots of pears but didn’t last long It got fire blight. We have over the years tried every thing we could to save this tree but nothing worked. We have pruned cleaned up and sprayed. My husband says it’s to much trouble and is taking the tree down. Didn’t know you could burn the infected limbs as it is air born Thanks for your info. Very helpful.

  16. Sissy on said:

    I didn’t get a reply from my last comment about the fire blight on our pear tree. Just wanted to say although we are cutting the tree down we will buy more trees from Stark Bros. just not fruit trees. By the way we didn’t buy that tree from you. should have.

    • Sarah on said:

      Sorry for not commenting before, Sissy, I just felt silly since I’m the one who directed you to this post from the How to tell when your pears are ready to harvest comment about your fire blight issue. ;)

      It might comfort you to know that trees like peaches, plums, and cherries are not affected by this bacteria (as it mostly targets trees like apples, pears, and quinces) if you still wanted to grow a fruit tree! Other types of trees are just as nice if you’re not looking for a tree that provides something edible. :)

  17. GREG BARNES on said:

    Can you use fire blight spray in conjunction with bonide orchard spray?

    • Sarah on said:

      Hi Greg! Our experts here use fire blight spray in conjuction with pesticides and insecticides. The advice we would provide is to spray the fire blight spray first, especially since it works systemically (absorbed into the tree to be effective). If you did the orchard spray first, you’d be breathing it in while applying the fire blight spray. The other way is safer for you and tends to be more effective for your trees! :)

  18. Hamid on said:

    Hello we have 5 Asian pears of different varieties from Stark Brothers that are doing great. One gets fire blight but it can be controlled. However we bought a Wine Sap and Granny Smith from the local big box store and both succumbed to fire blight last year. My question is can I plant over the old trees (with Stark Bro trees of course, learned my lessons the hard way) or is the ground toast and the new trees will also develop fire blight?

    • Sarah on said:

      Hello Hamid! Fire Blight is a bacterial disease that is systemic and very contagious. It’s not something that is restricted to the soil of the planting site where infected trees once grew. It can be spread by birds and insects and other critters climbing in infected trees and then spreading it to trees that have not been infected yet. The best method would be to plant more blight-resistant varieties (like Enterprise Apple and GoldRush Apple along with a Fire Blight Spray) but if you’re set on replanting with Winesap and Granny Smith apple trees, you can try to control the spread of the disease with the Fire Blight Spray and careful selective pruning cuts.

      Another thing you should consider is contacting your local County Extension [find yours online here: http://www.csrees.usda.gov/Extension/ and seeing if they have any more advice for your location there.

  19. Stanton de Riel in Hamilton, NJ on said:

    My Aromanatoya (sp?) edible quince, transplanted last year, is now 6′ high x 7′ wide and generally thriving. This spring, after setting ~60 fruit, isolated small branchlets (4-7 leaves) suddenly started wilting, with the leaves turning uniform dull brown. Sometimes these were tipped with a non-sizing-up fruit. I pull these shoots off and trash-bag them; there’s no sign of the wilt spreading into the parent twigs (yet!). Could this be fireblight, some other assorted minor infection, or just the tree self-pruning due to fruit load and hot, dry weather? If the last, would removal of some of the fruit be indicated?

    • Sarah on said:

      Do you have any photos of your quince tree with these brown, wilting limbs? It would be helpful to see, since this sort of thing can occur due to brown rot (fungus), black rot (fungus), fire blight (bacteria), or even scald (sun, drought).

      Trees typically don’t develop brown leaves and limbs when they naturally shed their fruit due to overproduction (fruit drop). Thinning the fruit, while improving the quality of your tree’s remaining ripening fruit, won’t help if it’s a disease that is occurring within your quince. If you can send any photos to us, please either link them here or email them to info@starkbros.com — you may also contact your local county Extension Service for locally-based growing advice and disease control/prevention there. :)

  20. Barbara in Seattle, Washington on said:

    Hi there. I have a Japanese plum that is bearing with tremendous enthusiasm and the green plums appear fine. But, as the fruit is ripening, there are large ovals of brown and the fruit is hard and discolored underneath. There is also a great deal of sap oozing from limbs. Can you tell me what this is and whether I can save any of this year’s crop? Many thanks

    • Sarah on said:

      Hi Barbara! It sounds very likely that your plum tree is experiencing Brown Rot. Brown rot is a disease that affects stone fruits like plums and is caused by a fungus. It is very common in moist regions and during wet springs/summers. It’s fairly easily treated with a fungicide that can be used on plum trees and that targets the cause of brown rot.

      Examples:
      Captan Fruit & Ornamental
      Fung-onil™ Multi-Purpose Fungicide

      Before spraying, and as a general precaution to avoid re-infecting the developing fruit, be sure to remove and destroy ALL of the fruit with these spots or any fruit that has become mummified on the tree or on the ground.

  21. Charles D. Miller on said:

    Lost two mature pears due to blight. Would there be any disadvantage to rubbing off any new buds on the trunk and main branches near trunk forcing all new growth well out? Seems that the three leaf growths on trunk brought the blight into the main structure so cutting out was impossible.

    • Sarah on said:

      I’m sorry to hear of your troubles with blight on your pear trees, Charles. :( Do you have any photos to share with us of the trunk where you think that blight got into your pear tree? It will help us see what you’re seeing*. If the blight has already gotten into the trunk, you will notice a canker form, which will eventually lead to the decline of the tree, since it’s in its vascular system then. I’m not sure it will be any help to encourage new growth toward the top once the trunk has already been infected.

      *You can send photos of your tree to us by email (info@starkbros.com attention: Sarah) or share them on our Facebook page (https://www.facebook.com/starkbros.co) :)

      • Charles D. Miller on said:

        Sarah, pics on the way of suspected fire blight. Title: Fire Blight 1 and 2, have to use two e-mails for all the pics.Tks.

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